diff --git a/lib/mix/tasks/toot.ex b/lib/mix/tasks/toot.ex
index 4b9f8dd7..ea3e268c 100644
--- a/lib/mix/tasks/toot.ex
+++ b/lib/mix/tasks/toot.ex
@@ -4,28 +4,12 @@ defmodule Mix.Tasks.Toot do
   """
 
   use Mix.Task
-  alias Mobilizon.Actors
-  alias Mobilizon.Actors.Actor
-  alias Mobilizon.Service.ActivityPub
-  alias Mobilizon.Service.ActivityPub.Utils
   require Logger
 
   @shortdoc "Toot to an user"
-  def run([from, to, content]) do
+  def run([from, content]) do
     Mix.Task.run("app.start")
 
-    with %Actor{} = from <- Actors.get_actor_by_name(from),
-         {:ok, %Actor{} = to} <- ActivityPub.find_or_make_actor_from_nickname(to) do
-      comment = Utils.make_comment_data(from.url, [to.url], content)
-
-      ActivityPub.create(%{
-        to: [to.url],
-        actor: from,
-        object: comment,
-        local: true
-      })
-    else
-      e -> Logger.error(inspect(e))
-    end
+    MobilizonWeb.API.Comments.create_comment(from, content)
   end
 end
diff --git a/lib/mobilizon/actors/actor.ex b/lib/mobilizon/actors/actor.ex
index be10814e..8972d000 100644
--- a/lib/mobilizon/actors/actor.ex
+++ b/lib/mobilizon/actors/actor.ex
@@ -167,6 +167,7 @@ defmodule Mobilizon.Actors.Actor do
     ])
     |> build_urls(:Group)
     |> put_change(:domain, nil)
+    |> put_change(:keys, Actors.create_keys())
     |> put_change(:type, :Group)
     |> validate_required([:url, :outbox_url, :inbox_url, :type, :preferred_username])
     |> unique_constraint(:preferred_username, name: :actors_preferred_username_domain_type_index)
@@ -292,7 +293,7 @@ defmodule Mobilizon.Actors.Actor do
          {:already_following, false} <- {:already_following, following?(follower, followed)} do
       do_follow(follower, followed, approved)
     else
-      {:already_following, _} ->
+      {:already_following, %Follower{}} ->
         {:error,
          "Could not follow actor: you are already following #{followed.preferred_username}"}
 
@@ -301,6 +302,17 @@ defmodule Mobilizon.Actors.Actor do
     end
   end
 
+  @spec unfollow(struct(), struct()) :: {:ok, Follower.t()} | {:error, Ecto.Changeset.t()}
+  def unfollow(%Actor{} = followed, %Actor{} = follower) do
+    with {:already_following, %Follower{} = follow} <-
+           {:already_following, following?(follower, followed)} do
+      Actors.delete_follower(follow)
+    else
+      {:already_following, false} ->
+        {:error, "Could not unfollow actor: you are not following #{followed.preferred_username}"}
+    end
+  end
+
   defp do_follow(%Actor{} = follower, %Actor{} = followed, approved) do
     Actors.create_follower(%{
       "actor_id" => follower.id,
@@ -311,12 +323,13 @@ defmodule Mobilizon.Actors.Actor do
 
   @spec following?(struct(), struct()) :: boolean()
   def following?(
-        %Actor{id: follower_actor_id} = _follower_actor,
-        %Actor{followers: followers} = _followed
+        %Actor{} = follower_actor,
+        %Actor{} = followed_actor
       ) do
-    followers
-    |> Enum.map(& &1.actor_id)
-    |> Enum.member?(follower_actor_id)
+    case Actors.get_follower(followed_actor, follower_actor) do
+      nil -> false
+      %Follower{} = follow -> follow
+    end
   end
 
   @spec actor_acct_from_actor(struct()) :: String.t()
diff --git a/lib/mobilizon/actors/actors.ex b/lib/mobilizon/actors/actors.ex
index f4d69c94..0b6a3069 100644
--- a/lib/mobilizon/actors/actors.ex
+++ b/lib/mobilizon/actors/actors.ex
@@ -162,16 +162,41 @@ defmodule Mobilizon.Actors do
     )
   end
 
-  def get_group_by_name(name) do
-    case String.split(name, "@") do
-      [name] ->
-        Repo.get_by(Actor, preferred_username: name, type: :Group)
+  @doc """
+  Get a group by it's title
+  """
+  @spec get_group_by_title(String.t()) :: Actor.t() | nil
+  def get_group_by_title(title) do
+    case String.split(title, "@") do
+      [title] ->
+        get_local_group_by_title(title)
 
-      [name, domain] ->
-        Repo.get_by(Actor, preferred_username: name, domain: domain, type: :Group)
+      [title, domain] ->
+        Repo.one(
+          from(a in Actor,
+            where: a.preferred_username == ^title and a.type == "Group" and a.domain == ^domain
+          )
+        )
     end
   end
 
+  @doc """
+  Get a local group by it's title
+  """
+  @spec get_local_group_by_title(String.t()) :: Actor.t() | nil
+  def get_local_group_by_title(title) do
+    title
+    |> do_get_local_group_by_title
+    |> Repo.one()
+  end
+
+  @spec do_get_local_group_by_title(String.t()) :: Ecto.Query.t()
+  defp do_get_local_group_by_title(title) do
+    from(a in Actor,
+      where: a.preferred_username == ^title and a.type == "Group" and is_nil(a.domain)
+    )
+  end
+
   @doc """
   Creates a group.
 
@@ -185,8 +210,6 @@ defmodule Mobilizon.Actors do
 
   """
   def create_group(attrs \\ %{}) do
-    attrs = Map.put(attrs, :keys, create_keys())
-
     %Actor{}
     |> Actor.group_creation(attrs)
     |> Repo.insert()
@@ -218,10 +241,11 @@ defmodule Mobilizon.Actors do
             keys: data.keys,
             avatar_url: data.avatar_url,
             banner_url: data.banner_url,
-            name: data.name
+            name: data.name,
+            summary: data.summary
           ]
         ],
-        conflict_target: [:preferred_username, :domain, :type]
+        conflict_target: [:url]
       )
 
     if preload, do: {:ok, Repo.preload(actor, [:followers])}, else: {:ok, actor}
@@ -516,9 +540,11 @@ defmodule Mobilizon.Actors do
     end
   end
 
-  # Create a new RSA key
+  @doc """
+  Create a new RSA key
+  """
   @spec create_keys() :: String.t()
-  defp create_keys() do
+  def create_keys() do
     key = :public_key.generate_key({:rsa, 2048, 65_537})
     entry = :public_key.pem_entry_encode(:RSAPrivateKey, key)
     [entry] |> :public_key.pem_encode() |> String.trim_trailing()
@@ -958,6 +984,13 @@ defmodule Mobilizon.Actors do
     |> Repo.preload([:actor, :target_actor])
   end
 
+  @spec get_follower(Actor.t(), Actor.t()) :: Follower.t()
+  def get_follower(%Actor{id: followed_id}, %Actor{id: follower_id}) do
+    Repo.one(
+      from(f in Follower, where: f.target_actor_id == ^followed_id and f.actor_id == ^follower_id)
+    )
+  end
+
   @doc """
   Creates a follower.
 
@@ -1013,6 +1046,24 @@ defmodule Mobilizon.Actors do
     Repo.delete(follower)
   end
 
+  @doc """
+  Delete a follower by followed and follower actors
+
+  ## Examples
+
+      iex> delete_follower(%Actor{}, %Actor{})
+      {:ok, %Mobilizon.Actors.Follower{}}
+
+      iex> delete_follower(%Actor{}, %Actor{})
+      {:error, %Ecto.Changeset{}}
+
+  """
+  @spec delete_follower(Actor.t(), Actor.t()) ::
+          {:ok, Follower.t()} | {:error, Ecto.Changeset.t()}
+  def delete_follower(%Actor{} = followed, %Actor{} = follower) do
+    get_follower(followed, follower) |> Repo.delete()
+  end
+
   @doc """
   Returns an `%Ecto.Changeset{}` for tracking follower changes.
 
diff --git a/lib/mobilizon/actors/follower.ex b/lib/mobilizon/actors/follower.ex
index a25fec3a..9fcdfcda 100644
--- a/lib/mobilizon/actors/follower.ex
+++ b/lib/mobilizon/actors/follower.ex
@@ -21,4 +21,8 @@ defmodule Mobilizon.Actors.Follower do
     |> validate_required([:score, :approved, :target_actor_id, :actor_id])
     |> unique_constraint(:target_actor_id, name: :followers_actor_target_actor_unique_index)
   end
+
+  def url(%Follower{id: id}) do
+    "#{MobilizonWeb.Endpoint.url()}/follow/#{id}/activity"
+  end
 end
diff --git a/lib/mobilizon/addresses/addresses.ex b/lib/mobilizon/addresses/addresses.ex
index 3a8a7f83..891167a3 100644
--- a/lib/mobilizon/addresses/addresses.ex
+++ b/lib/mobilizon/addresses/addresses.ex
@@ -116,7 +116,7 @@ defmodule Mobilizon.Addresses do
         rescue
           e in ArgumentError ->
             Logger.error("#{type_input} is not an existing atom : #{inspect(e)}")
-            nil
+            :invalid_type
         end
       else
         type_input
@@ -128,7 +128,7 @@ defmodule Mobilizon.Addresses do
           process_point(data["latitude"], data["longitude"])
       end
     else
-      {:error, nil}
+      {:error, :invalid_type}
     end
   end
 
diff --git a/lib/mobilizon/events/events.ex b/lib/mobilizon/events/events.ex
index 66a9730f..35e24d04 100644
--- a/lib/mobilizon/events/events.ex
+++ b/lib/mobilizon/events/events.ex
@@ -117,11 +117,30 @@ defmodule Mobilizon.Events do
     Repo.get_by!(Event, url: url)
   end
 
+  # @doc """
+  # Gets an event by it's UUID
+  # """
+  # @depreciated "Use get_event_full_by_uuid/3 instead"
+  # def get_event_by_uuid(uuid) do
+  #   Repo.get_by(Event, uuid: uuid)
+  # end
+
   @doc """
-  Gets an event by it's UUID
+  Gets a full event by it's UUID
   """
-  def get_event_by_uuid(uuid) do
-    Repo.get_by(Event, uuid: uuid)
+  @spec get_event_full_by_uuid(String.t()) :: Event.t()
+  def get_event_full_by_uuid(uuid) do
+    event = Repo.get_by(Event, uuid: uuid)
+
+    Repo.preload(event, [
+      :organizer_actor,
+      :category,
+      :sessions,
+      :tracks,
+      :tags,
+      :participants,
+      :physical_address
+    ])
   end
 
   @doc """
@@ -144,25 +163,31 @@ defmodule Mobilizon.Events do
   @doc """
   Gets an event by it's URL
   """
-  def get_event_full_by_url!(url) do
-    event = Repo.get_by!(Event, url: url)
-
-    Repo.preload(event, [
-      :organizer_actor,
-      :category,
-      :sessions,
-      :tracks,
-      :tags,
-      :participants,
-      :physical_address
-    ])
+  def get_event_full_by_url(url) do
+    case Repo.one(
+           from(e in Event,
+             where: e.url == ^url,
+             preload: [
+               :organizer_actor,
+               :category,
+               :sessions,
+               :tracks,
+               :tags,
+               :participants,
+               :physical_address
+             ]
+           )
+         ) do
+      nil -> {:error, :event_not_found}
+      event -> {:ok, event}
+    end
   end
 
   @doc """
-  Gets a full event by it's UUID
+  Gets an event by it's URL
   """
-  def get_event_full_by_uuid(uuid) do
-    event = Repo.get_by(Event, uuid: uuid)
+  def get_event_full_by_url!(url) do
+    event = Repo.get_by!(Event, url: url)
 
     Repo.preload(event, [
       :organizer_actor,
@@ -233,7 +258,7 @@ defmodule Mobilizon.Events do
          {:ok, %Participant{} = _participant} <-
            %Participant{}
            |> Participant.changeset(%{
-             actor_id: attrs.organizer_actor_id,
+             actor_id: event.organizer_actor_id,
              role: 4,
              event_id: event.id
            })
@@ -609,8 +634,12 @@ defmodule Mobilizon.Events do
     Participant.changeset(participant, %{})
   end
 
-  def list_requests_for_actor(%Actor{} = actor) do
-    Repo.all(from(p in Participant, where: p.actor_id == ^actor.id and p.approved == false))
+  @doc """
+  List event participation requests for an actor
+  """
+  @spec list_requests_for_actor(Actor.t()) :: list(Participant.t())
+  def list_requests_for_actor(%Actor{id: actor_id}) do
+    Repo.all(from(p in Participant, where: p.actor_id == ^actor_id and p.approved == false))
   end
 
   alias Mobilizon.Events.Session
@@ -631,24 +660,18 @@ defmodule Mobilizon.Events do
   @doc """
   Returns the list of sessions for an event
   """
-  def list_sessions_for_event(event_uuid) do
+  @spec list_sessions_for_event(Event.t()) :: list(Session.t())
+  def list_sessions_for_event(%Event{id: event_id}) do
     Repo.all(
       from(
         s in Session,
         join: e in Event,
         on: s.event_id == e.id,
-        where: e.uuid == ^event_uuid
+        where: e.id == ^event_id
       )
     )
   end
 
-  @doc """
-  Returns the list of sessions for a track
-  """
-  def list_sessions_for_track(track_id) do
-    Repo.all(from(s in Session, where: s.track_id == ^track_id))
-  end
-
   @doc """
   Gets a single session.
 
@@ -745,6 +768,14 @@ defmodule Mobilizon.Events do
     Repo.all(Track)
   end
 
+  @doc """
+  Returns the list of sessions for a track
+  """
+  @spec list_sessions_for_track(Track.t()) :: list(Session.t())
+  def list_sessions_for_track(%Track{id: track_id}) do
+    Repo.all(from(s in Session, where: s.track_id == ^track_id))
+  end
+
   @doc """
   Gets a single track.
 
@@ -880,9 +911,29 @@ defmodule Mobilizon.Events do
   """
   def get_comment!(id), do: Repo.get!(Comment, id)
 
-  def get_comment_from_uuid(uuid), do: Repo.get_by(Comment, uuid: uuid)
+  # @doc """
+  # Gets a single comment from it's UUID
 
-  def get_comment_from_uuid!(uuid), do: Repo.get_by!(Comment, uuid: uuid)
+  # """
+  # @spec get_comment_from_uuid(String.t) :: {:ok, Comment.t} | {:error, nil}
+  # def get_comment_from_uuid(uuid), do: Repo.get_by(Comment, uuid: uuid)
+
+  # @doc """
+  # Gets a single comment by it's UUID.
+
+  # Raises `Ecto.NoResultsError` if the Comment does not exist.
+
+  # ## Examples
+
+  #     iex> get_comment_from_uuid!("123AFV13")
+  #     %Comment{}
+
+  #     iex> get_comment_from_uuid!("20R9HKDJHF")
+  #     ** (Ecto.NoResultsError)
+
+  # """
+  # @spec get_comment_from_uuid(String.t) :: Comment.t
+  # def get_comment_from_uuid!(uuid), do: Repo.get_by!(Comment, uuid: uuid)
 
   def get_comment_full_from_uuid(uuid) do
     with %Comment{} = comment <- Repo.get_by!(Comment, uuid: uuid) do
@@ -894,9 +945,18 @@ defmodule Mobilizon.Events do
 
   def get_comment_from_url!(url), do: Repo.get_by!(Comment, url: url)
 
+  def get_comment_full_from_url(url) do
+    case Repo.one(
+           from(c in Comment, where: c.url == ^url, preload: [:actor, :in_reply_to_comment])
+         ) do
+      nil -> {:error, :comment_not_found}
+      comment -> {:ok, comment}
+    end
+  end
+
   def get_comment_full_from_url!(url) do
     with %Comment{} = comment <- Repo.get_by!(Comment, url: url) do
-      Repo.preload(comment, :actor)
+      Repo.preload(comment, [:actor, :in_reply_to_comment])
     end
   end
 
diff --git a/lib/mobilizon_web/api/comments.ex b/lib/mobilizon_web/api/comments.ex
new file mode 100644
index 00000000..0870d30d
--- /dev/null
+++ b/lib/mobilizon_web/api/comments.ex
@@ -0,0 +1,58 @@
+defmodule MobilizonWeb.API.Comments do
+  @moduledoc """
+  API for Comments
+  """
+
+  alias Mobilizon.Actors
+  alias Mobilizon.Actors.Actor
+  alias Mobilizon.Events.Comment
+  alias Mobilizon.Service.Formatter
+  alias Mobilizon.Service.ActivityPub
+  alias Mobilizon.Service.ActivityPub.Utils, as: ActivityPubUtils
+  import MobilizonWeb.API.Utils
+
+  @doc """
+  Create a comment
+
+  Creates a comment from an actor and a status
+  """
+  @spec create_comment(String.t(), String.t(), String.t()) :: {:ok, Activity.t()} | any()
+  def create_comment(from_username, status, visibility \\ "public", inReplyToCommentURL \\ nil) do
+    with %Actor{url: url} = actor <- Actors.get_local_actor_by_name(from_username),
+         status <- String.trim(status),
+         mentions <- Formatter.parse_mentions(status),
+         inReplyToComment <- get_in_reply_to_comment(inReplyToCommentURL),
+         {to, cc} <- to_for_actor_and_mentions(actor, mentions, inReplyToComment, visibility),
+         tags <- Formatter.parse_tags(status),
+         content_html <-
+           make_content_html(
+             status,
+             mentions,
+             tags,
+             "text/plain"
+           ),
+         comment <-
+           ActivityPubUtils.make_comment_data(
+             url,
+             to,
+             content_html,
+             inReplyToComment,
+             tags,
+             cc
+           ) do
+      ActivityPub.create(%{
+        to: ["https://www.w3.org/ns/activitystreams#Public"],
+        actor: actor,
+        object: comment,
+        local: true
+      })
+    end
+  end
+
+  @spec get_in_reply_to_comment(nil) :: nil
+  defp get_in_reply_to_comment(nil), do: nil
+  @spec get_in_reply_to_comment(String.t()) :: Comment.t()
+  defp get_in_reply_to_comment(inReplyToCommentURL) do
+    ActivityPub.fetch_object_from_url(inReplyToCommentURL)
+  end
+end
diff --git a/lib/mobilizon_web/api/events.ex b/lib/mobilizon_web/api/events.ex
new file mode 100644
index 00000000..a2587c08
--- /dev/null
+++ b/lib/mobilizon_web/api/events.ex
@@ -0,0 +1,54 @@
+defmodule MobilizonWeb.API.Events do
+  @moduledoc """
+  API for Events
+  """
+  alias Mobilizon.Actors
+  alias Mobilizon.Actors.Actor
+  alias Mobilizon.Service.Formatter
+  alias Mobilizon.Service.ActivityPub
+  alias Mobilizon.Service.ActivityPub.Utils, as: ActivityPubUtils
+  import MobilizonWeb.API.Utils
+
+  @spec create_event(map()) :: {:ok, Activity.t()} | any()
+  def create_event(
+        %{
+          title: title,
+          description: description,
+          organizer_actor_username: organizer_actor_username,
+          begins_on: begins_on,
+          category: category
+        } = args
+      ) do
+    with %Actor{url: url} = actor <- Actors.get_local_actor_by_name(organizer_actor_username),
+         title <- String.trim(title),
+         mentions <- Formatter.parse_mentions(description),
+         visibility <- Map.get(args, :visibility, "public"),
+         {to, cc} <- to_for_actor_and_mentions(actor, mentions, nil, visibility),
+         tags <- Formatter.parse_tags(description),
+         content_html <-
+           make_content_html(
+             description,
+             mentions,
+             tags,
+             "text/plain"
+           ),
+         event <-
+           ActivityPubUtils.make_event_data(
+             url,
+             to,
+             title,
+             content_html,
+             tags,
+             cc,
+             %{begins_on: begins_on},
+             category
+           ) do
+      ActivityPub.create(%{
+        to: ["https://www.w3.org/ns/activitystreams#Public"],
+        actor: actor,
+        object: event,
+        local: true
+      })
+    end
+  end
+end
diff --git a/lib/mobilizon_web/api/groups.ex b/lib/mobilizon_web/api/groups.ex
new file mode 100644
index 00000000..96e89185
--- /dev/null
+++ b/lib/mobilizon_web/api/groups.ex
@@ -0,0 +1,58 @@
+defmodule MobilizonWeb.API.Groups do
+  @moduledoc """
+  API for Events
+  """
+  alias Mobilizon.Actors
+  alias Mobilizon.Actors.Actor
+  alias Mobilizon.Service.Formatter
+  alias Mobilizon.Service.ActivityPub
+  alias Mobilizon.Service.ActivityPub.Utils, as: ActivityPubUtils
+  import MobilizonWeb.API.Utils
+
+  @spec create_group(map()) :: {:ok, Activity.t()} | any()
+  def create_group(
+        %{
+          preferred_username: title,
+          description: description,
+          admin_actor_username: admin_actor_username
+        } = args
+      ) do
+    with {:bad_actor, %Actor{url: url} = actor} <-
+           {:bad_actor, Actors.get_local_actor_by_name(admin_actor_username)},
+         {:existing_group, nil} <- {:existing_group, Actors.get_group_by_title(title)},
+         title <- String.trim(title),
+         mentions <- Formatter.parse_mentions(description),
+         visibility <- Map.get(args, :visibility, "public"),
+         {to, cc} <- to_for_actor_and_mentions(actor, mentions, nil, visibility),
+         tags <- Formatter.parse_tags(description),
+         content_html <-
+           make_content_html(
+             description,
+             mentions,
+             tags,
+             "text/plain"
+           ),
+         group <-
+           ActivityPubUtils.make_group_data(
+             url,
+             to,
+             title,
+             content_html,
+             tags,
+             cc
+           ) do
+      ActivityPub.create(%{
+        to: ["https://www.w3.org/ns/activitystreams#Public"],
+        actor: actor,
+        object: group,
+        local: true
+      })
+    else
+      {:existing_group, _} ->
+        {:error, :existing_group_name}
+
+      {:bad_actor} ->
+        {:error, :bad_admin_actor}
+    end
+  end
+end
diff --git a/lib/mobilizon_web/api/utils.ex b/lib/mobilizon_web/api/utils.ex
new file mode 100644
index 00000000..ad4ab283
--- /dev/null
+++ b/lib/mobilizon_web/api/utils.ex
@@ -0,0 +1,123 @@
+defmodule MobilizonWeb.API.Utils do
+  @moduledoc """
+  Utils for API
+  """
+  alias Mobilizon.Actors.Actor
+  alias Mobilizon.Service.Formatter
+
+  @doc """
+  Determines the full audience based on mentions for a public audience
+
+  Audience is:
+    * `to` : the mentionned actors, the eventual actor we're replying to and the public
+    * `cc` : the actor's followers
+  """
+  @spec to_for_actor_and_mentions(Actor.t(), list(), map(), String.t()) :: {list(), list()}
+  def to_for_actor_and_mentions(%Actor{} = actor, mentions, inReplyTo, "public") do
+    mentioned_actors = Enum.map(mentions, fn {_, %{url: url}} -> url end)
+
+    to = ["https://www.w3.org/ns/activitystreams#Public" | mentioned_actors]
+    cc = [actor.followers_url]
+
+    if inReplyTo do
+      {Enum.uniq([inReplyTo.actor | to]), cc}
+    else
+      {to, cc}
+    end
+  end
+
+  @doc """
+  Determines the full audience based on mentions based on a unlisted audience
+
+  Audience is:
+    * `to` : the mentionned actors, actor's followers and the eventual actor we're replying to
+    * `cc` : public
+  """
+  @spec to_for_actor_and_mentions(Actor.t(), list(), map(), String.t()) :: {list(), list()}
+  def to_for_actor_and_mentions(%Actor{} = actor, mentions, inReplyTo, "unlisted") do
+    mentioned_actors = Enum.map(mentions, fn {_, %{url: url}} -> url end)
+
+    to = [actor.followers_url | mentioned_actors]
+    cc = ["https://www.w3.org/ns/activitystreams#Public"]
+
+    if inReplyTo do
+      {Enum.uniq([inReplyTo.actor | to]), cc}
+    else
+      {to, cc}
+    end
+  end
+
+  @doc """
+  Determines the full audience based on mentions based on a private audience
+
+  Audience is:
+    * `to` : the mentionned actors, actor's followers and the eventual actor we're replying to
+    * `cc` : none
+  """
+  @spec to_for_actor_and_mentions(Actor.t(), list(), map(), String.t()) :: {list(), list()}
+  def to_for_actor_and_mentions(%Actor{} = actor, mentions, inReplyTo, "private") do
+    {to, cc} = to_for_actor_and_mentions(actor, mentions, inReplyTo, "direct")
+    {[actor.followers_url | to], cc}
+  end
+
+  @doc """
+  Determines the full audience based on mentions based on a direct audience
+
+  Audience is:
+    * `to` : the mentionned actors and the eventual actor we're replying to
+    * `cc` : none
+  """
+  @spec to_for_actor_and_mentions(Actor.t(), list(), map(), String.t()) :: {list(), list()}
+  def to_for_actor_and_mentions(_actor, mentions, inReplyTo, "direct") do
+    mentioned_actors = Enum.map(mentions, fn {_, %{url: url}} -> url end)
+
+    if inReplyTo do
+      {Enum.uniq([inReplyTo.actor | mentioned_actors]), []}
+    else
+      {mentioned_actors, []}
+    end
+  end
+
+  @doc """
+  Creates HTML content from text and mentions
+  """
+  @spec make_content_html(String.t(), list(), list(), String.t()) :: String.t()
+  def make_content_html(
+        status,
+        mentions,
+        tags,
+        content_type
+      ),
+      do: format_input(status, mentions, tags, content_type)
+
+  def format_input(text, mentions, tags, "text/plain") do
+    text
+    |> Formatter.html_escape("text/plain")
+    |> String.replace(~r/\r?\n/, "<br>")
+    |> (&{[], &1}).()
+    |> Formatter.add_links()
+    |> Formatter.add_actor_links(mentions)
+    |> Formatter.add_hashtag_links(tags)
+    |> Formatter.finalize()
+  end
+
+  def format_input(text, mentions, _tags, "text/html") do
+    text
+    |> Formatter.html_escape("text/html")
+    |> String.replace(~r/\r?\n/, "<br>")
+    |> (&{[], &1}).()
+    |> Formatter.add_actor_links(mentions)
+    |> Formatter.finalize()
+  end
+
+  def format_input(text, mentions, tags, "text/markdown") do
+    text
+    |> Earmark.as_html!()
+    |> Formatter.html_escape("text/html")
+    |> String.replace(~r/\r?\n/, "")
+    |> (&{[], &1}).()
+    |> Formatter.add_actor_links(mentions)
+    |> Formatter.add_hashtag_links(tags)
+    |> Formatter.finalize()
+  end
+end
diff --git a/lib/mobilizon_web/resolvers/category.ex b/lib/mobilizon_web/resolvers/category.ex
index dbc10274..514b8c53 100644
--- a/lib/mobilizon_web/resolvers/category.ex
+++ b/lib/mobilizon_web/resolvers/category.ex
@@ -2,6 +2,9 @@ defmodule MobilizonWeb.Resolvers.Category do
   require Logger
   alias Mobilizon.Actors.User
 
+  ###
+  # TODO : Refactor this into MobilizonWeb.API.Categories when a standard AS category is defined
+  ###
   def list_categories(_parent, %{page: page, limit: limit}, _resolution) do
     categories =
       Mobilizon.Events.list_categories(page, limit)
diff --git a/lib/mobilizon_web/resolvers/comment.ex b/lib/mobilizon_web/resolvers/comment.ex
new file mode 100644
index 00000000..be02e0ab
--- /dev/null
+++ b/lib/mobilizon_web/resolvers/comment.ex
@@ -0,0 +1,25 @@
+defmodule MobilizonWeb.Resolvers.Comment do
+  require Logger
+  alias Mobilizon.Events.Comment
+  alias Mobilizon.Activity
+  alias Mobilizon.Actors.User
+  alias MobilizonWeb.API.Comments
+
+  def create_comment(_parent, %{text: comment, actor_username: username}, %{
+        context: %{current_user: %User{} = _user}
+      }) do
+    with {:ok, %Activity{data: %{"object" => %{"type" => "Note"} = object}}} <-
+           Comments.create_comment(username, comment) do
+      {:ok,
+       %Comment{
+         text: object["content"],
+         url: object["id"],
+         uuid: object["uuid"]
+       }}
+    end
+  end
+
+  def create_comment(_parent, _args, %{}) do
+    {:error, "You are not allowed to create a comment if not connected"}
+  end
+end
diff --git a/lib/mobilizon_web/resolvers/event.ex b/lib/mobilizon_web/resolvers/event.ex
index 03a69de7..9c98d1bc 100644
--- a/lib/mobilizon_web/resolvers/event.ex
+++ b/lib/mobilizon_web/resolvers/event.ex
@@ -1,6 +1,8 @@
 defmodule MobilizonWeb.Resolvers.Event do
   alias Mobilizon.Service.ActivityPub
+  alias Mobilizon.Activity
   alias Mobilizon.Actors
+  alias Mobilizon.Events.Event
 
   def list_events(_parent, %{page: page, limit: limit}, _resolution) do
     {:ok, Mobilizon.Events.list_events(page, limit)}
@@ -63,10 +65,27 @@ defmodule MobilizonWeb.Resolvers.Event do
     {:ok, found}
   end
 
+  @doc """
+  Create an event
+  """
   def create_event(_parent, args, %{context: %{current_user: user}}) do
-    organizer_actor_id = Map.get(args, :organizer_actor_id) || Actors.get_actor_for_user(user).id
-    args = args |> Map.put(:organizer_actor_id, organizer_actor_id)
-    Mobilizon.Events.create_event(args)
+    with {:ok, %Activity{data: %{"object" => %{"type" => "Event"} = object}}} <-
+           args
+           # Set default organizer_actor_id if none set
+           |> Map.update(
+             :organizer_actor_username,
+             Actors.get_actor_for_user(user).preferred_username,
+             & &1
+           )
+           |> MobilizonWeb.API.Events.create_event() do
+      {:ok,
+       %Event{
+         title: object["name"],
+         description: object["content"],
+         uuid: object["uuid"],
+         url: object["id"]
+       }}
+    end
   end
 
   def create_event(_parent, _args, _resolution) do
diff --git a/lib/mobilizon_web/resolvers/group.ex b/lib/mobilizon_web/resolvers/group.ex
index 9144f086..542fb0fe 100644
--- a/lib/mobilizon_web/resolvers/group.ex
+++ b/lib/mobilizon_web/resolvers/group.ex
@@ -2,6 +2,7 @@ defmodule MobilizonWeb.Resolvers.Group do
   alias Mobilizon.Actors
   alias Mobilizon.Actors.{Actor}
   alias Mobilizon.Service.ActivityPub
+  alias Mobilizon.Activity
   require Logger
 
   @doc """
@@ -29,24 +30,36 @@ defmodule MobilizonWeb.Resolvers.Group do
   """
   def create_group(
         _parent,
-        %{preferred_username: preferred_username, creator_username: actor_username},
+        args,
         %{
-          context: %{current_user: user}
+          context: %{current_user: _user}
         }
       ) do
-    with %Actor{id: actor_id} <- Actors.get_local_actor_by_name(actor_username),
-         {:user_actor, true} <-
-           {:user_actor, actor_id in Enum.map(Actors.get_actors_for_user(user), & &1.id)},
-         {:ok, %Actor{} = group} <- Actors.create_group(%{preferred_username: preferred_username}) do
-      {:ok, group}
-    else
-      {:error, %Ecto.Changeset{errors: [url: {"has already been taken", []}]}} ->
-        {:error, :group_name_not_available}
-
-      err ->
-        Logger.error(inspect(err))
-        err
+    with {:ok, %Activity{data: %{"object" => %{"type" => "Group"} = object}}} <-
+           MobilizonWeb.API.Groups.create_group(args) do
+      {:ok,
+       %Actor{
+         preferred_username: object["preferredUsername"],
+         summary: object["summary"],
+         type: :Group,
+         #  uuid: object["uuid"],
+         url: object["id"]
+       }}
     end
+
+    # with %Actor{id: actor_id} <- Actors.get_local_actor_by_name(actor_username),
+    #      {:user_actor, true} <-
+    #        {:user_actor, actor_id in Enum.map(Actors.get_actors_for_user(user), & &1.id)},
+    #      {:ok, %Actor{} = group} <- Actors.create_group(%{preferred_username: preferred_username}) do
+    #   {:ok, group}
+    # else
+    #   {:error, %Ecto.Changeset{errors: [url: {"has already been taken", []}]}} ->
+    #     {:error, :group_name_not_available}
+
+    #   err ->
+    #     Logger.error(inspect(err))
+    #     err
+    # end
   end
 
   def create_group(_parent, _args, _resolution) do
diff --git a/lib/mobilizon_web/schema.ex b/lib/mobilizon_web/schema.ex
index cfbd783f..35a9c149 100644
--- a/lib/mobilizon_web/schema.ex
+++ b/lib/mobilizon_web/schema.ex
@@ -253,7 +253,7 @@ defmodule MobilizonWeb.Schema do
     field(:uuid, :uuid)
     field(:url, :string)
     field(:local, :boolean)
-    field(:content, :string)
+    field(:text, :string)
     field(:primaryLanguage, :string)
     field(:replies, list_of(:comment))
     field(:threadLanguages, non_null(list_of(:string)))
@@ -484,12 +484,20 @@ defmodule MobilizonWeb.Schema do
       arg(:address_type, non_null(:address_type))
       arg(:online_address, :string)
       arg(:phone, :string)
-      arg(:organizer_actor_id, non_null(:integer))
-      arg(:category_id, non_null(:integer))
+      arg(:organizer_actor_username, non_null(:string))
+      arg(:category, non_null(:string))
 
       resolve(&Resolvers.Event.create_event/3)
     end
 
+    @desc "Create a comment"
+    field :create_comment, type: :comment do
+      arg(:text, non_null(:string))
+      arg(:actor_username, non_null(:string))
+
+      resolve(&Resolvers.Comment.create_comment/3)
+    end
+
     @desc "Create a category with a title, description and picture"
     field :create_category, type: :category do
       arg(:title, non_null(:string))
@@ -552,8 +560,9 @@ defmodule MobilizonWeb.Schema do
     field :create_group, :group do
       arg(:preferred_username, non_null(:string), description: "The name for the group")
       arg(:name, :string, description: "The displayed name for the group")
+      arg(:description, :string, description: "The summary for the group", default_value: "")
 
-      arg(:creator_username, :string,
+      arg(:admin_actor_username, :string,
         description: "The actor's username which will be the admin (otherwise user's default one)"
       )
 
diff --git a/lib/service/activity_pub/activity_pub.ex b/lib/service/activity_pub/activity_pub.ex
index 22b97a1e..3786f999 100644
--- a/lib/service/activity_pub/activity_pub.ex
+++ b/lib/service/activity_pub/activity_pub.ex
@@ -13,6 +13,7 @@ defmodule Mobilizon.Service.ActivityPub do
 
   alias Mobilizon.Actors
   alias Mobilizon.Actors.Actor
+  alias Mobilizon.Actors.Follower
 
   alias Mobilizon.Service.Federator
   alias Mobilizon.Service.HTTPSignatures
@@ -36,7 +37,7 @@ defmodule Mobilizon.Service.ActivityPub do
   @spec insert(map(), boolean()) :: {:ok, %Activity{}} | {:error, any()}
   def insert(map, local \\ true) when is_map(map) do
     with map <- lazy_put_activity_defaults(map),
-         :ok <- insert_full_object(map, local) do
+         :ok <- insert_full_object(map) do
       object_id =
         cond do
           is_map(map["object"]) ->
@@ -46,7 +47,7 @@ defmodule Mobilizon.Service.ActivityPub do
             map["id"]
         end
 
-      map = Map.put(map, "id", "#{object_id}/activity")
+      map = if local, do: Map.put(map, "id", "#{object_id}/activity"), else: map
 
       activity = %Activity{
         data: map,
@@ -69,6 +70,8 @@ defmodule Mobilizon.Service.ActivityPub do
   """
   @spec fetch_object_from_url(String.t()) :: {:ok, %Event{}} | {:ok, %Comment{}} | {:error, any()}
   def fetch_object_from_url(url) do
+    Logger.info("Fetching object from url #{url}")
+
     with true <- String.starts_with?(url, "http"),
          nil <- Events.get_event_by_url(url),
          nil <- Events.get_comment_from_url(url),
@@ -94,17 +97,22 @@ defmodule Mobilizon.Service.ActivityPub do
           {:ok, Events.get_event_by_url!(activity.data["object"]["id"])}
 
         "Note" ->
-          {:ok, Events.get_comment_from_url!(activity.data["object"]["id"])}
+          {:ok, Events.get_comment_full_from_url!(activity.data["object"]["id"])}
+
+        other ->
+          {:error, other}
       end
     else
-      object = %Event{} -> {:ok, object}
-      object = %Comment{} -> {:ok, object}
+      %Event{url: event_url} -> {:ok, Events.get_event_by_url!(event_url)}
+      %Comment{url: comment_url} -> {:ok, Events.get_comment_full_from_url!(comment_url)}
       e -> {:error, e}
     end
   end
 
   def create(%{to: to, actor: actor, object: object} = params) do
     Logger.debug("creating an activity")
+    Logger.debug(inspect(params))
+    Logger.debug(inspect(object))
     additional = params[:additional] || %{}
     # only accept false as false value
     local = !(params[:local] == false)
@@ -115,6 +123,7 @@ defmodule Mobilizon.Service.ActivityPub do
              %{to: to, actor: actor, published: published, object: object},
              additional
            ),
+         :ok <- Logger.debug(inspect(create_data)),
          {:ok, activity} <- insert(create_data, local),
          :ok <- maybe_federate(activity) do
       # {:ok, actor} <- Actors.increase_event_count(actor) do
@@ -123,6 +132,7 @@ defmodule Mobilizon.Service.ActivityPub do
       err ->
         Logger.error("Something went wrong")
         Logger.error(inspect(err))
+        err
     end
   end
 
@@ -154,9 +164,82 @@ defmodule Mobilizon.Service.ActivityPub do
     end
   end
 
-  def follow(%Actor{} = follower, %Actor{} = followed, _activity_id \\ nil, local \\ true) do
-    with {:ok, follow} <- Actor.follow(followed, follower, true),
-         data <- make_follow_data(follower, followed, follow.id),
+  # TODO: This is weird, maybe we shouldn't check here if we can make the activity.
+  # def like(
+  #       %Actor{url: url} = actor,
+  #       object,
+  #       activity_id \\ nil,
+  #       local \\ true
+  #     ) do
+  #   with nil <- get_existing_like(url, object),
+  #        like_data <- make_like_data(user, object, activity_id),
+  #        {:ok, activity} <- insert(like_data, local),
+  #        {:ok, object} <- add_like_to_object(activity, object),
+  #        :ok <- maybe_federate(activity) do
+  #     {:ok, activity, object}
+  #   else
+  #     %Activity{} = activity -> {:ok, activity, object}
+  #     error -> {:error, error}
+  #   end
+  # end
+
+  # def unlike(
+  #       %User{} = actor,
+  #       %Object{} = object,
+  #       activity_id \\ nil,
+  #       local \\ true
+  #     ) do
+  #   with %Activity{} = like_activity <- get_existing_like(actor.ap_id, object),
+  #        unlike_data <- make_unlike_data(actor, like_activity, activity_id),
+  #        {:ok, unlike_activity} <- insert(unlike_data, local),
+  #        {:ok, _activity} <- Repo.delete(like_activity),
+  #        {:ok, object} <- remove_like_from_object(like_activity, object),
+  #        :ok <- maybe_federate(unlike_activity) do
+  #     {:ok, unlike_activity, like_activity, object}
+  #   else
+  #     _e -> {:ok, object}
+  #   end
+  # end
+
+  # def announce(
+  #       %Actor{} = actor,
+  #       object,
+  #       activity_id \\ nil,
+  #       local \\ true
+  #     ) do
+  #   #with true <- is_public?(object),
+  #        with announce_data <- make_announce_data(actor, object, activity_id),
+  #        {:ok, activity} <- insert(announce_data, local),
+  #       #  {:ok, object} <- add_announce_to_object(activity, object),
+  #        :ok <- maybe_federate(activity) do
+  #     {:ok, activity, object}
+  #   else
+  #     error -> {:error, error}
+  #   end
+  # end
+
+  # def unannounce(
+  #       %Actor{} = actor,
+  #       object,
+  #       activity_id \\ nil,
+  #       local \\ true
+  #     ) do
+  #   with %Activity{} = announce_activity <- get_existing_announce(actor.ap_id, object),
+  #        unannounce_data <- make_unannounce_data(actor, announce_activity, activity_id),
+  #        {:ok, unannounce_activity} <- insert(unannounce_data, local),
+  #        :ok <- maybe_federate(unannounce_activity),
+  #        {:ok, _activity} <- Repo.delete(announce_activity),
+  #        {:ok, object} <- remove_announce_from_object(announce_activity, object) do
+  #     {:ok, unannounce_activity, object}
+  #   else
+  #     _e -> {:ok, object}
+  #   end
+  # end
+
+  def follow(%Actor{} = follower, %Actor{} = followed, activity_id \\ nil, local \\ true) do
+    with {:ok, %Follower{} = follow} <- Actor.follow(followed, follower, true),
+         activity_follow_id <- activity_id || Follower.url(follow),
+         data <- make_follow_data(followed, follower, activity_follow_id),
          {:ok, activity} <- insert(data, local),
          :ok <- maybe_federate(activity) do
       {:ok, activity}
@@ -166,6 +249,23 @@ defmodule Mobilizon.Service.ActivityPub do
     end
   end
 
+  @spec unfollow(Actor.t(), Actor.t(), String.t(), boolean()) :: {:ok, map()} | any()
+  def unfollow(%Actor{} = followed, %Actor{} = follower, activity_id \\ nil, local \\ true) do
+    with {:ok, %Follower{id: follow_id}} <- Actor.unfollow(followed, follower),
+         # We recreate the follow activity
+         data <- make_follow_data(followed, follower, follow_id),
+         {:ok, follow_activity} <- insert(data, local),
+         unfollow_data <- make_unfollow_data(follower, followed, follow_activity, activity_id),
+         {:ok, activity} <- insert(unfollow_data, local),
+         :ok <- maybe_federate(activity) do
+      {:ok, activity}
+    else
+      err ->
+        Logger.error(inspect(err))
+        err
+    end
+  end
+
   def delete(object, local \\ true)
 
   def delete(%Event{url: url, organizer_actor: actor} = event, local) do
@@ -198,6 +298,21 @@ defmodule Mobilizon.Service.ActivityPub do
     end
   end
 
+  def delete(%Actor{url: url} = actor, local) do
+    data = %{
+      "type" => "Delete",
+      "actor" => url,
+      "object" => url,
+      "to" => [url <> "/followers", "https://www.w3.org/ns/activitystreams#Public"]
+    }
+
+    with Actors.delete_actor(actor),
+         {:ok, activity} <- insert(data, local),
+         :ok <- maybe_federate(activity) do
+      {:ok, activity}
+    end
+  end
+
   @doc """
   Create an actor locally by it's URL (AP ID)
   """
@@ -278,7 +393,7 @@ defmodule Mobilizon.Service.ActivityPub do
 
   def publish_one(%{inbox: inbox, json: json, actor: actor, id: id}) do
     Logger.info("Federating #{id} to #{inbox}")
-    {host, path} = URI.parse(inbox)
+    %URI{host: host, path: path} = URI.parse(inbox)
 
     digest = HTTPSignatures.build_digest(json)
     date = HTTPSignatures.generate_date_header()
@@ -333,15 +448,10 @@ defmodule Mobilizon.Service.ActivityPub do
   def actor_data_from_actor_object(data) when is_map(data) do
     actor_data = %{
       url: data["id"],
-      info: %{
-        "ap_enabled" => true,
-        "source_data" => data
-      },
       avatar_url: data["icon"]["url"],
       banner_url: data["image"]["url"],
       name: data["name"],
       preferred_username: data["preferredUsername"],
-      follower_address: data["followers"],
       summary: data["summary"],
       keys: data["publicKey"]["publicKeyPem"],
       inbox_url: data["inbox"],
@@ -416,7 +526,7 @@ defmodule Mobilizon.Service.ActivityPub do
 
   # Create an activity from a comment
   @spec comment_to_activity(%Comment{}, boolean()) :: Activity.t()
-  defp comment_to_activity(%Comment{} = comment, local \\ true) do
+  def comment_to_activity(%Comment{} = comment, local \\ true) do
     %Activity{
       recipients: ["https://www.w3.org/ns/activitystreams#Public"],
       actor: comment.actor.url,
@@ -471,4 +581,9 @@ defmodule Mobilizon.Service.ActivityPub do
   defp sanitize_ical_event_strings(nil) do
     nil
   end
+
+  def is_public?(activity) do
+    "https://www.w3.org/ns/activitystreams#Public" in (activity.data["to"] ++
+                                                         (activity.data["cc"] || []))
+  end
 end
diff --git a/lib/service/activity_pub/transmogrifier.ex b/lib/service/activity_pub/transmogrifier.ex
index e9dbea7e..72cfd5a0 100644
--- a/lib/service/activity_pub/transmogrifier.ex
+++ b/lib/service/activity_pub/transmogrifier.ex
@@ -2,14 +2,36 @@ defmodule Mobilizon.Service.ActivityPub.Transmogrifier do
   @moduledoc """
   A module to handle coding from internal to wire ActivityPub and back.
   """
-  alias Mobilizon.Actors.Actor
   alias Mobilizon.Actors
+  alias Mobilizon.Actors.Actor
+  alias Mobilizon.Events
   alias Mobilizon.Events.{Event, Comment}
   alias Mobilizon.Service.ActivityPub
   alias Mobilizon.Service.ActivityPub.Utils
 
   require Logger
 
+  def get_actor(%{"actor" => actor}) when is_binary(actor) do
+    actor
+  end
+
+  def get_actor(%{"actor" => actor}) when is_list(actor) do
+    if is_binary(Enum.at(actor, 0)) do
+      Enum.at(actor, 0)
+    else
+      Enum.find(actor, fn %{"type" => type} -> type in ["Person", "Service", "Application"] end)
+      |> Map.get("id")
+    end
+  end
+
+  def get_actor(%{"actor" => %{"id" => id}}) when is_bitstring(id) do
+    id
+  end
+
+  def get_actor(%{"actor" => nil, "attributedTo" => actor}) when not is_nil(actor) do
+    get_actor(%{"actor" => actor})
+  end
+
   @doc """
   Modifies an incoming AP object (mastodon format) to our internal format.
   """
@@ -48,6 +70,10 @@ defmodule Mobilizon.Service.ActivityPub.Transmogrifier do
         object
         |> Map.put("inReplyTo", replied_object.url)
 
+      {:error, {:error, :not_supported}} ->
+        Logger.info("Object reply origin has not a supported type")
+        object
+
       e ->
         Logger.error("Couldn't fetch #{in_reply_to_id} #{inspect(e)}")
         object
@@ -88,6 +114,7 @@ defmodule Mobilizon.Service.ActivityPub.Transmogrifier do
 
     with {:ok, %Actor{} = actor} <- Actors.get_or_fetch_by_url(data["actor"]) do
       Logger.debug("found actor")
+      Logger.debug(inspect(actor))
 
       params = %{
         to: data["to"],
@@ -136,78 +163,134 @@ defmodule Mobilizon.Service.ActivityPub.Transmogrifier do
   #      _e -> :error
   #    end
   #  end
-  #
+  # #
   # def handle_incoming(
   #       %{"type" => "Announce", "object" => object_id, "actor" => actor, "id" => id} = data
   #     ) do
-  #   with {:ok, %Actor{} = actor} <- Actors.get_or_fetch_by_url(actor),
-  #        {:ok, object} <-
-  #          fetch_obj_helper(object_id) || ActivityPub.fetch_object_from_url(object_id),
-  #        {:ok, activity, object} <- ActivityPub.announce(actor, object, id, false) do
+  #   with actor <- get_actor(data),
+  #        {:ok, %Actor{} = actor} <- Actors.get_or_fetch_by_url(actor),
+  #        {:ok, object} <- get_obj_helper(object_id) || fetch_obj_helper(object_id),
+  #        {:ok, activity, _object} <- ActivityPub.announce(actor, object, id, false) do
+  #     {:ok, activity}
+  #   else
+  #     e -> Logger.error(inspect e)
+  #       :error
+  #   end
+  # end
+
+  def handle_incoming(
+        %{"type" => "Update", "object" => %{"type" => object_type} = object, "actor" => _actor_id} =
+          data
+      )
+      when object_type in ["Person", "Application", "Service", "Organization"] do
+    with {:ok, %Actor{url: url}} <- Actors.get_actor_by_url(object["id"]) do
+      {:ok, new_actor_data} = ActivityPub.actor_data_from_actor_object(object)
+
+      Actors.insert_or_update_actor(new_actor_data)
+
+      ActivityPub.update(%{
+        local: false,
+        to: data["to"] || [],
+        cc: data["cc"] || [],
+        object: object,
+        actor: url
+      })
+    else
+      e ->
+        Logger.error(inspect(e))
+        :error
+    end
+  end
+
+  # def handle_incoming(
+  #       %{
+  #         "type" => "Undo",
+  #         "object" => %{"type" => "Announce", "object" => object_id},
+  #         "actor" => actor,
+  #         "id" => id
+  #       } = data
+  #     ) do
+  #   with actor <- get_actor(data),
+  #        {:ok, %Actor{} = actor} <- Actors.get_or_fetch_by_url(actor),
+  #        {:ok, object} <- get_obj_helper(object_id) || fetch_obj_helper(object_id),
+  #        {:ok, activity, _} <- ActivityPub.unannounce(actor, object, id, false) do
   #     {:ok, activity}
   #   else
   #     _e -> :error
   #   end
   # end
 
-  #
-  #  def handle_incoming(
-  #        %{"type" => "Update", "object" => %{"type" => "Person"} = object, "actor" => actor_id} =
-  #          data
-  #      ) do
-  #    with %User{ap_id: ^actor_id} = actor <- User.get_by_ap_id(object["id"]) do
-  #      {:ok, new_user_data} = ActivityPub.actor_data_from_actor_object(object)
-  #
-  #      banner = new_user_data[:info]["banner"]
-  #
-  #      update_data =
-  #        new_user_data
-  #        |> Map.take([:name, :bio, :avatar])
-  #        |> Map.put(:info, Map.merge(actor.info, %{"banner" => banner}))
-  #
-  #      actor
-  #      |> User.upgrade_changeset(update_data)
-  #      |> User.update_and_set_cache()
-  #
-  #      ActivityPub.update(%{
-  #        local: false,
-  #        to: data["to"] || [],
-  #        cc: data["cc"] || [],
-  #        object: object,
-  #        actor: actor_id
-  #      })
-  #    else
-  #      e ->
-  #        Logger.error(e)
-  #        :error
-  #    end
-  #  end
-  #
-  #  # TODO: Make secure.
-  #  def handle_incoming(
-  #        %{"type" => "Delete", "object" => object_id, "actor" => actor, "id" => id} = data
-  #      ) do
-  #    object_id =
-  #      case object_id do
-  #        %{"id" => id} -> id
-  #        id -> id
-  #      end
-  #
-  #    with %User{} = actor <- User.get_or_fetch_by_ap_id(actor),
-  #         {:ok, object} <-
-  #           fetch_obj_helper(object_id) || ActivityPub.fetch_object_from_id(object_id),
-  #         {:ok, activity} <- ActivityPub.delete(object, false) do
-  #      {:ok, activity}
-  #    else
-  #      e -> :error
-  #    end
-  #  end
+  def handle_incoming(
+        %{
+          "type" => "Undo",
+          "object" => %{"type" => "Follow", "object" => followed},
+          "actor" => follower,
+          "id" => id
+        } = _data
+      ) do
+    with {:ok, %Actor{domain: nil} = followed} <- Actors.get_actor_by_url(followed),
+         {:ok, %Actor{} = follower} <- Actors.get_actor_by_url(follower),
+         {:ok, activity} <- ActivityPub.unfollow(followed, follower, id, false) do
+      Actor.unfollow(follower, followed)
+      {:ok, activity}
+    else
+      e ->
+        Logger.error(inspect(e))
+        :error
+    end
+  end
+
+  # TODO: We presently assume that any actor on the same origin domain as the object being
+  # deleted has the rights to delete that object.  A better way to validate whether or not
+  # the object should be deleted is to refetch the object URI, which should return either
+  # an error or a tombstone.  This would allow us to verify that a deletion actually took
+  # place.
+  def handle_incoming(
+        %{"type" => "Delete", "object" => object, "actor" => _actor, "id" => _id} = data
+      ) do
+    object_id = Utils.get_url(object)
+
+    with actor <- get_actor(data),
+         {:ok, %Actor{url: _actor_url}} <- Actors.get_actor_by_url(actor),
+         {:ok, object} <- get_obj_helper(object_id) || fetch_obj_helper(object_id),
+         #  TODO : Validate that DELETE comes indeed form right domain (see above)
+         #  :ok <- contain_origin(actor_url, object.data),
+         {:ok, activity} <- ActivityPub.delete(object, false) do
+      {:ok, activity}
+    else
+      e ->
+        Logger.debug(inspect(e))
+        :error
+    end
+  end
+
   #
   #  # TODO
   #  # Accept
   #  # Undo
   #
-  def handle_incoming(_), do: :error
+  # def handle_incoming(
+  #       %{
+  #         "type" => "Undo",
+  #         "object" => %{"type" => "Like", "object" => object_id},
+  #         "actor" => _actor,
+  #         "id" => id
+  #       } = data
+  #     ) do
+  #   with actor <- get_actor(data),
+  #        %Actor{} = actor <- Actors.get_or_fetch_by_url(actor),
+  #        {:ok, object} <- get_obj_helper(object_id) || fetch_obj_helper(object_id),
+  #        {:ok, activity, _, _} <- ActivityPub.unlike(actor, object, id, false) do
+  #     {:ok, activity}
+  #   else
+  #     _e -> :error
+  #   end
+  # end
+
+  def handle_incoming(_) do
+    Logger.info("Handing something not supported")
+    {:error, :not_supported}
+  end
 
   def set_reply_to_uri(%{"inReplyTo" => in_reply_to} = object) do
     with false <- String.starts_with?(in_reply_to, "http"),
@@ -224,7 +307,7 @@ defmodule Mobilizon.Service.ActivityPub.Transmogrifier do
   def prepare_object(object) do
     object
     #    |> set_sensitive
-    #    |> add_hashtags
+    |> add_hashtags
     |> add_mention_tags
     #    |> add_emoji_tags
     |> add_attributed_to
@@ -326,7 +409,13 @@ defmodule Mobilizon.Service.ActivityPub.Transmogrifier do
 
     mentions =
       recipients
-      |> Enum.map(fn url -> Actors.get_actor_by_url!(url) end)
+      |> Enum.filter(& &1)
+      |> Enum.map(fn url ->
+        case Actors.get_actor_by_url(url) do
+          {:ok, actor} -> actor
+          _ -> nil
+        end
+      end)
       |> Enum.filter(& &1)
       |> Enum.map(fn actor ->
         %{"type" => "Mention", "href" => actor.url, "name" => "@#{actor.preferred_username}"}
@@ -391,4 +480,43 @@ defmodule Mobilizon.Service.ActivityPub.Transmogrifier do
 
   @spec fetch_obj_helper(map()) :: {:ok, %Event{}} | {:ok, %Comment{}} | {:error, any()}
   def fetch_obj_helper(obj) when is_map(obj), do: ActivityPub.fetch_object_from_url(obj["id"])
+
+  @spec get_obj_helper(String.t()) :: {:ok, struct()} | nil
+  def get_obj_helper(id) do
+    if object = normalize(id), do: {:ok, object}, else: nil
+  end
+
+  @spec normalize(map()) :: struct() | nil
+  def normalize(obj) when is_map(obj), do: get_anything_by_url(obj["id"])
+  @spec normalize(String.t()) :: struct() | nil
+  def normalize(url) when is_binary(url), do: get_anything_by_url(url)
+  @spec normalize(any()) :: nil
+  def normalize(_), do: nil
+
+  @spec normalize(String.t()) :: struct() | nil
+  def get_anything_by_url(url) do
+    Logger.debug("Getting anything from url #{url}")
+    get_actor_url(url) || get_event_url(url) || get_comment_url(url)
+  end
+
+  defp get_actor_url(url) do
+    case Actors.get_actor_by_url(url) do
+      {:ok, %Actor{} = actor} -> actor
+      _ -> nil
+    end
+  end
+
+  defp get_event_url(url) do
+    case Events.get_event_by_url(url) do
+      {:ok, %Event{} = event} -> event
+      _ -> nil
+    end
+  end
+
+  defp get_comment_url(url) do
+    case Events.get_comment_full_from_url(url) do
+      {:ok, %Comment{} = comment} -> comment
+      _ -> nil
+    end
+  end
 end
diff --git a/lib/service/activity_pub/utils.ex b/lib/service/activity_pub/utils.ex
index c00fc2bd..c878cc70 100644
--- a/lib/service/activity_pub/utils.ex
+++ b/lib/service/activity_pub/utils.ex
@@ -13,11 +13,17 @@ defmodule Mobilizon.Service.ActivityPub.Utils do
   alias Mobilizon.Events
   alias Mobilizon.Activity
   alias Mobilizon.Service.ActivityPub
-  alias Ecto.{Changeset, UUID}
+  alias Ecto.Changeset
   require Logger
 
-  def make_context(%Activity{data: %{"context" => context}}), do: context
-  def make_context(_), do: generate_context_id()
+  # Some implementations send the actor URI as the actor field, others send the entire actor object,
+  # so figure out what the actor's URI is based on what we have.
+  def get_url(object) do
+    case object do
+      %{"id" => id} -> id
+      id -> id
+    end
+  end
 
   def make_json_ld_header do
     %{
@@ -38,18 +44,6 @@ defmodule Mobilizon.Service.ActivityPub.Utils do
     DateTime.utc_now() |> DateTime.to_iso8601()
   end
 
-  def generate_activity_id do
-    generate_id("activities")
-  end
-
-  def generate_context_id do
-    generate_id("contexts")
-  end
-
-  def generate_id(type) do
-    "#{MobilizonWeb.Endpoint.url()}/#{type}/#{UUID.generate()}"
-  end
-
   @doc """
   Enqueues an activity for federation if it's local
   """
@@ -108,16 +102,42 @@ defmodule Mobilizon.Service.ActivityPub.Utils do
   end
 
   @doc """
-  Inserts a full object if it is contained in an activity.
+  Converts an AP object data to our internal data structure
   """
-  def insert_full_object(object_data, local \\ false)
+  def object_to_event_data(object) do
+    {:ok, %Actor{id: actor_id}} = Actors.get_actor_by_url(object["actor"])
+
+    %{
+      "title" => object["name"],
+      "description" => object["content"],
+      "organizer_actor_id" => actor_id,
+      "begins_on" => object["begins_on"],
+      "category_id" => Events.get_category_by_title(object["category"]).id,
+      "url" => object["id"]
+    }
+  end
 
   @doc """
   Inserts a full object if it is contained in an activity.
   """
-  def insert_full_object(%{"object" => %{"type" => type} = object_data}, local)
-      when is_map(object_data) and type == "Event" and not local do
-    with {:ok, _} <- Events.create_event(object_data) do
+  def insert_full_object(object_data)
+
+  @doc """
+  Inserts a full object if it is contained in an activity.
+  """
+  def insert_full_object(%{"object" => %{"type" => "Event"} = object_data})
+      when is_map(object_data) do
+    with object_data <- object_to_event_data(object_data),
+         {:ok, _} <- Events.create_event(object_data) do
+      :ok
+    end
+  end
+
+  def insert_full_object(%{"object" => %{"type" => "Group"} = object_data})
+      when is_map(object_data) do
+    with object_data <-
+           Map.put(object_data, "preferred_username", object_data["preferredUsername"]),
+         {:ok, _} <- Actors.create_group(object_data) do
       :ok
     end
   end
@@ -125,8 +145,11 @@ defmodule Mobilizon.Service.ActivityPub.Utils do
   @doc """
   Inserts a full object if it is contained in an activity.
   """
-  def insert_full_object(%{"object" => %{"type" => type} = object_data}, local)
-      when is_map(object_data) and type == "Note" and not local do
+  def insert_full_object(%{"object" => %{"type" => "Note"} = object_data})
+      when is_map(object_data) do
+    Logger.debug("Inserting full comment")
+    Logger.debug(inspect(object_data))
+
     with {:ok, %Actor{id: actor_id}} <- Actors.get_or_fetch_by_url(object_data["actor"]) do
       data = %{
         "text" => object_data["content"],
@@ -134,11 +157,12 @@ defmodule Mobilizon.Service.ActivityPub.Utils do
         "actor_id" => actor_id,
         "in_reply_to_comment_id" => nil,
         "event_id" => nil,
-        "uuid" => object_data["uuid"],
-        "local" => local
+        "uuid" => object_data["uuid"]
       }
 
       # We fetch the parent object
+      Logger.debug("We're fetching the parent object")
+
       data =
         if Map.has_key?(object_data, "inReplyTo") && object_data["inReplyTo"] != nil &&
              object_data["inReplyTo"] != "" do
@@ -159,7 +183,7 @@ defmodule Mobilizon.Service.ActivityPub.Utils do
               |> Map.put("origin_comment_id", comment |> Comment.get_thread_id())
 
             # Anthing else is kind of a MP
-            object ->
+            {:error, object} ->
               Logger.debug("Parent object is something we don't handle")
               Logger.debug(inspect(object))
               data
@@ -180,7 +204,7 @@ defmodule Mobilizon.Service.ActivityPub.Utils do
     end
   end
 
-  def insert_full_object(_, _), do: :ok
+  def insert_full_object(_), do: :ok
 
   #### Like-related helpers
 
@@ -206,6 +230,41 @@ defmodule Mobilizon.Service.ActivityPub.Utils do
   #    Repo.one(query)
   #  end
 
+  @doc """
+  Make an AP event object from an set of values
+  """
+  def make_event_data(
+        actor,
+        to,
+        title,
+        content_html,
+        # attachments,
+        tags \\ [],
+        # _cw \\ nil,
+        cc \\ [],
+        metadata \\ %{},
+        category \\ ""
+      ) do
+    Logger.debug("Making event data")
+    uuid = Ecto.UUID.generate()
+
+    %{
+      "type" => "Event",
+      "to" => to,
+      "cc" => cc,
+      "content" => content_html,
+      "name" => title,
+      # "summary" => cw,
+      # "attachment" => attachments,
+      "begins_on" => metadata.begins_on,
+      "category" => category,
+      "actor" => actor,
+      "id" => "#{MobilizonWeb.Endpoint.url()}/events/#{uuid}",
+      "uuid" => uuid,
+      "tag" => tags |> Enum.map(fn {_, tag} -> tag end) |> Enum.uniq()
+    }
+  end
+
   def make_event_data(
         %Event{title: title, organizer_actor: actor, uuid: uuid},
         to \\ ["https://www.w3.org/ns/activitystreams#Public"]
@@ -238,6 +297,7 @@ defmodule Mobilizon.Service.ActivityPub.Utils do
       "to" => to,
       "content" => text,
       "actor" => actor.url,
+      "attributedTo" => actor.url,
       "uuid" => uuid,
       "id" => "#{MobilizonWeb.Endpoint.url()}/comments/#{uuid}"
     }
@@ -249,14 +309,17 @@ defmodule Mobilizon.Service.ActivityPub.Utils do
     end
   end
 
+  @doc """
+  Make an AP comment object from an set of values
+  """
   def make_comment_data(
         actor,
         to,
         content_html,
         # attachments,
         inReplyTo \\ nil,
-        # tags,
-        _cw \\ nil,
+        tags \\ [],
+        # _cw \\ nil,
         cc \\ []
       ) do
     Logger.debug("Making comment data")
@@ -271,8 +334,8 @@ defmodule Mobilizon.Service.ActivityPub.Utils do
       # "attachment" => attachments,
       "actor" => actor,
       "id" => "#{MobilizonWeb.Endpoint.url()}/comments/#{uuid}",
-      "uuid" => uuid
-      # "tag" => tags |> Enum.map(fn {_, tag} -> tag end) |> Enum.uniq()
+      "uuid" => uuid,
+      "tag" => tags |> Enum.map(fn {_, tag} -> tag end) |> Enum.uniq()
     }
 
     if inReplyTo do
@@ -283,19 +346,54 @@ defmodule Mobilizon.Service.ActivityPub.Utils do
     end
   end
 
-  def make_like_data(%Actor{url: url} = actor, %{data: %{"id" => id}} = object, activity_id) do
-    data = %{
-      "type" => "Like",
-      "actor" => url,
-      "object" => id,
-      "to" => [actor.follower_address, object.data["actor"]],
-      "cc" => ["https://www.w3.org/ns/activitystreams#Public"],
-      "context" => object.data["context"]
-    }
+  def make_group_data(
+        actor,
+        to,
+        preferred_username,
+        content_html,
+        # attachments,
+        tags \\ [],
+        # _cw \\ nil,
+        cc \\ []
+      ) do
+    uuid = Ecto.UUID.generate()
 
-    if activity_id, do: Map.put(data, "id", activity_id), else: data
+    %{
+      "type" => "Group",
+      "to" => to,
+      "cc" => cc,
+      "summary" => content_html,
+      "attributedTo" => actor,
+      "preferredUsername" => preferred_username,
+      "id" => "#{MobilizonWeb.Endpoint.url()}/~#{preferred_username}",
+      "uuid" => uuid,
+      "tag" => tags |> Enum.map(fn {_, tag} -> tag end) |> Enum.uniq()
+    }
   end
 
+  #### Like-related helpers
+
+  @doc """
+  Returns an existing like if a user already liked an object
+  """
+  # @spec get_existing_like(Actor.t, map()) :: nil
+  # def get_existing_like(%Actor{url: url} = actor, %{data: %{"id" => id}}) do
+  #   nil
+  # end
+
+  # def make_like_data(%Actor{url: url} = actor, %{data: %{"id" => id}} = object, activity_id) do
+  #   data = %{
+  #     "type" => "Like",
+  #     "actor" => url,
+  #     "object" => id,
+  #     "to" => [actor.followers_url, object.data["actor"]],
+  #     "cc" => ["https://www.w3.org/ns/activitystreams#Public"],
+  #     "context" => object.data["context"]
+  #   }
+
+  #   if activity_id, do: Map.put(data, "id", activity_id), else: data
+  # end
+
   def update_element_in_object(property, element, object) do
     with new_data <-
            object.data
@@ -326,9 +424,9 @@ defmodule Mobilizon.Service.ActivityPub.Utils do
   #### Follow-related helpers
 
   @doc """
-  Makes a follow activity data for the given follower and followed
+  Makes a follow activity data for the given followed and follower
   """
-  def make_follow_data(%Actor{url: follower_id}, %Actor{url: followed_id}, activity_id) do
+  def make_follow_data(%Actor{url: followed_id}, %Actor{url: follower_id}, activity_id) do
     Logger.debug("Make follow data")
 
     data = %{
@@ -342,7 +440,7 @@ defmodule Mobilizon.Service.ActivityPub.Utils do
     Logger.debug(inspect(data))
 
     if activity_id,
-      do: Map.put(data, "id", "#{MobilizonWeb.Endpoint.url()}/follow/#{activity_id}/activity"),
+      do: Map.put(data, "id", activity_id),
       else: data
   end
 
@@ -352,17 +450,37 @@ defmodule Mobilizon.Service.ActivityPub.Utils do
   Make announce activity data for the given actor and object
   """
   def make_announce_data(
-        %Actor{url: url} = user,
-        %Event{id: id} = object,
+        %Actor{url: actor_url} = actor,
+        %Event{url: event_url} = object,
         activity_id
       ) do
     data = %{
       "type" => "Announce",
-      "actor" => url,
-      "object" => id,
-      "to" => [user.follower_address, object.data["actor"]],
-      "cc" => ["https://www.w3.org/ns/activitystreams#Public"],
-      "context" => object.data["context"]
+      "actor" => actor_url,
+      "object" => event_url,
+      "to" => [actor.followers_url, object.actor.url],
+      "cc" => ["https://www.w3.org/ns/activitystreams#Public"]
+      # "context" => object.data["context"]
+    }
+
+    if activity_id, do: Map.put(data, "id", activity_id), else: data
+  end
+
+  @doc """
+  Make announce activity data for the given actor and object
+  """
+  def make_announce_data(
+        %Actor{url: actor_url} = actor,
+        %Comment{url: comment_url} = object,
+        activity_id
+      ) do
+    data = %{
+      "type" => "Announce",
+      "actor" => actor_url,
+      "object" => comment_url,
+      "to" => [actor.followers_url, object.actor.url],
+      "cc" => ["https://www.w3.org/ns/activitystreams#Public"]
+      # "context" => object.data["context"]
     }
 
     if activity_id, do: Map.put(data, "id", activity_id), else: data
@@ -376,18 +494,32 @@ defmodule Mobilizon.Service.ActivityPub.Utils do
 
   #### Unfollow-related helpers
 
-  def make_unfollow_data(follower, followed, follow_activity) do
-    %{
+  @spec make_unfollow_data(Actor.t(), Actor.t(), map(), String.t()) :: map()
+  def make_unfollow_data(
+        %Actor{url: follower_url},
+        %Actor{url: followed_url},
+        follow_activity,
+        activity_id
+      ) do
+    data = %{
       "type" => "Undo",
-      "actor" => follower.url,
-      "to" => [followed.url],
-      "object" => follow_activity.data["id"]
+      "actor" => follower_url,
+      "to" => [followed_url],
+      "object" => follow_activity.data
     }
+
+    if activity_id, do: Map.put(data, "id", activity_id), else: data
   end
 
   #### Create-related helpers
 
+  @doc """
+  Make create activity data
+  """
+  @spec make_create_data(map(), map()) :: map()
   def make_create_data(params, additional \\ %{}) do
+    Logger.debug("Making create data")
+    Logger.debug(inspect(params))
     published = params.published || make_date()
 
     %{
diff --git a/lib/service/formatter/formatter.ex b/lib/service/formatter/formatter.ex
new file mode 100644
index 00000000..77c9ca00
--- /dev/null
+++ b/lib/service/formatter/formatter.ex
@@ -0,0 +1,157 @@
+defmodule Mobilizon.Service.Formatter do
+  alias Mobilizon.Actors.Actor
+  alias Mobilizon.Actors
+
+  @tag_regex ~r/\#\w+/u
+  def parse_tags(text, data \\ %{}) do
+    Regex.scan(@tag_regex, text)
+    |> Enum.map(fn ["#" <> tag = full_tag] -> {full_tag, String.downcase(tag)} end)
+    |> (fn map ->
+          if data["sensitive"] in [true, "True", "true", "1"],
+            do: [{"#nsfw", "nsfw"}] ++ map,
+            else: map
+        end).()
+  end
+
+  def parse_mentions(text) do
+    # Modified from https://www.w3.org/TR/html5/forms.html#valid-e-mail-address
+    regex =
+      ~r/@[a-zA-Z0-9.!#$%&'*+\/=?^_`{|}~-]*@?[a-zA-Z0-9_-](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?(?:\.[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?)*/u
+
+    Regex.scan(regex, text)
+    |> List.flatten()
+    |> Enum.uniq()
+    |> Enum.map(fn "@" <> match = full_match ->
+      {full_match, Actors.get_actor_by_name(match)}
+    end)
+    |> Enum.filter(fn {_match, user} -> user end)
+  end
+
+  # def emojify(text) do
+  #   emojify(text, Emoji.get_all())
+  # end
+
+  # def emojify(text, nil), do: text
+
+  # def emojify(text, emoji) do
+  #   Enum.reduce(emoji, text, fn {emoji, file}, text ->
+  #     emoji = HTML.strip_tags(emoji)
+  #     file = HTML.strip_tags(file)
+
+  #     String.replace(
+  #       text,
+  #       ":#{emoji}:",
+  #       "<img height='32px' width='32px' alt='#{emoji}' title='#{emoji}' src='#{
+  #         MediaProxy.url(file)
+  #       }' />"
+  #     )
+  #     |> HTML.filter_tags()
+  #   end)
+  # end
+
+  # def get_emoji(text) when is_binary(text) do
+  #   Enum.filter(Emoji.get_all(), fn {emoji, _} -> String.contains?(text, ":#{emoji}:") end)
+  # end
+
+  # def get_emoji(_), do: []
+
+  @link_regex ~r/[0-9a-z+\-\.]+:[0-9a-z$-_.+!*'(),]+/ui
+
+  @uri_schemes Application.get_env(:pleroma, :uri_schemes, [])
+  @valid_schemes Keyword.get(@uri_schemes, :valid_schemes, [])
+
+  # # TODO: make it use something other than @link_regex
+  # def html_escape(text, "text/html") do
+  #   HTML.filter_tags(text)
+  # end
+
+  def html_escape(text, "text/plain") do
+    Regex.split(@link_regex, text, include_captures: true)
+    |> Enum.map_every(2, fn chunk ->
+      {:safe, part} = Phoenix.HTML.html_escape(chunk)
+      part
+    end)
+    |> Enum.join("")
+  end
+
+  @doc "changes scheme:... urls to html links"
+  def add_links({subs, text}) do
+    links =
+      text
+      |> String.split([" ", "\t", "<br>"])
+      |> Enum.filter(fn word -> String.starts_with?(word, @valid_schemes) end)
+      |> Enum.filter(fn word -> Regex.match?(@link_regex, word) end)
+      |> Enum.map(fn url -> {Ecto.UUID.generate(), url} end)
+      |> Enum.sort_by(fn {_, url} -> -String.length(url) end)
+
+    uuid_text =
+      links
+      |> Enum.reduce(text, fn {uuid, url}, acc -> String.replace(acc, url, uuid) end)
+
+    subs =
+      subs ++
+        Enum.map(links, fn {uuid, url} ->
+          {uuid, "<a href=\"#{url}\">#{url}</a>"}
+        end)
+
+    {subs, uuid_text}
+  end
+
+  @doc "Adds the links to mentioned actors"
+  def add_actor_links({subs, text}, mentions) do
+    mentions =
+      mentions
+      |> Enum.sort_by(fn {name, _} -> -String.length(name) end)
+      |> Enum.map(fn {name, actor} -> {name, actor, Ecto.UUID.generate()} end)
+
+    uuid_text =
+      mentions
+      |> Enum.reduce(text, fn {match, _actor, uuid}, text ->
+        String.replace(text, match, uuid)
+      end)
+
+    subs =
+      subs ++
+        Enum.map(mentions, fn {match, %Actor{id: id, url: url}, uuid} ->
+          short_match = String.split(match, "@") |> tl() |> hd()
+
+          {uuid,
+           "<span><a data-user='#{id}' class='mention' href='#{url}'>@<span>#{short_match}</span></a></span>"}
+        end)
+
+    {subs, uuid_text}
+  end
+
+  @doc "Adds the hashtag links"
+  def add_hashtag_links({subs, text}, tags) do
+    tags =
+      tags
+      |> Enum.sort_by(fn {name, _} -> -String.length(name) end)
+      |> Enum.map(fn {name, short} -> {name, short, Ecto.UUID.generate()} end)
+
+    uuid_text =
+      tags
+      |> Enum.reduce(text, fn {match, _short, uuid}, text ->
+        String.replace(text, match, uuid)
+      end)
+
+    subs =
+      subs ++
+        Enum.map(tags, fn {tag_text, tag, uuid} ->
+          url =
+            "<a data-tag='#{tag}' href='#{MobilizonWeb.Endpoint.url()}/tag/#{tag}' rel='tag'>#{
+              tag_text
+            }</a>"
+
+          {uuid, url}
+        end)
+
+    {subs, uuid_text}
+  end
+
+  def finalize({subs, text}) do
+    Enum.reduce(subs, text, fn {uuid, replacement}, result_text ->
+      String.replace(result_text, uuid, replacement)
+    end)
+  end
+end
diff --git a/test/fixtures/mastodon-announce.json b/test/fixtures/mastodon-announce.json
new file mode 100644
index 00000000..26fb1a09
--- /dev/null
+++ b/test/fixtures/mastodon-announce.json
@@ -0,0 +1,37 @@
+{
+  "type": "Announce",
+  "to": [
+    "https://www.w3.org/ns/activitystreams#Public"
+  ],
+  "signature": {
+    "type": "RsaSignature2017",
+    "signatureValue": "T95DRE0eAligvMuRMkQA01lsoz2PKi4XXF+cyZ0BqbrO12p751TEWTyyRn5a+HH0e4kc77EUhQVXwMq80WAYDzHKVUTf2XBJPBa68vl0j6RXw3+HK4ef5hR4KWFNBU34yePS7S1fEmc1mTG4Yx926wtmZwDpEMTp1CXOeVEjCYzmdyHpepPPH2ZZettiacmPRSqBLPGWZoot7kH/SioIdnrMGY0I7b+rqkIdnnEcdhu9N1BKPEO9Sr+KmxgAUiidmNZlbBXX6gCxp8BiIdH4ABsIcwoDcGNkM5EmWunGW31LVjsEQXhH5c1Wly0ugYYPCg/0eHLNBOhKkY/teSM8Lg==",
+    "creator": "https://social.tcit.fr/users/tcit#main-key",
+    "created": "2018-02-17T19:39:15Z"
+  },
+  "published": "2018-02-17T19:39:15Z",
+  "object": "https://social.tcit.fr/@tcit/101188891162897047",
+  "id": "https://social.tcit.fr/users/tcit/statuses/101188891162897047/activity",
+  "cc": [
+    "https://social.tcit.fr/users/tcit",
+    "https://social.tcit.fr/users/tcit/followers"
+  ],
+  "atomUri": "https://social.tcit.fr/users/tcit/statuses/101188891162897047/activity",
+  "actor": "https://social.tcit.fr/users/tcit",
+  "@context": [
+    "https://www.w3.org/ns/activitystreams",
+    "https://w3id.org/security/v1",
+    {
+      "toot": "http://joinmastodon.org/ns#",
+      "sensitive": "as:sensitive",
+      "ostatus": "http://ostatus.org#",
+      "movedTo": "as:movedTo",
+      "manuallyApprovesFollowers": "as:manuallyApprovesFollowers",
+      "inReplyToAtomUri": "ostatus:inReplyToAtomUri",
+      "conversation": "ostatus:conversation",
+      "atomUri": "ostatus:atomUri",
+      "Hashtag": "as:Hashtag",
+      "Emoji": "toot:Emoji"
+    }
+  ]
+}
diff --git a/test/fixtures/mastodon-delete.json b/test/fixtures/mastodon-delete.json
new file mode 100644
index 00000000..87a58200
--- /dev/null
+++ b/test/fixtures/mastodon-delete.json
@@ -0,0 +1,33 @@
+{
+  "type": "Delete",
+  "signature": {
+    "type": "RsaSignature2017",
+    "signatureValue": "cw0RlfNREf+5VdsOYcCBDrv521eiLsDTAYNHKffjF0bozhCnOh+wHkFik7WamUk$
+uEiN4L2H6vPlGRprAZGRhEwgy+A7rIFQNmLrpW5qV5UNVI/2F7kngEHqZQgbQYj9hW+5GMYmPkHdv3D72ZefGw$
+4Xa2NBLGFpAjQllfzt7kzZLKKY2DM99FdUa64I2Wj3iD04Hs23SbrUdAeuGk/c1Cg6bwGNG4vxoiwn1jikgJLA$
+NAlSGjsRGdR7LfbC7GqWWsW3cSNsLFPoU6FyALjgTrrYoHiXe0QHggw+L3yMLfzB2S/L46/VRbyb+WDKMBIXUL$
+5owmzHSi6e/ZtCI3w==",
+    "creator": "http://mastodon.example.org/users/gargron#main-key",                       "created": "2018-03-03T16:24:11Z"
+  },
+  "object": {
+    "type": "Tombstone",
+    "id": "http://mastodon.example.org/users/gargron/statuses/99620895606148759",
+    "atomUri": "http://mastodon.example.org/users/gargron/statuses/99620895606148759"
+  },
+  "id": "http://mastodon.example.org/users/gargron/statuses/99620895606148759#delete",
+  "actor": "http://mastodon.example.org/users/gargron",
+  "@context": [
+    {
+      "toot": "http://joinmastodon.org/ns#",
+      "sensitive": "as:sensitive",
+      "ostatus": "http://ostatus.org#",
+      "movedTo": "as:movedTo",
+      "manuallyApprovesFollowers": "as:manuallyApprovesFollowers",
+      "inReplyToAtomUri": "ostatus:inReplyToAtomUri",
+      "conversation": "ostatus:conversation",
+      "atomUri": "ostatus:atomUri",
+      "Hashtag": "as:Hashtag",
+      "Emoji": "toot:Emoji"
+    }
+  ]
+}
diff --git a/test/fixtures/mastodon-follow-activity.json b/test/fixtures/mastodon-follow-activity.json
new file mode 100644
index 00000000..298847c0
--- /dev/null
+++ b/test/fixtures/mastodon-follow-activity.json
@@ -0,0 +1,29 @@
+{
+  "type": "Follow",
+  "signature": {
+    "type": "RsaSignature2017",
+    "signatureValue": "Kn1/UkAQGJVaXBfWLAHcnwHg8YMAUqlEaBuYLazAG+pz5hqivsyrBmPV186Xzr+B4ZLExA9+SnOoNx/GOz4hBm0kAmukNSILAsUd84tcJ2yT9zc1RKtembK4WiwOw7li0+maeDN0HaB6t+6eTqsCWmtiZpprhXD8V1GGT8yG7X24fQ9oFGn+ng7lasbcCC0988Y1eGqNe7KryxcPuQz57YkDapvtONzk8gyLTkZMV4De93MyRHq6GVjQVIgtiYabQAxrX6Q8C+4P/jQoqdWJHEe+MY5JKyNaT/hMPt2Md1ok9fZQBGHlErk22/zy8bSN19GdG09HmIysBUHRYpBLig==",
+    "creator": "https://social.tcit.fr/users/tcit#main-key",
+    "created": "2018-02-17T13:29:31Z"
+  },
+  "object": "http://localtesting.pleroma.lol/users/lain",
+  "nickname": "lain",
+  "id": "https://social.tcit.fr/users/tcit#follows/2",
+  "actor": "https://social.tcit.fr/users/tcit",
+  "@context": [
+    "https://www.w3.org/ns/activitystreams",
+    "https://w3id.org/security/v1",
+    {
+      "toot": "http://joinmastodon.org/ns#",
+      "sensitive": "as:sensitive",
+      "ostatus": "http://ostatus.org#",
+      "movedTo": "as:movedTo",
+      "manuallyApprovesFollowers": "as:manuallyApprovesFollowers",
+      "inReplyToAtomUri": "ostatus:inReplyToAtomUri",
+      "conversation": "ostatus:conversation",
+      "atomUri": "ostatus:atomUri",
+      "Hashtag": "as:Hashtag",
+      "Emoji": "toot:Emoji"
+    }
+  ]
+}
\ No newline at end of file
diff --git a/test/fixtures/mastodon-like.json b/test/fixtures/mastodon-like.json
new file mode 100644
index 00000000..39fb44c4
--- /dev/null
+++ b/test/fixtures/mastodon-like.json
@@ -0,0 +1,29 @@
+{
+  "type": "Like",
+  "signature": {
+    "type": "RsaSignature2017",
+    "signatureValue": "fdxMfQSMwbC6wP6sh6neS/vM5879K67yQkHTbiT5Npr5wAac0y6+o3Ij+41tN3rL6wfuGTosSBTHOtta6R4GCOOhCaCSLMZKypnp1VltCzLDoyrZELnYQIC8gpUXVmIycZbREk22qWUe/w7DAFaKK4UscBlHDzeDVcA0K3Se5Sluqi9/Zh+ldAnEzj/rSEPDjrtvf5wGNf3fHxbKSRKFt90JvKK6hS+vxKUhlRFDf6/SMETw+EhwJSNW4d10yMUakqUWsFv4Acq5LW7l+HpYMvlYY1FZhNde1+uonnCyuQDyvzkff8zwtEJmAXC4RivO/VVLa17SmqheJZfI8oluVg==",
+    "creator": "http://mastodon.example.org/users/admin#main-key",
+    "created": "2018-02-17T18:57:49Z"
+  },
+  "object": "http://localtesting.pleroma.lol/objects/eb92579d-3417-42a8-8652-2492c2d4f454",
+  "nickname": "lain",
+  "id": "http://mastodon.example.org/users/admin#likes/2",
+  "actor": "http://mastodon.example.org/users/admin",
+  "@context": [
+    "https://www.w3.org/ns/activitystreams",
+    "https://w3id.org/security/v1",
+    {
+      "toot": "http://joinmastodon.org/ns#",
+      "sensitive": "as:sensitive",
+      "ostatus": "http://ostatus.org#",
+      "movedTo": "as:movedTo",
+      "manuallyApprovesFollowers": "as:manuallyApprovesFollowers",
+      "inReplyToAtomUri": "ostatus:inReplyToAtomUri",
+      "conversation": "ostatus:conversation",
+      "atomUri": "ostatus:atomUri",
+      "Hashtag": "as:Hashtag",
+      "Emoji": "toot:Emoji"
+    }
+  ]
+}
\ No newline at end of file
diff --git a/test/fixtures/mastodon-post-activity-hashtag.json b/test/fixtures/mastodon-post-activity-hashtag.json
new file mode 100644
index 00000000..b556343e
--- /dev/null
+++ b/test/fixtures/mastodon-post-activity-hashtag.json
@@ -0,0 +1,70 @@
+{
+    "@context": [
+        "https://www.w3.org/ns/activitystreams",
+        "https://w3id.org/security/v1",
+        {
+            "Emoji": "toot:Emoji",
+            "Hashtag": "as:Hashtag",
+            "atomUri": "ostatus:atomUri",
+            "conversation": "ostatus:conversation",
+            "inReplyToAtomUri": "ostatus:inReplyToAtomUri",
+            "manuallyApprovesFollowers": "as:manuallyApprovesFollowers",
+            "movedTo": "as:movedTo",
+            "ostatus": "http://ostatus.org#",
+            "sensitive": "as:sensitive",
+            "toot": "http://joinmastodon.org/ns#"
+        }
+    ],
+    "actor": "https://framapiaf.org/users/admin",
+    "cc": [
+        "https://framapiaf.org/users/admin/followers",
+        "http://mobilizon.com/@tcit"
+    ],
+    "id": "https://framapiaf.org/users/admin/statuses/99512778738411822/activity",
+    "nickname": "lain",
+    "object": {
+        "atomUri": "https://framapiaf.org/users/admin/statuses/99512778738411822",
+        "attachment": [],
+        "attributedTo": "https://framapiaf.org/users/admin",
+        "cc": [
+            "https://framapiaf.org/users/admin/followers",
+            "http://localtesting.pleroma.lol/users/lain"
+        ],
+        "content": "<p><span class=\"h-card\"><a href=\"http://localtesting.pleroma.lol/users/lain\" class=\"u-url mention\">@<span>lain</span></a></span> #moo</p>",
+        "conversation": "tag:mastodon.example.org,2018-02-12:objectId=20:objectType=Conversation",
+        "id": "https://framapiaf.org/users/admin/statuses/99512778738411822",
+        "inReplyTo": null,
+        "inReplyToAtomUri": null,
+        "published": "2018-02-12T14:08:20Z",
+        "sensitive": true,
+        "summary": "cw",
+        "tag": [
+            {
+                "href": "http://localtesting.pleroma.lol/users/lain",
+                "name": "@lain@localtesting.pleroma.lol",
+                "type": "Mention"
+            },
+            {
+                "href": "http://mastodon.example.org/tags/moo",
+                "name": "#moo",
+                "type": "Hashtag"
+            }
+        ],
+        "to": [
+            "https://www.w3.org/ns/activitystreams#Public"
+        ],
+        "type": "Note",
+        "url": "https://framapiaf.org/@admin/99512778738411822"
+    },
+    "published": "2018-02-12T14:08:20Z",
+    "signature": {
+        "created": "2018-02-12T14:08:20Z",
+        "creator": "https://framapiaf.org/users/admin#main-key",
+        "signatureValue": "rnNfcopkc6+Ju73P806popcfwrK9wGYHaJVG1/ZvrlEbWVDzaHjkXqj9Q3/xju5l8CSn9tvSgCCtPFqZsFQwn/pFIFUcw7ZWB2xi4bDm3NZ3S4XQ8JRaaX7og5hFxAhWkGhJhAkfxVnOg2hG+w2d/7d7vRVSC1vo5ip4erUaA/PkWusZvPIpxnRWoXaxJsFmVx0gJgjpJkYDyjaXUlp+jmaoseeZ4EPQUWqHLKJ59PRG0mg8j2xAjYH9nQaN14qMRmTGPxY8gfv/CUFcatA+8VJU9KEsJkDAwLVvglydNTLGrxpAJU78a2eaht0foV43XUIZGe3DKiJPgE+UOKGCJw==",
+        "type": "RsaSignature2017"
+    },
+    "to": [
+        "https://www.w3.org/ns/activitystreams#Public"
+    ],
+    "type": "Create"
+}
diff --git a/test/fixtures/mastodon-post-activity.json b/test/fixtures/mastodon-post-activity.json
index 9adac0d5..69bd101b 100644
--- a/test/fixtures/mastodon-post-activity.json
+++ b/test/fixtures/mastodon-post-activity.json
@@ -15,24 +15,24 @@
             "toot": "http://joinmastodon.org/ns#"
         }
     ],
-    "actor": "http://framapiaf.org/users/admin",
+    "actor": "https://framapiaf.org/users/admin",
     "cc": [
-        "http://framapiaf.org/users/admin/followers",
+        "https://framapiaf.org/users/admin/followers",
         "http://mobilizon.com/@tcit"
     ],
-    "id": "http://framapiaf.org/users/admin/statuses/99512778738411822/activity",
+    "id": "https://framapiaf.org/users/admin/statuses/99512778738411822/activity",
     "nickname": "lain",
     "object": {
-        "atomUri": "http://framapiaf.org/users/admin/statuses/99512778738411822",
+        "atomUri": "https://framapiaf.org/users/admin/statuses/99512778738411822",
         "attachment": [],
-        "attributedTo": "http://framapiaf.org/users/admin",
+        "attributedTo": "https://framapiaf.org/users/admin",
         "cc": [
-            "http://framapiaf.org/users/admin/followers",
+            "https://framapiaf.org/users/admin/followers",
             "http://localtesting.pleroma.lol/users/lain"
         ],
         "content": "<p><span class=\"h-card\"><a href=\"http://localtesting.pleroma.lol/users/lain\" class=\"u-url mention\">@<span>lain</span></a></span></p>",
         "conversation": "tag:mastodon.example.org,2018-02-12:objectId=20:objectType=Conversation",
-        "id": "http://framapiaf.org/users/admin/statuses/99512778738411822",
+        "id": "https://framapiaf.org/users/admin/statuses/99512778738411822",
         "inReplyTo": null,
         "inReplyToAtomUri": null,
         "published": "2018-02-12T14:08:20Z",
@@ -49,12 +49,12 @@
             "https://www.w3.org/ns/activitystreams#Public"
         ],
         "type": "Note",
-        "url": "http://framapiaf.org/@admin/99512778738411822"
+        "url": "https://framapiaf.org/@admin/99512778738411822"
     },
     "published": "2018-02-12T14:08:20Z",
     "signature": {
         "created": "2018-02-12T14:08:20Z",
-        "creator": "http://framapiaf.org/users/admin#main-key",
+        "creator": "https://framapiaf.org/users/admin#main-key",
         "signatureValue": "rnNfcopkc6+Ju73P806popcfwrK9wGYHaJVG1/ZvrlEbWVDzaHjkXqj9Q3/xju5l8CSn9tvSgCCtPFqZsFQwn/pFIFUcw7ZWB2xi4bDm3NZ3S4XQ8JRaaX7og5hFxAhWkGhJhAkfxVnOg2hG+w2d/7d7vRVSC1vo5ip4erUaA/PkWusZvPIpxnRWoXaxJsFmVx0gJgjpJkYDyjaXUlp+jmaoseeZ4EPQUWqHLKJ59PRG0mg8j2xAjYH9nQaN14qMRmTGPxY8gfv/CUFcatA+8VJU9KEsJkDAwLVvglydNTLGrxpAJU78a2eaht0foV43XUIZGe3DKiJPgE+UOKGCJw==",
         "type": "RsaSignature2017"
     },
diff --git a/test/fixtures/mastodon-undo-announce.json b/test/fixtures/mastodon-undo-announce.json
new file mode 100644
index 00000000..05332bed
--- /dev/null
+++ b/test/fixtures/mastodon-undo-announce.json
@@ -0,0 +1,47 @@
+{
+   "type": "Undo",
+   "signature": {
+     "type": "RsaSignature2017",
+     "signatureValue": "VU9AmHf3Pus9cWtMG/TOdxr+MRQfPHdTVKBBgFJBXhAlMhxEtcbxsu7zmqBgfIz6u0HpTCi5jRXEMftc228OJf/aBUkr4hyWADgcdmhPQgpibouDLgQf9BmnrPqb2rMbzZyt49GJkQZma8taLh077TTq6OKcnsAAJ1evEKOcRYS4OxBSwh4nI726bOXzZWoNzpTcrnm+llcUEN980sDSAS0uyZdb8AxZdfdG6DJQX4AkUD5qTpfqP/vC1ISirrNphvVhlxjUV9Amr4SYTsLx80vdZe5NjeL5Ir4jTIIQLedpxaDu1M9Q+Jpc0fYByQ2hOwUq8JxEmvHvarKjrq0Oww==",
+     "creator": "http://mastodon.example.org/users/admin#main-key",
+     "created": "2018-05-11T16:23:45Z"
+   },
+   "object": {
+     "type": "Announce",
+     "to": [
+       "http://www.w3.org/ns/activitystreams#Public"
+     ],
+     "published": "2018-05-11T16:23:37Z",
+     "object": "http://mastodon.example.org/@admin/99541947525187367",
+     "id": "http://mastodon.example.org/users/admin/statuses/99542391527669785/activity",
+     "cc": [
+       "http://mastodon.example.org/users/admin",
+       "http://mastodon.example.org/users/admin/followers"
+     ],
+     "atomUri": "http://mastodon.example.org/users/admin/statuses/99542391527669785/activity",
+     "actor": "http://mastodon.example.org/users/admin"
+   },
+   "id": "http://mastodon.example.org/users/admin#announces/100011594053806179/undo",
+   "actor": "http://mastodon.example.org/users/admin",
+   "@context": [
+     "http://www.w3.org/ns/activitystreams",
+     "http://w3id.org/security/v1",
+     {
+       "toot": "http://joinmastodon.org/ns#",
+       "sensitive": "as:sensitive",
+       "ostatus": "http://ostatus.org#",
+       "movedTo": "as:movedTo",
+       "manuallyApprovesFollowers": "as:manuallyApprovesFollowers",
+       "inReplyToAtomUri": "ostatus:inReplyToAtomUri",
+       "focalPoint": {
+         "@id": "toot:focalPoint",
+         "@container": "@list"
+       },
+       "featured": "toot:featured",
+       "conversation": "ostatus:conversation",
+       "atomUri": "ostatus:atomUri",
+       "Hashtag": "as:Hashtag",
+       "Emoji": "toot:Emoji"
+     }
+   ]
+}
diff --git a/test/fixtures/mastodon-undo-like.json b/test/fixtures/mastodon-undo-like.json
new file mode 100644
index 00000000..0cbed30f
--- /dev/null
+++ b/test/fixtures/mastodon-undo-like.json
@@ -0,0 +1,34 @@
+{
+  "type": "Undo",
+  "signature": {
+    "type": "RsaSignature2017",
+    "signatureValue": "fdxMfQSMwbC6wP6sh6neS/vM5879K67yQkHTbiT5Npr5wAac0y6+o3Ij+41tN3rL6wfuGTosSBTHOtta6R4GCOOhCaCSLMZKypnp1VltCzLDoyrZELnYQIC8gpUXVmIycZbREk22qWUe/w7DAFaKK4UscBlHDzeDVcA0K3Se5Sluqi9/Zh+ldAnEzj/rSEPDjrtvf5wGNf3fHxbKSRKFt90JvKK6hS+vxKUhlRFDf6/SMETw+EhwJSNW4d10yMUakqUWsFv4Acq5LW7l+HpYMvlYY1FZhNde1+uonnCyuQDyvzkff8zwtEJmAXC4RivO/VVLa17SmqheJZfI8oluVg==",
+    "creator": "http://mastodon.example.org/users/admin#main-key",
+    "created": "2018-05-19T16:36:58Z"
+  },
+  "object": {
+    "type": "Like",
+    "object": "http://localtesting.pleroma.lol/objects/eb92579d-3417-42a8-8652-2492c2d4f454",
+    "id": "http://mastodon.example.org/users/admin#likes/2",
+    "actor": "http://mastodon.example.org/users/admin"
+  },
+  "nickname": "lain",
+  "id": "http://mastodon.example.org/users/admin#likes/2/undo",
+  "actor": "http://mastodon.example.org/users/admin",
+  "@context": [
+    "https://www.w3.org/ns/activitystreams",
+    "https://w3id.org/security/v1",
+    {
+      "toot": "http://joinmastodon.org/ns#",
+      "sensitive": "as:sensitive",
+      "ostatus": "http://ostatus.org#",
+      "movedTo": "as:movedTo",
+      "manuallyApprovesFollowers": "as:manuallyApprovesFollowers",
+      "inReplyToAtomUri": "ostatus:inReplyToAtomUri",
+      "conversation": "ostatus:conversation",
+      "atomUri": "ostatus:atomUri",
+      "Hashtag": "as:Hashtag",
+      "Emoji": "toot:Emoji"
+    }
+  ]
+}
\ No newline at end of file
diff --git a/test/fixtures/mastodon-unfollow-activity.json b/test/fixtures/mastodon-unfollow-activity.json
new file mode 100644
index 00000000..8b78524c
--- /dev/null
+++ b/test/fixtures/mastodon-unfollow-activity.json
@@ -0,0 +1,34 @@
+{
+   "@context":[
+      "https://www.w3.org/ns/activitystreams",
+      "https://w3id.org/security/v1",
+      {
+         "toot":"http://joinmastodon.org/ns#",
+         "sensitive":"as:sensitive",
+         "ostatus":"http://ostatus.org#",
+         "movedTo":"as:movedTo",
+         "manuallyApprovesFollowers":"as:manuallyApprovesFollowers",
+         "inReplyToAtomUri":"ostatus:inReplyToAtomUri",
+         "conversation":"ostatus:conversation",
+         "atomUri":"ostatus:atomUri",
+         "Hashtag":"as:Hashtag",
+         "Emoji":"toot:Emoji"
+      }
+   ],
+   "signature":{
+      "type":"RsaSignature2017",
+      "signatureValue":"Kn1/UkAQGJVaXBfWLAHcnwHg8YMAUqlEaBuYLazAG+pz5hqivsyrBmPV186Xzr+B4ZLExA9+SnOoNx/GOz4hBm0kAmukNSILAsUd84tcJ2yT9zc1RKtembK4WiwOw7li0+maeDN0HaB6t+6eTqsCWmtiZpprhXD8V1GGT8yG7X24fQ9oFGn+ng7lasbcCC0988Y1eGqNe7KryxcPuQz57YkDapvtONzk8gyLTkZMV4De93MyRHq6GVjQVIgtiYabQAxrX6Q8C+4P/jQoqdWJHEe+MY5JKyNaT/hMPt2Md1ok9fZQBGHlErk22/zy8bSN19GdG09HmIysBUHRYpBLig==",
+      "creator":"https://social.tcit.fr/users/tcit#main-key",
+      "created":"2018-02-17T13:29:31Z"
+   },
+   "type":"Undo",
+   "object":{
+      "type":"Follow",
+      "object":"http://localtesting.pleroma.lol/users/lain",
+      "nickname":"lain",
+      "id":"https://social.tcit.fr/users/tcit#follows/2",
+      "actor":"https://social.tcit.fr/users/tcit"
+   },
+   "actor":"https://social.tcit.fr/users/tcit",
+   "id": "https://social.tcit.fr/users/tcit#follow/2/undo"
+}
diff --git a/test/fixtures/mastodon-update.json b/test/fixtures/mastodon-update.json
new file mode 100644
index 00000000..f6713fea
--- /dev/null
+++ b/test/fixtures/mastodon-update.json
@@ -0,0 +1,43 @@
+{                                                                               
+  "type": "Update",                                                                    
+  "object": {                                                                          
+    "url": "http://mastodon.example.org/@gargron",                                     
+    "type": "Person",                                                                  
+    "summary": "<p>Some bio</p>",                                                              
+    "publicKey": {                                                                     
+      "publicKeyPem": "-----BEGIN PUBLIC KEY-----\nMIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEA0gs3VnQf6am3R+CeBV4H\nlfI1HZTNRIBHgvFszRZkCERbRgEWMu+P+I6/7GJC5H5jhVQ60z4MmXcyHOGmYMK/\n5XyuHQz7V2Ssu1AxLfRN5Biq1ayb0+DT/E7QxNXDJPqSTnstZ6C7zKH/uAETqg3l\nBonjCQWyds+IYbQYxf5Sp3yhvQ80lMwHML3DaNCMlXWLoOnrOX5/yK5+dedesg2\n/HIvGk+HEt36vm6hoH7bwPuEkgA++ACqwjXRe5Mta7i3eilHxFaF8XIrJFARV0t\nqOu4GID/jG6oA+swIWndGrtR2QRJIt9QIBFfK3HG5M0koZbY1eTqwNFRHFL3xaD\nUQIDAQAB\n-----END PUBLIC KEY-----\n",
+      "owner": "http://mastodon.example.org/users/gargron",
+      "id": "http://mastodon.example.org/users/gargron#main-key"
+    },
+    "preferredUsername": "gargron",
+    "outbox": "http://mastodon.example.org/users/gargron/outbox",
+    "name": "gargle",
+    "manuallyApprovesFollowers": false,
+    "inbox": "http://mastodon.example.org/users/gargron/inbox",
+    "id": "http://mastodon.example.org/users/gargron",
+    "following": "http://mastodon.example.org/users/gargron/following",
+    "followers": "http://mastodon.example.org/users/gargron/followers",
+    "endpoints": {
+      "sharedInbox": "http://mastodon.example.org/inbox"
+    },
+    "icon":{"type":"Image","mediaType":"image/jpeg","url":"https://cd.niu.moe/accounts/avatars/000/033/323/original/fd7f8ae0b3ffedc9.jpeg"},"image":{"type":"Image","mediaType":"image/png","url":"https://cd.niu.moe/accounts/headers/000/033/323/original/850b3448fa5fd477.png"}
+  },
+  "id": "http://mastodon.example.org/users/gargron#updates/1519563538",
+  "actor": "http://mastodon.example.org/users/gargron",
+  "@context": [
+    "https://www.w3.org/ns/activitystreams",
+    "https://w3id.org/security/v1",
+    {
+      "toot": "http://joinmastodon.org/ns#",
+      "sensitive": "as:sensitive",
+      "ostatus": "http://ostatus.org#",
+      "movedTo": "as:movedTo",
+      "manuallyApprovesFollowers": "as:manuallyApprovesFollowers",
+      "inReplyToAtomUri": "ostatus:inReplyToAtomUri",
+      "conversation": "ostatus:conversation",
+      "atomUri": "ostatus:atomUri",
+      "Hashtag": "as:Hashtag",
+      "Emoji": "toot:Emoji"
+    }
+  ]
+}
diff --git a/test/fixtures/prismo-url-map.json b/test/fixtures/prismo-url-map.json
new file mode 100644
index 00000000..4e2e2fd4
--- /dev/null
+++ b/test/fixtures/prismo-url-map.json
@@ -0,0 +1,65 @@
+{
+    "id": "https://prismo.news/posts/83#Create",
+    "type": "Create",
+    "actor": [
+        {
+            "type": "Person",
+            "id": "https://prismo.news/@mxb"
+        }
+    ],
+    "to": [
+        "https://www.w3.org/ns/activitystreams#Public"
+    ],
+    "object": {
+        "id": "https://prismo.news/posts/83",
+        "type": "Article",
+        "name": "Introducing: Federated follows!",
+        "published": "2018-11-01T07:10:05Z",
+        "content": "We are more than thrilled to announce that Prismo now supports federated follows! It means you ca...",
+        "url": {
+            "type": "Link",
+            "mimeType": "text/html",
+            "href": "https://prismo.news/posts/83"
+        },
+        "votes": 12,
+        "attributedTo": [
+            {
+                "type": "Person",
+                "id": "https://prismo.news/@mxb"
+            }
+        ],
+        "to": [
+            "https://www.w3.org/ns/activitystreams#Public"
+        ],
+        "tags": [
+            {
+                "type": "Hashtag",
+                "href": "https://prismo.news/tags/prismo",
+                "name": "#prismo"
+            },
+            {
+                "type": "Hashtag",
+                "href": "https://prismo.news/tags/prismodev",
+                "name": "#prismodev"
+            },
+            {
+                "type": "Hashtag",
+                "href": "https://prismo.news/tags/meta",
+                "name": "#meta"
+            }
+        ],
+        "@context": [
+            "https://www.w3.org/ns/activitystreams",
+            "https://w3id.org/security/v1",
+            {
+                "Hashtag": "as:Hashtag"
+            },
+            {
+                "votes": {
+                    "@id": "as:votes",
+                    "@type": "@id"
+                }
+            }
+        ]
+    }
+}
diff --git a/test/fixtures/vcr_cassettes/activity_pub/fetch_reply_to_framatube.json b/test/fixtures/vcr_cassettes/activity_pub/fetch_reply_to_framatube.json
new file mode 100644
index 00000000..c139ac15
--- /dev/null
+++ b/test/fixtures/vcr_cassettes/activity_pub/fetch_reply_to_framatube.json
@@ -0,0 +1,118 @@
+[
+  {
+    "request": {
+      "body": "",
+      "headers": {
+        "Accept": "application/activity+json"
+      },
+      "method": "get",
+      "options": {
+        "follow_redirect": "true",
+        "recv_timeout": 20000,
+        "connect_timeout": 10000
+      },
+      "request_body": "",
+      "url": "https://framatube.org/videos/watch/7e261f9e-242c-4100-a0bd-268dab321114"
+    },
+    "response": {
+      "binary": false,
+      "body": "{\"type\":\"Video\",\"id\":\"https://framatube.org/videos/watch/7e261f9e-242c-4100-a0bd-268dab321114\",\"name\":\"Contributopia : Peut-on faire du libre sans vision politique ? — Pierre-Yves Gosset\",\"duration\":\"PT4332S\",\"uuid\":\"7e261f9e-242c-4100-a0bd-268dab321114\",\"tag\":[{\"type\":\"Hashtag\",\"name\":\"contributopia\"},{\"type\":\"Hashtag\",\"name\":\"framaconf\"},{\"type\":\"Hashtag\",\"name\":\"framasoft\"},{\"type\":\"Hashtag\",\"name\":\"libre\"},{\"type\":\"Hashtag\",\"name\":\"politique\"}],\"category\":{\"identifier\":\"15\",\"name\":\"Science & Technology\"},\"licence\":{\"identifier\":\"2\",\"name\":\"Attribution - Share Alike\"},\"language\":{\"identifier\":\"fr\",\"name\":\"French\"},\"views\":83,\"sensitive\":false,\"waitTranscoding\":false,\"state\":1,\"commentsEnabled\":true,\"published\":\"2018-11-26T17:11:02.993Z\",\"updated\":\"2018-12-03T22:01:01.919Z\",\"mediaType\":\"text/markdown\",\"content\":\"Suite à sa campagne \\\"Dégooglisons Internet\\\" (oct 2014 - oct 2017), l'association a fait le bilan, calmement. 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new file mode 100644
index 00000000..17bb733a
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       "binary": false,
-      "body": "{\"@context\":[\"https://www.w3.org/ns/activitystreams\",\"https://w3id.org/security/v1\",{\"manuallyApprovesFollowers\":\"as:manuallyApprovesFollowers\",\"sensitive\":\"as:sensitive\",\"movedTo\":{\"@id\":\"as:movedTo\",\"@type\":\"@id\"},\"Hashtag\":\"as:Hashtag\",\"ostatus\":\"http://ostatus.org#\",\"atomUri\":\"ostatus:atomUri\",\"inReplyToAtomUri\":\"ostatus:inReplyToAtomUri\",\"conversation\":\"ostatus:conversation\",\"toot\":\"http://joinmastodon.org/ns#\",\"Emoji\":\"toot:Emoji\",\"focalPoint\":{\"@container\":\"@list\",\"@id\":\"toot:focalPoint\"},\"featured\":{\"@id\":\"toot:featured\",\"@type\":\"@id\"},\"schema\":\"http://schema.org#\",\"PropertyValue\":\"schema:PropertyValue\",\"value\":\"schema:value\"}],\"id\":\"https://framapiaf.org/users/admin\",\"type\":\"Person\",\"following\":\"https://framapiaf.org/users/admin/following\",\"followers\":\"https://framapiaf.org/users/admin/followers\",\"inbox\":\"https://framapiaf.org/users/admin/inbox\",\"outbox\":\"https://framapiaf.org/users/admin/outbox\",\"featured\":\"https://framapiaf.org/users/admin/collections/featured\",\"preferredUsername\":\"admin\",\"name\":\"\",\"summary\":\"\\u003cp\\u003e\\u003c/p\\u003e\",\"url\":\"https://framapiaf.org/@admin\",\"manuallyApprovesFollowers\":false,\"publicKey\":{\"id\":\"https://framapiaf.org/users/admin#main-key\",\"owner\":\"https://framapiaf.org/users/admin\",\"publicKeyPem\":\"-----BEGIN PUBLIC KEY-----\\nMIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAyHaU/AZ5dWtSxZXkPa89\\nDUQ4z+JQHGGUG/xkGuq0v8P6qJfQqtHPBO5vH0IQJqluXWQS96gqTwjZnYevcpNA\\nveYv0K25DWszx5Ehz6JX2/sSvu2rNUcQ3YZvSjdo/Yy1u5Fuc5lLmvw8uFzXYekD\\nWovTMOnp4mIKpVEm/G/v4w8jvFEKw88h743vwaEIim88GEQItMxzGAV6zSqV1DWO\\nLxtoRsinslJYfAG46ex4YUATFveWvOUeWk5W1sEa5f3c0moaTmBM/PAAo8vLxhlw\\nJhsHihsCH+BcXKVMjW8OCqYYqISMxEifUBX63HcJt78ELHpOuc1c2eG59PomtTjQ\\nywIDAQAB\\n-----END PUBLIC KEY-----\\n\"},\"tag\":[],\"attachment\":[],\"endpoints\":{\"sharedInbox\":\"https://framapiaf.org/inbox\"}}",
+      "body": "{\"@context\":[\"https://www.w3.org/ns/activitystreams\",\"https://w3id.org/security/v1\",{\"manuallyApprovesFollowers\":\"as:manuallyApprovesFollowers\",\"sensitive\":\"as:sensitive\",\"movedTo\":{\"@id\":\"as:movedTo\",\"@type\":\"@id\"},\"Hashtag\":\"as:Hashtag\",\"ostatus\":\"http://ostatus.org#\",\"atomUri\":\"ostatus:atomUri\",\"inReplyToAtomUri\":\"ostatus:inReplyToAtomUri\",\"conversation\":\"ostatus:conversation\",\"toot\":\"http://joinmastodon.org/ns#\",\"Emoji\":\"toot:Emoji\",\"focalPoint\":{\"@container\":\"@list\",\"@id\":\"toot:focalPoint\"},\"featured\":{\"@id\":\"toot:featured\",\"@type\":\"@id\"},\"schema\":\"http://schema.org#\",\"PropertyValue\":\"schema:PropertyValue\",\"value\":\"schema:value\"}],\"id\":\"https://framapiaf.org/users/admin\",\"type\":\"Service\",\"following\":\"https://framapiaf.org/users/admin/following\",\"followers\":\"https://framapiaf.org/users/admin/followers\",\"inbox\":\"https://framapiaf.org/users/admin/inbox\",\"outbox\":\"https://framapiaf.org/users/admin/outbox\",\"featured\":\"https://framapiaf.org/users/admin/collections/featured\",\"preferredUsername\":\"admin\",\"name\":\"Administrateur\",\"summary\":\"\\u003cp\\u003eJe ne suis qu\\u0026apos;un compte inutile. Merci nous de contacter via \\u003ca href=\\\"https://contact.framasoft.org/\\\" rel=\\\"nofollow noopener\\\" target=\\\"_blank\\\"\\u003e\\u003cspan class=\\\"invisible\\\"\\u003ehttps://\\u003c/span\\u003e\\u003cspan class=\\\"\\\"\\u003econtact.framasoft.org/\\u003c/span\\u003e\\u003cspan class=\\\"invisible\\\"\\u003e\\u003c/span\\u003e\\u003c/a\\u003e\\u003c/p\\u003e\",\"url\":\"https://framapiaf.org/@admin\",\"manuallyApprovesFollowers\":false,\"publicKey\":{\"id\":\"https://framapiaf.org/users/admin#main-key\",\"owner\":\"https://framapiaf.org/users/admin\",\"publicKeyPem\":\"-----BEGIN PUBLIC KEY-----\\nMIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAyHaU/AZ5dWtSxZXkPa89\\nDUQ4z+JQHGGUG/xkGuq0v8P6qJfQqtHPBO5vH0IQJqluXWQS96gqTwjZnYevcpNA\\nveYv0K25DWszx5Ehz6JX2/sSvu2rNUcQ3YZvSjdo/Yy1u5Fuc5lLmvw8uFzXYekD\\nWovTMOnp4mIKpVEm/G/v4w8jvFEKw88h743vwaEIim88GEQItMxzGAV6zSqV1DWO\\nLxtoRsinslJYfAG46ex4YUATFveWvOUeWk5W1sEa5f3c0moaTmBM/PAAo8vLxhlw\\nJhsHihsCH+BcXKVMjW8OCqYYqISMxEifUBX63HcJt78ELHpOuc1c2eG59PomtTjQ\\nywIDAQAB\\n-----END PUBLIC KEY-----\\n\"},\"tag\":[],\"attachment\":[{\"type\":\"PropertyValue\",\"name\":\"News\",\"value\":\"\\u003cspan class=\\\"h-card\\\"\\u003e\\u003ca href=\\\"https://framapiaf.org/@Framasoft\\\" class=\\\"u-url mention\\\"\\u003e@\\u003cspan\\u003eFramasoft\\u003c/span\\u003e\\u003c/a\\u003e\\u003c/span\\u003e\"},{\"type\":\"PropertyValue\",\"name\":\"Support\",\"value\":\"\\u003ca href=\\\"https://contact.framasoft.org/\\\" rel=\\\"me nofollow noopener\\\" target=\\\"_blank\\\"\\u003e\\u003cspan class=\\\"invisible\\\"\\u003ehttps://\\u003c/span\\u003e\\u003cspan class=\\\"\\\"\\u003econtact.framasoft.org/\\u003c/span\\u003e\\u003cspan class=\\\"invisible\\\"\\u003e\\u003c/span\\u003e\\u003c/a\\u003e\"},{\"type\":\"PropertyValue\",\"name\":\"Soutenir\",\"value\":\"\\u003ca href=\\\"https://soutenir.framasoft.org/\\\" rel=\\\"me nofollow noopener\\\" target=\\\"_blank\\\"\\u003e\\u003cspan class=\\\"invisible\\\"\\u003ehttps://\\u003c/span\\u003e\\u003cspan class=\\\"\\\"\\u003esoutenir.framasoft.org/\\u003c/span\\u003e\\u003cspan class=\\\"invisible\\\"\\u003e\\u003c/span\\u003e\\u003c/a\\u003e\"},{\"type\":\"PropertyValue\",\"name\":\"Site\",\"value\":\"\\u003ca href=\\\"https://framasoft.org/\\\" rel=\\\"me nofollow noopener\\\" target=\\\"_blank\\\"\\u003e\\u003cspan class=\\\"invisible\\\"\\u003ehttps://\\u003c/span\\u003e\\u003cspan class=\\\"\\\"\\u003eframasoft.org/\\u003c/span\\u003e\\u003cspan class=\\\"invisible\\\"\\u003e\\u003c/span\\u003e\\u003c/a\\u003e\"}],\"endpoints\":{\"sharedInbox\":\"https://framapiaf.org/inbox\"},\"icon\":{\"type\":\"Image\",\"mediaType\":\"image/jpeg\",\"url\":\"https://framapiaf.org/system/accounts/avatars/000/000/002/original/85fbb27ad5e3cf71.jpg?1544008249\"},\"image\":{\"type\":\"Image\",\"mediaType\":\"image/jpeg\",\"url\":\"https://framapiaf.org/system/accounts/headers/000/000/002/original/6aba75f1ab1ab6de.jpg?1544008352\"}}",
       "headers": {
-        "Date": "Tue, 13 Nov 2018 11:22:02 GMT",
+        "Date": "Wed, 05 Dec 2018 11:59:22 GMT",
         "Content-Type": "application/activity+json; charset=utf-8",
         "Transfer-Encoding": "chunked",
         "Connection": "keep-alive",
@@ -27,9 +27,9 @@
         "Link": "<https://framapiaf.org/.well-known/webfinger?resource=acct%3Aadmin%40framapiaf.org>; rel=\"lrdd\"; type=\"application/xrd+xml\", <https://framapiaf.org/users/admin.atom>; rel=\"alternate\"; type=\"application/atom+xml\", <https://framapiaf.org/users/admin>; rel=\"alternate\"; type=\"application/activity+json\"",
         "Vary": "Accept,Accept-Encoding",
         "Cache-Control": "max-age=180, public",
-        "ETag": "W/\"82f88eaea909e6c3f20f908ad16e4b54\"",
-        "X-Request-Id": "cef423e2-d143-422f-94b0-03450f70a32d",
-        "X-Runtime": "0.005097",
+        "ETag": "W/\"dff68e9e1738cc89f28a977f39715b36\"",
+        "X-Request-Id": "1f2f4f2b-567f-48b0-a3f9-fef153cfa793",
+        "X-Runtime": "0.013117",
         "Strict-Transport-Security": "max-age=31536000; includeSubDomains; preload",
         "Referrer-Policy": "same-origin"
       },
diff --git a/test/mobilizon/addresses/addresses_test.exs b/test/mobilizon/addresses/addresses_test.exs
index 1da92902..d737300b 100644
--- a/test/mobilizon/addresses/addresses_test.exs
+++ b/test/mobilizon/addresses/addresses_test.exs
@@ -98,6 +98,9 @@ defmodule Mobilizon.AddressesTest do
     test "process_geom/2 with invalid data returns nil" do
       attrs = %{"type" => :point, "data" => %{"latitude" => nil, "longitude" => nil}}
       assert {:error, "Latitude and longitude must be numbers"} = Addresses.process_geom(attrs)
+
+      attrs = %{"type" => :not_valid, "data" => %{"latitude" => nil, "longitude" => nil}}
+      assert {:error, :invalid_type} == Addresses.process_geom(attrs)
     end
   end
 end
diff --git a/test/mobilizon/events/events_test.exs b/test/mobilizon/events/events_test.exs
index 890572f0..8103f0e4 100644
--- a/test/mobilizon/events/events_test.exs
+++ b/test/mobilizon/events/events_test.exs
@@ -415,6 +415,12 @@ defmodule Mobilizon.EventsTest do
       assert [session.id] == Events.list_sessions() |> Enum.map(& &1.id)
     end
 
+    test "list_sessions_for_event/1 returns sessions for an event" do
+      event = insert(:event)
+      session = insert(:session, event: event)
+      assert Events.list_sessions_for_event(event) |> Enum.map(& &1.id) == [session.id]
+    end
+
     test "get_session!/1 returns the session with given id" do
       session = insert(:session)
       assert Events.get_session!(session.id).id == session.id
@@ -485,6 +491,13 @@ defmodule Mobilizon.EventsTest do
       assert [track.id] == Events.list_tracks() |> Enum.map(& &1.id)
     end
 
+    test "list_sessions_for_track/1 returns sessions for an event" do
+      event = insert(:event)
+      track = insert(:track, event: event)
+      session = insert(:session, track: track, event: event)
+      assert Events.list_sessions_for_track(track) |> Enum.map(& &1.id) == [session.id]
+    end
+
     test "get_track!/1 returns the track with given id" do
       track = insert(:track)
       assert Events.get_track!(track.id).id == track.id
diff --git a/test/mobilizon/service/activitypub/activitypub_test.exs b/test/mobilizon/service/activitypub/activitypub_test.exs
index d9c00410..d870afca 100644
--- a/test/mobilizon/service/activitypub/activitypub_test.exs
+++ b/test/mobilizon/service/activitypub/activitypub_test.exs
@@ -78,7 +78,30 @@ defmodule Mobilizon.Service.Activitypub.ActivitypubTest do
             "https://social.tcit.fr/users/tcit/statuses/99908779444618462"
           )
 
-        assert object == object_again
+        assert object.id == object_again.id
+      end
+    end
+
+    test "object reply by url" do
+      use_cassette "activity_pub/fetch_social_tcit_fr_reply" do
+        {:ok, object} =
+          ActivityPub.fetch_object_from_url(
+            "https://social.tcit.fr/users/tcit/statuses/101160654038714030"
+          )
+
+        assert object.in_reply_to_comment.url ==
+                 "https://social.tcit.fr/users/tcit/statuses/101160195754333819"
+      end
+    end
+
+    test "object reply to a video by url" do
+      use_cassette "activity_pub/fetch_reply_to_framatube" do
+        {:ok, object} =
+          ActivityPub.fetch_object_from_url(
+            "https://framapiaf.org/@troisiemelobe/101156292125317651"
+          )
+
+        assert object.in_reply_to_comment == nil
       end
     end
   end
diff --git a/test/mobilizon/service/activitypub/transmogrifier_test.exs b/test/mobilizon/service/activitypub/transmogrifier_test.exs
new file mode 100644
index 00000000..faa7e2d6
--- /dev/null
+++ b/test/mobilizon/service/activitypub/transmogrifier_test.exs
@@ -0,0 +1,894 @@
+defmodule Mobilizon.Service.Activitypub.TransmogrifierTest do
+  use Mobilizon.DataCase
+
+  import Mobilizon.Factory
+
+  alias Mobilizon.Activity
+  alias Mobilizon.Actors
+  alias Mobilizon.Actors.Actor
+  alias Mobilizon.Events
+  alias Mobilizon.Events.Comment
+  alias Mobilizon.Service.ActivityPub.Utils
+  alias Mobilizon.Service.ActivityPub.Transmogrifier
+  use ExVCR.Mock, adapter: ExVCR.Adapter.Hackney
+
+  setup_all do
+    HTTPoison.start()
+  end
+
+  describe "handle_incoming" do
+    # test "it ignores an incoming comment if we already have it" do
+    #   comment = insert(:comment)
+
+    #   activity = %{
+    #     "type" => "Create",
+    #     "to" => ["https://www.w3.org/ns/activitystreams#Public"],
+    #     "actor" => comment.actor.url,
+    #     "object" => Utils.make_comment_data(comment)
+    #   }
+
+    #   data =
+    #     File.read!("test/fixtures/mastodon-post-activity.json")
+    #     |> Poison.decode!()
+    #     |> Map.put("object", activity["object"])
+
+    #   {:ok, returned_activity} = Transmogrifier.handle_incoming(data)
+
+    #   assert activity == returned_activity.data
+    # end
+
+    # test "it fetches replied-to activities if we don't have them" do
+    #   data =
+    #     File.read!("test/fixtures/mastodon-post-activity.json")
+    #     |> Poison.decode!()
+
+    #   object =
+    #     data["object"]
+    #     |> Map.put("inReplyTo", "https://shitposter.club/notice/2827873")
+
+    #   data =
+    #     data
+    #     |> Map.put("object", object)
+
+    #   {:ok, returned_activity} = Transmogrifier.handle_incoming(data)
+
+    #   assert activity =
+    #            Activity.get_create_activity_by_object_ap_id(
+    #              "tag:shitposter.club,2017-05-05:noticeId=2827873:objectType=comment"
+    #            )
+
+    #   assert returned_activity.data["object"]["inReplyToAtomUri"] ==
+    #            "https://shitposter.club/notice/2827873"
+
+    #   assert returned_activity.data["object"]["inReplyToStatusId"] == activity.id
+    # end
+
+    test "it works for incoming notices" do
+      data = File.read!("test/fixtures/mastodon-post-activity.json") |> Poison.decode!()
+
+      {:ok, %Mobilizon.Activity{data: data, local: false}} = Transmogrifier.handle_incoming(data)
+
+      assert data["id"] == "https://framapiaf.org/users/admin/statuses/99512778738411822/activity"
+
+      assert data["to"] == ["https://www.w3.org/ns/activitystreams#Public"]
+
+      assert data["cc"] == [
+               "https://framapiaf.org/users/admin/followers",
+               "http://mobilizon.com/@tcit"
+             ]
+
+      assert data["actor"] == "https://framapiaf.org/users/admin"
+
+      object = data["object"]
+      assert object["id"] == "https://framapiaf.org/users/admin/statuses/99512778738411822"
+
+      assert object["to"] == ["https://www.w3.org/ns/activitystreams#Public"]
+
+      assert object["cc"] == [
+               "https://framapiaf.org/users/admin/followers",
+               "http://localtesting.pleroma.lol/users/lain"
+             ]
+
+      assert object["actor"] == "https://framapiaf.org/users/admin"
+      assert object["attributedTo"] == "https://framapiaf.org/users/admin"
+
+      assert object["sensitive"] == true
+
+      {:ok, %Actor{}} = Actors.get_actor_by_url(object["actor"])
+    end
+
+    test "it works for incoming notices with hashtags" do
+      data = File.read!("test/fixtures/mastodon-post-activity-hashtag.json") |> Poison.decode!()
+
+      {:ok, %Activity{data: data, local: false}} = Transmogrifier.handle_incoming(data)
+      assert Enum.at(data["object"]["tag"], 2) == "moo"
+    end
+
+    #     test "it works for incoming notices with contentMap" do
+    #       data =
+    #         File.read!("test/fixtures/mastodon-post-activity-contentmap.json") |> Poison.decode!()
+
+    #       {:ok, %Activity{data: data, local: false}} = Transmogrifier.handle_incoming(data)
+
+    #       assert data["object"]["content"] ==
+    #                "<p><span class=\"h-card\"><a href=\"http://localtesting.pleroma.lol/users/lain\" class=\"u-url mention\">@<span>lain</span></a></span></p>"
+    #     end
+
+    #     test "it works for incoming notices with to/cc not being an array (kroeg)" do
+    #       data = File.read!("test/fixtures/kroeg-post-activity.json") |> Poison.decode!()
+
+    #       {:ok, %Activity{data: data, local: false}} = Transmogrifier.handle_incoming(data)
+
+    #       assert data["object"]["content"] ==
+    #                "<p>henlo from my Psion netBook</p><p>message sent from my Psion netBook</p>"
+    #     end
+
+    #     test "it works for incoming announces with actor being inlined (kroeg)" do
+    #       data = File.read!("test/fixtures/kroeg-announce-with-inline-actor.json") |> Poison.decode!()
+
+    #       {:ok, %Activity{data: data, local: false}} = Transmogrifier.handle_incoming(data)
+
+    #       assert data["actor"] == "https://puckipedia.com/"
+    #     end
+
+    #     test "it works for incoming notices with tag not being an array (kroeg)" do
+    #       data = File.read!("test/fixtures/kroeg-array-less-emoji.json") |> Poison.decode!()
+
+    #       {:ok, %Activity{data: data, local: false}} = Transmogrifier.handle_incoming(data)
+
+    #       assert data["object"]["emoji"] == %{
+    #                "icon_e_smile" => "https://puckipedia.com/forum/images/smilies/icon_e_smile.png"
+    #              }
+
+    #       data = File.read!("test/fixtures/kroeg-array-less-hashtag.json") |> Poison.decode!()
+
+    #       {:ok, %Activity{data: data, local: false}} = Transmogrifier.handle_incoming(data)
+
+    #       assert "test" in data["object"]["tag"]
+    #     end
+
+    test "it works for incoming notices with url not being a string (prismo)" do
+      data = File.read!("test/fixtures/prismo-url-map.json") |> Poison.decode!()
+
+      assert {:error, :not_supported} == Transmogrifier.handle_incoming(data)
+      # Pages are not supported
+      # {:ok, %Activity{data: data, local: false}} = Transmogrifier.handle_incoming(data)
+
+      # assert data["object"]["url"] == "https://prismo.news/posts/83"
+    end
+
+    test "it works for incoming follow requests" do
+      actor = insert(:actor)
+
+      data =
+        File.read!("test/fixtures/mastodon-follow-activity.json")
+        |> Poison.decode!()
+        |> Map.put("object", actor.url)
+
+      {:ok, %Activity{data: data, local: false}} = Transmogrifier.handle_incoming(data)
+
+      assert data["actor"] == "https://social.tcit.fr/users/tcit"
+      assert data["type"] == "Follow"
+      assert data["id"] == "https://social.tcit.fr/users/tcit#follows/2"
+
+      actor = Actors.get_actor_with_everything!(actor.id)
+      assert Actor.following?(Actors.get_actor_by_url!(data["actor"], true), actor)
+    end
+
+    #     test "it works for incoming follow requests from hubzilla" do
+    #       user = insert(:user)
+
+    #       data =
+    #         File.read!("test/fixtures/hubzilla-follow-activity.json")
+    #         |> Poison.decode!()
+    #         |> Map.put("object", user.ap_id)
+    #         |> Utils.normalize_params()
+
+    #       {:ok, %Activity{data: data, local: false}} = Transmogrifier.handle_incoming(data)
+
+    #       assert data["actor"] == "https://hubzilla.example.org/channel/kaniini"
+    #       assert data["type"] == "Follow"
+    #       assert data["id"] == "https://hubzilla.example.org/channel/kaniini#follows/2"
+    #       assert User.following?(User.get_by_ap_id(data["actor"]), user)
+    #     end
+
+    # test "it works for incoming likes" do
+    #   %Comment{url: url} = insert(:comment)
+
+    #   data =
+    #     File.read!("test/fixtures/mastodon-like.json")
+    #     |> Poison.decode!()
+    #     |> Map.put("object", url)
+
+    #   {:ok, %Activity{data: data, local: false}} = Transmogrifier.handle_incoming(data)
+
+    #   assert data["actor"] == "http://mastodon.example.org/users/admin"
+    #   assert data["type"] == "Like"
+    #   assert data["id"] == "http://mastodon.example.org/users/admin#likes/2"
+    #   assert data["object"] == url
+    # end
+
+    # test "it returns an error for incoming unlikes wihout a like activity" do
+    #   %Comment{url: url} = insert(:comment)
+
+    #   data =
+    #     File.read!("test/fixtures/mastodon-undo-like.json")
+    #     |> Poison.decode!()
+    #     |> Map.put("object", url)
+
+    #   assert Transmogrifier.handle_incoming(data) == {:error, :not_supported}
+    # end
+
+    # test "it works for incoming unlikes with an existing like activity" do
+    #   comment = insert(:comment)
+
+    #   like_data =
+    #     File.read!("test/fixtures/mastodon-like.json")
+    #     |> Poison.decode!()
+    #     |> Map.put("object", comment.url)
+
+    #   {:ok, %Activity{data: like_data, local: false}} = Transmogrifier.handle_incoming(like_data)
+
+    #   data =
+    #     File.read!("test/fixtures/mastodon-undo-like.json")
+    #     |> Poison.decode!()
+    #     |> Map.put("object", like_data)
+    #     |> Map.put("actor", like_data["actor"])
+
+    #   {:ok, %Activity{data: data, local: false}} = Transmogrifier.handle_incoming(data)
+
+    #   assert data["actor"] == "http://mastodon.example.org/users/admin"
+    #   assert data["type"] == "Undo"
+    #   assert data["id"] == "http://mastodon.example.org/users/admin#likes/2/undo"
+    #   assert data["object"]["id"] == "http://mastodon.example.org/users/admin#likes/2"
+    # end
+
+    # test "it works for incoming announces" do
+    #   data = File.read!("test/fixtures/mastodon-announce.json") |> Poison.decode!()
+
+    #   {:ok, %Activity{data: data, local: false}} = Transmogrifier.handle_incoming(data)
+
+    #   assert data["actor"] == "https://social.tcit.fr/users/tcit"
+    #   assert data["type"] == "Announce"
+
+    #   assert data["id"] ==
+    #            "https://social.tcit.fr/users/tcit/statuses/101188891162897047/activity"
+
+    #   assert data["object"] ==
+    #            "https://social.tcit.fr/users/tcit/statuses/101188891162897047"
+
+    #   assert %Comment{} = Events.get_comment_from_url(data["object"])
+    # end
+
+    # test "it works for incoming announces with an existing activity" do
+    #   comment = insert(:comment)
+
+    #   data =
+    #     File.read!("test/fixtures/mastodon-announce.json")
+    #     |> Poison.decode!()
+    #     |> Map.put("object", comment.url)
+
+    #   {:ok, %Activity{data: data, local: false}} = Transmogrifier.handle_incoming(data)
+
+    #   assert data["actor"] == "https://social.tcit.fr/users/tcit"
+    #   assert data["type"] == "Announce"
+
+    #   assert data["id"] ==
+    #            "https://social.tcit.fr/users/tcit/statuses/101188891162897047/activity"
+
+    #   assert data["object"] == comment.url
+
+    #   # assert Activity.get_create_activity_by_object_ap_id(data["object"]).id == activity.id
+    # end
+
+    test "it works for incoming update activities" do
+      data = File.read!("test/fixtures/mastodon-post-activity.json") |> Poison.decode!()
+
+      {:ok, %Activity{data: data, local: false}} = Transmogrifier.handle_incoming(data)
+      update_data = File.read!("test/fixtures/mastodon-update.json") |> Poison.decode!()
+
+      object =
+        update_data["object"]
+        |> Map.put("actor", data["actor"])
+        |> Map.put("id", data["actor"])
+
+      update_data =
+        update_data
+        |> Map.put("actor", data["actor"])
+        |> Map.put("object", object)
+
+      {:ok, %Activity{data: data, local: false}} = Transmogrifier.handle_incoming(update_data)
+
+      {:ok, %Actor{} = actor} = Actors.get_actor_by_url(data["actor"])
+      assert actor.name == "gargle"
+
+      assert actor.avatar_url ==
+               "https://cd.niu.moe/accounts/avatars/000/033/323/original/fd7f8ae0b3ffedc9.jpeg"
+
+      assert actor.banner_url ==
+               "https://cd.niu.moe/accounts/headers/000/033/323/original/850b3448fa5fd477.png"
+
+      assert actor.summary == "<p>Some bio</p>"
+    end
+
+    #     test "it works for incoming update activities which lock the account" do
+    #       data = File.read!("test/fixtures/mastodon-post-activity.json") |> Poison.decode!()
+
+    #       {:ok, %Activity{data: data, local: false}} = Transmogrifier.handle_incoming(data)
+    #       update_data = File.read!("test/fixtures/mastodon-update.json") |> Poison.decode!()
+
+    #       object =
+    #         update_data["object"]
+    #         |> Map.put("actor", data["actor"])
+    #         |> Map.put("id", data["actor"])
+    #         |> Map.put("manuallyApprovesFollowers", true)
+
+    #       update_data =
+    #         update_data
+    #         |> Map.put("actor", data["actor"])
+    #         |> Map.put("object", object)
+
+    #       {:ok, %Activity{data: data, local: false}} = Transmogrifier.handle_incoming(update_data)
+
+    #       user = User.get_cached_by_ap_id(data["actor"])
+    #       assert user.info["locked"] == true
+    #     end
+
+    test "it works for incoming deletes" do
+      %Actor{url: actor_url} = actor = insert(:actor)
+      %Comment{url: comment_url} = insert(:comment, actor: actor)
+
+      data =
+        File.read!("test/fixtures/mastodon-delete.json")
+        |> Poison.decode!()
+
+      object =
+        data["object"]
+        |> Map.put("id", comment_url)
+
+      data =
+        data
+        |> Map.put("object", object)
+        |> Map.put("actor", actor_url)
+
+      assert Events.get_comment_from_url(comment_url)
+
+      {:ok, %Activity{local: false}} = Transmogrifier.handle_incoming(data)
+
+      refute Events.get_comment_from_url(comment_url)
+    end
+
+    #     TODO : make me ASAP
+    #     test "it fails for incoming deletes with spoofed origin" do
+    #       activity = insert(:note_activity)
+
+    #       data =
+    #         File.read!("test/fixtures/mastodon-delete.json")
+    #         |> Poison.decode!()
+
+    #       object =
+    #         data["object"]
+    #         |> Map.put("id", activity.data["object"]["id"])
+
+    #       data =
+    #         data
+    #         |> Map.put("object", object)
+
+    #       :error = Transmogrifier.handle_incoming(data)
+
+    #       assert Repo.get(Activity, activity.id)
+    #     end
+
+    # test "it works for incoming unannounces with an existing notice" do
+    #   comment = insert(:comment)
+
+    #   announce_data =
+    #     File.read!("test/fixtures/mastodon-announce.json")
+    #     |> Poison.decode!()
+    #     |> Map.put("object", comment.url)
+
+    #   {:ok, %Activity{data: announce_data, local: false}} =
+    #     Transmogrifier.handle_incoming(announce_data)
+
+    #   data =
+    #     File.read!("test/fixtures/mastodon-undo-announce.json")
+    #     |> Poison.decode!()
+    #     |> Map.put("object", announce_data)
+    #     |> Map.put("actor", announce_data["actor"])
+
+    #   {:ok, %Activity{data: data, local: false}} = Transmogrifier.handle_incoming(data)
+
+    #   assert data["type"] == "Undo"
+    #   assert data["object"]["type"] == "Announce"
+    #   assert data["object"]["object"] == comment.url
+
+    #   assert data["object"]["id"] ==
+    #            "http://mastodon.example.org/users/admin/statuses/99542391527669785/activity"
+    # end
+
+    test "it works for incomming unfollows with an existing follow" do
+      actor = insert(:actor)
+
+      follow_data =
+        File.read!("test/fixtures/mastodon-follow-activity.json")
+        |> Poison.decode!()
+        |> Map.put("object", actor.url)
+
+      {:ok, %Activity{data: _, local: false}} = Transmogrifier.handle_incoming(follow_data)
+
+      data =
+        File.read!("test/fixtures/mastodon-unfollow-activity.json")
+        |> Poison.decode!()
+        |> Map.put("object", follow_data)
+
+      {:ok, %Activity{data: data, local: false}} = Transmogrifier.handle_incoming(data)
+
+      assert data["type"] == "Undo"
+      assert data["object"]["type"] == "Follow"
+      assert data["object"]["object"] == actor.url
+      assert data["actor"] == "https://social.tcit.fr/users/tcit"
+
+      {:ok, followed} = Actors.get_actor_by_url(data["actor"])
+      refute Actor.following?(followed, actor)
+    end
+
+    #     test "it works for incoming blocks" do
+    #       user = insert(:user)
+
+    #       data =
+    #         File.read!("test/fixtures/mastodon-block-activity.json")
+    #         |> Poison.decode!()
+    #         |> Map.put("object", user.ap_id)
+
+    #       {:ok, %Activity{data: data, local: false}} = Transmogrifier.handle_incoming(data)
+
+    #       assert data["type"] == "Block"
+    #       assert data["object"] == user.ap_id
+    #       assert data["actor"] == "http://mastodon.example.org/users/admin"
+
+    #       blocker = User.get_by_ap_id(data["actor"])
+
+    #       assert User.blocks?(blocker, user)
+    #     end
+
+    #     test "incoming blocks successfully tear down any follow relationship" do
+    #       blocker = insert(:user)
+    #       blocked = insert(:user)
+
+    #       data =
+    #         File.read!("test/fixtures/mastodon-block-activity.json")
+    #         |> Poison.decode!()
+    #         |> Map.put("object", blocked.ap_id)
+    #         |> Map.put("actor", blocker.ap_id)
+
+    #       {:ok, blocker} = User.follow(blocker, blocked)
+    #       {:ok, blocked} = User.follow(blocked, blocker)
+
+    #       assert User.following?(blocker, blocked)
+    #       assert User.following?(blocked, blocker)
+
+    #       {:ok, %Activity{data: data, local: false}} = Transmogrifier.handle_incoming(data)
+
+    #       assert data["type"] == "Block"
+    #       assert data["object"] == blocked.ap_id
+    #       assert data["actor"] == blocker.ap_id
+
+    #       blocker = User.get_by_ap_id(data["actor"])
+    #       blocked = User.get_by_ap_id(data["object"])
+
+    #       assert User.blocks?(blocker, blocked)
+
+    #       refute User.following?(blocker, blocked)
+    #       refute User.following?(blocked, blocker)
+    #     end
+
+    #     test "it works for incoming unblocks with an existing block" do
+    #       user = insert(:user)
+
+    #       block_data =
+    #         File.read!("test/fixtures/mastodon-block-activity.json")
+    #         |> Poison.decode!()
+    #         |> Map.put("object", user.ap_id)
+
+    #       {:ok, %Activity{data: _, local: false}} = Transmogrifier.handle_incoming(block_data)
+
+    #       data =
+    #         File.read!("test/fixtures/mastodon-unblock-activity.json")
+    #         |> Poison.decode!()
+    #         |> Map.put("object", block_data)
+
+    #       {:ok, %Activity{data: data, local: false}} = Transmogrifier.handle_incoming(data)
+    #       assert data["type"] == "Undo"
+    #       assert data["object"]["type"] == "Block"
+    #       assert data["object"]["object"] == user.ap_id
+    #       assert data["actor"] == "http://mastodon.example.org/users/admin"
+
+    #       blocker = User.get_by_ap_id(data["actor"])
+
+    #       refute User.blocks?(blocker, user)
+    #     end
+
+    #     test "it works for incoming accepts which were pre-accepted" do
+    #       follower = insert(:user)
+    #       followed = insert(:user)
+
+    #       {:ok, follower} = User.follow(follower, followed)
+    #       assert User.following?(follower, followed) == true
+
+    #       {:ok, follow_activity} = ActivityPub.follow(follower, followed)
+
+    #       accept_data =
+    #         File.read!("test/fixtures/mastodon-accept-activity.json")
+    #         |> Poison.decode!()
+    #         |> Map.put("actor", followed.ap_id)
+
+    #       object =
+    #         accept_data["object"]
+    #         |> Map.put("actor", follower.ap_id)
+    #         |> Map.put("id", follow_activity.data["id"])
+
+    #       accept_data = Map.put(accept_data, "object", object)
+
+    #       {:ok, activity} = Transmogrifier.handle_incoming(accept_data)
+    #       refute activity.local
+
+    #       assert activity.data["object"] == follow_activity.data["id"]
+
+    #       follower = Repo.get(User, follower.id)
+
+    #       assert User.following?(follower, followed) == true
+    #     end
+
+    #     test "it works for incoming accepts which were orphaned" do
+    #       follower = insert(:user)
+    #       followed = insert(:user, %{info: %{"locked" => true}})
+
+    #       {:ok, follow_activity} = ActivityPub.follow(follower, followed)
+
+    #       accept_data =
+    #         File.read!("test/fixtures/mastodon-accept-activity.json")
+    #         |> Poison.decode!()
+    #         |> Map.put("actor", followed.ap_id)
+
+    #       accept_data =
+    #         Map.put(accept_data, "object", Map.put(accept_data["object"], "actor", follower.ap_id))
+
+    #       {:ok, activity} = Transmogrifier.handle_incoming(accept_data)
+    #       assert activity.data["object"] == follow_activity.data["id"]
+
+    #       follower = Repo.get(User, follower.id)
+
+    #       assert User.following?(follower, followed) == true
+    #     end
+
+    #     test "it works for incoming accepts which are referenced by IRI only" do
+    #       follower = insert(:user)
+    #       followed = insert(:user, %{info: %{"locked" => true}})
+
+    #       {:ok, follow_activity} = ActivityPub.follow(follower, followed)
+
+    #       accept_data =
+    #         File.read!("test/fixtures/mastodon-accept-activity.json")
+    #         |> Poison.decode!()
+    #         |> Map.put("actor", followed.ap_id)
+    #         |> Map.put("object", follow_activity.data["id"])
+
+    #       {:ok, activity} = Transmogrifier.handle_incoming(accept_data)
+    #       assert activity.data["object"] == follow_activity.data["id"]
+
+    #       follower = Repo.get(User, follower.id)
+
+    #       assert User.following?(follower, followed) == true
+    #     end
+
+    #     test "it fails for incoming accepts which cannot be correlated" do
+    #       follower = insert(:user)
+    #       followed = insert(:user, %{info: %{"locked" => true}})
+
+    #       accept_data =
+    #         File.read!("test/fixtures/mastodon-accept-activity.json")
+    #         |> Poison.decode!()
+    #         |> Map.put("actor", followed.ap_id)
+
+    #       accept_data =
+    #         Map.put(accept_data, "object", Map.put(accept_data["object"], "actor", follower.ap_id))
+
+    #       :error = Transmogrifier.handle_incoming(accept_data)
+
+    #       follower = Repo.get(User, follower.id)
+
+    #       refute User.following?(follower, followed) == true
+    #     end
+
+    #     test "it fails for incoming rejects which cannot be correlated" do
+    #       follower = insert(:user)
+    #       followed = insert(:user, %{info: %{"locked" => true}})
+
+    #       accept_data =
+    #         File.read!("test/fixtures/mastodon-reject-activity.json")
+    #         |> Poison.decode!()
+    #         |> Map.put("actor", followed.ap_id)
+
+    #       accept_data =
+    #         Map.put(accept_data, "object", Map.put(accept_data["object"], "actor", follower.ap_id))
+
+    #       :error = Transmogrifier.handle_incoming(accept_data)
+
+    #       follower = Repo.get(User, follower.id)
+
+    #       refute User.following?(follower, followed) == true
+    #     end
+
+    #     test "it works for incoming rejects which are orphaned" do
+    #       follower = insert(:user)
+    #       followed = insert(:user, %{info: %{"locked" => true}})
+
+    #       {:ok, follower} = User.follow(follower, followed)
+    #       {:ok, _follow_activity} = ActivityPub.follow(follower, followed)
+
+    #       assert User.following?(follower, followed) == true
+
+    #       reject_data =
+    #         File.read!("test/fixtures/mastodon-reject-activity.json")
+    #         |> Poison.decode!()
+    #         |> Map.put("actor", followed.ap_id)
+
+    #       reject_data =
+    #         Map.put(reject_data, "object", Map.put(reject_data["object"], "actor", follower.ap_id))
+
+    #       {:ok, activity} = Transmogrifier.handle_incoming(reject_data)
+    #       refute activity.local
+
+    #       follower = Repo.get(User, follower.id)
+
+    #       assert User.following?(follower, followed) == false
+    #     end
+
+    #     test "it works for incoming rejects which are referenced by IRI only" do
+    #       follower = insert(:user)
+    #       followed = insert(:user, %{info: %{"locked" => true}})
+
+    #       {:ok, follower} = User.follow(follower, followed)
+    #       {:ok, follow_activity} = ActivityPub.follow(follower, followed)
+
+    #       assert User.following?(follower, followed) == true
+
+    #       reject_data =
+    #         File.read!("test/fixtures/mastodon-reject-activity.json")
+    #         |> Poison.decode!()
+    #         |> Map.put("actor", followed.ap_id)
+    #         |> Map.put("object", follow_activity.data["id"])
+
+    #       {:ok, %Activity{data: _}} = Transmogrifier.handle_incoming(reject_data)
+
+    #       follower = Repo.get(User, follower.id)
+
+    #       assert User.following?(follower, followed) == false
+    #     end
+
+    #     test "it rejects activities without a valid ID" do
+    #       user = insert(:user)
+
+    #       data =
+    #         File.read!("test/fixtures/mastodon-follow-activity.json")
+    #         |> Poison.decode!()
+    #         |> Map.put("object", user.ap_id)
+    #         |> Map.put("id", "")
+
+    #       :error = Transmogrifier.handle_incoming(data)
+    #     end
+  end
+
+  describe "prepare outgoing" do
+    test "it turns mentions into tags" do
+      actor = insert(:actor)
+      other_actor = insert(:actor)
+
+      {:ok, activity} =
+        MobilizonWeb.API.Comments.create_comment(
+          actor.preferred_username,
+          "hey, @#{other_actor.preferred_username}, how are ya? #2hu"
+        )
+
+      {:ok, modified} = Transmogrifier.prepare_outgoing(activity.data)
+      object = modified["object"]
+
+      expected_mention = %{
+        "href" => other_actor.url,
+        "name" => "@#{other_actor.preferred_username}",
+        "type" => "Mention"
+      }
+
+      expected_tag = %{
+        "href" => MobilizonWeb.Endpoint.url() <> "/tags/2hu",
+        "type" => "Hashtag",
+        "name" => "#2hu"
+      }
+
+      assert Enum.member?(object["tag"], expected_tag)
+      assert Enum.member?(object["tag"], expected_mention)
+    end
+
+    #     test "it adds the sensitive property" do
+    #       user = insert(:user)
+
+    #       {:ok, activity} = CommonAPI.post(user, %{"status" => "#nsfw hey"})
+    #       {:ok, modified} = Transmogrifier.prepare_outgoing(activity.data)
+
+    #       assert modified["object"]["sensitive"]
+    #     end
+
+    test "it adds the json-ld context and the conversation property" do
+      actor = insert(:actor)
+
+      {:ok, activity} = MobilizonWeb.API.Comments.create_comment(actor.preferred_username, "hey")
+      {:ok, modified} = Transmogrifier.prepare_outgoing(activity.data)
+
+      assert modified["@context"] ==
+               Mobilizon.Service.ActivityPub.Utils.make_json_ld_header()["@context"]
+    end
+
+    test "it sets the 'attributedTo' property to the actor of the object if it doesn't have one" do
+      actor = insert(:actor)
+
+      {:ok, activity} = MobilizonWeb.API.Comments.create_comment(actor.preferred_username, "hey")
+      {:ok, modified} = Transmogrifier.prepare_outgoing(activity.data)
+
+      assert modified["object"]["actor"] == modified["object"]["attributedTo"]
+    end
+
+    test "it strips internal hashtag data" do
+      actor = insert(:actor)
+
+      {:ok, activity} = MobilizonWeb.API.Comments.create_comment(actor.preferred_username, "#2hu")
+
+      expected_tag = %{
+        "href" => MobilizonWeb.Endpoint.url() <> "/tags/2hu",
+        "type" => "Hashtag",
+        "name" => "#2hu"
+      }
+
+      {:ok, modified} = Transmogrifier.prepare_outgoing(activity.data)
+
+      assert modified["object"]["tag"] == [expected_tag]
+    end
+
+    test "it strips internal fields" do
+      actor = insert(:actor)
+
+      {:ok, activity} = MobilizonWeb.API.Comments.create_comment(actor.preferred_username, "#2hu")
+
+      {:ok, modified} = Transmogrifier.prepare_outgoing(activity.data)
+
+      # TODO : When and if custom emoji are implemented, this should be 2
+      assert length(modified["object"]["tag"]) == 1
+
+      assert is_nil(modified["object"]["emoji"])
+      assert is_nil(modified["object"]["likes"])
+      assert is_nil(modified["object"]["like_count"])
+      assert is_nil(modified["object"]["announcements"])
+      assert is_nil(modified["object"]["announcement_count"])
+      assert is_nil(modified["object"]["context_id"])
+    end
+
+    #   describe "actor rewriting" do
+    #     test "it fixes the actor URL property to be a proper URI" do
+    #       data = %{
+    #         "url" => %{"href" => "http://example.com"}
+    #       }
+
+    #       rewritten = Transmogrifier.maybe_fix_user_object(data)
+    #       assert rewritten["url"] == "http://example.com"
+    #     end
+    #   end
+
+    #   describe "actor origin containment" do
+    #     test "it rejects objects with a bogus origin" do
+    #       {:error, _} = ActivityPub.fetch_object_from_id("https://info.pleroma.site/activity.json")
+    #     end
+
+    #     test "it rejects activities which reference objects with bogus origins" do
+    #       data = %{
+    #         "@context" => "https://www.w3.org/ns/activitystreams",
+    #         "id" => "http://mastodon.example.org/users/admin/activities/1234",
+    #         "actor" => "http://mastodon.example.org/users/admin",
+    #         "to" => ["https://www.w3.org/ns/activitystreams#Public"],
+    #         "object" => "https://info.pleroma.site/activity.json",
+    #         "type" => "Announce"
+    #       }
+
+    #       :error = Transmogrifier.handle_incoming(data)
+    #     end
+
+    #     test "it rejects objects when attributedTo is wrong (variant 1)" do
+    #       {:error, _} = ActivityPub.fetch_object_from_id("https://info.pleroma.site/activity2.json")
+    #     end
+
+    #     test "it rejects activities which reference objects that have an incorrect attribution (variant 1)" do
+    #       data = %{
+    #         "@context" => "https://www.w3.org/ns/activitystreams",
+    #         "id" => "http://mastodon.example.org/users/admin/activities/1234",
+    #         "actor" => "http://mastodon.example.org/users/admin",
+    #         "to" => ["https://www.w3.org/ns/activitystreams#Public"],
+    #         "object" => "https://info.pleroma.site/activity2.json",
+    #         "type" => "Announce"
+    #       }
+
+    #       :error = Transmogrifier.handle_incoming(data)
+    #     end
+
+    #     test "it rejects objects when attributedTo is wrong (variant 2)" do
+    #       {:error, _} = ActivityPub.fetch_object_from_id("https://info.pleroma.site/activity3.json")
+    #     end
+
+    #     test "it rejects activities which reference objects that have an incorrect attribution (variant 2)" do
+    #       data = %{
+    #         "@context" => "https://www.w3.org/ns/activitystreams",
+    #         "id" => "http://mastodon.example.org/users/admin/activities/1234",
+    #         "actor" => "http://mastodon.example.org/users/admin",
+    #         "to" => ["https://www.w3.org/ns/activitystreams#Public"],
+    #         "object" => "https://info.pleroma.site/activity3.json",
+    #         "type" => "Announce"
+    #       }
+
+    #       :error = Transmogrifier.handle_incoming(data)
+    #     end
+    #   end
+
+    #   describe "general origin containment" do
+    #     test "contain_origin_from_id() catches obvious spoofing attempts" do
+    #       data = %{
+    #         "id" => "http://example.com/~alyssa/activities/1234.json"
+    #       }
+
+    #       :error =
+    #         Transmogrifier.contain_origin_from_id(
+    #           "http://example.org/~alyssa/activities/1234.json",
+    #           data
+    #         )
+    #     end
+
+    #     test "contain_origin_from_id() allows alternate IDs within the same origin domain" do
+    #       data = %{
+    #         "id" => "http://example.com/~alyssa/activities/1234.json"
+    #       }
+
+    #       :ok =
+    #         Transmogrifier.contain_origin_from_id(
+    #           "http://example.com/~alyssa/activities/1234",
+    #           data
+    #         )
+    #     end
+
+    #     test "contain_origin_from_id() allows matching IDs" do
+    #       data = %{
+    #         "id" => "http://example.com/~alyssa/activities/1234.json"
+    #       }
+
+    #       :ok =
+    #         Transmogrifier.contain_origin_from_id(
+    #           "http://example.com/~alyssa/activities/1234.json",
+    #           data
+    #         )
+    #     end
+
+    #     test "users cannot be collided through fake direction spoofing attempts" do
+    #       user =
+    #         insert(:user, %{
+    #           nickname: "rye@niu.moe",
+    #           local: false,
+    #           ap_id: "https://niu.moe/users/rye",
+    #           follower_address: User.ap_followers(%User{nickname: "rye@niu.moe"})
+    #         })
+
+    #       {:error, _} = User.get_or_fetch_by_ap_id("https://n1u.moe/users/rye")
+    #     end
+
+    #     test "all objects with fake directions are rejected by the object fetcher" do
+    #       {:error, _} =
+    #         ActivityPub.fetch_and_contain_remote_object_from_id(
+    #           "https://info.pleroma.site/activity4.json"
+    #         )
+    #     end
+  end
+end
diff --git a/test/mobilizon/service/activitypub/utils_test.exs b/test/mobilizon/service/activitypub/utils_test.exs
new file mode 100644
index 00000000..45b25efc
--- /dev/null
+++ b/test/mobilizon/service/activitypub/utils_test.exs
@@ -0,0 +1,40 @@
+defmodule Mobilizon.Service.Activitypub.UtilsTest do
+  use Mobilizon.DataCase
+  import Mobilizon.Factory
+  alias Mobilizon.Service.ActivityPub.Utils
+  use ExVCR.Mock, adapter: ExVCR.Adapter.Hackney
+
+  setup_all do
+    HTTPoison.start()
+  end
+
+  describe "make" do
+    test "comment data from struct" do
+      comment = insert(:comment)
+      reply = insert(:comment, in_reply_to_comment: comment)
+
+      assert %{
+               "type" => "Note",
+               "to" => ["https://www.w3.org/ns/activitystreams#Public"],
+               "content" => reply.text,
+               "actor" => reply.actor.url,
+               "uuid" => reply.uuid,
+               "id" => "#{MobilizonWeb.Endpoint.url()}/comments/#{reply.uuid}",
+               "inReplyTo" => comment.url,
+               "attributedTo" => reply.actor.url
+             } == Utils.make_comment_data(reply)
+    end
+
+    test "comment data from map" do
+      comment = insert(:comment)
+      reply = insert(:comment, in_reply_to_comment: comment)
+      to = ["https://www.w3.org/ns/activitystreams#Public"]
+      comment_data = Utils.make_comment_data(reply.actor.url, to, reply.text, comment.url)
+      assert comment_data["type"] == "Note"
+      assert comment_data["to"] == to
+      assert comment_data["content"] == reply.text
+      assert comment_data["actor"] == reply.actor.url
+      assert comment_data["inReplyTo"] == comment.url
+    end
+  end
+end
diff --git a/test/mobilizon_web/resolvers/comment_resolver_test.exs b/test/mobilizon_web/resolvers/comment_resolver_test.exs
new file mode 100644
index 00000000..654eae0a
--- /dev/null
+++ b/test/mobilizon_web/resolvers/comment_resolver_test.exs
@@ -0,0 +1,41 @@
+defmodule MobilizonWeb.Resolvers.CommentResolverTest do
+  use MobilizonWeb.ConnCase
+  alias Mobilizon.{Events, Actors}
+  alias Mobilizon.Actors.{Actor, User}
+  alias MobilizonWeb.AbsintheHelpers
+  import Mobilizon.Factory
+
+  @comment %{text: "some body"}
+
+  setup %{conn: conn} do
+    {:ok, %User{default_actor: %Actor{} = actor} = user} =
+      Actors.register(%{email: "test@test.tld", password: "testest", username: "test"})
+
+    {:ok, conn: conn, actor: actor, user: user}
+  end
+
+  describe "Comment Resolver" do
+    test "create_comment/3 creates a comment", %{conn: conn, actor: actor, user: user} do
+      category = insert(:category)
+
+      mutation = """
+          mutation {
+              createComment(
+                  text: "I love this event",
+                  actor_username: "#{actor.preferred_username}"
+              ) {
+                text,
+                uuid
+              }
+            }
+      """
+
+      res =
+        conn
+        |> auth_conn(user)
+        |> post("/api", AbsintheHelpers.mutation_skeleton(mutation))
+
+      assert json_response(res, 200)["data"]["createComment"]["text"] == "I love this event"
+    end
+  end
+end
diff --git a/test/mobilizon_web/resolvers/event_resolver_test.exs b/test/mobilizon_web/resolvers/event_resolver_test.exs
index ec18000a..898d3e0e 100644
--- a/test/mobilizon_web/resolvers/event_resolver_test.exs
+++ b/test/mobilizon_web/resolvers/event_resolver_test.exs
@@ -116,10 +116,10 @@ defmodule MobilizonWeb.Resolvers.EventResolverTest do
               createEvent(
                   title: "come to my event",
                   description: "it will be fine",
-                  beginsOn: "#{DateTime.utc_now() |> DateTime.to_iso8601()}",
-                  organizer_actor_id: #{actor.id},
-                  category_id: #{category.id},
-                  addressType: #{"OTHER"}
+                  begins_on: "#{DateTime.utc_now() |> DateTime.to_iso8601()}",
+                  organizer_actor_username: "#{actor.preferred_username}",
+                  category: "#{category.title}",
+                  address_type: #{"OTHER"}
               ) {
                 title,
                 uuid
diff --git a/test/mobilizon_web/resolvers/group_resolver_test.exs b/test/mobilizon_web/resolvers/group_resolver_test.exs
index 5395e15d..4522a4af 100644
--- a/test/mobilizon_web/resolvers/group_resolver_test.exs
+++ b/test/mobilizon_web/resolvers/group_resolver_test.exs
@@ -22,7 +22,7 @@ defmodule MobilizonWeb.Resolvers.GroupResolverTest do
           mutation {
             createGroup(
               preferred_username: "#{@new_group_params.groupname}",
-              creator_username: "#{actor.preferred_username}"
+              admin_actor_username: "#{actor.preferred_username}"
             ) {
                 preferred_username,
                 type
@@ -44,7 +44,7 @@ defmodule MobilizonWeb.Resolvers.GroupResolverTest do
           mutation {
             createGroup(
               preferred_username: "#{@new_group_params.groupname}",
-              creator_username: "#{actor.preferred_username}",
+              admin_actor_username: "#{actor.preferred_username}",
             ) {
                 preferred_username,
                 type
@@ -57,7 +57,7 @@ defmodule MobilizonWeb.Resolvers.GroupResolverTest do
         |> auth_conn(user)
         |> post("/api", AbsintheHelpers.mutation_skeleton(mutation))
 
-      assert hd(json_response(res, 200)["errors"])["message"] == "group_name_not_available"
+      assert hd(json_response(res, 200)["errors"])["message"] == "existing_group_name"
     end
 
     test "list_groups/3 returns all groups", context do