defmodule Mobilizon.Media do
  @moduledoc """
  The Media context.
  """

  import Ecto.Query, warn: false
  alias Mobilizon.Repo

  alias Mobilizon.Media.Picture
  alias Mobilizon.Media.File
  alias Ecto.Multi

  @doc false
  def data() do
    Dataloader.Ecto.new(Mobilizon.Repo, query: &query/2)
  end

  @doc false
  def query(queryable, _params) do
    queryable
  end

  @doc """
  Gets a single picture.

  Raises `Ecto.NoResultsError` if the Picture does not exist.

  ## Examples

      iex> get_picture!(123)
      %Picture{}

      iex> get_picture!(456)
      ** (Ecto.NoResultsError)

  """
  def get_picture!(id), do: Repo.get!(Picture, id)

  def get_picture(id), do: Repo.get(Picture, id)

  @doc """
  Get a picture by it's URL
  """
  @spec get_picture_by_url(String.t()) :: Picture.t() | nil
  def get_picture_by_url(url) do
    from(
      p in Picture,
      where: fragment("? @> ?", p.file, ~s|{"url": "#{url}"}|)
    )
    |> Repo.one()
  end

  @doc """
  Creates a picture.

  ## Examples

      iex> create_picture(%{field: value})
      {:ok, %Picture{}}

      iex> create_picture(%{field: bad_value})
      {:error, %Ecto.Changeset{}}

  """
  def create_picture(attrs \\ %{}) do
    %Picture{}
    |> Picture.changeset(attrs)
    |> Repo.insert()
  end

  @doc """
  Updates a picture.

  ## Examples

      iex> update_picture(picture, %{field: new_value})
      {:ok, %Picture{}}

      iex> update_picture(picture, %{field: bad_value})
      {:error, %Ecto.Changeset{}}

  """
  def update_picture(%Picture{} = picture, attrs) do
    picture
    |> Picture.changeset(attrs)
    |> Repo.update()
  end

  @doc """
  Deletes a Picture.

  ## Examples

      iex> delete_picture(picture)
      {:ok, %Picture{}}

      iex> delete_picture(picture)
      {:error, %Ecto.Changeset{}}

  """
  def delete_picture(%Picture{} = picture) do
    case Multi.new()
         |> Multi.delete(:picture, picture)
         |> Multi.run(:remove, fn _repo, %{picture: %Picture{file: %File{url: url}}} = _picture ->
           MobilizonWeb.Upload.remove(url)
         end)
         |> Repo.transaction() do
      {:ok, %{picture: %Picture{} = picture}} -> {:ok, picture}
      {:error, :remove, error, _} -> {:error, error}
    end
  end

  @doc """
  Returns an `%Ecto.Changeset{}` for tracking picture changes.

  ## Examples

      iex> change_picture(picture)
      %Ecto.Changeset{source: %Picture{}}

  """
  def change_picture(%Picture{} = picture) do
    Picture.changeset(picture, %{})
  end
end