defmodule MobilizonWeb.Email.User do
  @moduledoc """
  Handles emails sent to users.
  """

  use Bamboo.Phoenix, view: MobilizonWeb.EmailView

  import Bamboo.Phoenix

  import MobilizonWeb.Gettext

  alias Mobilizon.{Config, Crypto, Users}
  alias Mobilizon.Storage.Repo
  alias Mobilizon.Users.User

  alias MobilizonWeb.Email

  require Logger

  @spec confirmation_email(User.t(), String.t()) :: Bamboo.Email.t()
  def confirmation_email(
        %User{email: email, confirmation_token: confirmation_token},
        locale \\ "en"
      ) do
    MobilizonWeb.Gettext.put_locale(locale)

    subject =
      gettext(
        "Instructions to confirm your Mobilizon account on %{instance}",
        instance: Config.instance_name()
      )

    Email.base_email(to: email, subject: subject)
    |> assign(:locale, locale)
    |> assign(:token, confirmation_token)
    |> assign(:subject, subject)
    |> render(:registration_confirmation)
  end

  @spec reset_password_email(User.t(), String.t()) :: Bamboo.Email.t()
  def reset_password_email(
        %User{email: email, reset_password_token: reset_password_token},
        locale \\ "en"
      ) do
    MobilizonWeb.Gettext.put_locale(locale)

    subject =
      gettext(
        "Instructions to reset your password on %{instance}",
        instance: Config.instance_name()
      )

    Email.base_email(to: email, subject: subject)
    |> assign(:locale, locale)
    |> assign(:token, reset_password_token)
    |> assign(:subject, subject)
    |> render(:password_reset)
  end

  def check_confirmation_token(token) when is_binary(token) do
    with %User{} = user <- Users.get_user_by_activation_token(token),
         {:ok, %User{} = user} <-
           Users.update_user(user, %{
             "confirmed_at" => DateTime.utc_now() |> DateTime.truncate(:second),
             "confirmation_sent_at" => nil,
             "confirmation_token" => nil
           }) do
      Logger.info("User #{user.email} has been confirmed")
      {:ok, user}
    else
      _err ->
        {:error, :invalid_token}
    end
  end

  def resend_confirmation_email(%User{} = user, locale \\ "en") do
    with :ok <- we_can_send_email(user, :confirmation_sent_at),
         {:ok, user} <-
           Users.update_user(user, %{
             "confirmation_sent_at" => DateTime.utc_now() |> DateTime.truncate(:second)
           }) do
      send_confirmation_email(user, locale)
      Logger.info("Sent confirmation email again to #{user.email}")
      {:ok, user.email}
    end
  end

  def send_confirmation_email(%User{} = user, locale \\ "en") do
    user
    |> Email.User.confirmation_email(locale)
    |> Email.Mailer.deliver_later()
  end

  @doc """
  Check that the provided token is correct and update provided password
  """
  @spec check_reset_password_token(String.t(), String.t()) :: tuple
  def check_reset_password_token(password, token) do
    with %User{} = user <- Users.get_user_by_reset_password_token(token),
         {:ok, %User{} = user} <-
           Repo.update(
             User.password_reset_changeset(user, %{
               "password" => password,
               "reset_password_sent_at" => nil,
               "reset_password_token" => nil
             })
           ) do
      {:ok, user}
    else
      {:error, %Ecto.Changeset{errors: [password: {"registration.error.password_too_short", _}]}} ->
        {:error,
         "The password you have choosen is too short. Please make sure your password contains at least 6 charaters."}

      _err ->
        {:error,
         "The token you provided is invalid. Make sure that the URL is exactly the one provided inside the email you got."}
    end
  end

  @doc """
  Send the email reset password, if it's not too soon since the last send
  """
  @spec send_password_reset_email(User.t(), String.t()) :: tuple
  def send_password_reset_email(%User{} = user, locale \\ "en") do
    with :ok <- we_can_send_email(user, :reset_password_sent_at),
         {:ok, %User{} = user_updated} <-
           Repo.update(
             User.send_password_reset_changeset(user, %{
               "reset_password_token" => Crypto.random_string(30),
               "reset_password_sent_at" => DateTime.utc_now() |> DateTime.truncate(:second)
             })
           ) do
      mail =
        user_updated
        |> Email.User.reset_password_email(locale)
        |> Email.Mailer.deliver_later()

      {:ok, mail}
    else
      {:error, reason} -> {:error, reason}
    end
  end

  @spec we_can_send_email(User.t(), atom) :: :ok | {:error, :email_too_soon}
  defp we_can_send_email(%User{} = user, key) do
    case Map.get(user, key) do
      nil ->
        :ok

      _ ->
        case Timex.before?(
               Timex.shift(Map.get(user, key), hours: 1),
               DateTime.utc_now() |> DateTime.truncate(:second)
             ) do
          true ->
            :ok

          false ->
            {:error, :email_too_soon}
        end
    end
  end
end