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

  use Bamboo.Phoenix, view: Mobilizon.Web.EmailView

  import Bamboo.Phoenix

  import Mobilizon.Web.Gettext

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

  alias Mobilizon.Web.{Email, Gettext}

  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
    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
    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,
             email: user.unconfirmed_email || user.email
           }) 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)
           }),
         %Bamboo.Email{} <- send_confirmation_email(user, locale) do
      Logger.info("Sent confirmation email again to #{user.email}")
      {:ok, user.email}
    end
  end

  @spec send_confirmation_email(User.t(), String.t()) :: {:ok, Bamboo.Email.t()} | {:error, any()}
  def send_confirmation_email(%User{} = user, locale \\ "en") do
    user
    |> Email.User.confirmation_email(locale)
    |> Email.Mailer.send_email_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)
             })
           ),
         %Bamboo.Email{} = mail <-
           user_updated
           |> Email.User.reset_password_email(locale)
           |> Email.Mailer.send_email_later() do
      {:ok, mail}
    else
      {:error, reason} -> {:error, reason}
    end
  end

  def send_email_reset_old_email(
        %User{locale: user_locale, email: email, unconfirmed_email: unconfirmed_email} = _user,
        _locale \\ "en"
      ) do
    Gettext.put_locale(user_locale)

    subject =
      gettext(
        "Mobilizon on %{instance}: email changed",
        instance: Config.instance_name()
      )

    Email.base_email(to: email, subject: subject)
    |> assign(:locale, user_locale)
    |> assign(:subject, subject)
    |> assign(:new_email, unconfirmed_email)
    |> render(:email_changed_old)
  end

  def send_email_reset_new_email(
        %User{
          locale: user_locale,
          unconfirmed_email: unconfirmed_email,
          confirmation_token: confirmation_token
        } = _user,
        _locale \\ "en"
      ) do
    Gettext.put_locale(user_locale)
    instance_name = Config.instance_name()

    subject =
      gettext(
        "Mobilizon on %{instance}: confirm your email address",
        instance: instance_name
      )

    Email.base_email(to: unconfirmed_email, subject: subject)
    |> assign(:locale, user_locale)
    |> assign(:subject, subject)
    |> assign(:token, confirmation_token)
    |> assign(:instance_name, instance_name)
    |> render(:email_changed_new)
  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