defmodule Mobilizon.GraphQL.Resolvers.Person do
  @moduledoc """
  Handles the person-related GraphQL calls
  """

  import Mobilizon.Users.Guards

  alias Mobilizon.Actors
  alias Mobilizon.Actors.Actor
  alias Mobilizon.Admin
  alias Mobilizon.Events
  alias Mobilizon.Events.Participant
  alias Mobilizon.Storage.Page
  alias Mobilizon.Users
  alias Mobilizon.Users.User

  alias Mobilizon.Federation.ActivityPub

  alias Mobilizon.Web.{MediaProxy, Upload}

  @doc """
  Get a person
  """
  def get_person(_parent, %{id: id}, %{context: %{current_user: %User{role: role}}}) do
    with %Actor{suspended: suspended} = actor <- Actors.get_actor_with_preload(id, true),
         true <- suspended == false or is_moderator(role),
         actor <- proxify_pictures(actor) do
      {:ok, actor}
    else
      _ ->
        {:error, "Person with ID #{id} not found"}
    end
  end

  @doc """
  Find a person
  """
  def fetch_person(_parent, %{preferred_username: preferred_username}, _resolution) do
    with {:ok, %Actor{} = actor} <-
           ActivityPub.find_or_make_actor_from_nickname(preferred_username),
         actor <- proxify_pictures(actor) do
      {:ok, actor}
    else
      _ ->
        {:error, "Person with username #{preferred_username} not found"}
    end
  end

  def list_persons(
        _parent,
        %{
          preferred_username: preferred_username,
          name: name,
          domain: domain,
          local: local,
          suspended: suspended,
          page: page,
          limit: limit
        },
        %{
          context: %{current_user: %User{role: role}}
        }
      )
      when is_moderator(role) do
    {:ok,
     Actors.list_actors(:Person, preferred_username, name, domain, local, suspended, page, limit)}
  end

  def list_persons(_parent, _args, _resolution) do
    {:error, "You need to be logged-in and a moderator to list persons"}
  end

  @doc """
  Returns the current actor for the currently logged-in user
  """
  def get_current_person(_parent, _args, %{context: %{current_user: user}}) do
    {:ok, Users.get_actor_for_user(user)}
  end

  def get_current_person(_parent, _args, _resolution) do
    {:error, "You need to be logged-in to view current person"}
  end

  @doc """
  Returns the list of identities for the logged-in user
  """
  def identities(_parent, _args, %{context: %{current_user: user}}) do
    {:ok, Users.get_actors_for_user(user)}
  end

  def identities(_parent, _args, _resolution) do
    {:error, "You need to be logged-in to view your list of identities"}
  end

  @doc """
  This function is used to create more identities from an existing user
  """
  def create_person(
        _parent,
        %{preferred_username: _preferred_username} = args,
        %{context: %{current_user: user}} = _resolution
      ) do
    args = Map.put(args, :user_id, user.id)

    with args <- save_attached_pictures(args),
         {:ok, %Actor{} = new_person} <- Actors.new_person(args) do
      {:ok, new_person}
    end
  end

  @doc """
  This function is used to create more identities from an existing user
  """
  def create_person(_parent, _args, _resolution) do
    {:error, "You need to be logged-in to create a new identity"}
  end

  @doc """
  This function is used to update an existing identity
  """
  def update_person(
        _parent,
        %{id: id} = args,
        %{context: %{current_user: user}} = _resolution
      ) do
    args = Map.put(args, :user_id, user.id)

    with {:find_actor, %Actor{} = actor} <-
           {:find_actor, Actors.get_actor(id)},
         {:is_owned, %Actor{}} <- User.owns_actor(user, actor.id),
         args <- save_attached_pictures(args),
         {:ok, _activity, %Actor{} = actor} <- ActivityPub.update(:actor, actor, args, true) do
      {:ok, actor}
    else
      {:find_actor, nil} ->
        {:error, "Actor not found"}

      {:is_owned, nil} ->
        {:error, "Actor is not owned by authenticated user"}
    end
  end

  def update_person(_parent, _args, _resolution) do
    {:error, "You need to be logged-in to update an identity"}
  end

  @doc """
  This function is used to delete an existing identity
  """
  def delete_person(
        _parent,
        %{id: id} = _args,
        %{context: %{current_user: user}} = _resolution
      ) do
    with {:find_actor, %Actor{} = actor} <-
           {:find_actor, Actors.get_actor(id)},
         {:is_owned, %Actor{}} <- User.owns_actor(user, actor.id),
         {:last_identity, false} <- {:last_identity, last_identity?(user)},
         {:last_admin, false} <- {:last_admin, last_admin_of_a_group?(actor.id)},
         {:ok, actor} <- Actors.delete_actor(actor) do
      {:ok, actor}
    else
      {:find_actor, nil} ->
        {:error, "Actor not found"}

      {:last_identity, true} ->
        {:error, "Cannot remove the last identity of a user"}

      {:last_admin, true} ->
        {:error, "Cannot remove the last administrator of a group"}

      {:is_owned, nil} ->
        {:error, "Actor is not owned by authenticated user"}
    end
  end

  def delete_person(_parent, _args, _resolution) do
    {:error, "You need to be logged-in to delete an identity"}
  end

  defp last_identity?(user) do
    length(Users.get_actors_for_user(user)) <= 1
  end

  defp save_attached_pictures(args) do
    Enum.reduce([:avatar, :banner], args, fn key, args ->
      if Map.has_key?(args, key) && !is_nil(args[key][:picture]) do
        pic = args[key][:picture]

        with {:ok, %{name: name, url: url, content_type: content_type, size: _size}} <-
               Upload.store(pic.file, type: key, description: pic.alt) do
          Map.put(args, key, %{"name" => name, "url" => url, "mediaType" => content_type})
        end
      else
        args
      end
    end)
  end

  @doc """
  This function is used to register a person afterwards the user has been created (but not activated)
  """
  def register_person(_parent, args, _resolution) do
    with {:ok, %User{} = user} <- Users.get_user_by_email(args.email),
         user_actor <- Users.get_actor_for_user(user),
         no_actor <- is_nil(user_actor),
         {:no_actor, true} <- {:no_actor, no_actor},
         args <- Map.put(args, :user_id, user.id),
         args <- save_attached_pictures(args),
         {:ok, %Actor{} = new_person} <- Actors.new_person(args, true) do
      {:ok, new_person}
    else
      {:error, :user_not_found} ->
        {:error, "No user with this email was found"}

      {:no_actor, _} ->
        {:error, "You already have a profile for this user"}

      {:error, %Ecto.Changeset{} = e} ->
        {:error, e}
    end
  end

  @doc """
  Returns the participation for a specific event
  """
  def person_participations(
        %Actor{id: actor_id},
        %{event_id: event_id},
        %{context: %{current_user: user}}
      ) do
    with {:is_owned, %Actor{} = _actor} <- User.owns_actor(user, actor_id),
         {:no_participant, {:ok, %Participant{} = participant}} <-
           {:no_participant, Events.get_participant(event_id, actor_id)} do
      {:ok, %Page{elements: [participant], total: 1}}
    else
      {:is_owned, nil} ->
        {:error, "Actor id is not owned by authenticated user"}

      {:no_participant, _} ->
        {:ok, %Page{elements: [], total: 0}}
    end
  end

  @doc """
  Returns the list of events this person is going to
  """
  def person_participations(%Actor{id: actor_id} = actor, %{page: page, limit: limit}, %{
        context: %{current_user: %User{role: role} = user}
      }) do
    {:is_owned, actor_found} = User.owns_actor(user, actor_id)

    res =
      cond do
        not is_nil(actor_found) ->
          true

        is_moderator(role) ->
          true

        true ->
          false
      end

    with {:is_owned, true} <- {:is_owned, res},
         %Page{} = page <- Events.list_event_participations_for_actor(actor, page, limit) do
      {:ok, page}
    else
      {:is_owned, false} ->
        {:error, "Actor id is not owned by authenticated user"}
    end
  end

  @doc """
  Returns the list of events this person is going to
  """
  def person_memberships(%Actor{id: actor_id}, _args, %{context: %{current_user: user}}) do
    with {:is_owned, %Actor{} = actor} <- User.owns_actor(user, actor_id),
         participations <- Actors.list_members_for_actor(actor) do
      {:ok, participations}
    else
      {:is_owned, nil} ->
        {:error, "Actor id is not owned by authenticated user"}
    end
  end

  def proxify_pictures(%Actor{} = actor) do
    actor
    |> proxify_avatar
    |> proxify_banner
  end

  def user_for_person(%Actor{type: :Person, user_id: user_id}, _args, %{
        context: %{current_user: %User{role: role}}
      })
      when is_moderator(role) do
    with false <- is_nil(user_id),
         %User{} = user <- Users.get_user(user_id) do
      {:ok, user}
    else
      true ->
        {:ok, nil}

      _ ->
        {:error, "User not found"}
    end
  end

  def user_for_person(_, _args, _resolution), do: {:error, nil}

  def organized_events_for_person(
        %Actor{user_id: actor_user_id} = actor,
        %{page: page, limit: limit},
        %{
          context: %{current_user: %User{id: user_id, role: role}}
        }
      ) do
    with true <- actor_user_id == user_id or is_moderator(role),
         %Page{} = page <- Events.list_organized_events_for_actor(actor, page, limit) do
      {:ok, page}
    end
  end

  def suspend_profile(_parent, %{id: id}, %{
        context: %{current_user: %User{role: role} = user}
      })
      when is_moderator(role) do
    with {:moderator_actor, %Actor{} = moderator_actor} <-
           {:moderator_actor, Users.get_actor_for_user(user)},
         %Actor{suspended: false} = actor <- Actors.get_remote_actor_with_preload(id),
         {:ok, _} <- Actors.delete_actor(actor),
         {:ok, _} <- Admin.log_action(moderator_actor, "suspend", actor) do
      {:ok, actor}
    else
      {:moderator_actor, nil} ->
        {:error, "No actor found for the moderator user"}

      %Actor{suspended: true} ->
        {:error, "Actor already suspended"}

      nil ->
        {:error, "No remote profile found with this ID"}

      {:error, _} ->
        {:error, "Error while performing background task"}
    end
  end

  def suspend_profile(_parent, _args, _resolution) do
    {:error, "Only moderators and administrators can suspend a profile"}
  end

  def unsuspend_profile(_parent, %{id: id}, %{
        context: %{current_user: %User{role: role} = user}
      })
      when is_moderator(role) do
    with {:moderator_actor, %Actor{} = moderator_actor} <-
           {:moderator_actor, Users.get_actor_for_user(user)},
         %Actor{preferred_username: preferred_username, domain: domain} = actor <-
           Actors.get_remote_actor_with_preload(id, true),
         {:ok, _} <- Actors.update_actor(actor, %{suspended: false}),
         {:ok, %Actor{} = actor} <-
           ActivityPub.make_actor_from_nickname("#{preferred_username}@#{domain}"),
         {:ok, _} <- Admin.log_action(moderator_actor, "unsuspend", actor) do
      {:ok, actor}
    else
      {:moderator_actor, nil} ->
        {:error, "No actor found for the moderator user"}

      nil ->
        {:error, "No remote profile found with this ID"}

      {:error, _} ->
        {:error, "Error while performing background task"}
    end
  end

  def unsuspend_profile(_parent, _args, _resolution) do
    {:error, "Only moderators and administrators can unsuspend a profile"}
  end

  # We check that the actor is not the last administrator/creator of a group
  @spec last_admin_of_a_group?(integer()) :: boolean()
  defp last_admin_of_a_group?(actor_id) do
    length(Actors.list_group_ids_where_last_administrator(actor_id)) > 0
  end

  @spec proxify_avatar(Actor.t()) :: Actor.t()
  defp proxify_avatar(%Actor{avatar: %{url: avatar_url} = avatar} = actor) do
    actor |> Map.put(:avatar, avatar |> Map.put(:url, MediaProxy.url(avatar_url)))
  end

  @spec proxify_avatar(Actor.t()) :: Actor.t()
  defp proxify_avatar(%Actor{} = actor), do: actor

  @spec proxify_banner(Actor.t()) :: Actor.t()
  defp proxify_banner(%Actor{banner: %{url: banner_url} = banner} = actor) do
    actor |> Map.put(:banner, banner |> Map.put(:url, MediaProxy.url(banner_url)))
  end

  @spec proxify_banner(Actor.t()) :: Actor.t()
  defp proxify_banner(%Actor{} = actor), do: actor
end