defmodule Eventos.Service.ActivityPub.Transmogrifier do
  @moduledoc """
  A module to handle coding from internal to wire ActivityPub and back.
  """
  alias Eventos.Actors.Actor
  alias Eventos.Actors
  alias Eventos.Events.Event
  alias Eventos.Service.ActivityPub

  import Ecto.Query

  require Logger

  @doc """
  Modifies an incoming AP object (mastodon format) to our internal format.
  """
  def fix_object(object) do
    object
    |> Map.put("actor", object["attributedTo"])
    |> fix_attachments
    |> fix_context
    #|> fix_in_reply_to
    |> fix_emoji
    |> fix_tag
  end

#  def fix_in_reply_to(%{"inReplyTo" => in_reply_to_id} = object)
#      when not is_nil(in_reply_to_id) do
#    case ActivityPub.fetch_object_from_id(in_reply_to_id) do
#      {:ok, replied_object} ->
#        activity = Activity.get_create_activity_by_object_ap_id(replied_object.data["id"])
#
#        object
#        |> Map.put("inReplyTo", replied_object.data["id"])
#        |> Map.put("inReplyToAtomUri", object["inReplyToAtomUri"] || in_reply_to_id)
#        |> Map.put("inReplyToStatusId", activity.id)
#        |> Map.put("conversation", replied_object.data["context"] || object["conversation"])
#        |> Map.put("context", replied_object.data["context"] || object["conversation"])
#
#      e ->
#        Logger.error("Couldn't fetch #{object["inReplyTo"]} #{inspect(e)}")
#        object
#    end
#  end

  def fix_in_reply_to(object), do: object

  def fix_context(object) do
    object
    |> Map.put("context", object["conversation"])
  end

  def fix_attachments(object) do
    attachments =
      (object["attachment"] || [])
      |> Enum.map(fn data ->
        url = [%{"type" => "Link", "mediaType" => data["mediaType"], "href" => data["url"]}]
        Map.put(data, "url", url)
      end)

    object
    |> Map.put("attachment", attachments)
  end

  def fix_emoji(object) do
    tags = object["tag"] || []
    emoji = tags |> Enum.filter(fn data -> data["type"] == "Emoji" and data["icon"] end)

    emoji =
      emoji
      |> Enum.reduce(%{}, fn data, mapping ->
        name = data["name"]

        if String.starts_with?(name, ":") do
          name = name |> String.slice(1..-2)
        end

        mapping |> Map.put(name, data["icon"]["url"])
      end)

    # we merge mastodon and pleroma emoji into a single mapping, to allow for both wire formats
    emoji = Map.merge(object["emoji"] || %{}, emoji)

    object
    |> Map.put("emoji", emoji)
  end

  def fix_tag(object) do
    tags =
      (object["tag"] || [])
      |> Enum.filter(fn data -> data["type"] == "Hashtag" and data["name"] end)
      |> Enum.map(fn data -> String.slice(data["name"], 1..-1) end)

    combined = (object["tag"] || []) ++ tags

    object
    |> Map.put("tag", combined)
  end

  # TODO: validate those with a Ecto scheme
  # - tags
  # - emoji
  def handle_incoming(%{"type" => "Create", "object" => %{"type" => "Note"} = object} = data) do
    Logger.debug("Handle incoming to create notes")
    with %Actor{} = actor <- Actor.get_or_fetch_by_url(data["actor"]) do
      Logger.debug("found actor")
      object = fix_object(data["object"])

      params = %{
        to: data["to"],
        object: object,
        actor: actor,
        context: object["conversation"],
        local: false,
        published: data["published"],
        additional:
          Map.take(data, [
            "cc",
            "id"
          ])
      }

      ActivityPub.create(params)
    end
  end

  def handle_incoming(%{"type" => "Follow", "object" => followed, "actor" => follower, "id" => id} = data) do
    with %Actor{} = followed <- Actors.get_actor_by_url(followed),
         %Actor{} = follower <- Actors.get_or_fetch_by_url(follower),
         {:ok, activity} <- ActivityPub.follow(follower, followed, id, false) do
      ActivityPub.accept(%{to: [follower.url], actor: followed.url, object: data, local: true})

      #Actors.follow(follower, followed)
      {:ok, activity}
    else
      _e -> :error
    end
  end
#
#  def handle_incoming(
#        %{"type" => "Like", "object" => object_id, "actor" => actor, "id" => id} = data
#      ) do
#    with %User{} = actor <- User.get_or_fetch_by_ap_id(actor),
#         {:ok, object} <-
#           get_obj_helper(object_id) || ActivityPub.fetch_object_from_id(object_id),
#         {:ok, activity, object} <- ActivityPub.like(actor, object, id, false) do
#      {:ok, activity}
#    else
#      _e -> :error
#    end
#  end
#
#  def handle_incoming(
#        %{"type" => "Announce", "object" => object_id, "actor" => actor, "id" => id} = data
#      ) do
#    with %User{} = actor <- User.get_or_fetch_by_ap_id(actor),
#         {:ok, object} <-
#           get_obj_helper(object_id) || ActivityPub.fetch_object_from_id(object_id),
#         {:ok, activity, object} <- ActivityPub.announce(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.user_data_from_user_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} <-
#           get_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
#
#  # TODO
#  # Accept
#  # Undo
#
#  def handle_incoming(_), do: :error
#
#  def get_obj_helper(id) do
#    if object = Object.get_by_ap_id(id), do: {:ok, object}, else: nil
#  end
#
#  def set_reply_to_uri(%{"inReplyTo" => inReplyTo} = object) do
#    with false <- String.starts_with?(inReplyTo, "http"),
#         {:ok, %{data: replied_to_object}} <- get_obj_helper(inReplyTo) do
#      Map.put(object, "inReplyTo", replied_to_object["external_url"] || inReplyTo)
#    else
#      _e -> object
#    end
#  end
#
#  def set_reply_to_uri(obj), do: obj
#
#  # Prepares the object of an outgoing create activity.
#  def prepare_object(object) do
#    object
#    |> set_sensitive
#    |> add_hashtags
#    |> add_mention_tags
#    |> add_emoji_tags
#    |> add_attributed_to
#    |> prepare_attachments
#    |> set_conversation
#    |> set_reply_to_uri
#  end

  @doc
  """
  internal -> Mastodon
  """

  def prepare_outgoing(%{"type" => "Create", "object" => %{"type" => "Note"} = object} = data) do
    object =
      object
      #|> prepare_object

    data =
      data
      |> Map.put("object", object)
      |> Map.put("@context", "https://www.w3.org/ns/activitystreams")

    {:ok, data}
  end

  def prepare_outgoing(%{"type" => type} = data) do
    data =
      data
      #|> maybe_fix_object_url
      |> Map.put("@context", "https://www.w3.org/ns/activitystreams")

    {:ok, data}
  end

  def prepare_outgoing(%Event{} = event) do
    event =
      event
      |> Map.from_struct
      |> Map.drop([:"__meta__"])
      |> Map.put(:"@context", "https://www.w3.org/ns/activitystreams")

    {:ok, event}
  end
#
#  def maybe_fix_object_url(data) do
#    if is_binary(data["object"]) and not String.starts_with?(data["object"], "http") do
#      case ActivityPub.fetch_object_from_id(data["object"]) do
#        {:ok, relative_object} ->
#          if relative_object.data["external_url"] do
#            data =
#              data
#              |> Map.put("object", relative_object.data["external_url"])
#          else
#            data
#          end
#
#        e ->
#          Logger.error("Couldn't fetch #{data["object"]} #{inspect(e)}")
#          data
#      end
#    else
#      data
#    end
#  end
#
#  def add_hashtags(object) do
#    tags =
#      (object["tag"] || [])
#      |> Enum.map(fn tag ->
#        %{
#          "href" => Pleroma.Web.Endpoint.url() <> "/tags/#{tag}",
#          "name" => "##{tag}",
#          "type" => "Hashtag"
#        }
#      end)
#
#    object
#    |> Map.put("tag", tags)
#  end
#
#  def add_mention_tags(object) do
#    recipients = object["to"] ++ (object["cc"] || [])
#
#    mentions =
#      recipients
#      |> Enum.map(fn ap_id -> User.get_cached_by_ap_id(ap_id) end)
#      |> Enum.filter(& &1)
#      |> Enum.map(fn user ->
#        %{"type" => "Mention", "href" => user.ap_id, "name" => "@#{user.nickname}"}
#      end)
#
#    tags = object["tag"] || []
#
#    object
#    |> Map.put("tag", tags ++ mentions)
#  end
#
#  # TODO: we should probably send mtime instead of unix epoch time for updated
#  def add_emoji_tags(object) do
#    tags = object["tag"] || []
#    emoji = object["emoji"] || []
#
#    out =
#      emoji
#      |> Enum.map(fn {name, url} ->
#        %{
#          "icon" => %{"url" => url, "type" => "Image"},
#          "name" => ":" <> name <> ":",
#          "type" => "Emoji",
#          "updated" => "1970-01-01T00:00:00Z",
#          "id" => url
#        }
#      end)
#
#    object
#    |> Map.put("tag", tags ++ out)
#  end
#
#  def set_conversation(object) do
#    Map.put(object, "conversation", object["context"])
#  end
#
#  def set_sensitive(object) do
#    tags = object["tag"] || []
#    Map.put(object, "sensitive", "nsfw" in tags)
#  end
#
#  def add_attributed_to(object) do
#    attributedTo = object["attributedTo"] || object["actor"]
#
#    object
#    |> Map.put("attributedTo", attributedTo)
#  end
#
#  def prepare_attachments(object) do
#    attachments =
#      (object["attachment"] || [])
#      |> Enum.map(fn data ->
#        [%{"mediaType" => media_type, "href" => href} | _] = data["url"]
#        %{"url" => href, "mediaType" => media_type, "name" => data["name"], "type" => "Document"}
#      end)
#
#    object
#    |> Map.put("attachment", attachments)
#  end
#
#  defp user_upgrade_task(user) do
#    old_follower_address = User.ap_followers(user)
#
#    q =
#      from(
#        u in User,
#        where: ^old_follower_address in u.following,
#        update: [
#          set: [
#            following:
#              fragment(
#                "array_replace(?,?,?)",
#                u.following,
#                ^old_follower_address,
#                ^user.follower_address
#              )
#          ]
#        ]
#      )
#
#    Repo.update_all(q, [])
#
#    maybe_retire_websub(user.ap_id)
#
#    # Only do this for recent activties, don't go through the whole db.
#    # Only look at the last 1000 activities.
#    since = (Repo.aggregate(Activity, :max, :id) || 0) - 1_000
#
#    q =
#      from(
#        a in Activity,
#        where: ^old_follower_address in a.recipients,
#        where: a.id > ^since,
#        update: [
#          set: [
#            recipients:
#              fragment(
#                "array_replace(?,?,?)",
#                a.recipients,
#                ^old_follower_address,
#                ^user.follower_address
#              )
#          ]
#        ]
#      )
#
#    Repo.update_all(q, [])
#  end
#
#  def upgrade_user_from_ap_id(ap_id, async \\ true) do
#    with %User{local: false} = user <- User.get_by_ap_id(ap_id),
#         {:ok, data} <- ActivityPub.fetch_and_prepare_user_from_ap_id(ap_id) do
#      data =
#        data
#        |> Map.put(:info, Map.merge(user.info, data[:info]))
#
#      already_ap = User.ap_enabled?(user)
#
#      {:ok, user} =
#        User.upgrade_changeset(user, data)
#        |> Repo.update()
#
#      if !already_ap do
#        # This could potentially take a long time, do it in the background
#        if async do
#          Task.start(fn ->
#            user_upgrade_task(user)
#          end)
#        else
#          user_upgrade_task(user)
#        end
#      end
#
#      {:ok, user}
#    else
#      e -> e
#    end
#  end
#
#  def maybe_retire_websub(ap_id) do
#    # some sanity checks
#    if is_binary(ap_id) && String.length(ap_id) > 8 do
#      q =
#        from(
#          ws in Pleroma.Web.Websub.WebsubClientSubscription,
#          where: fragment("? like ?", ws.topic, ^"#{ap_id}%")
#        )
#
#      Repo.delete_all(q)
#    end
#  end
end