# Pleroma: A lightweight social networking server
# Copyright © 2017-2019 Pleroma Authors <https://pleroma.social/>
# SPDX-License-Identifier: AGPL-3.0-only

defmodule Pleroma.Notification do
  use Ecto.Schema

  alias Pleroma.Activity
  alias Pleroma.Notification
  alias Pleroma.Object
  alias Pleroma.Pagination
  alias Pleroma.Repo
  alias Pleroma.User
  alias Pleroma.Web.CommonAPI
  alias Pleroma.Web.CommonAPI.Utils
  alias Pleroma.Web.Push
  alias Pleroma.Web.Streamer

  import Ecto.Query
  import Ecto.Changeset

  schema "notifications" do
    field(:seen, :boolean, default: false)
    belongs_to(:user, User, type: Pleroma.FlakeId)
    belongs_to(:activity, Activity, type: Pleroma.FlakeId)

    timestamps()
  end

  def changeset(%Notification{} = notification, attrs) do
    notification
    |> cast(attrs, [:seen])
  end

  def for_user_query(user) do
    Notification
    |> where(user_id: ^user.id)
    |> where(
      [n, a],
      fragment(
        "? not in (SELECT ap_id FROM users WHERE info->'deactivated' @> 'true')",
        a.actor
      )
    )
    |> join(:inner, [n], activity in assoc(n, :activity))
    |> join(:left, [n, a], object in Object,
      on:
        fragment(
          "(?->>'id') = COALESCE((? -> 'object'::text) ->> 'id'::text)",
          object.data,
          a.data
        )
    )
    |> preload([n, a, o], activity: {a, object: o})
  end

  def for_user(user, opts \\ %{}) do
    user
    |> for_user_query()
    |> Pagination.fetch_paginated(opts)
  end

  def set_read_up_to(%{id: user_id} = _user, id) do
    query =
      from(
        n in Notification,
        where: n.user_id == ^user_id,
        where: n.id <= ^id,
        update: [
          set: [seen: true]
        ]
      )

    Repo.update_all(query, [])
  end

  def read_one(%User{} = user, notification_id) do
    with {:ok, %Notification{} = notification} <- get(user, notification_id) do
      notification
      |> changeset(%{seen: true})
      |> Repo.update()
    end
  end

  def get(%{id: user_id} = _user, id) do
    query =
      from(
        n in Notification,
        where: n.id == ^id,
        join: activity in assoc(n, :activity),
        preload: [activity: activity]
      )

    notification = Repo.one(query)

    case notification do
      %{user_id: ^user_id} ->
        {:ok, notification}

      _ ->
        {:error, "Cannot get notification"}
    end
  end

  def clear(user) do
    from(n in Notification, where: n.user_id == ^user.id)
    |> Repo.delete_all()
  end

  def destroy_multiple(%{id: user_id} = _user, ids) do
    from(n in Notification,
      where: n.id in ^ids,
      where: n.user_id == ^user_id
    )
    |> Repo.delete_all()
  end

  def dismiss(%{id: user_id} = _user, id) do
    notification = Repo.get(Notification, id)

    case notification do
      %{user_id: ^user_id} ->
        Repo.delete(notification)

      _ ->
        {:error, "Cannot dismiss notification"}
    end
  end

  def create_notifications(%Activity{data: %{"to" => _, "type" => "Create"}} = activity) do
    object = Object.normalize(activity)

    unless object && object.data["type"] == "Answer" do
      users = get_notified_from_activity(activity)
      notifications = Enum.map(users, fn user -> create_notification(activity, user) end)
      {:ok, notifications}
    else
      {:ok, []}
    end
  end

  def create_notifications(%Activity{data: %{"to" => _, "type" => type}} = activity)
      when type in ["Like", "Announce", "Follow"] do
    users = get_notified_from_activity(activity)
    notifications = Enum.map(users, fn user -> create_notification(activity, user) end)
    {:ok, notifications}
  end

  def create_notifications(_), do: {:ok, []}

  # TODO move to sql, too.
  def create_notification(%Activity{} = activity, %User{} = user) do
    unless skip?(activity, user) do
      notification = %Notification{user_id: user.id, activity: activity}
      {:ok, notification} = Repo.insert(notification)
      Streamer.stream("user", notification)
      Streamer.stream("user:notification", notification)
      Push.send(notification)
      notification
    end
  end

  def get_notified_from_activity(activity, local_only \\ true)

  def get_notified_from_activity(
        %Activity{data: %{"to" => _, "type" => type} = _data} = activity,
        local_only
      )
      when type in ["Create", "Like", "Announce", "Follow"] do
    recipients =
      []
      |> Utils.maybe_notify_to_recipients(activity)
      |> Utils.maybe_notify_mentioned_recipients(activity)
      |> Utils.maybe_notify_subscribers(activity)
      |> Enum.uniq()

    User.get_users_from_set(recipients, local_only)
  end

  def get_notified_from_activity(_, _local_only), do: []

  def skip?(activity, user) do
    [
      :self,
      :blocked,
      :muted,
      :followers,
      :follows,
      :non_followers,
      :non_follows,
      :recently_followed
    ]
    |> Enum.any?(&skip?(&1, activity, user))
  end

  def skip?(:self, activity, user) do
    activity.data["actor"] == user.ap_id
  end

  def skip?(:blocked, activity, user) do
    actor = activity.data["actor"]
    User.blocks?(user, %{ap_id: actor})
  end

  def skip?(:muted, activity, user) do
    actor = activity.data["actor"]

    User.mutes?(user, %{ap_id: actor}) or CommonAPI.thread_muted?(user, activity)
  end

  def skip?(
        :followers,
        activity,
        %{info: %{notification_settings: %{"followers" => false}}} = user
      ) do
    actor = activity.data["actor"]
    follower = User.get_cached_by_ap_id(actor)
    User.following?(follower, user)
  end

  def skip?(
        :non_followers,
        activity,
        %{info: %{notification_settings: %{"non_followers" => false}}} = user
      ) do
    actor = activity.data["actor"]
    follower = User.get_cached_by_ap_id(actor)
    !User.following?(follower, user)
  end

  def skip?(:follows, activity, %{info: %{notification_settings: %{"follows" => false}}} = user) do
    actor = activity.data["actor"]
    followed = User.get_cached_by_ap_id(actor)
    User.following?(user, followed)
  end

  def skip?(
        :non_follows,
        activity,
        %{info: %{notification_settings: %{"non_follows" => false}}} = user
      ) do
    actor = activity.data["actor"]
    followed = User.get_cached_by_ap_id(actor)
    !User.following?(user, followed)
  end

  def skip?(:recently_followed, %{data: %{"type" => "Follow"}} = activity, user) do
    actor = activity.data["actor"]

    Notification.for_user(user)
    |> Enum.any?(fn
      %{activity: %{data: %{"type" => "Follow", "actor" => ^actor}}} -> true
      _ -> false
    end)
  end

  def skip?(_, _, _), do: false
end