# Pleroma: A lightweight social networking server
# Copyright © 2017-2020 Pleroma Authors <https://pleroma.social/>
# SPDX-License-Identifier: AGPL-3.0-only

defmodule Pleroma.Backup do
  use Ecto.Schema

  import Ecto.Changeset
  import Ecto.Query

  alias Pleroma.Activity
  alias Pleroma.Bookmark
  alias Pleroma.Repo
  alias Pleroma.User
  alias Pleroma.Web.ActivityPub.ActivityPub
  alias Pleroma.Web.ActivityPub.Transmogrifier
  alias Pleroma.Web.ActivityPub.UserView
  alias Pleroma.Workers.BackupWorker

  schema "backups" do
    field(:content_type, :string)
    field(:file_name, :string)
    field(:file_size, :integer, default: 0)
    field(:processed, :boolean, default: false)

    belongs_to(:user, User, type: FlakeId.Ecto.CompatType)

    timestamps()
  end

  def create(user) do
    with :ok <- validate_limit(user),
         {:ok, backup} <- user |> new() |> Repo.insert() do
      BackupWorker.process(backup)
    end
  end

  def new(user) do
    rand_str = :crypto.strong_rand_bytes(32) |> Base.url_encode64(padding: false)
    datetime = Calendar.NaiveDateTime.Format.iso8601_basic(NaiveDateTime.utc_now())
    name = "archive-#{user.nickname}-#{datetime}-#{rand_str}.zip"

    %__MODULE__{
      user_id: user.id,
      content_type: "application/zip",
      file_name: name
    }
  end

  def delete(backup) do
    uploader = Pleroma.Config.get([Pleroma.Upload, :uploader])

    with :ok <- uploader.delete_file("backups/" <> backup.file_name) do
      Repo.delete(backup)
    end
  end

  defp validate_limit(user) do
    case get_last(user.id) do
      %__MODULE__{inserted_at: inserted_at} ->
        days = Pleroma.Config.get([Pleroma.Backup, :limit_days])
        diff = Timex.diff(NaiveDateTime.utc_now(), inserted_at, :days)

        if diff > days do
          :ok
        else
          {:error, "Last export was less than #{days} days ago"}
        end

      nil ->
        :ok
    end
  end

  def get_last(user_id) do
    __MODULE__
    |> where(user_id: ^user_id)
    |> order_by(desc: :id)
    |> limit(1)
    |> Repo.one()
  end

  def remove_outdated(%__MODULE__{id: latest_id, user_id: user_id}) do
    __MODULE__
    |> where(user_id: ^user_id)
    |> where([b], b.id != ^latest_id)
    |> Repo.all()
    |> Enum.each(&BackupWorker.delete/1)
  end

  def get(id), do: Repo.get(__MODULE__, id)

  def process(%__MODULE__{} = backup) do
    with {:ok, zip_file} <- zip(backup),
         {:ok, %{size: size}} <- File.stat(zip_file),
         {:ok, _upload} <- upload(backup, zip_file) do
      backup
      |> cast(%{file_size: size, processed: true}, [:file_size, :processed])
      |> Repo.update()
    end
  end

  @files ['actor.json', 'outbox.json', 'likes.json', 'bookmarks.json']
  def zip(%__MODULE__{} = backup) do
    backup = Repo.preload(backup, :user)
    name = String.trim_trailing(backup.file_name, ".zip")
    dir = Path.join(System.tmp_dir!(), name)

    with :ok <- File.mkdir(dir),
         :ok <- actor(dir, backup.user),
         :ok <- statuses(dir, backup.user),
         :ok <- likes(dir, backup.user),
         :ok <- bookmarks(dir, backup.user),
         {:ok, zip_path} <- :zip.create(String.to_charlist(dir <> ".zip"), @files, cwd: dir),
         {:ok, _} <- File.rm_rf(dir) do
      {:ok, :binary.list_to_bin(zip_path)}
    end
  end

  def upload(%__MODULE__{} = backup, zip_path) do
    uploader = Pleroma.Config.get([Pleroma.Upload, :uploader])

    upload = %Pleroma.Upload{
      name: backup.file_name,
      tempfile: zip_path,
      content_type: backup.content_type,
      path: "backups/" <> backup.file_name
    }

    with {:ok, _} <- Pleroma.Uploaders.Uploader.put_file(uploader, upload),
         :ok <- File.rm(zip_path) do
      {:ok, upload}
    end
  end

  defp actor(dir, user) do
    with {:ok, json} <-
           UserView.render("user.json", %{user: user})
           |> Map.merge(%{"likes" => "likes.json", "bookmarks" => "bookmarks.json"})
           |> Jason.encode() do
      File.write(dir <> "/actor.json", json)
    end
  end

  defp write_header(file, name) do
    IO.write(
      file,
      """
      {
        "@context": "https://www.w3.org/ns/activitystreams",
        "id": "#{name}.json",
        "type": "OrderedCollection",
        "orderedItems": [
      """
    )
  end

  defp write(query, dir, name, fun) do
    path = dir <> "/#{name}.json"

    with {:ok, file} <- File.open(path, [:write, :utf8]),
         :ok <- write_header(file, name) do
      counter = :counters.new(1, [])

      query
      |> Pleroma.RepoStreamer.chunk_stream(100)
      |> Stream.each(fn items ->
        Enum.each(items, fn i ->
          with {:ok, str} <- fun.(i),
               :ok <- IO.write(file, str <> ",\n") do
            :counters.add(counter, 1, 1)
          end
        end)
      end)
      |> Stream.run()

      total = :counters.get(counter, 1)

      with :ok <- :file.pwrite(file, {:eof, -2}, "\n],\n  \"totalItems\": #{total}}") do
        File.close(file)
      end
    end
  end

  defp bookmarks(dir, %{id: user_id} = _user) do
    Bookmark
    |> where(user_id: ^user_id)
    |> join(:inner, [b], activity in assoc(b, :activity))
    |> select([b, a], %{id: b.id, object: fragment("(?)->>'object'", a.data)})
    |> write(dir, "bookmarks", fn a -> {:ok, "\"#{a.object}\""} end)
  end

  defp likes(dir, user) do
    user.ap_id
    |> Activity.Queries.by_actor()
    |> Activity.Queries.by_type("Like")
    |> select([like], %{id: like.id, object: fragment("(?)->>'object'", like.data)})
    |> write(dir, "likes", fn a -> {:ok, "\"#{a.object}\""} end)
  end

  defp statuses(dir, user) do
    opts =
      %{}
      |> Map.put(:type, ["Create", "Announce"])
      |> Map.put(:blocking_user, user)
      |> Map.put(:muting_user, user)
      |> Map.put(:reply_filtering_user, user)
      |> Map.put(:announce_filtering_user, user)
      |> Map.put(:user, user)

    [[user.ap_id], User.following(user), Pleroma.List.memberships(user)]
    |> Enum.concat()
    |> ActivityPub.fetch_activities_query(opts)
    |> write(dir, "outbox", fn a ->
      with {:ok, activity} <- Transmogrifier.prepare_outgoing(a.data) do
        activity |> Map.delete("@context") |> Jason.encode()
      end
    end)
  end
end