akkoma/lib/pleroma/web/controller_helper.ex

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

defmodule Pleroma.Web.ControllerHelper do
  use Pleroma.Web, :controller

  # As in Mastodon API, per https://api.rubyonrails.org/classes/ActiveModel/Type/Boolean.html
  @falsy_param_values [false, 0, "0", "f", "F", "false", "False", "FALSE", "off", "OFF"]

  def explicitly_falsy_param?(value), do: value in @falsy_param_values

  # Note: `nil` and `""` are considered falsy values in Pleroma
  def falsy_param?(value),
    do: explicitly_falsy_param?(value) or value in [nil, ""]

  def truthy_param?(value), do: not falsy_param?(value)

  def json_response(conn, status, json) do
    conn
    |> put_status(status)
    |> json(json)
  end

  @spec fetch_integer_param(map(), String.t(), integer() | nil) :: integer() | nil
  def fetch_integer_param(params, name, default \\ nil) do
    params
    |> Map.get(name, default)
    |> param_to_integer(default)
  end

  defp param_to_integer(val, _) when is_integer(val), do: val

  defp param_to_integer(val, default) when is_binary(val) do
    case Integer.parse(val) do
      {res, _} -> res
      _ -> default
    end
  end

  defp param_to_integer(_, default), do: default

  def add_link_headers(conn, activities, extra_params \\ %{})

  def add_link_headers(%{assigns: %{skip_link_headers: true}} = conn, _activities, _extra_params),
    do: conn

  def add_link_headers(conn, activities, extra_params) do
    case List.last(activities) do
      %{id: max_id} ->
        params =
          conn.params
          |> Map.drop(Map.keys(conn.path_params))
          |> Map.drop(["since_id", "max_id", "min_id"])
          |> Map.merge(extra_params)

        limit =
          params
          |> Map.get("limit", "20")
          |> String.to_integer()

        min_id =
          if length(activities) <= limit do
            activities
            |> List.first()
            |> Map.get(:id)
          else
            activities
            |> Enum.at(limit * -1)
            |> Map.get(:id)
          end

        next_url = current_url(conn, Map.merge(params, %{max_id: max_id}))
        prev_url = current_url(conn, Map.merge(params, %{min_id: min_id}))

        put_resp_header(conn, "link", "<#{next_url}>; rel=\"next\", <#{prev_url}>; rel=\"prev\"")

      _ ->
        conn
    end
  end

  def assign_account_by_id(conn, _) do
    # TODO: use `conn.params[:id]` only after moving to OpenAPI
    case Pleroma.User.get_cached_by_id(conn.params[:id] || conn.params["id"]) do
      %Pleroma.User{} = account -> assign(conn, :account, account)
      nil -> Pleroma.Web.MastodonAPI.FallbackController.call(conn, {:error, :not_found}) |> halt()
    end
  end

  def try_render(conn, target, params) when is_binary(target) do
    case render(conn, target, params) do
      nil -> render_error(conn, :not_implemented, "Can't display this activity")
      res -> res
    end
  end

  def try_render(conn, _, _) do
    render_error(conn, :not_implemented, "Can't display this activity")
  end

  @spec put_if_exist(map(), atom() | String.t(), any) :: map()
  def put_if_exist(map, _key, nil), do: map

  def put_if_exist(map, key, value), do: Map.put(map, key, value)

  def embed_relationships?(params) do
    # To do: change to `truthy_param?(params["embed_relationships"])` once PleromaFE supports it
    not explicitly_falsy_param?(params["embed_relationships"])
  end
end