Pleroma/lib/pleroma/web/controller_helper.ex

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

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

  # As in MastoAPI, per https://api.rubyonrails.org/classes/ActiveModel/Type/Boolean.html
  @falsy_param_values [false, 0, "0", "f", "F", "false", "FALSE", "off", "OFF"]
  def truthy_param?(blank_value) when blank_value in [nil, ""], do: nil
  def truthy_param?(value), do: value not in @falsy_param_values

  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 \\ %{}) 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
end