defmodule Rtp.LiveStream do
  import Plug.Conn

  def init(options), do: options

  def call(conn, _opts) do
    case conn.path_info do
      ["rooms", room_name, "recording.mp4"] ->
        file_path = "priv/static/rooms/#{room_name}/recording.mp4"
        if File.exists?(file_path) do
          conn = conn
                 |> put_resp_header("content-type", "video/mp4")
                 |> put_resp_header("cache-control", "no-cache")
                 |> send_chunked(200)

          stream_growing_file(conn, file_path, 0)
          |> halt()
        else
          conn |> send_resp(404, "Not Found") |> halt()
        end
      ["rooms", room_name, file_name] ->
        file_path = "priv/static/rooms/#{room_name}/#{file_name}"
        cond do
          file_name == "index.m3u8" ->
            if File.exists?(file_path) do
              conn
              |> put_resp_header("content-type", "application/vnd.apple.mpegurl")
              |> put_resp_header("cache-control", "no-store, no-cache, must-revalidate, max-age=0")
              |> send_resp(200, File.read!(file_path))
              |> halt()
            else
              conn 
              |> put_resp_header("cache-control", "no-store, no-cache, must-revalidate, max-age=0")
              |> send_resp(404, "Not Found") 
              |> halt()
            end
          String.ends_with?(file_name, ".ts") ->
            if File.exists?(file_path) do
              {time_us, conn} = :timer.tc(fn ->
                conn
                |> put_resp_header("content-type", "video/mp2t")
                |> put_resp_header("cache-control", "no-store, no-cache, must-revalidate, max-age=0")
                |> send_file(200, file_path)
              end)
              require Logger
              Logger.info("Served #{file_name} in #{time_us / 1000} ms")
              conn |> halt()
            else
              conn |> send_resp(404, "Not Found") |> halt()
            end
          true ->
            conn
        end
      _ ->
        conn
    end
  end

  defp stream_growing_file(conn, file_path, offset) do
    case File.open(file_path, [:read, :binary]) do
      {:ok, file} ->
        :file.position(file, {:bof, offset})
        case IO.binread(file, 65536) do
          :eof ->
            File.close(file)
            stream_growing_file(conn, file_path, offset)
          data when is_binary(data) ->
            File.close(file)
            case chunk(conn, data) do
              {:ok, conn} ->
                stream_growing_file(conn, file_path, offset + byte_size(data))
              {:error, :closed} ->
                conn
            end
        end
      {:error, _} ->
        stream_growing_file(conn, file_path, offset)
    end
  end
end