defmodule LSG.IRC.LinkPlugin.PDF do
  require Logger
  @behaviour LSG.IRC.LinkPlugin

  @impl true
  def match(_, _), do: false

  @impl true
  def post_match(_url, "application/pdf"<>_, _header, _opts) do
    {:file, nil}
  end

  def post_match(_, _, _, _), do: false

  @impl true
  def post_expand(url, file, _, _) do
    case System.cmd("pdftitle", ["-p", file]) do
      {text, 0} ->
        text = text
               |> String.trim()

        if text == "" do
          :error
        else
          basename = Path.basename(url, ".pdf")
          text = "[#{basename}] " <> text
               |> String.split("\n")
          {:ok, text}
        end
      {_, 127} ->
        Logger.error("dependency `pdftitle` is missing, please install it: `pip3 install pdftitle`.")
        :error
      {error, code} ->
        Logger.warn("command `pdftitle` exited with status code #{code}:\n#{inspect error}")
        :error
    end
  end

end