defmodule Nola.IRC.LinkPlugin.YouTube do
  @behaviour Nola.IRC.LinkPlugin

  @moduledoc """
  # YouTube link preview

  needs an API key:

  ```
  config :nola, :youtube,
    api_key: "xxxxxxxxxxxxx"
  ```

  options:

  * `invidious`: Add a link to invidious.
  """

  @impl true
  def match(uri = %URI{host: yt, path: "/watch", query: "v="<>video_id}, _opts) when yt in ["youtube.com", "www.youtube.com"] do
    {true, %{video_id: video_id}}
  end

  def match(%URI{host: "youtu.be", path: "/"<>video_id}, _opts) do
    {true, %{video_id: video_id}}
  end

  def match(_, _), do: false

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

  @impl true
  def expand(uri, %{video_id: video_id}, opts) do
    key = Application.get_env(:nola, :youtube)[:api_key]
    params = %{
      "part" => "snippet,contentDetails,statistics",
      "id" => video_id,
      "key" => key
    }
    headers = []
    options = [params: params]
    case HTTPoison.get("https://www.googleapis.com/youtube/v3/videos", [], options) do
      {:ok, %HTTPoison.Response{status_code: 200, body: body}} ->
        case Jason.decode(body) do
          {:ok, json} ->
            item = List.first(json["items"])
            if item do
              snippet = item["snippet"]
              duration = item["contentDetails"]["duration"] |> String.replace("PT", "") |> String.downcase
              date = snippet["publishedAt"]
                     |> DateTime.from_iso8601()
                     |> elem(1)
                     |> Timex.format("{relative}", :relative)
                     |> elem(1)

              line = if host = Keyword.get(opts, :invidious) do
                ["-> https://#{host}/watch?v=#{video_id}"]
              else
                  []
              end
              {:ok, line ++ ["#{snippet["title"]}", "— #{duration} — uploaded by #{snippet["channelTitle"]} — #{date}"
                     <> " — #{item["statistics"]["viewCount"]} views, #{item["statistics"]["likeCount"]} likes"]}
            else
              :error
            end
          _ -> :error
        end
    end
  end

end