defmodule LSG.IRC.WikipediaPlugin do
  require Logger

  @moduledoc """
  # wikipédia

  * **!wp `<recherche>`**: retourne le premier résultat de la `<recherche>` Wikipedia
  * **!wp**: un article Wikipédia au hasard
  """

  def irc_doc, do: @moduledoc

  def start_link() do
    GenServer.start_link(__MODULE__, [])
  end

  def init(_) do
    {:ok, _} = Registry.register(IRC.PubSub, "trigger:wp", [])
    {:ok, nil}
  end

  def handle_info({:irc, :trigger, "wp", message = %IRC.Message{trigger: %IRC.Trigger{args: []}}}, state) do
    irc_random(message)
    {:noreply, state}
  end
  def handle_info({:irc, :trigger, "wp", message = %IRC.Message{trigger: %IRC.Trigger{args: args}}}, state) do
    irc_search(Enum.join(args, " "), message)
    {:noreply, state}
  end

  def handle_info(info, state) do
    {:noreply, state}
  end

  defp irc_search("", message), do: irc_random(message)
  defp irc_search(query, message) do
    params = %{
      "action" => "query",
      "list" => "search",
      "srsearch" => String.strip(query),
      "srlimit" => 1,
    }
    case query_wikipedia(params) do
      {:ok, %{"query" => %{"search" => [item | _]}}} ->
        title = item["title"]
        url = "https://fr.wikipedia.org/wiki/" <> String.replace(title, " ", "_")
        msg = "Wikipédia: #{title} — #{url}"
        message.replyfun.(msg)
      _ ->
        nil
    end
  end

  defp irc_random(message) do
    params = %{
      "action" => "query",
      "generator" => "random",
      "grnnamespace" => 0,
      "prop" => "info"
    }
    case query_wikipedia(params) do
      {:ok, %{"query" => %{"pages" => map = %{}}}} ->
        [{_, item}] = Map.to_list(map)
        title = item["title"]
        url = "https://fr.wikipedia.org/wiki/" <> String.replace(title, " ", "_")
        msg = "Wikipédia: #{title} — #{url}"
        message.replyfun.(msg)
      _ ->
        nil
    end
  end

  defp query_wikipedia(params) do
    url = "https://fr.wikipedia.org/w/api.php"
    params = params
    |> Map.put("format", "json")
    |> Map.put("utf8", "")

    case HTTPoison.get(url, [], params: params) do
      {:ok, %HTTPoison.Response{status_code: 200, body: body}} -> Jason.decode(body)
      {:ok, %HTTPoison.Response{status_code: 400, body: body}} ->
        Logger.error "Wikipedia HTTP 400: #{inspect body}"
        {:error, "http 400"}
      error ->
        Logger.error "Wikipedia http error: #{inspect error}"
        {:error, "http client error"}
    end
  end

end