const fetch = require("node-fetch")
const { Track } = require("./track")
const { Playlist } = require("./playlist")
const ytdl = require('ytdl-core')

/**
* Centralize all youtube requests within a single interface.
* It allows searching infos (tracks, playlists, metadata) over youtube.
*/
class Youtube {
  constructor() {}

  async #get_json_from_url(url) {
    const req = await fetch(url, {'headers': {'Cookie': 'CONSENT=YES+cb.20210622-13-p0.fr+FX+073'}})
    const body = await req.text()
    return JSON.parse(body.match(/ytInitialData = (.*?);<\/script>/)[1])
  }

  async #get_json_from_route(route) {
    return await this.#get_json_from_url('https://www.youtube.com/' + route)
  }

  /**
   * @param {string} search The search pattern that will be sent to Youtube
   * @return {Track[]} An array of objects representing the search results. <code>source</code> is set to <code>"youtube"</code>
   */
  async search_track(search) {
    const json = await this.#get_json_from_route('results?search_query='
                                                 + encodeURIComponent(search))
    const results = json.contents.twoColumnSearchResultsRenderer.primaryContents.sectionListRenderer.contents[0].itemSectionRenderer.contents
    return results
      .filter(e => e.videoRenderer)
      .map(e => {
        return new Track({
          url: 'https://www.youtube.com/watch?v=' + e.videoRenderer.videoId,
          title: e.videoRenderer.title.runs[0].text,
          length: e.videoRenderer.lengthText?.simpleText || null,
          source: 'youtube',
        })
      })
  }

  /**
   * Retrieve all tracks of the playlist on youtube
   * @param {string} playlist_query an url or id of the youtube playlist. It will recognize the list=xxx pattern.
   * @returns {Playlist}
   */
  async get_playlist(playlist_query) {
    const playlist_id = playlist_query.match(/list=([\w-]+)/)?.[1] || playlist_query
    const json = await this.#get_json_from_route('playlist?list='
                                                 + encodeURIComponent(playlist_id))
    // console.log(JSON.stringify(json, null, 2))
    const results = json.contents.twoColumnBrowseResultsRenderer.tabs[0].tabRenderer.content.sectionListRenderer.contents[0].itemSectionRenderer.contents[0].playlistVideoListRenderer.contents
    
    const tracks = results
          .filter(video => video?.playlistVideoRenderer?.lengthText)
          .map((video) => new Track({
            title: video.playlistVideoRenderer.title.runs[0].text,
            url: 'https://www.youtube.com/watch?v=' + video.playlistVideoRenderer.videoId,
            length: video.playlistVideoRenderer.lengthText?.simpleText || null,
            source: 'youtube',
          }))
    return new Playlist({ tracks })
  }

  /**
   * Retrieve the metadata of a YouTube video
   * @param {string} url
   * @returns {Track}
   */
  async get_metadata(url) {
    const video_infos = (await ytdl.getBasicInfo(url)).videoDetails
    return new Track({
      url: video_infos.video_url,
      title: video_infos.title,
      length: parseInt(video_infos.lengthSeconds),
      source: 'youtube'
    })
  }
}

const youtube_instance = new Youtube()

module.exports = {
  Youtube,
  youtube_instance,
}