'use strict';

const ResultsParser = require('../parser/contents');
const { InnertubeError } = require('../utils/Utils');

// TODO: add a way subdivide into sections and return subfeeds?

class Feed {
  #page;

  /** @type {import('../parser/contents/classes/ContinuationItem')[]} */
  #continuation;

  /** @type {import('../core/Actions')} */
  #actions;

  #memo;

  constructor(actions, data, already_parsed = false) {
    if (data.on_response_received_actions || data.on_response_received_endpoints || already_parsed) {
      this.#page = data;
    } else {
      this.#page = ResultsParser.parseResponse(data);
    }

    this.#memo =

    this.#page.on_response_received_commands ?
      this.#page.on_response_received_commands_memo :

      this.#page.on_response_received_endpoints ?
        this.#page.on_response_received_endpoints_memo :

        this.#page.contents ?
          this.#page.contents_memo :

          this.#page.on_response_received_actions ?
            this.#page.on_response_received_actions_memo : [];

    this.#actions = actions;
  }

  /**
   * Get all videos on a given page via memo
   *
   * @param {Map<string, any[]>} memo
   * @returns {Array<import('../parser/contents/classes/Video') | import('../parser/contents/classes/GridVideo') | import('../parser/contents/classes/CompactVideo') | import('../parser/contents/classes/PlaylistVideo') | import('../parser/contents/classes/PlaylistPanelVideo') | import('../parser/contents/classes/WatchCardCompactVideo')>}
   */
  static getVideosFromMemo(memo) {
    const videos = memo.get('Video') || [];
    const grid_videos = memo.get('GridVideo') || [];
    const compact_videos = memo.get('CompactVideo') || [];
    const playlist_videos = memo.get('PlaylistVideo') || [];
    const playlist_panel_videos = memo.get('PlaylistPanelVideo') || [];
    const watch_card_compact_videos = memo.get('WatchCardCompactVideo') || [];

    return [
      ...videos,
      ...grid_videos,
      ...compact_videos,
      ...playlist_videos,
      ...playlist_panel_videos,
      ...watch_card_compact_videos
    ];
  }

  /**
   * Get all playlists on a given page via memo
   *
   * @param {Map<string, any[]>} memo
   * @returns {Array<import('../parser/contents/classes/Playlist') | import('../parser/contents/classes/GridPlaylist')>}
   */
  static getPlaylistsFromMemo(memo) {
    const playlists = memo.get('Playlist') || [];
    const grid_playlists = memo.get('GridPlaylist') || [];
    return [ ...playlists, ...grid_playlists ];
  }

  /**
   * Get all the videos in the feed
   */
  get videos() {
    return Feed.getVideosFromMemo(this.#memo);
  }

  /**
   * Get all the community posts in the feed
   *
   * @returns {import('../parser/contents/classes/BackstagePost')[] | import('../parser/contents/classes/Post')[]}
   */
  get posts() {
    return this.#memo.get('BackstagePost') || this.#memo.get('Post') || [];
  }

  /**
   * Get all the channels in the feed
   *
   * @returns {Array<import('../parser/contents/Channel') | import('../parser/contents/GridChannel')>}
   */
  get channels() {
    const channels = this.#memo.get('Channel') || [];
    const grid_channels = this.#memo.get('GridChannel') || [];
    return [ ...channels, ...grid_channels ];
  }

  /**
   * Get all playlists in the feed
   *
   * @returns {Array<import('../parser/contents/classes/Playlist') | import('../parser/contents/classes/GridPlaylist')>}
   */
  get playlists() {
    return Feed.getPlaylistsFromMemo(this.#memo);
  }

  get memo() {
    return this.#memo;
  }

  /**
   * Returns contents from the page.
   *
   * @returns {*}
   */
  get contents() {
    const tab_content = this.#memo.get('Tab')?.[0]?.content;
    const reload_continuation_items = this.#memo.get('reloadContinuationItemsCommand')?.[0];
    const append_continuation_items = this.#memo.get('appendContinuationItemsAction')?.[0];

    return tab_content || reload_continuation_items || append_continuation_items;
  }

  /**
   * Returns all segments/sections from the page.
   *
   * @returns {import('../parser/contents/Shelf')[] | import('../parser/contents/RichShelf')[] | import('../parser/contents/ReelShelf')[]}
   */
  get shelves() {
    const shelf = this.#page.contents_memo.get('Shelf') || [];
    const rich_shelf = this.#page.contents_memo.get('RichShelf') || [];
    const reel_shelf = this.#page.contents_memo.get('ReelShelf') || [];

    return [ ...shelf, ...rich_shelf, ...reel_shelf ];
  }

  /**
   * Finds shelf by title.
   *
   * @param {string} title
   */
  getShelf(title) {
    return this.shelves.find((shelf) => shelf.title.toString() === title);
  }

  /**
   * Returns secondary contents from the page.
   *
   * @returns {*}
   */
  get secondary_contents() {
    return this.page.contents?.secondary_contents;
  }

  get actions() {
    return this.#actions;
  }

  /**
   * Get the original page data
   */
  get page() {
    return this.#page;
  }

  /**
   * Checks if the feed has continuation.
   *
   * @returns {boolean}
   */
  get has_continuation() {
    return (this.#memo.get('ContinuationItem') || []).length > 0;
  }

  /**
   * Retrieves continuation data as it is.
   *
   * @returns {Promise.<any>}
   */
  async getContinuationData() {
    if (this.#continuation) {
      if (this.#continuation.length > 1)
        throw new InnertubeError('There are too many continuations, you\'ll need to find the correct one yourself in this.page');
      if (this.#continuation.length === 0)
        throw new InnertubeError('There are no continuations');

      const response = await this.#continuation[0].endpoint.call(this.#actions);

      return response;
    }

    this.#continuation = this.#memo.get('ContinuationItem');

    if (this.#continuation)
      return this.getContinuationData();

    return null;
  }

  /**
   * Retrieves next batch of contents and returns a new {@link Feed} object.
   *
   * @returns {Promise.<Feed>}
   */
  async getContinuation() {
    const continuation_data = await this.getContinuationData();
    return new Feed(this.actions, continuation_data, true);
  }
}

module.exports = Feed;