youtube_explode/lib/src/reverse_engineering/responses/channel_upload_page.dart

import 'dart:convert';

import 'package:html/dom.dart';
import 'package:html/parser.dart' as parser;

import '../../channels/channel_video.dart';
import '../../exceptions/exceptions.dart';
import '../../retry.dart';
import '../../videos/videos.dart';
import '../youtube_http_client.dart';
import 'generated/channel_upload_page_id.g.dart';

///
class ChannelUploadPage {
  ///
  final String channelId;
  final Document _root;

  _InitialData _initialData;

  ///
  _InitialData get initialData => _initialData ??= _InitialData(
      ChannelUploadPageId.fromJson(json.decode(_extractJson(
          _root
              .querySelectorAll('script')
              .map((e) => e.text)
              .toList()
              .firstWhere((e) => e.contains('window["ytInitialData"] =')),
          'window["ytInitialData"] ='))));

  String _extractJson(String html, String separator) {
    return _matchJson(
        html.substring(html.indexOf(separator) + separator.length));
  }

  String _matchJson(String str) {
    var bracketCount = 0;
    int lastI;
    for (var i = 0; i < str.length; i++) {
      lastI = i;
      if (str[i] == '{') {
        bracketCount++;
      } else if (str[i] == '}') {
        bracketCount--;
      } else if (str[i] == ';') {
        if (bracketCount == 0) {
          return str.substring(0, i);
        }
      }
    }
    return str.substring(0, lastI + 1);
  }

  ///
  ChannelUploadPage(this._root, this.channelId, [_InitialData initialData])
      : _initialData = initialData;

  ///
  Future<ChannelUploadPage> nextPage(YoutubeHttpClient httpClient) {
    if (initialData.continuation.isEmpty) {
      return Future.value(null);
    }
    var url =
        'https://www.youtube.com/browse_ajax?ctoken=${initialData.continuation}&continuation=${initialData.continuation}&itct=${initialData.clickTrackingParams}';
    return retry(() async {
      var raw = await httpClient.getString(url);
      return ChannelUploadPage(null, channelId,
          _InitialData(ChannelUploadPageId.fromJson(json.decode(raw)[1])));
    });
  }

  ///
  static Future<ChannelUploadPage> get(
      YoutubeHttpClient httpClient, String channelId, String sorting) {
    assert(sorting != null);
    var url =
        'https://www.youtube.com/channel/$channelId/videos?view=0&sort=$sorting&flow=grid';
    return retry(() async {
      var raw = await httpClient.getString(url);
      return ChannelUploadPage.parse(raw, channelId);
    });
  }

  ///
  ChannelUploadPage.parse(String raw, this.channelId)
      : _root = parser.parse(raw);
}

void x() {
  ChannelUploadPageId _id;
  // @getContentContext
  var x = _id.contents.twoColumnBrowseResultsRenderer.tabs
      .map((e) => e.tabRenderer)
      .firstWhere((e) => e.selected)
      .content
      .sectionListRenderer
      .contents
      .first
      .itemSectionRenderer
      .contents
      .first
      .gridRenderer
      .items;

  _id.response.continuationContents.gridContinuation.items;
}

class _InitialData {
  // Json parsed map
  final ChannelUploadPageId root;

  _InitialData(this.root);

  /* Cache results */

  List<ChannelVideo> _uploads;
  String _continuation;
  String _clickTrackingParams;

  List<GridContinuationItem> getContentContext() {
    if (root.contents != null) {
      return root.contents.twoColumnBrowseResultsRenderer.tabs
          .map((e) => e.tabRenderer)
          .firstWhere((e) => e.selected)
          .content
          .sectionListRenderer
          .contents
          .first
          .itemSectionRenderer
          .contents
          .first
          .gridRenderer
          .items;
    }
    if (root.response != null) {
      return root.response.continuationContents.gridContinuation.items;
    }
    throw FatalFailureException('Failed to get initial data context.');
  }

  NextContinuationData getContinuationContext() {
    if (root.contents != null) {
      return root.contents.twoColumnBrowseResultsRenderer.tabs
          .map((e) => e.tabRenderer)
          .firstWhere((e) => e.selected)
          .content
          .sectionListRenderer
          .contents
          .first
          .itemSectionRenderer
          .contents
          .first
          .gridRenderer
          .continuations
          .first
          .nextContinuationData;
    }
    if (root.response != null) {
      return root.response.continuationContents.gridContinuation.continuations
          .first.nextContinuationData;
    }
    return null;
  }

  List<ChannelVideo> get uploads => _uploads ??= getContentContext()
      ?.map(_parseContent)
      ?.where((e) => e != null)
      ?.toList()
      ?.cast<ChannelVideo>();

  String get continuation =>
      _continuation ??= getContinuationContext().continuation ?? '';

  String get clickTrackingParams => _clickTrackingParams ??=
      getContinuationContext()?.clickTrackingParams ?? '';

  dynamic _parseContent(GridContinuationItem content) {
    if (content == null || content.gridVideoRenderer == null) {
      return null;
    }
    var video = content.gridVideoRenderer;
    return ChannelVideo(VideoId(video.videoId), video.title.simpleText);
  }
}