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

import 'dart:convert';

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

import '../../../youtube_explode_dart.dart';
import '../../exceptions/exceptions.dart';
import '../../extensions/helpers_extension.dart';
import '../../retry.dart';
import '../youtube_http_client.dart';

///
class ChannelAboutPage {
  final Document _root;

  ///
  late final _InitialData initialData = _getInitialData();

  _InitialData _getInitialData() {
    final scriptText = _root
        .querySelectorAll('script')
        .map((e) => e.text)
        .toList(growable: false);

    var initialDataText = scriptText.firstWhere(
        (e) => e.contains('window["ytInitialData"] ='),
        orElse: () => '');
    if (initialDataText.isNotEmpty) {
      return _InitialData(json
          .decode(_extractJson(initialDataText, 'window["ytInitialData"] =')));
    }

    initialDataText = scriptText.firstWhere(
        (e) => e.contains('var ytInitialData = '),
        orElse: () => '');
    if (initialDataText.isNotEmpty) {
      return _InitialData(
          json.decode(_extractJson(initialDataText, 'var ytInitialData = ')));
    }

    throw TransientFailureException(
        'Failed to retrieve initial data from the channel about page, please report this to the project GitHub page.'); // ignore: lines_longer_than_80_chars
  }

  ///
  String get description => initialData.description;

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

  String _matchJson(String str) {
    var bracketCount = 0;
    late 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);
  }

  ///
  ChannelAboutPage(this._root);

  ///
  ChannelAboutPage.parse(String raw) : _root = parser.parse(raw);

  ///
  static Future<ChannelAboutPage> get(YoutubeHttpClient httpClient, String id) {
    var url = 'https://www.youtube.com/channel/$id/about?hl=en';

    return retry(() async {
      var raw = await httpClient.getString(url);
      var result = ChannelAboutPage.parse(raw);

      return result;
    });
  }

  ///
  static Future<ChannelAboutPage> getByUsername(
      YoutubeHttpClient httpClient, String username) {
    var url = 'https://www.youtube.com/user/$username/about?hl=en';

    return retry(() async {
      var raw = await httpClient.getString(url);
      var result = ChannelAboutPage.parse(raw);

      return result;
    });
  }
}

final _urlExp = RegExp(r'q=([^=]*)$');

class _InitialData {
  // Json parsed map
  final Map<String, dynamic> root;

  _InitialData(this.root);

  late final Map<String, dynamic> content = _getContentContext();

  Map<String, dynamic> _getContentContext() {
    return root
        .get('contents')!
        .get('twoColumnBrowseResultsRenderer')!
        .getList('tabs')!
        .elementAtSafe(5)!
        .get('tabRenderer')!
        .get('content')!
        .get('sectionListRenderer')!
        .getList('contents')!
        .firstOrNull!
        .get('itemSectionRenderer')!
        .getList('contents')!
        .firstOrNull!
        .get('channelAboutFullMetadataRenderer')!;
  }

  late final String description =
      content.get('description')!.getT<String>('simpleText')!;

  late final List<ChannelLink> channelLinks = content
      .getList('primaryLinks')!
      .map((e) => ChannelLink(
          e.get('title')?.getT<String>('simpleText') ?? '',
          extractUrl(e
                  .get('navigationEndpoint')
                  ?.get('commandMetadata')
                  ?.get('webCommandMetadata')
                  ?.getT<String>('url') ??
              e
                  .get('navigationEndpoint')
                  ?.get('urlEndpoint')
                  ?.getT<String>('url') ??
              ''),
          Uri.parse(e
                  .get('icon')
                  ?.getList('thumbnails')
                  ?.firstOrNull
                  ?.getT<String>('url') ??
              '')))
      .toList();

  late final int viewCount = int.parse(content
      .get('viewCountText')!
      .getT<String>('simpleText')!
      .stripNonDigits());

  late final String joinDate =
      content.get('joinedDateText')!.getList('runs')![1].getT<String>('text')!;

  late final String title = content.get('title')!.getT<String>('simpleText')!;

  late final List<Map<String, dynamic>> avatar =
      content.get('avatar')!.getList('thumbnails')!;

  String get country => content.get('country')!.getT<String>('simpleText')!;

  String parseRuns(List<dynamic>? runs) =>
      runs?.map((e) => e.text).join() ?? '';

  Uri extractUrl(String text) =>
      Uri.parse(Uri.decodeFull(_urlExp.firstMatch(text)?.group(1) ?? ''));
}