import 'dart:typed_data';

import 'package:venera/foundation/cache_manager.dart';
import 'package:venera/foundation/comic_source/comic_source.dart';
import 'package:venera/foundation/consts.dart';

import 'app_dio.dart';

class ImageDownloader {
  static Stream<ImageDownloadProgress> loadThumbnail(
      String url, String? sourceKey) async* {
    final cacheKey = "$url@$sourceKey";
    final cache = await CacheManager().findCache(cacheKey);

    if (cache != null) {
      var data = await cache.readAsBytes();
      yield ImageDownloadProgress(
        currentBytes: data.length,
        totalBytes: data.length,
        imageBytes: data,
      );
    }

    var configs = <String, dynamic>{};
    if (sourceKey != null) {
      var comicSource = ComicSource.find(sourceKey);
      configs = comicSource!.getThumbnailLoadingConfig?.call(url) ?? {};
    }
    configs['headers'] ??= {};
    if(configs['headers']['user-agent'] == null
        && configs['headers']['User-Agent'] == null) {
      configs['headers']['user-agent'] = webUA;
    }

    var dio = AppDio(BaseOptions(
      headers: Map<String, dynamic>.from(configs['headers']),
      method: configs['method'] ?? 'GET',
      responseType: ResponseType.stream,
    ));

    var req = await dio.request<ResponseBody>(configs['url'] ?? url,
        data: configs['data']);
    var stream = req.data?.stream ?? (throw "Error: Empty response body.");
    int? expectedBytes = req.data!.contentLength;
    if (expectedBytes == -1) {
      expectedBytes = null;
    }
    var buffer = <int>[];
    await for (var data in stream) {
      buffer.addAll(data);
      if (expectedBytes != null) {
        yield ImageDownloadProgress(
          currentBytes: buffer.length,
          totalBytes: expectedBytes,
        );
      }
    }

    if (configs['onResponse'] != null) {
      buffer = configs['onResponse'](buffer);
    }

    await CacheManager().writeCache(cacheKey, buffer);
    yield ImageDownloadProgress(
      currentBytes: buffer.length,
      totalBytes: buffer.length,
      imageBytes: Uint8List.fromList(buffer),
    );
  }

  static Stream<ImageDownloadProgress> loadComicImage(
      String imageKey, String? sourceKey, String cid, String eid) async* {
    final cacheKey = "$imageKey@$sourceKey@$cid@$eid";
    final cache = await CacheManager().findCache(cacheKey);

    if (cache != null) {
      var data = await cache.readAsBytes();
      yield ImageDownloadProgress(
        currentBytes: data.length,
        totalBytes: data.length,
        imageBytes: data,
      );
    }

    var configs = <String, dynamic>{};
    if (sourceKey != null) {
      var comicSource = ComicSource.find(sourceKey);
      configs = (await comicSource!.getImageLoadingConfig
              ?.call(imageKey, cid, eid)) ?? {};
    }
    configs['headers'] ??= {
      'user-agent': webUA,
    };

    var dio = AppDio(BaseOptions(
      headers: configs['headers'],
      method: configs['method'] ?? 'GET',
      responseType: ResponseType.stream,
    ));

    var req = await dio.request<ResponseBody>(configs['url'] ?? imageKey,
        data: configs['data']);
    var stream = req.data?.stream ?? (throw "Error: Empty response body.");
    int? expectedBytes = req.data!.contentLength;
    if (expectedBytes == -1) {
      expectedBytes = null;
    }
    var buffer = <int>[];
    await for (var data in stream) {
      buffer.addAll(data);
      if (expectedBytes != null) {
        yield ImageDownloadProgress(
          currentBytes: buffer.length,
          totalBytes: expectedBytes,
        );
      }
    }

    if (configs['onResponse'] != null) {
      buffer = configs['onResponse'](buffer);
    }

    await CacheManager().writeCache(cacheKey, buffer);
    yield ImageDownloadProgress(
      currentBytes: buffer.length,
      totalBytes: buffer.length,
      imageBytes: Uint8List.fromList(buffer),
    );
  }
}

class ImageDownloadProgress {
  final int currentBytes;

  final int totalBytes;

  final Uint8List? imageBytes;

  const ImageDownloadProgress({
    required this.currentBytes,
    required this.totalBytes,
    this.imageBytes,
  });
}