import 'dart:async';

import 'package:bloc/bloc.dart';
import 'package:hadi_hoda_flutter/core/params/no_params.dart';
import 'package:hadi_hoda_flutter/core/status/base_status.dart';
import 'package:hadi_hoda_flutter/core/utils/pre_cache_image.dart';
import 'package:hadi_hoda_flutter/features/download/domain/entities/download_entity.dart';
import 'package:hadi_hoda_flutter/features/download/domain/usecases/batch_download_usecase.dart';
import 'package:hadi_hoda_flutter/features/download/domain/usecases/cancel_download_usecase.dart';
import 'package:hadi_hoda_flutter/features/download/domain/usecases/get_last_downloaded_level.dart';
import 'package:hadi_hoda_flutter/features/download/domain/usecases/loading_stream_usecase.dart';
import 'package:hadi_hoda_flutter/features/download/domain/usecases/save_levels_usecase.dart';
import 'package:hadi_hoda_flutter/features/download/presentation/bloc/download_event.dart';
import 'package:hadi_hoda_flutter/features/download/presentation/bloc/download_state.dart';

class DownloadBloc extends Bloc<DownloadEvent, DownloadState> {
  /// ------------constructor------------
  DownloadBloc(
    this._loadingStreamUseCase,
    this._saveLevelsUseCase,
    this._cancelDownloadUseCase,
    this._getLastDownloadedLevel,
    this._batchDownloadUseCase,
  ) : super(const DownloadState()) {
    preCacheImages();
    on<StartDownloadEvent>(_startDownloadEvent);
    on<SaveLevelsEvent>(_saveLevelsEvent);
    on<CancelDownloadEvent>(_cancelDownloadEvent);
    loadingStream = _loadingStreamUseCase();
  }

  /// ------------UseCases------------
  final SaveLevelsUseCase _saveLevelsUseCase;
  final BatchDownloadUseCase _batchDownloadUseCase;
  final LoadingStreamUseCase _loadingStreamUseCase;
  final CancelDownloadUseCase _cancelDownloadUseCase;
  final GetLastDownloadedLevel _getLastDownloadedLevel;

  Stream<DownloadEntity> loadingStream = const Stream.empty();
  bool _isDownloading = false;
  bool _isCancelled = false;

  bool get isDownloading => _isDownloading;

  FutureOr<void> _startDownloadEvent(
    StartDownloadEvent event,
    Emitter<DownloadState> emit,
  ) async {
    _isCancelled = false;
    _isDownloading = true;
    emit(state.copyWith(status: const BaseLoading()));

    final levelResult = await _saveLevelsUseCase(NoParams());

    if (levelResult.isError) {
      _isDownloading = false;
      emit(state.copyWith(status: BaseError(levelResult.error!.errorMessage)));
      return;
    }

    final downloadResult = await _batchDownloadUseCase(event.toLevel);

    downloadResult.fold(
      (_) {
        _isDownloading = false;
        emit(state.copyWith(status: const BaseComplete('')));
      },
      (e) {
        _isDownloading = false;
        emit(state.copyWith(status: BaseError(e.errorMessage)));
      },
    );

    // if (event.types.contains(DownloadType.levels)) {
    //   await LocalStorage.saveData(
    //     key: MyConstants.firstDownload,
    //     value: 'true',
    //   );
    // }

    // if (MyContext.get.mounted && event.destinationRoute != null) {
    //   MyContext.get.goNamed(event.destinationRoute!);
    // }
  }

  Future<int> lastDownloadedLevel() async =>
      (await _getLastDownloadedLevel(NoParams())).data ?? 0;

  /// Orchestrates batch download (level-by-level).
  /// If a download is already in progress, just updates the destination
  /// so the running download navigates there when it finishes.
  // FutureOr<void> _startBatchDownloadEvent(
  //   StartBatchDownloadEvent event,
  //   Emitter<DownloadState> emit,
  // ) async {
  //   _isCancelled = false;
  //   final String lang = event.batchParams.lang;
  //   final int alreadyDownloaded = int.tryParse(
  //     LocalStorage.readData(key: '${MyConstants.downloadedLevelCount}_$lang') ?? '0',
  //   ) ?? 0;
  //   final int neededUpTo =
  //       event.batchParams.batchStart + event.batchParams.batchSize - 1;
  //
  //   // Already downloaded — skip straight to destination.
  //   if (alreadyDownloaded >= neededUpTo) {
  //     emit(state.copyWith(getFilesStatus: const BaseComplete('')));
  //     if (MyContext.get.mounted && event.destinationRoute != null) {
  //       MyContext.get.goNamed(
  //         event.destinationRoute!,
  //         pathParameters: event.destinationPathParameters ?? {},
  //       );
  //     }
  //     return;
  //   }
  //
  //   // A download is already running — just update the destination so the
  //   // ongoing download navigates there when it finishes.
  //   if (_isBatchDownloading) {
  //     emit(state.copyWith(
  //       destinationRoute: event.destinationRoute,
  //       destinationPathParameters: event.destinationPathParameters,
  //     ));
  //     return;
  //   }
  //
  //   _isBatchDownloading = true;
  //
  //   emit(state.copyWith(
  //     getFilesStatus: const BaseLoading(),
  //     batchParams: event.batchParams,
  //     destinationRoute: event.destinationRoute,
  //     destinationPathParameters: event.destinationPathParameters,
  //   ));
  //
  //   final levelsResult = await _saveLevelsUseCase(NoParams());
  //   if (levelsResult.isError) {
  //     if (_isCancelled) return;
  //     _isBatchDownloading = false;
  //     emit(state.copyWith(
  //       getFilesStatus: BaseError(levelsResult.error!.errorMessage),
  //     ));
  //     return;
  //   }
  //
  //   if (_isCancelled) return;
  //   final result = await _batchDownloadUseCase(event.batchParams);
  //   if (result.isError) {
  //     if (_isCancelled) return;
  //     _isBatchDownloading = false;
  //     emit(state.copyWith(
  //       getFilesStatus: BaseError(result.error!.errorMessage),
  //     ));
  //     return;
  //   }
  //
  //   if (_isCancelled) return;
  //   _isBatchDownloading = false;
  //
  //   emit(state.copyWith(getFilesStatus: const BaseComplete('')));
  //
  //   await LocalStorage.saveData(
  //     key: '${MyConstants.downloadedLevelCount}_$lang',
  //     value: '$neededUpTo',
  //   );
  //
  //   await LocalStorage.saveData(
  //     key: MyConstants.firstDownload,
  //     value: 'true',
  //   );
  //
  //   // Read destination from state (may have been updated by a later event).
  //   if (MyContext.get.mounted && state.destinationRoute != null) {
  //     MyContext.get.goNamed(
  //       state.destinationRoute!,
  //       pathParameters: state.destinationPathParameters ?? {},
  //     );
  //   }
  // }

  /// Downloads images only (standalone, no chaining).
  // FutureOr<void> _getImagesEvent(
  //   GetImagesEvent event,
  //   Emitter<DownloadState> emit,
  // ) async {
  //   _isCancelled = false;
  //   emit(state.copyWith(getFilesStatus: const BaseLoading()));
  //   final result = await _getImagesUseCase(NoParams());
  //   if (result.isError) {
  //     if (_isCancelled) return;
  //     emit(state.copyWith(getFilesStatus: BaseError(result.error!.errorMessage)));
  //   } else {
  //     if (_isCancelled) return;
  //     emit(state.copyWith(getFilesStatus: const BaseComplete('')));
  //   }
  // }

  /// Downloads audios only (standalone, no chaining).
  // FutureOr<void> _getAudiosEvent(
  //   GetAudiosEvent event,
  //   Emitter<DownloadState> emit,
  // ) async {
  //   _isCancelled = false;
  //   emit(state.copyWith(getFilesStatus: const BaseLoading()));
  //   final result = await _getAudiosUseCase(NoParams());
  //   if (result.isError) {
  //     if (_isCancelled) return;
  //     emit(state.copyWith(getFilesStatus: BaseError(result.error!.errorMessage)));
  //   } else {
  //     if (_isCancelled) return;
  //     emit(state.copyWith(getFilesStatus: const BaseComplete('')));
  //   }
  // }

  /// Saves levels only (standalone, no chaining).
  FutureOr<void> _saveLevelsEvent(
    SaveLevelsEvent event,
    Emitter<DownloadState> emit,
  ) async {
    _isCancelled = false;
    emit(state.copyWith(status: const BaseLoading()));
    final result = await _saveLevelsUseCase(NoParams());
    if (result.isError) {
      if (_isCancelled) return;
      emit(state.copyWith(status: BaseError(result.error!.errorMessage)));
    } else {
      if (_isCancelled) return;
      emit(state.copyWith(status: const BaseComplete('')));
    }
  }

  FutureOr<void> _cancelDownloadEvent(
    CancelDownloadEvent event,
    Emitter<DownloadState> emit,
  ) {
    _isCancelled = true;
    _isDownloading = false;
    _cancelDownloadUseCase(NoParams());
    emit(state.copyWith(status: const BaseInit()));
  }
}