import 'dart:async';

import 'package:flutter/foundation.dart';
import 'package:flutter/widgets.dart';
import 'package:flutter_cache_manager/flutter_cache_manager.dart';

import '/features/core/abstracts/base_view_model.dart';
import '/features/core/data/extensions/value_notifier_extensions.dart';
import '/features/core/services/navigation_service.dart';
import '/locator.dart';
import '../../data/enums/search_option.dart';
import '../../data/models/image_model.dart';
import '../../services/image_cache_manager_service.dart';
import '../../services/images_service.dart';
import '../image_carousel/image_carousel_view.dart';

class GalleryViewModel extends BaseViewModel {
  GalleryViewModel({
    required ImagesService imagesService,
    required NavigationService navigationService,
    required ImageCacheManagerService imageCacheManagerService,
  })  : _imagesService = imagesService,
        _navigationService = navigationService,
        _imageCacheManagerService = imageCacheManagerService;

  final ImagesService _imagesService;
  final NavigationService _navigationService;
  //todo(mehul): Use to implement pull-to-refresh or an extra widget
  final ImageCacheManagerService _imageCacheManagerService;

  final ValueNotifier<bool> _isDisplayingPressingPrompt = ValueNotifier(true);
  ValueListenable<bool> get isDisplayingPressingPrompt => _isDisplayingPressingPrompt;

  final ValueNotifier<bool> _isSearchingNotifier = ValueNotifier(false);
  ValueListenable<bool> get isSearchingListenable => _isSearchingNotifier;
  final ValueNotifier<SearchOption> _searchOptionNotifier = ValueNotifier(SearchOption.web);
  ValueListenable<SearchOption> get searchOptionListenable => _searchOptionNotifier;
  final ValueNotifier<List<ImageModel>> _imageSearchResultsNotifier = ValueNotifier([]);
  ValueListenable<List<ImageModel>> get imageSearchResultsListenable => _imageSearchResultsNotifier;

  final ValueNotifier<bool> _isViewingFavouriteNotifier = ValueNotifier(false);
  ValueListenable<bool> get isViewingFavouriteListenable => _isViewingFavouriteNotifier;

  @override
  Future<void> initialise(bool Function() mounted, [Object? arguments]) async {
    super.initialise(mounted, arguments);
  }

  @override
  Future<void> dispose() async {
    super.dispose();
  }

  Future<void> onSearchTermUpdate(String searchTerm) async {
    // If empty-string (from backspacing) -> reset state.
    if (searchTerm.isEmpty) {
      _imageSearchResultsNotifier.value = [];
      log.info('Clearing results on search string removal');
      return;
    }

    // Detached call to prevent UI blocking
    unawaited(
      _imagesService
          .searchImages(
            imageNamePart: searchTerm,
            searchOption: searchOptionListenable.value,
          )
          .then(
              (final fetchedImageModels) => _imageSearchResultsNotifier.value = fetchedImageModels),
    );

    // Force-update to trigger listening to `lastQueryResultDone()`.
    _imageSearchResultsNotifier.notifyListeners();
  }

  void searchPressed() {
    // If transitioning from 'Searching', clear previous results immediately
    if (_isSearchingNotifier.value) {
      _imageSearchResultsNotifier.value = [];
      log.info('Clearing of results on view mode change');
    }

    _isSearchingNotifier.flipValue();
  }

  Future<void> get lastQueryResultDone => _imagesService.lastQueryIsCompleted;

  void onSearchOptionChanged(SearchOption? option) {
    _searchOptionNotifier.value = option!;
    log.info('Switched over to $option search');

    _imageSearchResultsNotifier.value = [];
    log.info('Cleared resultsw from view');

    //todo(mehul): Either redo search or force user to type in new (trigger) by clearing field
  }

  void onFavouriteViewChange(bool newValue) => _isViewingFavouriteNotifier.value = newValue;

  void updateImageFavouriteStatus({
    required ImageModel imageModel,
    required bool newFavouriteStatus,
  }) {
    _imagesService.updateImageFavouriteStatus(
      imageModel: imageModel,
      newFavouriteStatus: newFavouriteStatus,
    );
  }

  Iterable<ImageModel> get favouriteImageModels =>
      imageModels.where((final imageModel) => imageModel.isFavourite);

  void onPromptPressed() => _isDisplayingPressingPrompt.value = false;

  Iterable<ImageModel> get imageModels => _imagesService.imageModels;
  Future<void> get initImageFetchIsDone => _imagesService.initAwaiter;

  double? downloadProgressValue({required DownloadProgress progress}) =>
      progress.totalSize != null ? progress.downloaded / progress.totalSize! : null;

  void pushImageCarouselView(BuildContext context, {required ImageModel imageModel}) =>
      _navigationService.pushImageCarouselView(
        context,
        imageCarouselViewArguments: ImageCarouselViewArguments(
          imageIndexKey: imageModel.imageIndex,
        ),
      );

  static GalleryViewModel get locate => Locator.locate();
}