live local search

todos

improve local search

lib/features/core/data/constants/const_sorters.dart

@@ -0,0 +1,8 @@
+import 'package:string_similarity/string_similarity.dart';
+
+abstract class ConstSorters {
+  /// Uses Dice's Coefficient as a similarity metric, for a 2-way comparison, between a [targetWord]
+  /// and given words.
+  static int stringsSimilarityTarget(String a, String b, {required String targetWord}) =>
+      a.similarityTo(targetWord).compareTo(b.similarityTo(targetWord));
+}

lib/features/core/data/extensions/map_extensions.dart

@@ -1,3 +1,6 @@
 extension MapExtensions<A, B> on Map<A, B> {
   Map<A, B> get deepCopy => {...this};
+
+  /// Returns the values of a [Map] at given [keys] indices.
+  Iterable<B> valuesByKeys({required Iterable<A> keys}) => keys.map((final key) => this[key]!);
 }

lib/features/core/data/extensions/object_extensions.dart

@@ -0,0 +1,8 @@
+extension ObjectExtensions on Object? {
+  E asType<E>() => this as E;
+  E? asNullableType<E>() => this as E?;
+}
+
+extension AsCallback<T extends Object> on T {
+  T Function() get asCallback => () => this;
+}

lib/features/core/data/extensions/string_extensions.dart

@@ -0,0 +1,14 @@
+extension StringExtensions on String {
+  /// Returns true if given word contains atleast all the characters in [targetChars], and `false` otherwise
+  ///
+  /// Very efficient `O(n)` instead of naive `O(n*m)`
+  bool containsAllCharacters({required String targetChars}) {
+    final Set<String> characterSet = Set.from(targetChars.split(''));
+    for (final testChar in split('')) {
+      characterSet.remove(testChar);
+      if (characterSet.isEmpty) return true;
+    }
+
+    return false;
+  }
+}

lib/features/home/services/images_service.dart

@@ -1,12 +1,16 @@
 import 'dart:async';
 
+import 'package:mc_gallery/features/core/data/extensions/string_extensions.dart';
+
+import '/features/core/data/constants/const_sorters.dart';
 import '/features/core/data/extensions/iterable_extensions.dart';
+import '/features/core/data/extensions/map_extensions.dart';
 import '/features/core/services/logging_service.dart';
 import '/features/core/utils/mutex.dart';
-import '/features/home/data/models/image_model.dart';
 import '/locator.dart';
 import '../abstracts/images_api.dart';
 import '../data/enums/search_option.dart';
+import '../data/models/image_model.dart';
 
 /// Handles fetching and storing of Images.
 ///
@@ -24,8 +28,9 @@ class ImagesService {
   final ImagesApi _imagesApi;
   final LoggingService _loggingService;
 
-  late final Iterable<ImageModel> _imageModels;
-  Iterable<ImageModel> get imageModels => _imageModels.deepCopy;
+  late final Map<String, ImageModel> _imageModels;
+  Iterable<ImageModel> get imageModels => _imageModels.values.deepCopy;
+
   final Mutex _searchMutex = Mutex();
 
   /// Manual initialization triggering
@@ -36,7 +41,10 @@ class ImagesService {
 
   Future<void> _init() async {
     _loggingService.info('Fetching and creating image models...');
-    _imageModels = await _imagesApi.fetchImageUri(token: '');
+    _imageModels = {
+      for (final imageModel in await _imagesApi.fetchImageUri(token: ''))
+        imageModel.imageName: imageModel
+    };
 
     _imageModels.isNotEmpty
         ? _loggingService.good("Created ${_imageModels.length} images' models")
@@ -49,19 +57,38 @@ class ImagesService {
   int get lastAvailableImageIndex => _imageModels.length - 1;
   int get numberOfImages => _imageModels.length;
 
-  ImageModel imageModelAt({required int index}) => _imageModels.elementAt(index);
+  ImageModel imageModelAt({required int index}) => _imageModels.values.elementAt(index);
 
   Future<void> get lastQueryIsCompleted => _searchMutex.lastOperationCompletionAwaiter;
 
+  /// Performs searching on images, both locally and by a Web API endpoint.
+  ///
+  /// For now, a simple mechanism is used for handling async calls between (posssible) API fetches ->
+  /// just 'pile-up'. A mechanism can be made to 'cancel' a fetch if a newer search request comes in,
+  /// but that may be more complicated, and not the point of the assignment I think.
+  /// There are lots of optimizations possible for new inputs, for example reducing search frontier
+  /// by using set-cover/subsetting optimizations on backspace, and so on, but again, not the point,
+  /// I think.
   Future<List<ImageModel>> searchImages({
     required SearchOption searchOption,
     required String imageNamePart,
+    bool treatAsInSequence = false,
   }) async {
     return await _searchMutex.lockAndRun(run: (final unlock) async {
       try {
         switch (searchOption) {
           case SearchOption.local:
-            return [];
+            final rankedKeys = _imageModels.keys
+                // Reduce number of results by atleast occurring
+                .where((final imageName) => treatAsInSequence
+                    ? imageName.contains(imageNamePart)
+                    : imageName.containsAllCharacters(targetChars: imageNamePart))
+                .toList(growable: false)
+              // Sorting by the highest similarity first
+              ..sort((final a, final b) =>
+                  ConstSorters.stringsSimilarityTarget(targetWord: imageNamePart, a, b))
+              ..reversed;
+            return _imageModels.valuesByKeys(keys: rankedKeys).toList(growable: false);
           case SearchOption.web:
             return await _imagesApi.searchImages(
               searchStr: imageNamePart,

lib/features/home/views/gallery/gallery_view_model.dart

@@ -7,12 +7,12 @@ import 'package:flutter_cache_manager/flutter_cache_manager.dart';
 import '/features/core/abstracts/base_view_model.dart';
 import '/features/core/services/logging_service.dart';
 import '/features/core/services/navigation_service.dart';
-import '/features/home/data/models/image_model.dart';
-import '/features/home/services/image_cache_manager_service.dart';
-import '/features/home/services/images_service.dart';
-import '/features/home/views/image_carousel/image_carousel_view.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({
@@ -54,17 +54,20 @@ class GalleryViewModel extends BaseViewModel {
     // If empty-string (from backspacing) -> reset state.
     if (searchTerm.isEmpty) {
       _imageSearchResultsNotifier.value = [];
+      _loggingService.info('Clearing results on search string removal');
       return;
     }
 
     // Detached call to prevent UI blocking
-    unawaited(_imagesService
+    unawaited(
+      _imagesService
           .searchImages(
             imageNamePart: searchTerm,
             searchOption: searchOptionListenable.value,
           )
           .then(
-            (final fetchedImageModels) => _imageSearchResultsNotifier.value = fetchedImageModels));
+              (final fetchedImageModels) => _imageSearchResultsNotifier.value = fetchedImageModels),
+    );
 
     // Force-update to trigger listening to `lastQueryResultDone()`.
     _imageSearchResultsNotifier.notifyListeners();
@@ -72,14 +75,25 @@ class GalleryViewModel extends BaseViewModel {
 
   void searchPressed() {
     // If transitioning from 'Searching', clear previous results immediately
-    if (_isSearchingNotifier.value) _imageSearchResultsNotifier.value = [];
+    if (_isSearchingNotifier.value) {
+      _imageSearchResultsNotifier.value = [];
+      _loggingService.info('Clearing of results on view mode change');
+    }
 
     _isSearchingNotifier.value = !_isSearchingNotifier.value;
   }
 
   Future<void> get lastQueryResultDone => _imagesService.lastQueryIsCompleted;
 
-  void onSearchOptionChanged(SearchOption? option) => _searchOptionNotifier.value = option!;
+  void onSearchOptionChanged(SearchOption? option) {
+    _searchOptionNotifier.value = option!;
+    _loggingService.info('Switched over to $option search');
+
+    _imageSearchResultsNotifier.value = [];
+    _loggingService.info('Cleared resultsw from view');
+
+    //todo(mehul): Either redo search or force user to type in by clearing field
+  }
 
   void onPromptPressed() => _isDisplayingPressingPrompt.value = false;
 

lib/features/home/views/gallery/search_gallery_view.dart

@@ -24,7 +24,31 @@ class _SearchGalleryView extends StatelessWidget {
               displayedWidget = const CircularProgressIndicator();
               break;
             case ConnectionState.done:
-              displayedWidget = Wrap(
+              displayedWidget = ValueListenableBuilder<SearchOption>(
+                valueListenable: galleryViewModel.searchOptionListenable,
+                builder: (context, final searchOption, child) {
+                  switch (searchOption) {
+                    case SearchOption.local:
+                      return Wrap(
+                        runSpacing: 24,
+                        spacing: 8,
+                        alignment: WrapAlignment.center,
+                        runAlignment: WrapAlignment.center,
+                        crossAxisAlignment: WrapCrossAlignment.center,
+                        children: [
+                          for (final resultsImageModel in resultsImageModels)
+                            CachedNetworkImage(
+                              imageUrl: resultsImageModel.uri.toString(),
+                              cacheKey: resultsImageModel.imageIndex.toString(),
+                              progressIndicatorBuilder: (_, __, final progress) =>
+                                  CircularProgressIndicator(
+                                value: galleryViewModel.downloadProgressValue(progress: progress),
+                              ),
+                            ),
+                        ],
+                      );
+                    case SearchOption.web:
+                      return Wrap(
                         runSpacing: 24,
                         spacing: 8,
                         alignment: WrapAlignment.center,
@@ -49,6 +73,9 @@ class _SearchGalleryView extends StatelessWidget {
                         ],
                       );
                   }
+                },
+              );
+          }
 
           return AnimatedSwitcher(
             duration: ConstDurations.halfDefaultAnimationDuration,

pubspec.lock

@@ -546,6 +546,13 @@ packages:
       url: "https://pub.dartlang.org"
     source: hosted
     version: "1.1.1"
+  string_similarity:
+    dependency: "direct main"
+    description:
+      name: string_similarity
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "2.0.0"
   synchronized:
     dependency: transitive
     description:

pubspec.yaml

@@ -29,6 +29,7 @@ dependencies:
   intl_utils: ^2.8.1
   connectivity_plus: ^3.0.2
   internet_connection_checker: ^1.0.0+1
+  string_similarity: ^2.0.0
 
   # Util frontend
   flutter_markdown: ^0.6.13