Restructure folders (#184)

* Split up `video_chat.dart`

* Restructure home folder

* Restructure settings folder

* Restructure channel folder

* More restructuring

lib/screens/home/search/search_store.dart

@@ -0,0 +1,98 @@
+import 'package:flutter/widgets.dart';
+import 'package:frosty/apis/twitch_api.dart';
+import 'package:frosty/models/category.dart';
+import 'package:frosty/models/channel.dart';
+import 'package:frosty/screens/settings/stores/auth_store.dart';
+import 'package:mobx/mobx.dart';
+import 'package:shared_preferences/shared_preferences.dart';
+
+part 'search_store.g.dart';
+
+class SearchStore = SearchStoreBase with _$SearchStore;
+
+abstract class SearchStoreBase with Store {
+  final AuthStore authStore;
+
+  final TwitchApi twitchApi;
+
+  final textEditingController = TextEditingController();
+
+  final textFieldFocusNode = FocusNode();
+
+  @readonly
+  var _searchText = '';
+
+  @readonly
+  var _searchHistory = ObservableList<String>();
+
+  @readonly
+  ObservableFuture<List<ChannelQuery>>? _channelFuture;
+
+  @readonly
+  ObservableFuture<CategoriesTwitch?>? _categoryFuture;
+
+  SearchStoreBase({required this.authStore, required this.twitchApi}) {
+    init();
+  }
+
+  @action
+  Future<void> init() async {
+    // Retrieve the instance that will allow us to retrieve local search history.
+    final prefs = await SharedPreferences.getInstance();
+
+    // Retrieve the search history from local storage. If it doesn't exist, use an empty list.
+    _searchHistory = prefs.getStringList('search_history')?.asObservable() ?? ObservableList<String>();
+
+    // Create a reaction that will limit the history to 8 entries and update it to local storage automatically.
+    autorun((_) {
+      if (_searchHistory.length > 8) _searchHistory.removeLast();
+      prefs.setStringList('search_history', _searchHistory);
+    });
+
+    // Add a listener to update the cancel button visibility whenever the text changes.
+    textEditingController.addListener(() => _searchText = textEditingController.text);
+  }
+
+  /// Obtain the channels and categories that match the provided [query].
+  @action
+  void handleQuery(String query) {
+    if (query.isEmpty) return;
+
+    // Move the query to the most recent result (top of the stack).
+    _searchHistory.remove(query);
+    _searchHistory.insert(0, query);
+
+    // Fetch the matching channels, sort it by live status, and then set it.
+    _channelFuture = twitchApi
+        .searchChannels(
+      query: query,
+      headers: authStore.headersTwitch,
+    )
+        .then(
+      (channels) {
+        channels.sort((c1, c2) => c2.isLive ? 1 : -1);
+        return channels;
+      },
+    ).asObservable();
+
+    // Fetch and set the categories that match the query.
+    _categoryFuture = twitchApi
+        .searchCategories(
+          query: query,
+          headers: authStore.headersTwitch,
+        )
+        .asObservable();
+  }
+
+  /// Find a specific channel provided the [query].
+  /// This is used for channels that may not show up in the search results.
+  Future<Channel> searchChannel(String query) async {
+    final user = await twitchApi.getUser(userLogin: query, headers: authStore.headersTwitch);
+    return await twitchApi.getChannel(userId: user.id, headers: authStore.headersTwitch);
+  }
+
+  void dispose() {
+    textEditingController.dispose();
+    textFieldFocusNode.dispose();
+  }
+}