Add settings page (#46)

Fixes #37, fixes #47.

Reviewed-on: Nexus/nexus#46

lib/controllers/settings_controller.dart

@@ -0,0 +1,27 @@
+import "dart:convert";
+import "package:flutter_riverpod/flutter_riverpod.dart";
+import "package:nexus/controllers/settings_file_controller.dart";
+import "package:nexus/models/settings.dart";
+
+class SettingsController extends AsyncNotifier<Settings> {
+  @override
+  Future<Settings> build() async {
+    final file = await ref.watch(SettingsFileController.provider.future);
+
+    try {
+      return Settings.fromJson(json.decode(await file.readAsString()));
+    } catch (_) {
+      return Settings();
+    }
+  }
+
+  Future<void> set(Settings settings) async {
+    state = AsyncData(settings);
+    final file = await ref.watch(SettingsFileController.provider.future);
+    await file.writeAsString(json.encode(settings.toJson()));
+  }
+
+  static final provider = AsyncNotifierProvider<SettingsController, Settings>(
+    SettingsController.new,
+  );
+}

lib/controllers/settings_file_controller.dart

@@ -0,0 +1,23 @@
+import "dart:io";
+import "package:flutter_riverpod/flutter_riverpod.dart";
+import "package:path/path.dart";
+import "package:path_provider/path_provider.dart";
+import "package:xdg_directories/xdg_directories.dart";
+
+class SettingsFileController extends AsyncNotifier<File> {
+  @override
+  Future<File> build() async {
+    final directory = await switch (Platform.isLinux) {
+      true => Directory(
+        join(configHome.absolute.path, "nexus"),
+      ).create(recursive: true),
+      false => getApplicationSupportDirectory(),
+    };
+
+    return File(join(directory.absolute.path, "config.json"));
+  }
+
+  static final provider = AsyncNotifierProvider<SettingsFileController, File>(
+    SettingsFileController.new,
+  );
+}

lib/controllers/settings_sections_controller.dart

@@ -0,0 +1,98 @@
+import "dart:io";
+import "package:fast_immutable_collections/fast_immutable_collections.dart";
+import "package:flutter/material.dart";
+import "package:flutter_riverpod/flutter_riverpod.dart";
+import "package:intl/intl.dart";
+import "package:nexus/controllers/settings_controller.dart";
+import "package:nexus/models/settings_category.dart";
+import "package:nexus/main.dart";
+import "package:nexus/widgets/settings/dialog_list_tile.dart";
+
+class SettingsSectionsController
+    extends AsyncNotifier<IMap<String, IList<SettingsCategory>>> {
+  @override
+  Future<IMap<String, IList<SettingsCategory>>> build() async {
+    final settings = await ref.watch(SettingsController.provider.future);
+
+    return .new({
+      "General": .new([
+        .new(
+          title: "Appearance",
+          icon: Icons.brush,
+          settings: .new([
+            .new(
+              title: "Theme",
+              description:
+                  "Toggle between Light Mode, Dark Mode, and System themes.",
+              icon: Icons.contrast,
+              builder: (title, description, icon) => DialogListTile<ThemeMode>(
+                icon: Icon(icon),
+                title: title,
+                subtitle: Text(description),
+                initialValue: settings.theme,
+                options: ThemeMode.values,
+                getName: (option) => toBeginningOfSentenceCase(option.name),
+                onChanged: (value) => ref
+                    .watch(SettingsController.provider.notifier)
+                    .set(settings.copyWith(theme: value))
+                    .onError(showError),
+              ),
+            ),
+            .new(
+              title: "Use Dynamic Theme",
+              icon: Icons.palette,
+              description:
+                  "Toggle on or off Dynamic Theme. Only available on Android, Linux, Windows, or MacOS.",
+              builder: (title, description, icon) => SwitchListTile(
+                title: Text(title),
+                subtitle: Text(description),
+                secondary: Icon(icon),
+                value: settings.useDynamicTheming,
+                onChanged:
+                    (Platform.isAndroid ||
+                        Platform.isLinux ||
+                        Platform.isMacOS ||
+                        Platform.isWindows)
+                    ? (value) => ref
+                          .watch(SettingsController.provider.notifier)
+                          .set(settings.copyWith(useDynamicTheming: value))
+                          .onError(showError)
+                    : null,
+              ),
+            ),
+          ]),
+        ),
+        .new(
+          title: "Behavior",
+          icon: Icons.psychology,
+          settings: .new([
+            .new(
+              title: "Linux Mobile Mode",
+              description:
+                  "Enables some fixes for Linux mobile, e.g. disabling dragging appbar for moving window.",
+              icon: Icons.construction,
+              builder: (title, description, icon) => SwitchListTile(
+                title: Text(title),
+                subtitle: Text(description),
+                secondary: Icon(icon),
+                value: settings.linuxMobileMode,
+                onChanged: Platform.isLinux
+                    ? (value) => ref
+                          .watch(SettingsController.provider.notifier)
+                          .set(settings.copyWith(linuxMobileMode: value))
+                          .onError(showError)
+                    : null,
+              ),
+            ),
+          ]),
+        ),
+      ]),
+    });
+  }
+
+  static final provider =
+      AsyncNotifierProvider<
+        SettingsSectionsController,
+        IMap<String, IList<SettingsCategory>>
+      >(SettingsSectionsController.new);
+}