feat(i18n): implements network data source

packages/wyatt_i18n/lib/src/data/data_sources/network_data_source_impl.dart

@@ -14,21 +14,117 @@
 // You should have received a copy of the GNU General Public License
 // along with this program. If not, see <https://www.gnu.org/licenses/>.
 
+import 'package:flutter/services.dart';
+import 'package:http/http.dart' as http;
 import 'package:wyatt_i18n/src/core/enums/format.dart';
+import 'package:wyatt_i18n/src/core/exceptions/exceptions.dart';
+import 'package:wyatt_i18n/src/core/utils/assets_utils.dart';
 import 'package:wyatt_i18n/src/domain/data_sources/i18n_data_source.dart';
 
+/// {@template network_data_source_impl}
+/// Implementation of [I18nDataSource] that loads i18n files from the network.
+///
+/// The [baseUri] is the base uri where the i18n files are located.
+/// The [baseName] is the name of the i18n files without the extension.
+/// The [fallbackAssetPath] is the path to the fallback i18n files.
+/// The [format] is the format of the i18n files.
+///
+/// For example, if the i18n files are located at `https://example.com/i18n/`
+/// and are named `i18n.en.arb`, `i18n.fr.arb`, etc., then the [baseUri] is
+/// `https://example.com/i18n/` and the [baseName] is `i18n` and the
+/// [format] is [Format.arb].
+///
+/// If the i18n file for the given locale is not found or if the fetch fails,
+/// then the fallback i18n files are loaded from the [fallbackAssetPath] in
+/// the root bundle.
+///
+/// For example, if the fallback i18n files are located in the `assets` and are
+/// named `i18n.arb`, `i18n.en.arb`, `i18n.fr.arb`, etc., then the
+/// [fallbackAssetPath] is `assets`.
+/// {@endtemplate}
 class NetworkDataSourceImpl extends I18nDataSource {
-  const NetworkDataSourceImpl({super.format = Format.arb}) : super();
-  
-  @override
-  Future<String> load({required String? locale}) {
-    // TODO(wyatt): implement load
-    throw UnimplementedError();
+  /// {@macro network_data_source_impl}
+  const NetworkDataSourceImpl({
+    required this.baseUri,
+    this.baseName = 'i18n',
+    this.fallbackAssetPath = 'assets',
+    super.format = Format.arb,
+    super.defaultLocale = 'en',
+  }) : super();
+
+  /// The base uri where the i18n files are located.
+  final Uri baseUri;
+
+  /// The name of the i18n files without the extension.
+  final String baseName;
+
+  /// The path to the fallback i18n files.
+  ///
+  /// This is used when the i18n file for the given locale is not found or
+  /// if the fetch fails.
+  final String fallbackAssetPath;
+
+  /// Tries to load the i18n file from the given [locale].
+  Future<String> _tryLoad(String? locale, {Uri? overrideUri}) async {
+    String? content;
+    final ext = format.name;
+
+    /// If the locale is null, then we try to load the default i18n file from
+    /// the fallback asset path.
+    /// Otherwise, we try to load the i18n file for the given locale from the
+    /// base uri.
+    final path = AssetsUtils.cleanPath(
+      locale == null
+          ? '$fallbackAssetPath/$baseName.$defaultLocale.$ext'
+          : overrideUri?.toString() ?? '$baseUri/$baseName.$locale.$ext',
+    );
+
+    if (locale == null) {
+      /// Load the default i18n file from the fallback asset path.
+      try {
+        if (await AssetsUtils.assetExists(path)) {
+          content = await rootBundle.loadString(path);
+        }
+      } catch (_) {
+        content = null;
+      }
+    } else {
+      /// Load the i18n file for the given locale from the base uri.
+      try {
+        final response = await http.get(Uri.parse(path));
+        if (response.statusCode >= 200 && response.statusCode < 300) {
+          content = response.body;
+        }
+      } catch (_) {
+        content = null;
+      }
+    }
+
+    /// If the i18n file is not found, then we try to load the
+    /// default i18n file.
+    if (content == null && locale != null) {
+      try {
+        final fallbackPath = AssetsUtils.cleanPath(
+          '$fallbackAssetPath/$baseName.$defaultLocale.$ext',
+        );
+        content = await rootBundle.loadString(fallbackPath);
+      } catch (_) {
+        throw SourceNotFoundException(path, format: format);
+      }
+    }
+
+    /// If the default i18n file is not found, then we throw an exception.
+    /// This case should happen only if the locale is null.
+    if (content == null) {
+      throw SourceNotFoundException(path, format: format);
+    }
+
+    return content;
   }
-  
+
   @override
-  Future<String> loadFrom(Uri uri) {
-    // TODO(wyatt): implement loadFrom
-    throw UnimplementedError();
-  }
+  Future<String> load({required String? locale}) async => _tryLoad(locale);
+
+  @override
+  Future<String> loadFrom(Uri uri) async => _tryLoad(null, overrideUri: uri);
 }

packages/wyatt_i18n/pubspec.yaml

@@ -9,6 +9,7 @@ environment:
 dependencies:
   collection: ^1.17.0
   flutter: {sdk: flutter}
+  http: ^0.13.5
   intl: ^0.18.0
   path: ^1.8.0
   petitparser: ^5.1.0