http-local-asset translation loader

lib/src/local-http-asset-assetloader.dart

@@ -0,0 +1,155 @@
+import 'dart:convert';
+import 'dart:developer';
+import 'dart:io';
+
+import 'package:flutter/material.dart';
+import 'package:flutter/services.dart';
+import 'package:http/http.dart' as http;
+
+import 'asset_loader.dart';
+
+/// if you are in need of particular type of requirement such as:
+
+/// your translations in asset are not complete  so that you want to use the remote translations but want to make available for offilne use
+/// this makes app useable if there is no internet connection to fetch the new transaltions everytime.
+
+///if there is translation file locally(cached) then
+
+///1. merge the local translation file with the asset-bundler translation file but give priority to the local translation.
+///2. if the local localization is older than [one day] then fetch the new localization from backend and save in local(cache) and perform 1st step.
+class HttpLocalAssetLoader extends AssetLoader {
+  final String httpPathBase;
+
+  /// path where the transaltion file is stored
+  /// use as such
+  // final applicationDirectory = await getApplicationSupportDirectory(); using path_provider pacakge
+  final String localFilePath;
+
+  /// base path to the localization in remote http
+  HttpLocalAssetLoader(
+      {required this.httpPathBase, required this.localFilePath});
+
+  /// here asset path is the path to the assetbundle file
+  @override
+  Future<Map<String, dynamic>> load(String assetPath, Locale locale) async {
+    try {
+      final localeFromLocal = await _getJsonFromLocaleFile(locale);
+      final localeFromAsset = await _getJsonFromAsset(assetPath, locale);
+
+      if (localeFromLocal != null) {
+        if (localeFromAsset != null) {
+          localeFromAsset.addAll(localeFromLocal);
+          return localeFromAsset;
+        } else {
+          return localeFromLocal;
+        }
+      } else {
+        final localeFromHtpp = await _getFromHttp(httpPathBase, locale);
+
+        if (localeFromHtpp != null) {
+          if (localeFromAsset != null) {
+            localeFromAsset.addAll(localeFromHtpp);
+            return localeFromAsset;
+          } else {
+            return localeFromHtpp;
+          }
+        } else {
+          if (localeFromAsset != null) {
+            return localeFromAsset;
+          } else {
+            return Future.value({'error': 'no translation'});
+          }
+        }
+      }
+    } catch (e) {
+      return Future.value({'error_${locale.countryCode}': '$e'});
+    }
+  }
+
+  String _getAssetBundleLocalePath(String basePath, Locale locale) {
+    return '$basePath/${locale.toStringWithSeparator(separator: "-")}.json';
+  }
+
+  Future<String> _getLocalLocalePath(Locale locale) async {
+    return "$localFilePath/${locale.toStringWithSeparator(separator: "-")}.json";
+  }
+
+  String _getHttpPath(String base, Locale local) {
+    return '$base/${local.languageCode}';
+  }
+
+  Future<Map<String, dynamic>?> _getJsonFromAsset(
+      String path, Locale locale) async {
+    try {
+      var localePath = _getAssetBundleLocalePath(path, locale);
+      log('Load asset from $path');
+      return json.decode(await rootBundle.loadString(localePath));
+    } catch (e) {
+      log('Load asset failed from $path $e');
+
+      return Future.value();
+    }
+  }
+
+  Future<Map<String, dynamic>?> _getJsonFromLocaleFile(Locale locale) async {
+    try {
+      log('getting transalation from local file');
+      var localePath = await _getLocalLocalePath(locale);
+      final localFile = File(localePath);
+      if (await localFile.exists()) {
+        log(' transalation in local file found');
+        final lastModified = await localFile.lastModified();
+        if (lastModified.difference(DateTime.now()).abs().inHours > 24) {
+          log(' transalation in local file is older than 24hr');
+          return Future.value();
+        }
+
+        final translation = json.decode(await localFile.readAsString());
+        log('Load asset from $localePath');
+        return translation;
+      }
+      log(' no transalation found in local file ');
+
+      return Future.value();
+    } catch (e) {
+      log('Load asset failed from local file $e');
+
+      return Future.value();
+    }
+  }
+
+  Future<Map<String, dynamic>?> _getFromHttp(String path, Locale locale) async {
+    try {
+      log('Loading asset from http');
+
+      var url = Uri.parse(_getHttpPath(path, locale));
+      final localeResponse = await http.get(url);
+      if (localeResponse.statusCode != 200) {
+        log('Loading asset from ${url.toString()} failed ${localeResponse.body}');
+        return Future.value();
+      }
+
+      try {
+        log('Writing the translation json in local');
+        final file = File(await _getLocalLocalePath(locale));
+        await file.create(recursive: true);
+        await file.writeAsString(localeResponse.body, flush: true);
+      } catch (e) {
+        log('Failed to cache the remote translation in cache $e');
+      }
+
+      return jsonDecode(localeResponse.body);
+    } catch (e) {
+      log('easy localization loader: load http $path error: $e');
+      //Catch network exceptions
+      return Future.value();
+    }
+  }
+}
+
+extension LocaleToStringHelper on Locale {
+  /// Convert [locale] to String with custom separator
+  String toStringWithSeparator({String separator = '_'}) {
+    return toString().split('_').join(separator);
+  }
+}

pubspec.lock

@@ -7,7 +7,7 @@ packages:
       name: async
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "2.5.0"
+    version: "2.8.2"
   boolean_selector:
     dependency: transitive
     description:
@@ -21,14 +21,14 @@ packages:
       name: characters
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.1.0"
+    version: "1.2.0"
   charcode:
     dependency: transitive
     description:
       name: charcode
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.2.0"
+    version: "1.3.1"
   clock:
     dependency: transitive
     description:
@@ -87,14 +87,21 @@ packages:
       name: matcher
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "0.12.10"
+    version: "0.12.11"
+  material_color_utilities:
+    dependency: transitive
+    description:
+      name: material_color_utilities
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "0.1.3"
   meta:
     dependency: transitive
     description:
       name: meta
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.3.0"
+    version: "1.7.0"
   path:
     dependency: transitive
     description:
@@ -127,7 +134,7 @@ packages:
       name: source_span
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.8.0"
+    version: "1.8.1"
   stack_trace:
     dependency: transitive
     description:
@@ -162,7 +169,7 @@ packages:
       name: test_api
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "0.2.19"
+    version: "0.4.8"
   typed_data:
     dependency: transitive
     description:
@@ -176,7 +183,7 @@ packages:
       name: vector_math
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "2.1.0"
+    version: "2.1.1"
   xml:
     dependency: "direct main"
     description:
@@ -192,4 +199,4 @@ packages:
     source: hosted
     version: "3.1.0"
 sdks:
-  dart: ">=2.12.0 <3.0.0"
+  dart: ">=2.14.0 <3.0.0"