#94 UTF-8 as default charset for response body decoding (#95)

* UTF-8 as default charset for response body decoding

* make encodingForCharset private
add opportunity to configure default encoding

* add tests

* refactor

Author: sanekyy

lib/src/client/dart_http.dart

@@ -1,21 +1,57 @@
+import 'dart:convert';
+
 import 'package:http/http.dart';
+import 'package:http_parser/http_parser.dart';
 import 'package:json_api/http.dart';
 
 /// A handler using the Dart's built-in http client
 class DartHttp implements HttpHandler {
-  DartHttp(this._client);
+  DartHttp(this._client, [this._defaultEncoding = utf8])
+      : assert(_defaultEncoding != null, "Default encoding can't be null");
 
   @override
   Future<HttpResponse> call(HttpRequest request) async {
     final response = await _send(Request(request.method, request.uri)
       ..headers.addAll(request.headers)
       ..body = request.body);
-    return HttpResponse(response.statusCode,
-        body: response.body, headers: response.headers);
+    final responseBody =
+        _encodingForHeaders(response.headers).decode(response.bodyBytes);
+    return HttpResponse(
+      response.statusCode,
+      body: responseBody,
+      headers: response.headers,
+    );
   }
 
   final Client _client;
+  final Encoding _defaultEncoding;
 
   Future<Response> _send(Request dartRequest) async =>
       Response.fromStream(await _client.send(dartRequest));
+
+  /// Returns the encoding to use for a response with the given headers.
+  ///
+  /// Defaults to [_defaultEncoding] if the headers don't specify a charset or if that
+  /// charset is unknown.
+  Encoding _encodingForHeaders(Map<String, String> headers) =>
+      _encodingForCharset(
+          _contentTypeForHeaders(headers).parameters['charset']);
+
+  /// Returns the [Encoding] that corresponds to [charset].
+  ///
+  /// Returns [_defaultEncoding] if [charset] is null or if no [Encoding] was found that
+  /// corresponds to [charset].
+  Encoding _encodingForCharset(String charset) {
+    if (charset == null) return _defaultEncoding;
+    return Encoding.getByName(charset) ?? _defaultEncoding;
+  }
+
+  /// Returns the [MediaType] object for the given headers's content-type.
+  ///
+  /// Defaults to `application/octet-stream`.
+  MediaType _contentTypeForHeaders(Map<String, String> headers) {
+    var contentType = headers['content-type'];
+    if (contentType != null) return MediaType.parse(contentType);
+    return MediaType('application', 'octet-stream');
+  }
 }

pubspec.yaml

@@ -6,6 +6,7 @@ environment:
   sdk: '>=2.6.0 <3.0.0'
 dependencies:
   http: ^0.12.0
+  http_parser: ^3.1.4
 dev_dependencies:
   args: ^1.5.2
   pedantic: ^1.9.0

test/unit/client/dart_http_test.dart

@@ -0,0 +1,52 @@
+import 'dart:convert';
+
+import 'package:http/http.dart' as http;
+import 'package:http/testing.dart';
+import 'package:json_api/client.dart';
+import 'package:json_api/http.dart';
+import 'package:test/test.dart';
+
+void main() {
+  group('Decode body with', () {
+    final stringBodyRu = 'йцукен';
+    final bytesBodyRu = utf8.encode(stringBodyRu);
+    final stringBodyEn = 'qwerty';
+    final bytesBodyEn = utf8.encode(stringBodyEn);
+
+    final buildResponse = (
+      List<int> bytesBody,
+      Encoding encoding,
+    ) async {
+      final dartHttp = DartHttp(
+        MockClient(
+          (request) async {
+            return http.Response.bytes(bytesBody, 200);
+          },
+        ),
+        encoding,
+      );
+
+      return dartHttp.call(HttpRequest('', Uri.parse('http://test.com')));
+    };
+
+    test('UTF-8 ru', () async {
+      final response = await buildResponse(bytesBodyRu, utf8);
+      expect(response.body, equals(stringBodyRu));
+    });
+
+    test('latin1 ru', () async {
+      final response = await buildResponse(bytesBodyRu, latin1);
+      expect(response.body, isNot(equals(stringBodyRu)));
+    });
+
+    test('UTF-8 en', () async {
+      final response = await buildResponse(bytesBodyEn, utf8);
+      expect(response.body, equals(stringBodyEn));
+    });
+
+    test('latin1 en', () async {
+      final response = await buildResponse(bytesBodyEn, latin1);
+      expect(response.body, equals(stringBodyEn));
+    });
+  });
+}