new start

lib/shared/api_client.dart

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+import 'dart:convert';
+import 'package:http/http.dart' as http;
+
+class ApiClient {
+  ApiClient(this.baseUrl, {this.getAccessToken});
+  final String baseUrl; // z.B. https://api.example.com
+  final Future<String?> Function()? getAccessToken;
+
+  Future<http.Response> _send(String method, String path,
+      {Object? body}) async {
+    final uri = Uri.parse('$baseUrl$path');
+    final headers = {'Content-Type': 'application/json'};
+    final token = await getAccessToken?.call();
+    if (token != null) headers['Authorization'] = 'Bearer $token';
+    switch (method) {
+      case 'GET':
+        return http.get(uri, headers: headers);
+      case 'POST':
+        return http.post(uri, headers: headers, body: jsonEncode(body));
+      case 'PUT':
+        return http.put(uri, headers: headers, body: jsonEncode(body));
+      case 'DELETE':
+        return http.delete(uri, headers: headers);
+      default:
+        throw UnimplementedError(method);
+    }
+  }
+
+  Future<Map<String, dynamic>> get(String path) async =>
+      _decode(await _send('GET', path));
+  Future<Map<String, dynamic>> post(
+          String path, Map<String, dynamic> body) async =>
+      _decode(await _send('POST', path, body: body));
+  Future<Map<String, dynamic>> put(
+          String path, Map<String, dynamic> body) async =>
+      _decode(await _send('PUT', path, body: body));
+  Future<Map<String, dynamic>> delete(String path) async =>
+      _decode(await _send('DELETE', path));
+  Map<String, dynamic> _decode(http.Response r) {
+    if (r.statusCode >= 200 && r.statusCode < 300) {
+      if (r.body.isEmpty) return {};
+      return jsonDecode(r.body) as Map<String, dynamic>;
+    }
+    throw ApiException(r.statusCode, r.body);
+  }
+}
+
+class ApiException implements Exception {
+  final int status;
+  final String body;
+  ApiException(this.status, this.body);
+  @override
+  String toString() => 'ApiException($status): $body';
+}