feat: Implement a structured API service layer for authentication and user management, replacing the old API utility.

src/services/api.ts

@@ -0,0 +1,120 @@
+import axios, { AxiosError, AxiosInstance, InternalAxiosRequestConfig } from 'axios';
+
+// API Response types
+export interface ApiResponse<T = unknown> {
+  success: boolean;
+  data: T;
+  statusCode?: number;
+  timestamp?: string;
+  message?: string;
+}
+
+export interface ApiErrorResponse {
+  success: false;
+  statusCode: number;
+  timestamp: string;
+  path: string;
+  method: string;
+  error: string;
+  message: string | string[];
+  errors?: Array<{ field: string; errors: string[] }>;
+}
+
+// Create axios instance
+const api: AxiosInstance = axios.create({
+  baseURL: process.env.NEXT_PUBLIC_API_URL || 'http://localhost:3001/api/v1',
+  timeout: 30000,
+  headers: {
+    'Content-Type': 'application/json',
+  },
+});
+
+// Request interceptor
+api.interceptors.request.use(
+  (config: InternalAxiosRequestConfig) => {
+    // Add auth token if available
+    if (typeof window !== 'undefined') {
+      const token = localStorage.getItem('accessToken');
+      if (token && config.headers) {
+        config.headers.Authorization = `Bearer ${token}`;
+      }
+    }
+    return config;
+  },
+  (error: AxiosError) => {
+    return Promise.reject(error);
+  }
+);
+
+// Response interceptor
+api.interceptors.response.use(
+  (response) => {
+    return response;
+  },
+  async (error: AxiosError<ApiErrorResponse>) => {
+    const originalRequest = error.config as InternalAxiosRequestConfig & { _retry?: boolean };
+
+    // Handle 401 Unauthorized - try to refresh token
+    if (error.response?.status === 401 && !originalRequest._retry) {
+      originalRequest._retry = true;
+
+      try {
+        const refreshToken = localStorage.getItem('refreshToken');
+        if (refreshToken) {
+          const response = await axios.post(
+            `${process.env.NEXT_PUBLIC_API_URL || 'http://localhost:3001/api/v1'}/auth/refresh`,
+            { refreshToken }
+          );
+
+          const { accessToken, refreshToken: newRefreshToken } = response.data.data;
+          localStorage.setItem('accessToken', accessToken);
+          localStorage.setItem('refreshToken', newRefreshToken);
+
+          // Retry original request with new token
+          if (originalRequest.headers) {
+            originalRequest.headers.Authorization = `Bearer ${accessToken}`;
+          }
+          return api(originalRequest);
+        }
+      } catch (refreshError) {
+        // Refresh failed, clear storage and redirect to login
+        localStorage.removeItem('accessToken');
+        localStorage.removeItem('refreshToken');
+        localStorage.removeItem('user');
+
+        if (typeof window !== 'undefined') {
+          window.location.href = '/login';
+        }
+      }
+    }
+
+    return Promise.reject(error);
+  }
+);
+
+// Helper to extract error message
+export function getErrorMessage(error: unknown): string {
+  if (error instanceof AxiosError) {
+    const apiError = error.response?.data as ApiErrorResponse;
+    if (apiError?.message) {
+      return Array.isArray(apiError.message)
+        ? apiError.message.join(', ')
+        : apiError.message;
+    }
+  }
+  if (error instanceof Error) {
+    return error.message;
+  }
+  return 'An unexpected error occurred';
+}
+
+// Helper to extract field errors
+export function getFieldErrors(error: unknown): Array<{ field: string; errors: string[] }> {
+  if (error instanceof AxiosError) {
+    const apiError = error.response?.data as ApiErrorResponse;
+    return apiError?.errors || [];
+  }
+  return [];
+}
+
+export default api;