import type { LoginRequest, RegisterRequest, AuthResponse, RegisterResponse } from '../types/auth';
import type { User } from '../types/user';

const API_URL = import.meta.env.VITE_API_URL || '';

class ApiClient {
  private async request<T>(input: RequestInfo, init?: RequestInit): Promise<T> {
    const token = localStorage.getItem('token');
    
    const headers = new Headers(init?.headers);
    if (token) {
      headers.set('Authorization', `Bearer ${token}`);
    }
    
    const response = await fetch(`${API_URL}${input}`, {
      ...init,
      headers,
    });
    
    // Handle 401 Unauthorized - clear token and redirect to login
    if (response.status === 401) {
      localStorage.removeItem('token');
      window.location.href = '/login';
      throw new Error('Unauthorized');
    }
    
if (!response.ok) {
       const errorData = await response.json().catch(() => ({}));
       // Handle both { error: "message" } and { message: "..." } formats
       const errorMessage = errorData.error || errorData.message || `Error ${response.status}`;
       throw new Error(errorMessage);
     }
    
    return response.json();
  }
  
  async login(data: LoginRequest): Promise<AuthResponse> {
    return this.request<AuthResponse>('/api/auth/login', {
      method: 'POST',
      headers: { 'Content-Type': 'application/json' },
      body: JSON.stringify(data),
    });
  }
  
  async register(data: RegisterRequest): Promise<RegisterResponse> {
    return this.request<RegisterResponse>('/api/auth/register', {
      method: 'POST',
      headers: { 'Content-Type': 'application/json' },
      body: JSON.stringify(data),
    });
  }
  
  async getUsers(): Promise<User[]> {
    return this.request<User[]>('/api/users', {
      method: 'GET',
    });
  }
}

export const apiClient = new ApiClient();