import { ApiResponse } from './types';

const API_BASE_URL = process.env.NEXT_PUBLIC_API_URL || 'http://localhost:8000/api';

class ApiClient {
  private getToken(): string | null {
    if (typeof window === 'undefined') return null;
    return localStorage.getItem('auth_token');
  }

  private async request<T>(
    endpoint: string,
    options: RequestInit = {}
  ): Promise<ApiResponse<T>> {
    const token = this.getToken();
    const headers: Record<string, string> = {
      'Content-Type': 'application/json',
      ...(options.headers as Record<string, string>),
    };

    if (token) {
      headers['Authorization'] = `Bearer ${token}`;
    }

    try {
      const response = await fetch(`${API_BASE_URL}${endpoint}`, {
        ...options,
        headers,
      });

      const data = await response.json();

      if (!response.ok) {
        if (response.status === 401) {
          // Unauthorized - clear token and redirect to login
          if (typeof window !== 'undefined') {
            localStorage.removeItem('auth_token');
            window.location.href = '/login';
          }
        }
        throw new Error(data.message || 'API request failed');
      }

      return data;
    } catch (error) {
      console.error('API Error:', error);
      throw error;
    }
  }

  async get<T>(endpoint: string): Promise<ApiResponse<T>> {
    return this.request<T>(endpoint, { method: 'GET' });
  }

  async post<T>(endpoint: string, body?: any): Promise<ApiResponse<T>> {
    return this.request<T>(endpoint, {
      method: 'POST',
      body: body ? JSON.stringify(body) : undefined,
    });
  }

  async put<T>(endpoint: string, body?: any): Promise<ApiResponse<T>> {
    return this.request<T>(endpoint, {
      method: 'PUT',
      body: body ? JSON.stringify(body) : undefined,
    });
  }

  async delete<T>(endpoint: string): Promise<ApiResponse<T>> {
    return this.request<T>(endpoint, { method: 'DELETE' });
  }

  // File upload with multipart/form-data
  async upload<T>(endpoint: string, formData: FormData): Promise<ApiResponse<T>> {
    const token = this.getToken();
    const headers: Record<string, string> = {};

    if (token) {
      headers['Authorization'] = `Bearer ${token}`;
    }

    try {
      const response = await fetch(`${API_BASE_URL}${endpoint}`, {
        method: 'POST',
        headers,
        body: formData,
      });

      const data = await response.json();

      if (!response.ok) {
        if (response.status === 401) {
          if (typeof window !== 'undefined') {
            localStorage.removeItem('auth_token');
            window.location.href = '/login';
          }
        }
        throw new Error(data.message || 'Upload failed');
      }

      return data;
    } catch (error) {
      console.error('Upload Error:', error);
      throw error;
    }
  }
}

export const apiClient = new ApiClient();