import axios, { AxiosInstance, AxiosRequestConfig, AxiosResponse, AxiosError } from 'axios';
import { API_URL } from '../utils/config';
import { getToken, removeToken, removeUser } from '../utils/storage';

export interface ApiError {
  message: string;
  status?: number;
  code?: string;
}

class ApiService {
  private axiosInstance: AxiosInstance;

  constructor() {
    this.axiosInstance = axios.create({
      baseURL: API_URL,
      timeout: 30000, // 30 seconds timeout
      headers: {
        'Content-Type': 'application/json',
      },
    });

    // Request interceptor: Add Authorization header with JWT
    this.axiosInstance.interceptors.request.use(
      (config) => {
        const token = getToken();
        if (token) {
          config.headers.Authorization = `Bearer ${token}`;
        }
        return config;
      },
      (error) => {
        console.error('Request interceptor error:', error);
        return Promise.reject(this.handleError(error));
      }
    );

    // Response interceptor: Handle errors
    this.axiosInstance.interceptors.response.use(
      (response) => response,
      (error: AxiosError) => {
        if (error.response?.status === 401) {
          // Clear tokens and redirect to login
          console.warn('Unauthorized request, redirecting to login');
          removeToken();
          removeUser();
          window.location.href = '/login';
        }
        return Promise.reject(this.handleError(error));
      }
    );
  }

  private handleError(error: AxiosError): ApiError {
    if (error.response) {
      // Server responded with error
      const message = (error.response.data as any)?.message ||
                     (error.response.data as any)?.error ||
                     error.message ||
                     'Ein Fehler ist aufgetreten';
      return {
        message,
        status: error.response.status,
        code: error.code,
      };
    } else if (error.request) {
      // Request was made but no response received
      return {
        message: 'Keine Antwort vom Server. Bitte überprüfen Sie Ihre Internetverbindung.',
        code: error.code,
      };
    } else {
      // Something else happened
      return {
        message: error.message || 'Ein unerwarteter Fehler ist aufgetreten',
        code: error.code,
      };
    }
  }

  async get<T = any>(url: string, config?: AxiosRequestConfig): Promise<AxiosResponse<T>> {
    return this.axiosInstance.get<T>(url, config);
  }

  async post<T = any>(url: string, data?: any, config?: AxiosRequestConfig): Promise<AxiosResponse<T>> {
    return this.axiosInstance.post<T>(url, data, config);
  }

  async put<T = any>(url: string, data?: any, config?: AxiosRequestConfig): Promise<AxiosResponse<T>> {
    return this.axiosInstance.put<T>(url, data, config);
  }

  async delete<T = any>(url: string, config?: AxiosRequestConfig): Promise<AxiosResponse<T>> {
    return this.axiosInstance.delete<T>(url, config);
  }

  async patch<T = any>(url: string, data?: any, config?: AxiosRequestConfig): Promise<AxiosResponse<T>> {
    return this.axiosInstance.patch<T>(url, data, config);
  }
}

export const api = new ApiService();