/**
 * API Client
 *
 * Axios-based API client with authentication support
 */

import axios, { AxiosInstance, AxiosRequestConfig, AxiosError } from 'axios';

const API_BASE_URL = process.env.NEXT_PUBLIC_API_URL || 'http://localhost:4000';

export class ApiClient {
  private client: AxiosInstance;

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

    // Request interceptor to add auth token
    this.client.interceptors.request.use(
      config => {
        const token = this.getAccessToken();
        if (token) {
          config.headers.Authorization = `Bearer ${token}`;
        }
        return config;
      },
      error => Promise.reject(error)
    );

    // Response interceptor to handle token refresh
    this.client.interceptors.response.use(
      response => response,
      async (error: AxiosError) => {
        const originalRequest = error.config as AxiosRequestConfig & {
          _retry?: boolean;
        };

        // If 401 and not already retried, try to refresh token
        if (error.response?.status === 401 && !originalRequest._retry) {
          originalRequest._retry = true;

          try {
            const refreshToken = this.getRefreshToken();
            if (refreshToken) {
              const { data } = await axios.post(`${API_BASE_URL}/api/v1/auth/refresh`, {
                refreshToken,
              });

              this.setAccessToken(data.accessToken);

              // Retry original request with new token
              if (originalRequest.headers) {
                originalRequest.headers.Authorization = `Bearer ${data.accessToken}`;
              }
              return this.client(originalRequest);
            }
          } catch (refreshError) {
            // Refresh failed, clear tokens and redirect to login
            this.clearTokens();
            if (typeof window !== 'undefined') {
              window.location.href = '/login';
            }
            return Promise.reject(refreshError);
          }
        }

        return Promise.reject(error);
      }
    );
  }

  private getAccessToken(): string | null {
    if (typeof window === 'undefined') return null;
    return localStorage.getItem('accessToken');
  }

  private getRefreshToken(): string | null {
    if (typeof window === 'undefined') return null;
    return localStorage.getItem('refreshToken');
  }

  private setAccessToken(token: string): void {
    if (typeof window !== 'undefined') {
      localStorage.setItem('accessToken', token);
    }
  }

  private clearTokens(): void {
    if (typeof window !== 'undefined') {
      localStorage.removeItem('accessToken');
      localStorage.removeItem('refreshToken');
    }
  }

  async get<T>(url: string, config?: AxiosRequestConfig): Promise<T> {
    const response = await this.client.get<T>(url, config);
    return response.data;
  }

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

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

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

  async delete<T>(url: string, config?: AxiosRequestConfig): Promise<T> {
    const response = await this.client.delete<T>(url, config);
    return response.data;
  }
}

export const apiClient = new ApiClient();