// /src/api/axiosInstance.js
import axios from 'axios';
import Cookies from 'js-cookie';

const API_BASE_URL = import.meta.env.VITE_API_BASE_URL || 'http://localhost:5000/api';

const axiosInstance = axios.create({
  baseURL: API_BASE_URL,
  headers: {
    'Content-Type': 'application/json',
    'Accept': 'application/json'
  },
  timeout: 15000
});

// Request interceptor: attach token
axiosInstance.interceptors.request.use(
  (config) => {
    const token = localStorage.getItem('accessToken') || Cookies.get('accessToken');
    if (token) {
      config.headers.Authorization = `Bearer ${token}`;
    }

    // Ask backend for Persian (or stored) localized error messages
    const lang = localStorage.getItem('lang') || 'fa';
    config.headers['Accept-Language'] = lang;
    if (!config.params) config.params = {};
    if (config.params.lang == null) {
      config.params.lang = lang;
    }

    const isFormData = typeof FormData !== 'undefined' && config.data instanceof FormData;
    if (isFormData) {
      // Let the browser set multipart boundary — a bare multipart/form-data header breaks Multer
      if (typeof config.headers?.delete === 'function') {
        config.headers.delete('Content-Type');
        config.headers.delete('content-type');
      } else {
        delete config.headers['Content-Type'];
        delete config.headers['content-type'];
      }
      config.timeout = Math.max(config.timeout || 0, 120000);
    }

    return config;
  },
  (error) => Promise.reject(error)
);

// Response interceptor: auto-refresh token on 401
let isRefreshing = false;
let failedQueue = [];

const processQueue = (error, token = null) => {
  failedQueue.forEach(prom => {
    if (error) {
      prom.reject(error);
    } else {
      prom.resolve(token);
    }
  });
  failedQueue = [];
};

axiosInstance.interceptors.response.use(
  (response) => response.data,
  async (error) => {
    const originalRequest = error.config;

    if (error.response?.status === 401 && !originalRequest._retry) {
      if (originalRequest.url.includes('/auth/login') || originalRequest.url.includes('/auth/refresh')) {
        return Promise.reject(error);
      }

      if (isRefreshing) {
        return new Promise((resolve, reject) => {
          failedQueue.push({ resolve, reject });
        })
          .then((token) => {
            originalRequest.headers.Authorization = `Bearer ${token}`;
            return axiosInstance(originalRequest);
          })
          .catch((err) => Promise.reject(err));
      }

      originalRequest._retry = true;
      isRefreshing = true;

      const refreshToken = localStorage.getItem('refreshToken') || Cookies.get('refreshToken');

      if (!refreshToken) {
        isRefreshing = false;
        localStorage.removeItem('accessToken');
        localStorage.removeItem('refreshToken');
        window.location.href = '/login';
        return Promise.reject(error);
      }

      try {
        const refreshResponse = await axios.post(`${API_BASE_URL}/auth/refresh`, { refreshToken });
        const data = refreshResponse.data?.data || refreshResponse.data;
        const newAccessToken = data.accessToken;
        const newRefreshToken = data.refreshToken;

        localStorage.setItem('accessToken', newAccessToken);
        Cookies.set('accessToken', newAccessToken);
        if (newRefreshToken) {
          localStorage.setItem('refreshToken', newRefreshToken);
          Cookies.set('refreshToken', newRefreshToken);
        }

        axiosInstance.defaults.headers.common.Authorization = `Bearer ${newAccessToken}`;
        originalRequest.headers.Authorization = `Bearer ${newAccessToken}`;

        processQueue(null, newAccessToken);
        return axiosInstance(originalRequest);
      } catch (refreshErr) {
        processQueue(refreshErr, null);
        localStorage.removeItem('accessToken');
        localStorage.removeItem('refreshToken');
        Cookies.remove('accessToken');
        Cookies.remove('refreshToken');
        window.location.href = '/login';
        return Promise.reject(refreshErr);
      } finally {
        isRefreshing = false;
      }
    }

    return Promise.reject(error);
  }
);

export default axiosInstance;