import axios, { AxiosError, InternalAxiosRequestConfig } from 'axios';
import { API_BASE_URL } from './config';

// Create axios instance
export const apiClient = axios.create({
  baseURL: API_BASE_URL,
  headers: {
    'Content-Type': 'application/json',
  },
});

// Token management
const TOKEN_KEY = 'colaflow_access_token';
const REFRESH_TOKEN_KEY = 'colaflow_refresh_token';

export const tokenManager = {
  getAccessToken: () => {
    if (typeof window === 'undefined') return null;
    return localStorage.getItem(TOKEN_KEY);
  },

  setAccessToken: (token: string) => {
    if (typeof window === 'undefined') return;
    localStorage.setItem(TOKEN_KEY, token);
  },

  getRefreshToken: () => {
    if (typeof window === 'undefined') return null;
    return localStorage.getItem(REFRESH_TOKEN_KEY);
  },

  setRefreshToken: (token: string) => {
    if (typeof window === 'undefined') return;
    localStorage.setItem(REFRESH_TOKEN_KEY, token);
  },

  clearTokens: () => {
    if (typeof window === 'undefined') return;
    localStorage.removeItem(TOKEN_KEY);
    localStorage.removeItem(REFRESH_TOKEN_KEY);
  },
};

// Request interceptor: automatically add Access Token
apiClient.interceptors.request.use(
  (config: InternalAxiosRequestConfig) => {
    const token = tokenManager.getAccessToken();
    if (token) {
      config.headers.Authorization = `Bearer ${token}`;
    }
    return config;
  },
  (error) => Promise.reject(error)
);

// Response interceptor: automatically refresh Token
let isRefreshing = false;
let failedQueue: Array<{
  resolve: (value?: unknown) => void;
  reject: (reason?: unknown) => void;
}> = [];

const processQueue = (error: unknown, token: string | null = null) => {
  failedQueue.forEach((prom) => {
    if (error) {
      prom.reject(error);
    } else {
      prom.resolve(token);
    }
  });

  failedQueue = [];
};

apiClient.interceptors.response.use(
  (response) => response,
  async (error: AxiosError) => {
    const originalRequest = error.config as InternalAxiosRequestConfig & {
      _retry?: boolean;
    };

    // If 401 and not a refresh token request, try to refresh token
    if (error.response?.status === 401 && !originalRequest._retry) {
      if (isRefreshing) {
        // If already refreshing, queue this request
        return new Promise((resolve, reject) => {
          failedQueue.push({ resolve, reject });
        }).then((token) => {
          originalRequest.headers.Authorization = `Bearer ${token}`;
          return apiClient(originalRequest);
        });
      }

      originalRequest._retry = true;
      isRefreshing = true;

      const refreshToken = tokenManager.getRefreshToken();

      if (!refreshToken) {
        tokenManager.clearTokens();
        if (typeof window !== 'undefined') {
          window.location.href = '/login';
        }
        return Promise.reject(error);
      }

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

        tokenManager.setAccessToken(data.accessToken);
        tokenManager.setRefreshToken(data.refreshToken);

        apiClient.defaults.headers.common.Authorization = `Bearer ${data.accessToken}`;
        originalRequest.headers.Authorization = `Bearer ${data.accessToken}`;

        processQueue(null, data.accessToken);

        return apiClient(originalRequest);
      } catch (refreshError) {
        processQueue(refreshError, null);
        tokenManager.clearTokens();
        if (typeof window !== 'undefined') {
          window.location.href = '/login';
        }
        return Promise.reject(refreshError);
      } finally {
        isRefreshing = false;
      }
    }

    return Promise.reject(error);
  }
);