import axios, {
  AxiosInstance,
  AxiosRequestConfig,
  InternalAxiosRequestConfig,
  AxiosResponse,
  AxiosError,
} from 'axios';
import AsyncStorage from '@react-native-async-storage/async-storage';
import { Store } from '@reduxjs/toolkit';

// ─── Storage Keys ────────────────────────────────────────────────────────────
const STORAGE_KEYS = {
  ACCESS_TOKEN: '@auth_access_token',
  REFRESH_TOKEN: '@auth_refresh_token',
} as const;

// ─── Config ──────────────────────────────────────────────────────────────────
const BASE_URL = 'https://8415-202-8-116-13.ngrok-free.app'; // TODO: replace with your actual base URL

// ─── Token Helpers ───────────────────────────────────────────────────────────
export const tokenManager = {
  async getAccessToken(): Promise<string | null> {
    return AsyncStorage.getItem(STORAGE_KEYS.ACCESS_TOKEN);
  },

  async getRefreshToken(): Promise<string | null> {
    return AsyncStorage.getItem(STORAGE_KEYS.REFRESH_TOKEN);
  },

  async setTokens(accessToken: string, refreshToken: string): Promise<void> {
    await AsyncStorage.setItem(STORAGE_KEYS.ACCESS_TOKEN, accessToken);
    await AsyncStorage.setItem(STORAGE_KEYS.REFRESH_TOKEN, refreshToken);
  },

  async clearTokens(): Promise<void> {
    await AsyncStorage.removeItem(STORAGE_KEYS.ACCESS_TOKEN);
    await AsyncStorage.removeItem(STORAGE_KEYS.REFRESH_TOKEN);
  },
};

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

// ─── Request Interceptor — Attach Access Token ──────────────────────────────
axiosInstance.interceptors.request.use(
  async (config: InternalAxiosRequestConfig) => {
    // Skip attaching token for auth endpoints (login, register, refresh)
    const publicPaths = [
      '/auth/otp/request',
      '/auth/otp/verify',
      '/auth/refresh-token',
    ];
    const isPublic = publicPaths.some(path => config.url?.includes(path));

    if (!isPublic) {
      const token = await tokenManager.getAccessToken();
      if (token) {
        config.headers.Authorization = `Bearer ${token}`;
      }
    }

    // When the body is FormData, delete the Content-Type header entirely.
    // This forces the native XMLHttpRequest layer to auto-generate the correct
    // header: 'multipart/form-data; boundary=------xxxx'. The boundary is
    // required for the server to parse the multipart body — it cannot be set
    // manually because only XMLHttpRequest knows the generated boundary string.
    if (config.data instanceof FormData) {
      delete config.headers['Content-Type'];
    }

    // Debug logging (remove in production)
    if (__DEV__) {
      // console.log(`🚀 [API] ${config.method?.toUpperCase()} ${config.url}`);
    }

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

// ─── Response Interceptor — Handle Token Refresh ────────────────────────────
let isRefreshing = false;
let failedQueue: Array<{
  resolve: (token: string) => void;
  reject: (error: unknown) => void;
}> = [];

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

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

    // If 401 and we haven't already retried this request
    if (error.response?.status === 401 && !originalRequest._retry) {
      // If already refreshing, queue this request
      if (isRefreshing) {
        return new Promise<AxiosResponse>((resolve, reject) => {
          failedQueue.push({
            resolve: (token: string) => {
              originalRequest.headers.Authorization = `Bearer ${token}`;
              resolve(axiosInstance(originalRequest));
            },
            reject,
          });
        });
      }

      originalRequest._retry = true;
      isRefreshing = true;

      try {
        const refreshToken = await tokenManager.getRefreshToken();

        if (!refreshToken) {
          throw new Error('No refresh token available');
        }

        // Call refresh endpoint (uses a fresh axios call to avoid interceptor loop)
        const { data } = await axios.post(`${BASE_URL}/auth/refresh-token`, {
          refreshToken,
        });

        const { accessToken: newAccessToken, refreshToken: newRefreshToken } =
          data;

        await tokenManager.setTokens(newAccessToken, newRefreshToken);

        // Retry all queued requests with the new token
        processQueue(null, newAccessToken);

        // Retry the original request
        originalRequest.headers.Authorization = `Bearer ${newAccessToken}`;
        return axiosInstance(originalRequest);
      } catch (refreshError) {
        processQueue(refreshError, null);
        await tokenManager.clearTokens();

        // TODO: Navigate to login screen or dispatch a logout action
        // e.g. store.dispatch(logout());

        return Promise.reject(refreshError);
      } finally {
        isRefreshing = false;
      }
    }

    // For all other errors, reject as-is
    return Promise.reject(error);
  },
);
let storeInstance: Store | null = null;
export const injectStore = (_store: Store | null): void => {
  storeInstance = _store;
};

// ─── API Methods ─────────────────────────────────────────────────────────────
export const apiClient = {
  async get<T>(url: string, config?: AxiosRequestConfig): Promise<T> {
    const response = await axiosInstance.get<T>(url, config);
    return response.data;
  },

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

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

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

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

// Export the raw instance if needed for advanced usage
export { axiosInstance };