import React, { createContext, useCallback, useContext, useEffect, useMemo, useState } from 'react';
import {
  DOORMILE_TOKEN_KEY,
  DOORMILE_USER_KEY,
  loginAdmin,
  logoutAdmin,
  readStoredToken,
  readStoredUser,
} from '@/api/doormile';

/**
 * Auth for the Doormile Express console.
 *
 * `POST /admin/login` returns a JWT and the admin record, and every subsequent
 * request carries that token — so the session lives entirely in localStorage
 * and there is nothing to fetch on boot. The provider still resolves
 * asynchronously (`isLoadingAuth`) rather than reading storage inline, because
 * rendering a route tree before the token is known flashes the login page at an
 * already-signed-in operator on every refresh.
 *
 * The axios client clears the same two keys and hard-navigates to `/login` on a
 * 401, so an expired token ends the session the same way signing out does — a
 * shell that renders but 401s on every fetch is worse than being sent back.
 */

const AuthContext = createContext(/** @type {any} */ (null));

/** @param {any} props */
export const AuthProvider = ({ children }) => {
  const [user, setUser] = useState(null);
  const [isAuthenticated, setIsAuthenticated] = useState(false);
  const [isLoadingAuth, setIsLoadingAuth] = useState(true);
  const [authChecked, setAuthChecked] = useState(false);
  const [authError, setAuthError] = useState(null);

  const checkUserAuth = useCallback(() => {
    setIsLoadingAuth(true);
    const token = readStoredToken();
    const stored = readStoredUser();
    setIsAuthenticated(Boolean(token));
    setUser(token ? stored : null);
    setIsLoadingAuth(false);
    setAuthChecked(true);
  }, []);

  useEffect(() => {
    checkUserAuth();
  }, [checkUserAuth]);

  /* A sign-out in another tab has to end the session in this one too —
     otherwise this tab keeps a rendered console around a token that is gone. */
  useEffect(() => {
    const onStorage = (event) => {
      if (event.key === DOORMILE_TOKEN_KEY || event.key === DOORMILE_USER_KEY) checkUserAuth();
    };
    window.addEventListener('storage', onStorage);
    return () => window.removeEventListener('storage', onStorage);
  }, [checkUserAuth]);

  /**
   * Signs in. Resolves to the API's own `{ success, message }` rather than
   * throwing on a refused credential, so the login form can show the server's
   * wording instead of a generic failure.
   */
  const login = useCallback(async (email, password) => {
    setAuthError(null);
    try {
      const result = await loginAdmin(email, password);
      if (result?.success) {
        setUser(result.user ?? readStoredUser());
        setIsAuthenticated(true);
        return { success: true };
      }
      const message = result?.message || 'Those credentials were not accepted';
      setAuthError(message);
      return { success: false, message };
    } catch (err) {
      const message = err?.message || 'Could not reach the Doormile API';
      setAuthError(message);
      return { success: false, message };
    }
  }, []);

  const logout = useCallback((shouldRedirect = true) => {
    logoutAdmin();
    setUser(null);
    setIsAuthenticated(false);
    if (shouldRedirect) window.location.replace('/login');
  }, []);

  const navigateToLogin = useCallback(() => window.location.replace('/login'), []);

  const value = useMemo(
    () => ({
      user,
      isAuthenticated,
      isLoadingAuth,
      /* No remote app settings on this backend — kept so consumers that gate on
         it stay unchanged. */
      isLoadingPublicSettings: false,
      appPublicSettings: null,
      authError,
      authChecked,
      login,
      logout,
      navigateToLogin,
      checkUserAuth,
      checkAppState: checkUserAuth,
    }),
    [user, isAuthenticated, isLoadingAuth, authError, authChecked, login, logout, navigateToLogin, checkUserAuth]
  );

  return <AuthContext.Provider value={value}>{children}</AuthContext.Provider>;
};

export const useAuth = () => {
  const context = useContext(AuthContext);
  if (!context) {
    throw new Error('useAuth must be used within an AuthProvider');
  }
  return context;
};