'use client';

import { useCallback, useEffect, useRef, useState } from 'react';
import { AnimatePresence, motion } from 'motion/react';
import { useRouter, useSearchParams } from 'next/navigation';
import { toast } from 'sonner';
import { Spinner } from '@/components/ui/spinner';
import { LoginForm } from '@/components/auth/login-form';
import { AuthShell } from '@/components/auth/auth-shell';
import { Check } from 'lucide-react';

import { AuthService } from '@/lib/services/auth';
import { useAuth } from '@/components/providers/auth-provider';
import { safeRedirectTarget } from '@/lib/utils';
import { useTranslations } from 'next-intl';

/**
 * 登录页面组件
 * 显示登录表单和登录按钮
 *
 * @example
 * ```tsx
 * <LoginPage />
 * ```
 * @returns {React.ReactNode} 登录页面组件
 */
export function LoginPage() {
  const router = useRouter();
  const searchParams = useSearchParams();
  const { user, loading, setUser } = useAuth();
  const t = useTranslations('auth.login');
  const [showOTP, setShowOTP] = useState(false);

  /* 处理OAuth回调 */
  const isOAuthCallback = !!(
    searchParams.get('state') && searchParams.get('code')
  );
  const [isProcessingCallback, setIsProcessingCallback] =
    useState(isOAuthCallback);
  const isCheckingSession = !isOAuthCallback && loading;

  const [loginSuccess, setLoginSuccess] = useState(false);
  const redirectedRef = useRef(false);
  const callbackProcessedRef = useRef(false);

  const resolveRedirectTarget = useCallback(() => {
    const callbackUrl = searchParams.get('callbackUrl');
    const storedRedirect = sessionStorage.getItem('redirect_after_login');
    const target = callbackUrl || storedRedirect || '/';

    if (storedRedirect) {
      sessionStorage.removeItem('redirect_after_login');
    }

    return safeRedirectTarget(target);
  }, [searchParams]);

  const resolveRedirectTargetRef = useRef(resolveRedirectTarget);
  useEffect(() => {
    resolveRedirectTargetRef.current = resolveRedirectTarget;
  }, [resolveRedirectTarget]);

  /* 登录页兜底：已登录用户直接跳转 */
  useEffect(() => {
    const state = searchParams.get('state');
    const code = searchParams.get('code');

    if ((state && code) || loading || !user) {
      return;
    }

    if (!redirectedRef.current) {
      redirectedRef.current = true;
      router.replace(resolveRedirectTargetRef.current());
    }
  }, [loading, router, searchParams, user]);

  /* 回调逻辑 */
  useEffect(() => {
    const handleOAuthCallback = async () => {
      const state = searchParams.get('state');
      const code = searchParams.get('code');

      if (state && code) {
        if (callbackProcessedRef.current) return;
        callbackProcessedRef.current = true;

        setIsProcessingCallback(true);
        try {
          const result = await AuthService.handleCallback({ state, code });
          if (result.status === 'need_bind') {
            toast.info(t('needBind'));
            setIsProcessingCallback(false);
            router.replace('/login');
            return;
          }
          if (result.user) {
            setUser(result.user);
          }
          setLoginSuccess(true);
          toast.success(
            result.status === 'bound' ? t('bindSuccess') : t('success'),
          );

          setTimeout(() => {
            if (!redirectedRef.current) {
              redirectedRef.current = true;
              router.replace(resolveRedirectTargetRef.current());
            }
          }, 1500);
        } catch (error) {
          console.error('OAuth callback error:', error);
          toast.error(error instanceof Error ? error.message : t('failed'));
          setIsProcessingCallback(false);
          router.replace('/login');
        }
      }
    };
    handleOAuthCallback();
  }, [router, searchParams, setUser, t]);

  return (
    <AuthShell wide={showOTP}>
      <div className='w-full'>
        <AnimatePresence mode='wait'>
          {isProcessingCallback || isCheckingSession ? (
            <motion.div
              key={isProcessingCallback ? 'processing' : 'session-check'}
              initial={{ opacity: 0 }}
              animate={{ opacity: 1 }}
              exit={{ opacity: 0 }}
              className='w-full'
            >
              {isCheckingSession ? (
                <div className='flex flex-col items-center justify-center gap-4 py-16'>
                  <div className='relative'>
                    <Spinner className='size-8' />
                  </div>
                  <div className='flex flex-col gap-2 text-center'>
                    <h3 className='font-semibold tracking-tight text-foreground'>
                      {t('checkingSession')}
                    </h3>
                    <p className='text-xs text-muted-foreground'>
                      {t('checkingSessionDesc')}
                    </p>
                  </div>
                </div>
              ) : loginSuccess ? (
                <div className='flex flex-col items-center justify-center gap-4 py-16'>
                  <motion.div
                    initial={{ scale: 0.5, opacity: 0 }}
                    animate={{ scale: 1, opacity: 1 }}
                    transition={{ type: 'spring', stiffness: 300, damping: 20 }}
                    className='flex size-8 items-center justify-center rounded-full bg-primary/10 text-primary ring-1 ring-primary/20'
                  >
                    <Check className='size-6' strokeWidth={3} />
                  </motion.div>
                  <div className='flex flex-col gap-2 text-center'>
                    <h3 className='font-semibold tracking-tight text-foreground'>
                      {t('success')}
                    </h3>
                    <p className='text-xs text-muted-foreground'>
                      {t('redirecting')}
                    </p>
                  </div>
                </div>
              ) : (
                <div className='flex flex-col items-center justify-center gap-4 py-16'>
                  <div className='relative'>
                    <Spinner className='size-8' />
                  </div>
                  <div className='flex flex-col gap-2 text-center'>
                    <h3 className='font-semibold tracking-tight text-foreground'>
                      {t('verifyingCredentials')}
                    </h3>
                    <p className='text-xs text-muted-foreground'>
                      {t('establishingSession')}
                    </p>
                  </div>
                </div>
              )}
            </motion.div>
          ) : (
            <motion.div
              key='login-form-wrapper'
              initial={{ opacity: 0 }}
              animate={{ opacity: 1 }}
              transition={{ duration: 0.4 }}
              className='w-full'
            >
              <LoginForm onOTPStateChange={setShowOTP} />
            </motion.div>
          )}
        </AnimatePresence>
      </div>
    </AuthShell>
  );
}