import React, { useEffect, useMemo, useState, useCallback } from 'react';
import { Navigate, useNavigate, useLocation } from 'react-router-dom';
import { useTranslation } from 'react-i18next';
import { Button } from '@/components/ui/Button';
import { Input } from '@/components/ui/Input';
import { IconEye, IconEyeOff } from '@/components/ui/icons';
import { useAuthStore, useLanguageStore, useNotificationStore } from '@/stores';
import { detectApiBaseFromLocation, normalizeApiBase } from '@/utils/connection';
import { LANGUAGE_LABEL_KEYS, LANGUAGE_ORDER } from '@/utils/constants';
import { isSupportedLanguage } from '@/utils/language';
import { INLINE_LOGO_JPEG } from '@/assets/logoInline';
import type { ApiError } from '@/types';
import styles from './LoginPage.module.scss';

/**
 * 将 API 错误转换为本地化的用户友好消息
 */
type RedirectState = { from?: { pathname?: string } };

function getLocalizedErrorMessage(error: unknown, t: (key: string) => string): string {
  const apiError = error as Partial<ApiError>;
  const status = typeof apiError.status === 'number' ? apiError.status : undefined;
  const code = typeof apiError.code === 'string' ? apiError.code : undefined;
  const message =
    error instanceof Error
      ? error.message
      : typeof apiError.message === 'string'
        ? apiError.message
        : typeof error === 'string'
          ? error
          : '';

  // 根据 HTTP 状态码判断
  if (status === 401) {
    return t('login.error_unauthorized');
  }
  if (status === 403) {
    return t('login.error_forbidden');
  }
  if (status === 404) {
    return t('login.error_not_found');
  }
  if (status && status >= 500) {
    return t('login.error_server');
  }

  // 根据 axios 错误码判断
  if (code === 'ECONNABORTED' || message.toLowerCase().includes('timeout')) {
    return t('login.error_timeout');
  }
  if (code === 'ERR_NETWORK' || message.toLowerCase().includes('network error')) {
    return t('login.error_network');
  }
  if (code === 'ERR_CERT_AUTHORITY_INVALID' || message.toLowerCase().includes('certificate')) {
    return t('login.error_ssl');
  }

  // 检查 CORS 错误
  if (message.toLowerCase().includes('cors') || message.toLowerCase().includes('cross-origin')) {
    return t('login.error_cors');
  }

  // 默认错误消息
  return t('login.error_invalid');
}

export function LoginPage() {
  const { t } = useTranslation();
  const navigate = useNavigate();
  const location = useLocation();
  const { showNotification } = useNotificationStore();
  const language = useLanguageStore((state) => state.language);
  const setLanguage = useLanguageStore((state) => state.setLanguage);
  const isAuthenticated = useAuthStore((state) => state.isAuthenticated);
  const login = useAuthStore((state) => state.login);
  const restoreSession = useAuthStore((state) => state.restoreSession);
  const storedBase = useAuthStore((state) => state.apiBase);
  const storedKey = useAuthStore((state) => state.managementKey);
  const storedRememberPassword = useAuthStore((state) => state.rememberPassword);

  const [apiBase, setApiBase] = useState('');
  const [managementKey, setManagementKey] = useState('');
  const [showCustomBase, setShowCustomBase] = useState(false);
  const [showKey, setShowKey] = useState(false);
  const [rememberPassword, setRememberPassword] = useState(false);
  const [loading, setLoading] = useState(false);
  const [autoLoading, setAutoLoading] = useState(true);
  const [autoLoginSuccess, setAutoLoginSuccess] = useState(false);
  const [error, setError] = useState('');

  const detectedBase = useMemo(() => detectApiBaseFromLocation(), []);
  const handleLanguageChange = useCallback(
    (event: React.ChangeEvent<HTMLSelectElement>) => {
      const selectedLanguage = event.target.value;
      if (!isSupportedLanguage(selectedLanguage)) {
        return;
      }
      setLanguage(selectedLanguage);
    },
    [setLanguage]
  );

  useEffect(() => {
    const init = async () => {
      try {
        const autoLoggedIn = await restoreSession();
        if (autoLoggedIn) {
          setAutoLoginSuccess(true);
          // 延迟跳转，让用户看到成功动画
          setTimeout(() => {
            const redirect = (location.state as RedirectState | null)?.from?.pathname || '/';
            navigate(redirect, { replace: true });
          }, 1500);
        } else {
          setApiBase(storedBase || detectedBase);
          setManagementKey(storedKey || '');
          setRememberPassword(storedRememberPassword || Boolean(storedKey));
        }
      } finally {
        if (!autoLoginSuccess) {
          setAutoLoading(false);
        }
      }
    };

    init();
    // eslint-disable-next-line react-hooks/exhaustive-deps
  }, []);

  const handleSubmit = useCallback(async () => {
    if (!managementKey.trim()) {
      setError(t('login.error_required'));
      return;
    }

    const baseToUse = apiBase ? normalizeApiBase(apiBase) : detectedBase;
    setLoading(true);
    setError('');
    try {
      await login({
        apiBase: baseToUse,
        managementKey: managementKey.trim(),
        rememberPassword
      });
      showNotification(t('common.connected_status'), 'success');
      navigate('/', { replace: true });
    } catch (err: unknown) {
      const message = getLocalizedErrorMessage(err, t);
      setError(message);
      showNotification(`${t('notification.login_failed')}: ${message}`, 'error');
    } finally {
      setLoading(false);
    }
  }, [apiBase, detectedBase, login, managementKey, navigate, rememberPassword, showNotification, t]);

  const handleSubmitKeyDown = useCallback(
    (event: React.KeyboardEvent) => {
      if (event.key === 'Enter' && !loading) {
        event.preventDefault();
        handleSubmit();
      }
    },
    [loading, handleSubmit]
  );

  if (isAuthenticated && !autoLoading && !autoLoginSuccess) {
    const redirect = (location.state as RedirectState | null)?.from?.pathname || '/';
    return <Navigate to={redirect} replace />;
  }

  // 显示启动动画（自动登录中或自动登录成功）
  const showSplash = autoLoading || autoLoginSuccess;

  return (
    <div className={styles.container}>
      {/* 左侧品牌展示区 */}
      <div className={styles.brandPanel}>
        <div className={styles.brandContent}>
          <span className={styles.brandWord}>CLI</span>
          <span className={styles.brandWord}>PROXY</span>
          <span className={styles.brandWord}>API</span>
        </div>
      </div>

      {/* 右侧功能交互区 */}
      <div className={styles.formPanel}>
        {showSplash ? (
          /* 启动动画 */
          <div className={styles.splashContent}>
            <img src={INLINE_LOGO_JPEG} alt="CPAMC" className={styles.splashLogo} />
            <h1 className={styles.splashTitle}>CLI Proxy API</h1>
            <p className={styles.splashSubtitle}>Management Center</p>
            <div className={styles.splashLoader}>
              <div className={styles.splashLoaderBar} />
            </div>
          </div>
        ) : (
          /* 登录表单 */
          <div className={styles.formContent}>
            {/* Logo */}
            <img src={INLINE_LOGO_JPEG} alt="Logo" className={styles.logo} />

            {/* 登录表单卡片 */}
            <div className={styles.loginCard}>
              <div className={styles.loginHeader}>
                <div className={styles.titleRow}>
                  <div className={styles.title}>{t('title.login')}</div>
                  <select
                    className={styles.languageSelect}
                    value={language}
                    onChange={handleLanguageChange}
                    title={t('language.switch')}
                    aria-label={t('language.switch')}
                  >
                    {LANGUAGE_ORDER.map((lang) => (
                      <option key={lang} value={lang}>
                        {t(LANGUAGE_LABEL_KEYS[lang])}
                      </option>
                    ))}
                  </select>
                </div>
                <div className={styles.subtitle}>{t('login.subtitle')}</div>
              </div>

              <div className={styles.connectionBox}>
                <div className={styles.label}>{t('login.connection_current')}</div>
                <div className={styles.value}>{apiBase || detectedBase}</div>
                <div className={styles.hint}>{t('login.connection_auto_hint')}</div>
              </div>

              <div className={styles.toggleAdvanced}>
                <input
                  id="custom-connection-toggle"
                  type="checkbox"
                  checked={showCustomBase}
                  onChange={(e) => setShowCustomBase(e.target.checked)}
                />
                <label htmlFor="custom-connection-toggle">{t('login.custom_connection_label')}</label>
              </div>

              {showCustomBase && (
                <Input
                  label={t('login.custom_connection_label')}
                  placeholder={t('login.custom_connection_placeholder')}
                  value={apiBase}
                  onChange={(e) => setApiBase(e.target.value)}
                  hint={t('login.custom_connection_hint')}
                />
              )}

              <Input
                autoFocus
                label={t('login.management_key_label')}
                placeholder={t('login.management_key_placeholder')}
                type={showKey ? 'text' : 'password'}
                value={managementKey}
                onChange={(e) => setManagementKey(e.target.value)}
                onKeyDown={handleSubmitKeyDown}
                rightElement={
                  <button
                    type="button"
                    className="btn btn-ghost btn-sm"
                    onClick={() => setShowKey((prev) => !prev)}
                    aria-label={
                      showKey
                        ? t('login.hide_key', { defaultValue: '隐藏密钥' })
                        : t('login.show_key', { defaultValue: '显示密钥' })
                    }
                    title={
                      showKey
                        ? t('login.hide_key', { defaultValue: '隐藏密钥' })
                        : t('login.show_key', { defaultValue: '显示密钥' })
                    }
                  >
                    {showKey ? <IconEyeOff size={16} /> : <IconEye size={16} />}
                  </button>
                }
              />

              <div className={styles.toggleAdvanced}>
                <input
                  id="remember-password-toggle"
                  type="checkbox"
                  checked={rememberPassword}
                  onChange={(e) => setRememberPassword(e.target.checked)}
                />
                <label htmlFor="remember-password-toggle">{t('login.remember_password_label')}</label>
              </div>

              <Button fullWidth onClick={handleSubmit} loading={loading}>
                {loading ? t('login.submitting') : t('login.submit_button')}
              </Button>

              {error && <div className={styles.errorBox}>{error}</div>}
            </div>
          </div>
        )}
      </div>
    </div>
  );
}
