'use client';

import { useEffect, useState, useCallback, useRef } from 'react';
import { useRouter } from 'next/navigation';
import { useAuth } from '@/components/admin/auth-context';
import { adminApi } from '@/lib/admin-api';
import { toast } from '@/components/ui/sonner';
import {
  Bell,
  CheckCheck,
  Mail,
  MailOpen,
  Clock,
  AlertCircle,
  CheckCircle,
  XCircle,
  Archive,
  ExternalLink,
  RefreshCw,
} from 'lucide-react';

interface NotificationItem {
  id: string;
  type: string;
  title: string;
  message: string;
  read: boolean;
  relatedItemId: string;
  relatedModelCode: string;
  createdAt: string;
}

const NOTIFICATION_TYPE_LABELS: Record<string, string> = {
  review_pending: '待审核',
  review_approved: '审核通过',
  review_rejected: '审核驳回',
  item_archived: '已归档',
};

const NOTIFICATION_TYPE_ICONS: Record<string, React.ReactNode> = {
  review_pending: <AlertCircle className="w-4 h-4 text-warning-text" />,
  review_approved: <CheckCircle className="w-4 h-4 text-success-text" />,
  review_rejected: <XCircle className="w-4 h-4 text-error-text" />,
  item_archived: <Archive className="w-4 h-4 text-text-muted" />,
};

const NOTIFICATION_TYPE_COLORS: Record<string, string> = {
  review_pending: 'bg-warning-bg border-border-secondary',
  review_approved: 'bg-success-bg border-border-secondary',
  review_rejected: 'bg-error-bg border-border-secondary',
  item_archived: 'bg-bg-secondary border-border-primary',
};

export default function NotificationsPage() {
  const { user, loading: authLoading } = useAuth();
  const router = useRouter();

  const [notifications, setNotifications] = useState<NotificationItem[]>([]);
  const [total, setTotal] = useState(0);
  const [page, setPage] = useState(1);
  const [loading, setLoading] = useState(true);
  const [error, setError] = useState('');
  const [unreadOnly, setUnreadOnly] = useState(false);
  const [unreadCount, setUnreadCount] = useState(0);
  const pageSize = 20;
  // 单调递增的请求序号：只有最新一次请求的响应可以写进 state
  const fetchSeqRef = useRef(0);

  const fetchNotifications = useCallback(async () => {
    const seq = ++fetchSeqRef.current;
    setLoading(true);
    setError('');
    try {
      const query = new URLSearchParams();
      query.set('page', String(page));
      query.set('pageSize', String(pageSize));
      if (unreadOnly) query.set('unreadOnly', 'true');

      const data = await adminApi.request<{
        items: NotificationItem[];
        total: number;
        page: number;
        pageSize: number;
        totalPages: number;
      }>(`/api/admin/notifications?${query.toString()}`);
      if (seq !== fetchSeqRef.current) return;
      setNotifications(data.items || []);
      setTotal(data.total || 0);
    } catch (err) {
      if (seq !== fetchSeqRef.current) return;
      setError(err instanceof Error ? err.message : '加载失败');
    } finally {
      if (seq === fetchSeqRef.current) setLoading(false);
    }
  }, [page, unreadOnly]);

  const fetchUnreadCount = useCallback(async () => {
    try {
      const data = await adminApi.request<{ count: number }>('/api/admin/notifications/unread-count');
      setUnreadCount(data.count || 0);
    } catch {
      // Non-critical
    }
  }, []);

  useEffect(() => {
    if (!authLoading && !user) {
      router.push('/admin/login');
      return;
    }
    if (user) {
      fetchNotifications();
      fetchUnreadCount();
    }
  }, [user, authLoading, router, fetchNotifications, fetchUnreadCount]);

  const handleMarkAsRead = async (id: string) => {
    try {
      await adminApi.request(`/api/admin/notifications/${id}/read`, { method: 'POST' });
      setNotifications((prev) =>
        prev.map((n) => (n.id === id ? { ...n, read: true } : n))
      );
      setUnreadCount((prev) => Math.max(0, prev - 1));
    } catch {
      toast.error('标记已读失败');
    }
  };

  const handleMarkAllAsRead = async () => {
    try {
      await adminApi.request('/api/admin/notifications/read-all', { method: 'POST' });
      setNotifications((prev) => prev.map((n) => ({ ...n, read: true })));
      setUnreadCount(0);
      toast.success('全部标记为已读');
    } catch {
      toast.error('操作失败');
    }
  };

  const handleViewRelated = (item: NotificationItem) => {
    if (item.relatedItemId && item.relatedModelCode) {
      router.push(`/admin/content/${item.relatedModelCode}/${item.relatedItemId}`);
    }
  };

  const totalPages = Math.ceil(total / pageSize);

  if (authLoading || (!user && typeof window !== 'undefined')) {
    return (
      <div className="flex items-center justify-center h-64">
        <div className="animate-spin w-8 h-8 border-2 border-border-dark border-t-transparent rounded-full" />
      </div>
    );
  }

  return (
    <div className="space-y-6">
      <div className="flex items-center justify-between">
        <div>
          <h1 className="text-xl font-bold text-text-primary">通知中心</h1>
          <p className="text-sm text-text-muted mt-1">
            共 {total} 条通知
            {unreadCount > 0 && (
              <span className="ml-2 inline-flex items-center px-2 py-0.5 rounded-full text-xs font-medium bg-error-bg text-error-text">
                {unreadCount} 条未读
              </span>
            )}
          </p>
        </div>
        <div className="flex items-center gap-2">
          <button
            onClick={() => { setUnreadOnly((prev) => !prev); setPage(1); }}
            className={`flex items-center gap-2 px-3 py-2 rounded-lg text-sm font-medium border transition-colors ${
              unreadOnly
                ? 'bg-dark-bg text-white border-border-dark'
                : 'bg-bg-primary text-text-tertiary border-border-primary hover:border-border-secondary'
            }`}
          >
            <Mail className="w-4 h-4" />
            仅未读
          </button>
          {unreadCount > 0 && (
            <button
              onClick={handleMarkAllAsRead}
              className="flex items-center gap-2 px-3 py-2 bg-bg-primary text-text-tertiary rounded-lg text-sm font-medium border border-border-primary hover:border-border-secondary transition-colors"
            >
              <CheckCheck className="w-4 h-4" />
              全部已读
            </button>
          )}
          <button
            onClick={() => { fetchNotifications(); fetchUnreadCount(); }}
            className="flex items-center gap-2 px-3 py-2 bg-bg-primary text-text-tertiary rounded-lg text-sm font-medium border border-border-primary hover:border-border-secondary transition-colors"
          >
            <RefreshCw className="w-4 h-4" />
            刷新
          </button>
        </div>
      </div>

      {error && (
        <div className="p-4 bg-error-bg border border-border-secondary rounded-lg text-sm text-error-text">
          {error}
        </div>
      )}

      {/* Notifications list */}
      <div className="space-y-2">
        {loading ? (
          <div className="flex items-center justify-center py-12 text-text-muted">
            <div className="flex items-center gap-2">
              <div className="animate-spin w-4 h-4 border-2 border-border-secondary border-t-transparent rounded-full" />
              加载中...
            </div>
          </div>
        ) : notifications.length === 0 ? (
          <div className="flex flex-col items-center justify-center py-16 text-text-muted">
            <Bell className="w-12 h-12 mb-3 text-text-muted" />
            <p className="text-sm">暂无通知</p>
            {unreadOnly && (
              <p className="text-xs text-text-muted mt-1">没有未读通知，试试查看全部</p>
            )}
          </div>
        ) : (
          notifications.map((item) => (
            <div
              key={item.id}
              className={`relative flex items-start gap-4 p-4 rounded-lg border transition-colors ${
                item.read
                  ? 'bg-bg-primary border-border-light'
                  : NOTIFICATION_TYPE_COLORS[item.type] || 'bg-info-bg border-border-secondary'
              }`}
            >
              {/* Unread indicator */}
              {!item.read && (
                <div className="absolute top-4 left-4 w-2 h-2 rounded-full bg-info" />
              )}

              {/* Type icon */}
              <div className={`flex-shrink-0 w-8 h-8 rounded-full flex items-center justify-center ${
                item.read ? 'bg-bg-hover' : 'bg-bg-primary'
              }`}>
                {NOTIFICATION_TYPE_ICONS[item.type] || <Bell className="w-4 h-4 text-text-muted" />}
              </div>

              {/* Content */}
              <div className="flex-1 min-w-0">
                <div className="flex items-center gap-2 mb-1">
                  <span className={`text-xs font-medium px-1.5 py-0.5 rounded ${
                    item.read ? 'text-text-muted' : ''
                  }`}>
                    {NOTIFICATION_TYPE_LABELS[item.type] || item.type}
                  </span>
                  <span className="text-xs text-text-muted flex items-center gap-1">
                    <Clock className="w-3 h-3" />
                    {new Date(item.createdAt).toLocaleString('zh-CN', {
                      year: 'numeric',
                      month: '2-digit',
                      day: '2-digit',
                      hour: '2-digit',
                      minute: '2-digit',
                    })}
                  </span>
                </div>
                <h3 className={`text-sm font-medium ${item.read ? 'text-text-tertiary' : 'text-text-primary'}`}>
                  {item.title}
                </h3>
                <p className={`text-xs mt-0.5 ${item.read ? 'text-text-muted' : 'text-text-muted'}`}>
                  {item.message}
                </p>

                {/* Actions */}
                <div className="flex items-center gap-3 mt-2">
                  {!item.read && (
                    <button
                      onClick={() => handleMarkAsRead(item.id)}
                      className="text-xs text-text-muted hover:text-text-secondary flex items-center gap-1"
                    >
                      <MailOpen className="w-3 h-3" />
                      标记已读
                    </button>
                  )}
                  {item.relatedItemId && item.relatedModelCode && (
                    <button
                      onClick={() => handleViewRelated(item)}
                      className="text-xs text-info-text hover:text-info flex items-center gap-1"
                    >
                      <ExternalLink className="w-3 h-3" />
                      查看详情
                    </button>
                  )}
                </div>
              </div>
            </div>
          ))
        )}
      </div>

      {/* Pagination */}
      {totalPages > 1 && (
        <div className="flex items-center justify-between px-4 py-3 bg-bg-primary rounded-lg border border-border-primary">
          <span className="text-sm text-text-muted">
            共 {total} 条，第 {page}/{totalPages} 页
          </span>
          <div className="flex items-center gap-2">
            <button
              onClick={() => setPage((p) => Math.max(1, p - 1))}
              disabled={page <= 1}
              className="px-3 py-1.5 text-sm rounded border border-border-primary hover:bg-bg-hover disabled:opacity-50 disabled:cursor-not-allowed"
            >
              上一页
            </button>
            <button
              onClick={() => setPage((p) => Math.min(totalPages, p + 1))}
              disabled={page >= totalPages}
              className="px-3 py-1.5 text-sm rounded border border-border-primary hover:bg-bg-hover disabled:opacity-50 disabled:cursor-not-allowed"
            >
              下一页
            </button>
          </div>
        </div>
      )}
    </div>
  );
}