import { useState, useEffect, useCallback } from 'react';
import {
  Clock, XCircle, CheckCircle, AlertTriangle,
  Database, Zap, Loader2, Calendar, Ban,
} from 'lucide-react';
import api from '@/api/request';

interface ScheduledTicket {
  id: number;
  ticket_no: string;
  title: string;
  db_type: string;
  instance_name: string;
  instance_db_type: string;
  target_database: string;
  sql_content: string;
  status: string;
  scheduled_at: string | null;
  priority: string;
  create_time: string | null;
}

const DB_TYPE_ICON: Record<string, string> = {
  mysql: '🐬', postgres: '🐘', redis: '🔴', mongo: '🍃',
};
const DB_TYPE_LABEL: Record<string, string> = {
  mysql: 'MySQL', postgres: 'PostgreSQL', redis: 'Redis', mongo: 'MongoDB',
};

export default function AutoTaskPage() {
  const [tasks, setTasks] = useState<ScheduledTicket[]>([]);
  const [loading, setLoading] = useState(true);
  const [error, setError] = useState('');
  const [cancelling, setCancelling] = useState<number | null>(null);

  const fetchTasks = useCallback(async () => {
    setLoading(true);
    setError('');
    try {
      const res = await api.get('/tickets/scheduled/list') as { items: ScheduledTicket[]; total: number };
      setTasks(res.items || []);
    } catch {
      setError('加载定时任务失败');
    } finally {
      setLoading(false);
    }
  }, []);

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

  // 自动刷新（每 30 秒）
  useEffect(() => {
    const timer = setInterval(fetchTasks, 30000);
    return () => clearInterval(timer);
  }, [fetchTasks]);

  const handleCancel = useCallback(async (id: number) => {
    setCancelling(id);
    try {
      await api.post(`/tickets/${id}/cancel-schedule`);
      setTasks(prev => prev.filter(t => t.id !== id));
    } catch {
      setError('取消定时任务失败');
    } finally {
      setCancelling(null);
    }
  }, []);

  const formatTime = (iso: string | null) => {
    if (!iso) return '-';
    return new Date(iso).toLocaleString('zh-CN', {
      year: 'numeric', month: '2-digit', day: '2-digit',
      hour: '2-digit', minute: '2-digit', second: '2-digit',
    });
  };

  const getCountdown = (iso: string | null) => {
    if (!iso) return '';
    const diff = new Date(iso).getTime() - Date.now();
    if (diff <= 0) return '即将执行';
    const h = Math.floor(diff / 3600000);
    const m = Math.floor((diff % 3600000) / 60000);
    const s = Math.floor((diff % 60000) / 1000);
    if (h > 0) return `${h}h ${m}m 后执行`;
    if (m > 0) return `${m}m ${s}s 后执行`;
    return `${s}s 后执行`;
  };

  return (
    <div className="space-y-5">
      {/* Header */}
      <div className="flex items-center justify-between">
        <div className="flex items-center gap-3">
          <Clock className="w-5 h-5 text-blue-400" />
          <h1 className="text-xl font-semibold">定时执行任务</h1>
          <span className="text-sm text-[var(--dg-text-muted)]">
            审批通过并设置定时执行的工单，到时间后自动执行 SQL
          </span>
        </div>
        <button onClick={fetchTasks} disabled={loading}
          className="flex items-center gap-1.5 px-3 py-1.5 text-sm bg-[var(--dg-bg-secondary)] border border-[var(--dg-border)] rounded-lg hover:bg-[var(--dg-bg-hover)] transition-colors disabled:opacity-50">
          {loading ? <Loader2 className="w-3.5 h-3.5 animate-spin" /> : <Zap className="w-3.5 h-3.5" />}
          刷新
        </button>
      </div>

      {/* Error */}
      {error && (
        <div className="flex items-center gap-2 text-sm text-red-400 bg-red-500/10 px-4 py-3 rounded-lg">
          <AlertTriangle className="w-4 h-4 shrink-0" /> {error}
        </div>
      )}

      {/* Empty */}
      {!loading && tasks.length === 0 && (
        <div className="text-center py-16">
          <Clock className="w-12 h-12 text-[var(--dg-text-muted)] mx-auto mb-3 opacity-30" />
          <p className="text-[var(--dg-text-muted)]">暂无定时执行中的工单</p>
          <p className="text-xs text-[var(--dg-text-muted)] mt-1">
            在「新建数据变更工单」中勾选「定时执行」可创建定时任务
          </p>
        </div>
      )}

      {/* Task Cards */}
      <div className="space-y-3">
        {tasks.map(task => {
          const countdown = getCountdown(task.scheduled_at);
          return (
            <div key={task.id}
              className="bg-[var(--dg-bg-secondary)] rounded-lg p-4 space-y-3">
              {/* Row 1: Title + Status + Countdown */}
              <div className="flex items-center gap-3">
                <span className="text-lg">{DB_TYPE_ICON[task.db_type] || '💾'}</span>
                <div className="flex-1 min-w-0">
                  <div className="flex items-center gap-2">
                    <span className="font-medium truncate">{task.title}</span>
                    <span className="text-xs px-1.5 py-0.5 rounded bg-amber-500/15 text-amber-400 font-medium shrink-0">
                      定时执行中
                    </span>
                  </div>
                  <div className="flex items-center gap-2 mt-1 text-xs text-[var(--dg-text-muted)]">
                    <span className="font-mono">{task.ticket_no}</span>
                    <span>·</span>
                    <Database className="w-3 h-3" />
                    <span>{task.instance_name}</span>
                    <span>·</span>
                    <span>{DB_TYPE_LABEL[task.db_type] || task.db_type}</span>
                    <span>·</span>
                    <span>{task.target_database}</span>
                  </div>
                </div>
                {/* Countdown */}
                <div className="text-right shrink-0">
                  <div className="text-sm font-medium text-blue-400">{countdown}</div>
                  <div className="text-[10px] text-[var(--dg-text-muted)] mt-0.5">
                    <Calendar className="w-3 h-3 inline mr-0.5" />
                    {formatTime(task.scheduled_at)}
                  </div>
                </div>
              </div>

              {/* Row 2: SQL Preview */}
              <div className="bg-[var(--dg-bg-primary)] rounded p-2.5">
                <pre className="text-[11px] font-mono text-[var(--dg-text-secondary)] overflow-x-auto whitespace-pre-wrap max-h-[60px] overflow-y-auto">
                  {task.sql_content}
                </pre>
              </div>

              {/* Row 3: Actions */}
              <div className="flex items-center justify-between">
                <span className="text-[10px] text-[var(--dg-text-muted)]">
                  创建于 {formatTime(task.create_time)}
                </span>
                <button onClick={() => handleCancel(task.id)} disabled={cancelling === task.id}
                  className="flex items-center gap-1.5 px-3 py-1.5 text-xs font-medium text-red-400 bg-red-500/10 rounded-md hover:bg-red-500/20 transition-colors disabled:opacity-50">
                  {cancelling === task.id
                    ? <><Loader2 className="w-3 h-3 animate-spin" /> 取消中...</>
                    : <><Ban className="w-3 h-3" /> 取消定时执行</>}
                </button>
              </div>
            </div>
          );
        })}
      </div>
    </div>
  );
}