import { useState, useCallback, useEffect } from 'react';
import { Card, Row, Col, Statistic, Tag, List, Select, Badge, Typography, Space, Empty, Result } from 'antd';
import { AlertOutlined } from '@ant-design/icons';
import { useVitalSSE } from '../../hooks/useVitalSSE';
import { usePermission } from '../../hooks/usePermission';
import { alertApi, type Alert } from '../../api/health/alerts';
import { PageContainer } from '../../components/PageContainer';
import { SEVERITY_COLOR, SEVERITY_LABEL, VITAL_CARD_METRICS } from '../../constants/health';

interface PatientAlertSummary {
  patient_id: string;
  critical: number;
  high: number;
  medium: number;
  low: number;
}

/**
 * 实时体征监控台 — 医生 Web 端。
 *
 * SSE 实时接收体征更新，按告警严重度排序患者列表。
 */
export default function RealtimeMonitor() {
  const { hasPermission } = usePermission('health.alerts.list');
  const [alerts, setAlerts] = useState<Alert[]>([]);
  const [loading, setLoading] = useState(true);
  const [selectedPatientId, setSelectedPatientId] = useState<string | null>(null);
  const [alertSummary, setAlertSummary] = useState<PatientAlertSummary[]>([]);

  const { connected, patientVitals } = useVitalSSE({ enabled: true });

  const fetchAlerts = useCallback(async () => {
    try {
      setLoading(true);
      const result = await alertApi.list({ page: 1, page_size: 100, status: 'pending' });
      setAlerts(result.data);

      const summaryMap = new Map<string, PatientAlertSummary>();
      for (const alert of result.data) {
        const existing = summaryMap.get(alert.patient_id) ?? {
          patient_id: alert.patient_id,
          critical: 0, high: 0, medium: 0, low: 0,
        };
        const sev = alert.severity;
        if (sev === 'critical') existing.critical++;
        else if (sev === 'high') existing.high++;
        else if (sev === 'medium') existing.medium++;
        else existing.low++;
        summaryMap.set(alert.patient_id, existing);
      }
      setAlertSummary(Array.from(summaryMap.values()));
    } catch {
      // 静默降级
    } finally {
      setLoading(false);
    }
  }, []);

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

  const sortedPatients = [...alertSummary].sort((a, b) => {
    const score = (s: PatientAlertSummary) => s.critical * 4 + s.high * 3 + s.medium * 2 + s.low;
    return score(b) - score(a);
  });

  const totalCritical = alertSummary.reduce((s, a) => s + a.critical, 0);
  const totalHigh = alertSummary.reduce((s, a) => s + a.high, 0);
  const totalMedium = alertSummary.reduce((s, a) => s + a.medium, 0);
  const totalLow = alertSummary.reduce((s, a) => s + a.low, 0);

  if (!hasPermission) {
    return <Result status="403" title="权限不足" subTitle="您没有访问实时体征监控的权限" />;
  }

  return (
    <PageContainer
      title="实时体征监控"
      actions={
        <Space>
          <Badge status={connected ? 'success' : 'error'} text={connected ? '已连接' : '断开'} />
          <Select
            placeholder="筛选患者"
            allowClear
            style={{ width: 200 }}
            onChange={(v) => setSelectedPatientId(v ?? null)}
            options={sortedPatients.map((p) => ({
              value: p.patient_id,
              label: p.patient_id,
            }))}
          />
        </Space>
      }
    >
      <Row gutter={16} style={{ marginBottom: 16 }}>
        <Col span={6}><Card><Statistic title="危急" value={totalCritical} valueStyle={{ color: '#cf1322' }} prefix={<AlertOutlined />} /></Card></Col>
        <Col span={6}><Card><Statistic title="高危" value={totalHigh} valueStyle={{ color: '#ff4d4f' }} prefix={<AlertOutlined />} /></Card></Col>
        <Col span={6}><Card><Statistic title="中等" value={totalMedium} valueStyle={{ color: '#fa8c16' }} prefix={<AlertOutlined />} /></Card></Col>
        <Col span={6}><Card><Statistic title="低危" value={totalLow} valueStyle={{ color: '#8c8c8c' }} prefix={<AlertOutlined />} /></Card></Col>
      </Row>

      <Card title={`患者列表（${sortedPatients.length} 人有活跃告警）`} loading={loading}>
        {sortedPatients.length === 0 ? (
          <Empty description="暂无活跃告警" />
        ) : (
          <List
            dataSource={selectedPatientId ? sortedPatients.filter((p) => p.patient_id === selectedPatientId) : sortedPatients}
            renderItem={(item) => {
              const vitalKeys = Array.from(patientVitals.entries())
                .filter(([key]) => key.startsWith(item.patient_id));
              const latestVitals = vitalKeys.map(([, v]) => v);

              return (
                <List.Item
                  style={{ cursor: 'pointer', padding: '12px 16px' }}
                  onClick={() => setSelectedPatientId(
                    selectedPatientId === item.patient_id ? null : item.patient_id,
                  )}
                >
                  <List.Item.Meta
                    title={
                      <Space>
                        <Typography.Text>{item.patient_id}</Typography.Text>
                        {item.critical > 0 && <Tag color="red">{item.critical} 危急</Tag>}
                        {item.high > 0 && <Tag color="volcano">{item.high} 高危</Tag>}
                        {item.medium > 0 && <Tag color="orange">{item.medium} 中等</Tag>}
                      </Space>
                    }
                    description={
                      <Space wrap>
                        {latestVitals.map((v) => {
                          const metric = VITAL_CARD_METRICS.find((m) => m.key === v.device_type);
                          if (!metric) return null;
                          return (
                            <Tag key={v.device_type} color="blue">
                              {metric.label}: {v.latest_value ?? '-'} {metric.unit}
                            </Tag>
                          );
                        })}
                        {latestVitals.length === 0 && <Typography.Text type="secondary">暂无实时数据</Typography.Text>}
                      </Space>
                    }
                  />
                </List.Item>
              );
            }}
          />
        )}
      </Card>
    </PageContainer>
  );
}