import { Button, Card, Col, Row, Space, Statistic, Table, Tag, Typography, Empty } from 'antd';
import type { ColumnsType } from 'antd/es/table';
import {
  ApartmentOutlined,
  ThunderboltOutlined,
  TeamOutlined,
  CheckCircleOutlined,
  DollarOutlined,
  DownloadOutlined,
} from '@ant-design/icons';
import { useQuery } from '@tanstack/react-query';
import { useNavigate } from 'react-router-dom';
import { fetchFleetDashboard, type FleetCustomerSummary } from '../api/fleet';
import { downloadFleetDashboardXlsx } from '../api/dashboard';

const { Text } = Typography;

export function AdminFleetDashboardPage() {
  const navigate = useNavigate();
  const { data, isLoading } = useQuery({
    queryKey: ['fleet-dashboard'],
    queryFn: fetchFleetDashboard,
    refetchInterval: 30_000,
  });

  const columns: ColumnsType<FleetCustomerSummary> = [
    { title: 'Code', dataIndex: 'code', key: 'code', render: (v) => <Text strong>{v}</Text> },
    { title: 'Name', dataIndex: 'name', key: 'name' },
    {
      title: 'Status',
      dataIndex: 'isActive',
      key: 'active',
      render: (v: boolean) =>
        v ? <Tag color="green">Active</Tag> : <Tag color="red">Disabled</Tag>,
    },
    {
      title: 'Last push',
      dataIndex: 'lastSeenAt',
      key: 'last',
      render: (v: string | null) => (v ? lagDescription(v) : <Text type="secondary">Never</Text>),
    },
    { title: 'Sites', dataIndex: 'sites', key: 'sites' },
    { title: 'Devices', dataIndex: 'devices', key: 'devices' },
    {
      title: 'Today (rows)',
      dataIndex: 'measurementsToday',
      key: 'mt',
      render: (n: number) => n.toLocaleString(),
    },
    {
      title: 'Today (kWh imp.)',
      dataIndex: 'kwhImportedToday',
      key: 'kwh',
      render: (v: number | null) => (v == null ? '—' : v.toFixed(2)),
    },
    {
      title: 'Today (cost)',
      dataIndex: 'costToday',
      key: 'cost',
      render: (v: number | null) =>
        v == null ? <Text type="secondary">—</Text> : <Text strong>{v.toFixed(2)}</Text>,
    },
  ];

  return (
    <div>
      <Row gutter={16} style={{ marginBottom: 16 }}>
        <Col span={5}>
          <Card>
            <Statistic
              title="Customers"
              value={data?.totalCustomers ?? 0}
              prefix={<TeamOutlined />}
              loading={isLoading}
            />
          </Card>
        </Col>
        <Col span={5}>
          <Card>
            <Statistic
              title="Active (last hr)"
              value={data?.activeCustomers ?? 0}
              suffix={data ? `/ ${data.totalCustomers}` : ''}
              prefix={<CheckCircleOutlined />}
              loading={isLoading}
            />
          </Card>
        </Col>
        <Col span={5}>
          <Card>
            <Statistic
              title="Measurements today"
              value={data?.totalMeasurementsToday ?? 0}
              prefix={<ApartmentOutlined />}
              loading={isLoading}
            />
          </Card>
        </Col>
        <Col span={4}>
          <Card>
            <Statistic
              title="kWh today"
              value={data?.totalKwhImportedToday ?? 0}
              precision={2}
              prefix={<ThunderboltOutlined />}
              loading={isLoading}
            />
          </Card>
        </Col>
        <Col span={5}>
          <Card>
            <Statistic
              title="Cost today"
              value={data?.totalCostToday ?? 0}
              precision={2}
              prefix={<DollarOutlined />}
              valueStyle={{ color: '#3f8600' }}
              loading={isLoading}
            />
          </Card>
        </Col>
      </Row>

      <Card
        title="Customers"
        extra={
          <Space>
            <Button
              icon={<DownloadOutlined />}
              onClick={() => downloadFleetDashboardXlsx()}
              disabled={!data || data.customers.length === 0}
            >
              Export to Excel
            </Button>
          </Space>
        }
      >
        {data && data.customers.length === 0 ? (
          <Empty description="No customers registered yet. Go to Customers to register the first one." />
        ) : (
          <Table<FleetCustomerSummary>
            rowKey="id"
            columns={columns}
            dataSource={data?.customers ?? []}
            loading={isLoading}
            pagination={{ pageSize: 25 }}
            onRow={(record) => ({
              onClick: () => navigate(`/admin/customers/${record.id}`),
              style: { cursor: 'pointer' },
            })}
          />
        )}
      </Card>
    </div>
  );
}

function lagDescription(iso: string): React.ReactNode {
  const ts = new Date(iso).getTime();
  const ageMs = Date.now() - ts;
  const ageMin = Math.floor(ageMs / 60_000);
  if (ageMin < 1) return <Tag color="green">just now</Tag>;
  if (ageMin < 5) return <Tag color="green">{ageMin}m ago</Tag>;
  if (ageMin < 60) return <Tag color="orange">{ageMin}m ago</Tag>;
  const ageHr = Math.floor(ageMin / 60);
  if (ageHr < 24) return <Tag color="red">{ageHr}h ago</Tag>;
  return <Tag color="red">{Math.floor(ageHr / 24)}d ago</Tag>;
}