import React, { useEffect, useState, useContext, useRef, useMemo } from 'react';
import { Typography, Spin, Message, Card, Grid } from '@arco-design/web-react';
import '@arco-design/web-react/dist/css/arco.css';
import { initVChartArcoTheme } from '@visactor/vchart-arco-theme';
import { VChart } from '@visactor/react-vchart';
import API_BASE_URL from '../config';
import { MarketContext, MARKET_FULL_NAMES } from '../App';

// TODO:
//
// - [ ] Cancel Promise if market changes
// - [ ] Fix Data Zoom being reset

const { Row, Col } = Grid;

function TimeAgo({ timestamp, prefix }) {
  const [now, setNow] = useState(new Date());

  useEffect(() => {
    const timer = setInterval(() => setNow(new Date()), 1000);
    return () => clearInterval(timer);
  }, []);

  const formatTimeAgo = () => {
    if (!timestamp) return '';
    const seconds = Math.floor((now - timestamp) / 1000);
    if (seconds < 60) return `${seconds} sec ago`;
    const minutes = Math.floor(seconds / 60);
    if (minutes < 60) return `${minutes} min ago`;
    const hours = Math.floor(minutes / 60);
    return `${hours} hr ago`;
  };

  return (
    <Typography.Text type="secondary" style={{ fontSize: 12, display: 'block', marginTop: 8 }}>
      {prefix}: {formatTimeAgo()}
    </Typography.Text>
  );
}

function MarketDataPage() {
  const { selectedMarket } = useContext(MarketContext);
  const fiveMinChartRef = useRef(null);
    const dayAheadChartRef = useRef(null);
  const [fiveMinZoom, setFiveMinZoom] = useState({ start: 0.9, end: 1 });
  const [dayAheadZoom, setDayAheadZoom] = useState({ start: 0.05, end: 1 });
  const [fiveMinData, setFiveMinData] = useState([]);
  const [dayAheadData, setDayAheadData] = useState([]);
  const [loading, setLoading] = useState(true);
  const [fiveMinLastUpdated, setFiveMinLastUpdated] = useState(null);
  const [dayAheadLastUpdated, setDayAheadLastUpdated] = useState(null);
  const [, setNow] = useState(new Date());

  const handleZoomChange = (e, title) => {
     if (!e?.start || !e?.end) return;
     if (title === 'fiveMin') {
       setFiveMinZoom({ start: e.start, end: e.end });
     } else {
       setDayAheadZoom({ start: e.start, end: e.end });
     }
   };

  useEffect(() => {
    const fetchFiveMinData = async () => {
      try {
        const res = await fetch(`${API_BASE_URL}/market/real-time?market=${selectedMarket}`);
        if (!res.ok) throw new Error('Failed to fetch real-time data');
        const json = await res.json();
        setFiveMinData(json);
        setFiveMinLastUpdated(new Date());
      } catch (err) {
        console.error(err);
        Message.error('Failed to load real-time market data.');
      }
    };

    const fetchDayAheadData = async () => {
      try {
        const res = await fetch(`${API_BASE_URL}/market/day-ahead?market=${selectedMarket}`);
        if (!res.ok) throw new Error('Failed to fetch day-ahead data');
        const json = await res.json();
        setDayAheadData(json);
        setDayAheadLastUpdated(new Date());
      } catch (err) {
        console.error(err);
        Message.error('Failed to load day-ahead market data.');
      }
    };

    const initialize = async () => {
      setLoading(true);
      await Promise.all([fetchFiveMinData(), fetchDayAheadData()]);
      setLoading(false);

      initVChartArcoTheme({
        defaultMode: 'light',
        isWatchingMode: true
      });
    };

    initialize();

    const fiveMinInterval = setInterval(fetchFiveMinData, 5 * 60 * 1000);
    const dayAheadInterval = setInterval(fetchDayAheadData, 60 * 60 * 1000);
    const timer = setInterval(() => setNow(new Date()), 1000);

    return () => {
      clearInterval(fiveMinInterval);
      clearInterval(dayAheadInterval);
      clearInterval(timer);
    };
  }, [selectedMarket]);

  const fiveMinSpec = useMemo(() => ({
      type: 'line',
      data: {
        values: fiveMinData.map(d => ({
          timestamp: new Date(d.timestamp).toLocaleString(),
          LMP: d.lmp,
          Energy: d.energy,
          Congestion: d.congestion,
          Loss: d.loss
        })),
        transforms: [{
          type: 'fold',
          options: { key: 'name', value: 'value', fields: ['LMP', 'Energy', 'Congestion', 'Loss'] }
        }]
      },
      xField: 'timestamp',
      yField: 'value',
      seriesField: 'name',
      smooth: true,
      legend: { position: 'top' },
      tooltip: {
        formatter: (datum) => ({
          name: datum.name,
          value: datum.value.toFixed(2)
        })
      },
      dataZoom: [{
        orient: 'bottom',
        height: 20,
        start: fiveMinZoom.start,
        end: fiveMinZoom.end
      }]
    }), [fiveMinData, fiveMinZoom]); // <== DEPENDENCIES

    const dayAheadSpec = useMemo(() => ({
      type: 'line',
      data: {
        values: dayAheadData.map(d => ({
          timestamp: new Date(d.timestamp).toLocaleString(),
          LMP: d.lmp,
          Energy: d.energy,
          Congestion: d.congestion,
          Loss: d.loss
        })),
        transforms: [{
          type: 'fold',
          options: { key: 'name', value: 'value', fields: ['LMP', 'Energy', 'Congestion', 'Loss'] }
        }]
      },
      xField: 'timestamp',
      yField: 'value',
      seriesField: 'name',
      smooth: true,
      legend: { position: 'top' },
      tooltip: {
        formatter: (datum) => ({
          name: datum.name,
          value: datum.value.toFixed(2)
        })
      },
      dataZoom: [{
        orient: 'bottom',
        height: 20,
        start: dayAheadZoom.start,
        end: dayAheadZoom.end
      }]
    }), [dayAheadData, dayAheadZoom]);

  const computeKPIs = (data) => {
    if (!data.length) return { avgLmp: 0, totalEnergy: 0, maxCongestion: 0, avgLoss: 0 };
    const avgLmp = data.reduce((sum, d) => sum + d.lmp, 0) / data.length;
    const totalEnergy = data.reduce((sum, d) => sum + d.energy, 0);
    const maxCongestion = Math.max(...data.map(d => d.congestion));
    const avgLoss = data.reduce((sum, d) => sum + d.loss, 0) / data.length;
    return { avgLmp, totalEnergy, maxCongestion, avgLoss };
  };

  const fiveMinKPIs = computeKPIs(fiveMinData);
  const dayAheadKPIs = computeKPIs(dayAheadData);

  return (
    <div className="page-container">
      <Typography.Title heading={3} style={{ textAlign: 'center', marginBottom: 20 }} className="market-page-title" >
        Market Data for {MARKET_FULL_NAMES[selectedMarket]}
      </Typography.Title>

      {loading ? (
        <Spin style={{ display: 'block', margin: '80px auto' }} />
      ) : (
        <>
         <Row gutter={24} style={{ marginBottom: 30 }}>
            {[
              { label: 'Avg Real-Time LMP ($/MWh)', value: fiveMinKPIs.avgLmp },
              { label: 'Total Real-Time Energy (MWh)', value: fiveMinKPIs.totalEnergy },
              { label: 'Max Real-Time Congestion ($)', value: fiveMinKPIs.maxCongestion },
              { label: 'Avg Real-Time Loss ($)', value: fiveMinKPIs.avgLoss }
            ].map((item, idx) => (
              <Col xs={12} md={6} key={idx} style={{ marginBottom: 16 }}>
                <Card
                  hoverable
                  style={{
                    textAlign: 'center',
                    borderRadius: 12,
                    boxShadow: '0 4px 12px rgba(0,0,0,0.05)'
                  }}
                  title={item.label}
                >
                  <Typography.Title heading={5}>${item.value.toFixed(2)}</Typography.Title>
                </Card>
              </Col>
            ))}
          </Row>

          <Row gutter={24} style={{ marginBottom: 30 }}>
            {[
              { label: 'Avg Day-Ahead LMP ($/MWh)', value: dayAheadKPIs.avgLmp },
              { label: 'Total Day-Ahead Energy (MWh)', value: dayAheadKPIs.totalEnergy },
              { label: 'Max Day-Ahead Congestion ($)', value: dayAheadKPIs.maxCongestion },
              { label: 'Avg Day-Ahead Loss ($)', value: dayAheadKPIs.avgLoss }
            ].map((item, idx) => (
              <Col xs={12} md={6} key={idx} style={{ marginBottom: 16 }}>
                <Card
                  hoverable
                  style={{
                    textAlign: 'center',
                    borderRadius: 12,
                    boxShadow: '0 4px 12px rgba(0,0,0,0.05)'
                  }}
                  title={item.label}
                >
                  <Typography.Title heading={5}>${item.value.toFixed(2)}</Typography.Title>
                </Card>
              </Col>
            ))}
          </Row>

          <Row gutter={24}>
            <Col xs={24} md={12}>
              <Card title="Real-Time Market Data" extra={<TimeAgo timestamp={fiveMinLastUpdated} prefix="Updated" />} style={{ borderRadius: 12, marginBottom: 24 }}>
                <div style={{ padding: 10 }}>
                  <VChart
                                spec={fiveMinSpec}
                                ref={fiveMinChartRef}
                                onDataZoom={(e) => handleZoomChange(e.detail, 'fiveMin')}
                              />
                </div>
              </Card>
            </Col>
            <Col xs={24} md={12}>
              <Card title="Day-Ahead Market Data" extra={<TimeAgo timestamp={dayAheadLastUpdated} prefix="Updated" />} style={{ borderRadius: 12, marginBottom: 24 }}>
                <div style={{ padding: 10 }}>
                  <VChart
                                spec={dayAheadSpec}
                                ref={dayAheadChartRef}
                                onDataZoom={(e) => handleZoomChange(e.detail, 'dayAhead')}
                              />
                </div>
              </Card>
            </Col>
          </Row>
        </>
      )}

      <style>{`
        @keyframes fadeIn {
          from { opacity: 0; transform: translateY(10px); }
          to { opacity: 1; transform: translateY(0); }
        }

        .arco-card-header-title {
          white-space: normal !important; /* allow wrapping */
          word-break: break-word;
        }

        /* Optional: smaller text on tiny devices */
        @media (max-width: 768px) {
          .arco-card-header-title {
            font-size: 14px;
          }
        }

        .market-page-title {
          white-space: normal;
          word-break: keep-all;
          overflow-wrap: break-word;
          text-align: center;
        }

        .page-container {
          padding: 15px;
          background: var(--color-fill-2);
          animation: fadeIn 0.5s ease;
          overflow-x: hidden; /* Also good practice */
        }

        /* Responsive: remove padding on small screens */
        @media (max-width: 768px) {
          .page-container {
            padding: 0;
          }
        }
      `}</style>
    </div>
  );
}

export default MarketDataPage;