import React, { useRef, useEffect } from 'react';
import { createChart, LineStyle } from 'lightweight-charts';

const cardStyle = {
  background: '#1a1a1a',
  padding: '1.5rem',
  borderRadius: '12px',
  border: '1px solid #333',
  marginBottom: '1.5rem',
};

const fullscreenStyle = {
  position: 'fixed',
  top: 0, left: 0, right: 0, bottom: 0,
  zIndex: 9999,
  background: '#0d0d0d',
  padding: '1.5rem',
  display: 'flex',
  flexDirection: 'column',
};

const headerStyle = {
  display: 'flex',
  justifyContent: 'space-between',
  alignItems: 'center',
  marginBottom: '1rem',
};

const titleStyle = { fontSize: '1.1rem', fontWeight: 700, color: '#f7931a' };

const btnStyle = {
  background: 'none',
  border: '1px solid #555',
  color: '#aaa',
  borderRadius: '6px',
  padding: '0.4rem 1rem',
  cursor: 'pointer',
  fontSize: '0.85rem',
  marginLeft: '0.5rem',
};

export default function BTCCandlestickChart({ candles, purchases, stats, fullscreen, onToggleFullscreen }) {
  const containerRef = useRef(null);
  const chartRef = useRef(null);
  const candleSeriesRef = useRef(null);

  // Build/rebuild chart when candles data or fullscreen changes
  useEffect(() => {
    if (!containerRef.current || !candles || candles.length === 0) return;

    const container = containerRef.current;
    const { width, height } = container.getBoundingClientRect();

    const chart = createChart(container, {
      width: width || 800,
      height: fullscreen ? height - 20 : 350,
      layout: {
        background: { color: fullscreen ? '#0d0d0d' : '#1a1a1a' },
        textColor: '#ccc',
      },
      grid: {
        vertLines: { color: '#2a2a2a' },
        horzLines: { color: '#2a2a2a' },
      },
      crosshair: { mode: 1 },
      rightPriceScale: { borderColor: '#333' },
      timeScale: { borderColor: '#333', timeVisible: false },
    });

    chartRef.current = chart;

    // Candlestick series
    const candleSeries = chart.addCandlestickSeries({
      upColor: '#6bff8e',
      downColor: '#ff6b6b',
      borderUpColor: '#6bff8e',
      borderDownColor: '#ff6b6b',
      wickUpColor: '#6bff8e',
      wickDownColor: '#ff6b6b',
    });
    candleSeriesRef.current = candleSeries;

    const candleData = candles.map(c => ({
      time: c.date,
      open: c.open,
      high: c.high,
      low: c.low,
      close: c.close,
    }));
    candleSeries.setData(candleData);

    // Average buy price line
    const avgPrice = stats?.average_price ?? 0;
    if (avgPrice > 0) {
      const avgSeries = chart.addLineSeries({
        color: '#4fc3f7',
        lineWidth: 1,
        lineStyle: LineStyle.Dashed,
        priceLineVisible: false,
        lastValueVisible: false,
        title: `Avg Buy €${avgPrice.toLocaleString()}`,
      });
      avgSeries.setData(candles.map(c => ({ time: c.date, value: avgPrice })));
    }

    // Purchase markers — use nearest-candle lookup so purchases always show
    if (purchases && purchases.length > 0) {
      const sortedDates = candles.map(c => c.date).sort();

      const nearestDate = (target) => {
        let closest = sortedDates[0];
        for (const d of sortedDates) {
          if (d <= target) closest = d;
          else break;
        }
        return closest;
      };

      // Merge multiple purchases on the same candle into one marker
      const markerMap = {};
      for (const p of purchases) {
        const d = nearestDate(p.date);
        if (!markerMap[d]) {
          markerMap[d] = { time: d, position: 'belowBar', color: '#f7931a', shape: 'arrowUp', text: `€${p.amount_eur.toLocaleString()}` };
        } else {
          markerMap[d].text += ` +€${p.amount_eur.toLocaleString()}`;
        }
      }
      const markers = Object.values(markerMap).sort((a, b) => a.time.localeCompare(b.time));
      if (markers.length > 0) candleSeries.setMarkers(markers);
    }

    chart.timeScale().fitContent();

    // Responsive resize
    const observer = new ResizeObserver(entries => {
      const entry = entries[0];
      if (!entry) return;
      chart.applyOptions({
        width: entry.contentRect.width,
        height: fullscreen ? entry.contentRect.height - 20 : 350,
      });
    });
    observer.observe(container);

    return () => {
      observer.disconnect();
      chart.remove();
      chartRef.current = null;
      candleSeriesRef.current = null;
    };
  }, [candles, purchases, stats, fullscreen]);

  const handleSave = () => {
    if (!chartRef.current) return;
    const canvas = chartRef.current.takeScreenshot();
    const a = document.createElement('a');
    a.href = canvas.toDataURL('image/png');
    a.download = 'btc-candles.png';
    a.click();
  };

  const containerWrapStyle = fullscreen
    ? { flex: 1, minHeight: 0 }
    : { width: '100%' };

  return (
    <div style={fullscreen ? fullscreenStyle : cardStyle}>
      <div style={headerStyle}>
        <div style={titleStyle}>BTC Candles (EUR)</div>
        <div>
          <button style={btnStyle} onClick={handleSave}>Save as PNG</button>
          <button style={btnStyle} onClick={onToggleFullscreen}>
            {fullscreen ? 'Exit Fullscreen' : 'Fullscreen'}
          </button>
        </div>
      </div>

      {(!candles || candles.length === 0) ? (
        <div style={{ color: '#666', padding: '1rem 0' }}>Loading price data…</div>
      ) : (
        <div ref={containerRef} style={containerWrapStyle} />
      )}
    </div>
  );
}