/** RX quality vs distance chart for TX/RX track compare. */
(function (global) {
  'use strict';

  function niceMeterStep(span) {
    if (span <= 50) return 10;
    if (span <= 150) return 25;
    if (span <= 400) return 50;
    return 100;
  }

  function niceMeterTicks(minD, maxD) {
    const span = Math.max(maxD - minD, 1);
    const step = niceMeterStep(span);
    const ticks = [];
    const start = Math.ceil(minD / step) * step;
    for (let d = start; d <= maxD + step * 0.01; d += step) {
      if (d >= minD - step * 0.01 && d <= maxD + step * 0.01) {
        ticks.push(d);
      }
    }
    if (!ticks.length || ticks[0] > minD + 0.5) {
      ticks.unshift(minD);
    }
    if (ticks[ticks.length - 1] < maxD - 0.5) {
      ticks.push(maxD);
    }
    return ticks;
  }

  function drawMeterAxis(ctx, margin, plotW, plotH, h, minD, span, w) {
    const ticks = niceMeterTicks(minD, minD + span);
    const minLabelGap = 28;
    const maxLabels = Math.max(2, Math.floor(plotW / minLabelGap));
    const labelEvery = ticks.length > maxLabels
      ? Math.ceil(ticks.length / maxLabels)
      : 1;

    ctx.strokeStyle = '#2a2a3a';
    ctx.lineWidth = 1;
    ticks.forEach((d, i) => {
      const x = margin.l + ((d - minD) / span) * plotW;
      ctx.beginPath();
      ctx.moveTo(x, margin.t);
      ctx.lineTo(x, margin.t + plotH);
      ctx.stroke();

      if (i % labelEvery === 0 || i === ticks.length - 1) {
        const label = `${Math.round(d)}m`;
        ctx.fillStyle = '#888';
        ctx.font = '9px system-ui';
        const tw = ctx.measureText(label).width;
        let lx = x - tw / 2;
        lx = Math.max(margin.l, Math.min(lx, margin.l + plotW - tw));
        ctx.fillText(label, lx, h - 4);
      }
    });
  }

  function drawQualityDistChart(canvas, samples, qualityColor, highlightDist) {
    if (!canvas) return;
    const ctx = canvas.getContext('2d');
    const w = canvas.clientWidth || 280;
    const h = canvas.clientHeight || 140;
    if (canvas.width !== w) canvas.width = w;
    if (canvas.height !== h) canvas.height = h;
    ctx.fillStyle = '#0a0a14';
    ctx.fillRect(0, 0, w, h);

    if (!samples?.length) {
      ctx.fillStyle = '#888';
      ctx.font = '11px system-ui';
      ctx.fillText('нет данных качества', 12, h / 2);
      return;
    }

    const dists = samples.map(s => s.distM);
    const minD = Math.min(...dists);
    const maxD = Math.max(...dists);
    const span = Math.max(maxD - minD, 1);
    const binCount = Math.min(40, Math.max(8, Math.ceil(span / 5)));
    const binW = span / binCount;
    const bins = Array.from({ length: binCount }, (_, i) => ({
      min: minD + i * binW,
      max: minD + (i + 1) * binW,
      qualities: [],
    }));
    for (const s of samples) {
      let idx = Math.floor((s.distM - minD) / binW);
      if (idx >= binCount) idx = binCount - 1;
      if (idx < 0) idx = 0;
      bins[idx].qualities.push(s.quality);
    }

    const margin = { l: 36, r: 8, t: 16, b: 30 };
    const plotW = w - margin.l - margin.r;
    const plotH = h - margin.t - margin.b;
    const distBandH = Math.round(plotH * 0.25);
    const qualBandH = plotH - distBandH - 4;
    const qualTop = margin.t;
    const distTop = margin.t + qualBandH + 4;
    const axisY = margin.t + plotH;

    ctx.strokeStyle = '#333';
    ctx.beginPath();
    ctx.moveTo(margin.l, qualTop);
    ctx.lineTo(margin.l, axisY);
    ctx.lineTo(margin.l + plotW, axisY);
    ctx.stroke();

    ctx.fillStyle = '#888';
    ctx.font = '9px system-ui';
    ctx.fillText('0%', 2, distTop - 2);
    ctx.fillText('100%', 2, qualTop + 8);
    ctx.fillStyle = '#666';
    ctx.fillText('точки', 2, distTop + distBandH - 2);

    drawMeterAxis(ctx, margin, plotW, plotH, h, minD, span, w);

    const barW = plotW / binCount;
    let maxCount = 1;
    bins.forEach(b => {
      if (b.qualities.length > maxCount) maxCount = b.qualities.length;
    });

    bins.forEach((b, i) => {
      const x = margin.l + i / binCount * plotW;
      const count = b.qualities.length;
      const highlight = highlightDist != null
        && highlightDist >= b.min && highlightDist < b.max;

      if (count === 0) {
        ctx.fillStyle = 'rgba(255,255,255,0.08)';
        ctx.fillRect(x, distTop + distBandH - 1, barW, 1);
      } else {
        const distBarH = (count / maxCount) * distBandH;
        const intensity = 0.35 + 0.65 * (count / maxCount);
        ctx.fillStyle = `rgba(74, 85, 104, ${intensity})`;
        ctx.fillRect(x, distTop + distBandH - distBarH, barW, distBarH);

        const avg = b.qualities.reduce((a, v) => a + v, 0) / count;
        const qualBarH = (avg / 100) * qualBandH;
        const y = qualTop + qualBandH - qualBarH;
        const col = qualityColor ? qualityColor(avg) : '#888';
        ctx.fillStyle = col;
        ctx.globalAlpha = highlight ? 1 : 0.75;
        ctx.fillRect(x, y, barW, qualBarH);
        ctx.globalAlpha = 1;
        if (highlight) {
          ctx.strokeStyle = '#fff';
          ctx.lineWidth = 1.5;
          ctx.strokeRect(x, y, barW, qualBarH);
          ctx.strokeRect(x, distTop + distBandH - distBarH, barW, distBarH);
        }
      }
    });

    ctx.fillStyle = 'rgba(255,255,255,0.25)';
    samples.forEach(s => {
      const x = margin.l + ((s.distM - minD) / span) * plotW;
      const y = qualTop + qualBandH - (s.quality / 100) * qualBandH;
      ctx.beginPath();
      ctx.arc(x, y, 1.5, 0, Math.PI * 2);
      ctx.fill();
    });
  }

  global.QualityViz = {
    drawQualityDistChart,
  };
})(typeof window !== 'undefined' ? window : globalThis);