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

  const METER_STEP = 10;
  const QUALITY_BUCKET = 10;

  function niceMeterStep() {
    return METER_STEP;
  }

  function niceMeterTicks(minD, maxD) {
    const span = Math.max(maxD - minD, 1);
    const step = METER_STEP;
    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 qualityBucket(quality) {
    const q = Math.round(Number(quality) / QUALITY_BUCKET) * QUALITY_BUCKET;
    return Math.min(100, Math.max(0, q));
  }

  function colorWithAlpha(hex, alpha) {
    if (!hex || typeof hex !== 'string') {
      return `rgba(136, 136, 136, ${alpha})`;
    }
    const h = hex.replace('#', '');
    if (h.length !== 6) {
      return `rgba(136, 136, 136, ${alpha})`;
    }
    const r = parseInt(h.slice(0, 2), 16);
    const g = parseInt(h.slice(2, 4), 16);
    const b = parseInt(h.slice(4, 6), 16);
    return `rgba(${r}, ${g}, ${b}, ${alpha})`;
  }

  function drawMeterAxis(ctx, margin, plotW, plotH, h, minD, span) {
    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 histogramInBin(qualities) {
    const hist = new Map();
    for (const q of qualities) {
      const bucket = qualityBucket(q);
      hist.set(bucket, (hist.get(bucket) || 0) + 1);
    }
    return hist;
  }

  /** Solid horizontal quality distribution inside one distance bin (0% left → 100% right). */
  function drawBinQualityStrip(ctx, x0, barW, plotTop, plotH, hist, maxInBin, qualityColor, highlight) {
    const cellW = barW / (100 / QUALITY_BUCKET);
    const buckets = Array.from(hist.keys()).sort((a, b) => a - b);

    for (const bq of buckets) {
      const n = hist.get(bq);
      if (!n) continue;
      const frac = n / maxInBin;
      const cellX = x0 + (bq / 100) * barW;
      const fillH = Math.max(1, frac * plotH);
      const y = plotTop + plotH - fillH;
      const base = qualityColor ? qualityColor(bq) : '#888888';
      const alpha = highlight ? 0.35 + 0.65 * frac : 0.18 + 0.72 * frac;
      ctx.fillStyle = colorWithAlpha(base, alpha);
      ctx.fillRect(cellX, y, Math.max(1, cellW + 0.5), fillH);
    }

    // Smooth overlap between neighbours for a continuous look
    if (buckets.length >= 2) {
      for (let i = 0; i < buckets.length - 1; i++) {
        const q0 = buckets[i];
        const q1 = buckets[i + 1];
        const n0 = hist.get(q0);
        const n1 = hist.get(q1);
        const h0 = (n0 / maxInBin) * plotH;
        const h1 = (n1 / maxInBin) * plotH;
        const x0p = x0 + (q0 / 100) * barW;
        const x1p = x0 + (q1 / 100) * barW;
        const midX = (x0p + x1p + cellW) / 2;
        const midH = Math.max(h0, h1) * 0.55;
        const midQ = (q0 + q1) / 2;
        const base = qualityColor ? qualityColor(midQ) : '#888888';
        ctx.fillStyle = colorWithAlpha(base, highlight ? 0.22 : 0.12);
        ctx.fillRect(midX - cellW * 0.4, plotTop + plotH - midH, cellW * 0.8, midH);
      }
    }
  }

  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.max(1, Math.ceil(span / METER_STEP));
    const binWDist = span / binCount;
    const bins = Array.from({ length: binCount }, (_, i) => ({
      min: minD + i * binWDist,
      max: minD + (i + 1) * binWDist,
      qualities: [],
    }));
    for (const s of samples) {
      let idx = Math.floor((s.distM - minD) / binWDist);
      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: 34 };
    const plotW = w - margin.l - margin.r;
    const plotH = h - margin.t - margin.b;
    const barW = plotW / binCount;
    const plotTop = margin.t;

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

    ctx.fillStyle = '#888';
    ctx.font = '9px system-ui';
    ctx.fillText('0', 2, plotTop + plotH);
    ctx.fillText('max', 2, plotTop + 8);

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

    ctx.fillStyle = '#666';
    ctx.font = '8px system-ui';
    ctx.fillText('RX 0%', margin.l, h - 14);
    const rx100 = 'RX 100%';
    const rx100w = ctx.measureText(rx100).width;
    ctx.fillText(rx100, margin.l + plotW - rx100w, h - 14);
    ctx.fillText('плотность ↑', 2, plotTop + plotH / 2 + 12);

    bins.forEach((b, i) => {
      const x0 = margin.l + i / binCount * plotW;
      const highlight = highlightDist != null
        && highlightDist >= b.min && highlightDist < b.max;
      const count = b.qualities.length;

      if (i > 0) {
        ctx.strokeStyle = 'rgba(255,255,255,0.04)';
        ctx.lineWidth = 1;
        ctx.beginPath();
        ctx.moveTo(x0, plotTop);
        ctx.lineTo(x0, plotTop + plotH);
        ctx.stroke();
      }

      if (count === 0) {
        ctx.fillStyle = 'rgba(255,255,255,0.04)';
        ctx.fillRect(x0, plotTop + plotH - 1, barW, 1);
        return;
      }

      const hist = histogramInBin(b.qualities);
      let maxInBin = 1;
      hist.forEach(c => {
        if (c > maxInBin) maxInBin = c;
      });

      if (highlight) {
        ctx.fillStyle = 'rgba(255,255,255,0.05)';
        ctx.fillRect(x0, plotTop, barW, plotH);
      }

      drawBinQualityStrip(
        ctx, x0, barW, plotTop, plotH, hist, maxInBin, qualityColor, highlight);

      if (highlight) {
        ctx.strokeStyle = 'rgba(255,255,255,0.8)';
        ctx.lineWidth = 1.5;
        ctx.strokeRect(x0 + 0.5, plotTop + 0.5, barW - 1, plotH - 1);
      }
    });
  }

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