// 횡단 Y축 눈금이 플롯 안(상단~X축선)에만 놓이는지 확인 — crossPlotMetrics + Cross_View 로직 복제.
// 실행: node tmp/tests/test_cross_y_ticks.mjs
import assert from "node:assert/strict";

const CROSS_PAD = { left: 58, right: 20, top: 10, bottom: 52 };
const CROSS_HEIGHT = 250;
const AREA_OVERLAY_HEADROOM_PX = 58;

function niceTickStep(span, targetCount, maxCount) {
  if (!(span > 0)) return 1;
  const exponent = Math.floor(Math.log10(span / targetCount));
  let best = Math.pow(10, exponent + 2);
  let bestError = Infinity;
  for (const power of [exponent - 1, exponent, exponent + 1, exponent + 2]) {
    for (const mantissa of [1, 2, 5]) {
      const step = mantissa * Math.pow(10, power);
      const count = Math.floor(span / step) + 1;
      if (count > Math.max(2, maxCount)) continue;
      const error = Math.abs(count - targetCount);
      if (error < bestError) {
        bestError = error;
        best = step;
      }
    }
  }
  return best;
}

function ticksOf({ rawMin, rawMax, halfWidth, widthPx = 630, exaggeration = 1 }) {
  const minOffset = -halfWidth;
  const maxOffset = halfWidth;
  const elevationMid = (rawMin + rawMax) / 2;
  const padding = rawMax > rawMin ? (rawMax - rawMin) * 0.08 : 0.5;
  const pixelsPerMeter = (widthPx - CROSS_PAD.left - CROSS_PAD.right) / (maxOffset - minOffset);
  const rawSpan = Math.max((rawMax - rawMin + padding * 2) * Math.max(exaggeration, 0.1), 1e-6);
  const naturalHeight =
    rawSpan * pixelsPerMeter + CROSS_PAD.top + CROSS_PAD.bottom + AREA_OVERLAY_HEADROOM_PX;
  const heightPx = Math.max(naturalHeight, CROSS_HEIGHT);
  const displaySpan = Math.max(heightPx - CROSS_PAD.top - CROSS_PAD.bottom, 1e-6) / pixelsPerMeter;
  const displayMax = elevationMid + displaySpan / 2 + AREA_OVERLAY_HEADROOM_PX / pixelsPerMeter / 2;
  const y = (elevation) => CROSS_PAD.top + (displayMax - elevation) * pixelsPerMeter;

  const rawDisplaySpan = displaySpan / exaggeration;
  const rawTop = elevationMid + (displayMax - elevationMid) / exaggeration;
  const rawBottom = rawTop - rawDisplaySpan;
  const plotHeightPx = heightPx - CROSS_PAD.top - CROSS_PAD.bottom;
  // 표고 눈금 최소 1m(2026-08-23) — 화면 로직과 같게 맞춘다.
  const step = Math.max(niceTickStep(rawDisplaySpan, 10, Math.floor(plotHeightPx / 14)), 1);
  const out = [];
  for (let tick = Math.ceil(rawBottom / step) * step; tick <= rawTop + 1e-9; tick += step) {
    out.push({ tick, y: y(elevationMid + (tick - elevationMid) * exaggeration) });
  }
  return { out, step, top: CROSS_PAD.top, bottom: heightPx - CROSS_PAD.bottom, heightPx };
}

const CASES = [
  { rawMin: 536.0, rawMax: 541.0, halfWidth: 12 }, // 스크린샷과 비슷한 성토 단면
  { rawMin: 530.0, rawMax: 530.4, halfWidth: 6 }, // 거의 평탄(1m 눈금 두세 줄만 나온다)
  { rawMin: 500.0, rawMax: 528.0, halfWidth: 20 }, // 급경사 절토
  { rawMin: 536.0, rawMax: 541.0, halfWidth: 12, exaggeration: 2 }, // 과장 2배
];
for (const c of CASES) {
  const { out, step, top, bottom } = ticksOf(c);
  assert.ok(out.length >= 2, `눈금 부족: ${JSON.stringify(c)} → ${out.length}`);
  assert.ok(step >= 1 - 1e-9, `1m 미만 눈금: ${step}`);
  for (const t of out) {
    assert.ok(Math.abs(t.tick - Math.round(t.tick)) < 1e-6, `정수 아닌 표고 눈금 ${t.tick}`);
  }
  for (const t of out) {
    assert.ok(
      t.y >= top - 1e-6 && t.y <= bottom + 1e-6,
      `플롯 밖 눈금 ${t.tick.toFixed(2)} y=${t.y.toFixed(1)} (허용 ${top}~${bottom.toFixed(1)})`,
    );
  }
  const spacing = out.length > 1 ? Math.abs(out[1].y - out[0].y) : Infinity;
  assert.ok(spacing >= 14 - 1e-6, `눈금 간격 과밀 ${spacing.toFixed(1)}px (step=${step})`);
}
console.log("ok");