import { test } from 'node:test';
import assert from 'node:assert/strict';
import {
  STAGE_H, STAGE_W, clampTickPair, containFit, defaultTape, defaultTicks,
  lineX, stageToImage, tapeEndpoints,
} from './tapeGeometry.ts';
import { cropMarginFraction, DEFAULT_CROP_FILL } from '../png/crop.ts';

test('defaultTicks sit at crop insets for 90% fill', () => {
  const t = defaultTicks(0.9);
  const inset = STAGE_H * cropMarginFraction(0.9);
  assert.ok(Math.abs(t.tickA - inset) < 1e-9);
  assert.ok(Math.abs(t.tickB - (STAGE_H - inset)) < 1e-9);
});

test('lineX is the middle of the 3:4 stage', () => {
  assert.equal(lineX(), STAGE_W / 2);
});

test('identity tape: stage centre maps near image centre', () => {
  const imgW = 480, imgH = 640;
  const tape = defaultTape(DEFAULT_CROP_FILL, 0);
  const [ix, iy] = stageToImage(STAGE_W / 2, STAGE_H / 2, tape, imgW, imgH);
  assert.ok(Math.abs(ix - imgW / 2) < 1e-6, `ix=${ix}`);
  assert.ok(Math.abs(iy - imgH / 2) < 1e-6, `iy=${iy}`);
});

test('tapeEndpoints span equals tick distance in image px at identity (matching aspect)', () => {
  const imgW = 480, imgH = 640;
  const tape = defaultTape(0.9, 0);
  const ep = tapeEndpoints(tape, imgW, imgH);
  const { scale0 } = containFit(imgW, imgH);
  const expected = Math.abs(tape.tickB - tape.tickA) / scale0;
  assert.ok(Math.abs(ep.spanPx - expected) < 1e-6, `span ${ep.spanPx} vs ${expected}`);
  // Direction should be +y (down the stage → down the image)
  assert.ok(Math.abs(ep.ux) < 1e-6, `ux=${ep.ux}`);
  assert.ok(ep.uy > 0.99, `uy=${ep.uy}`);
});

test('zoom scales inverse: 2× zoom halves image-space tick span', () => {
  const imgW = 480, imgH = 640;
  const base = defaultTape(0.9, 0);
  const zoomed = { ...base, zoom: 2 };
  const a = tapeEndpoints(base, imgW, imgH).spanPx;
  const b = tapeEndpoints(zoomed, imgW, imgH).spanPx;
  assert.ok(Math.abs(b * 2 - a) < 1e-6, `base=${a} zoomed=${b}`);
});

test('clampTickPair enforces gap and order', () => {
  const p = clampTickPair(400, 100, 40);
  assert.ok(p.tickB - p.tickA >= 40);
  assert.ok(p.tickA <= p.tickB);
});