// SHARPENING is an unsharp mask MASKED BY AN EDGE DETECTOR and CORED —
// thay_doi_thong_so_giong_lightroom.md §4.2, "Chỉ có viền mắt, lông mi, sợi vải,
// kẽ lá nhận Mask = 1; bầu trời phẳng và làn da mịn màng nhận Mask = 0".
//
// The knob used to be the same 3x3 kernel with Mask = 1 everywhere and no
// coring, so a flat field of grain took the same gain an eyelash did and a
// rising SHARPENING raised the frame's noise with it. This check pins the three
// things the doc asks for and that the old kernel could not do:
//
//   1. a flat field comes back untouched (no gain on noise),
//   2. a soft step below the edge threshold comes back untouched (Mask = 0),
//   3. a hard step gains contrast on both sides of it (Mask = 1).
//
//   node scripts/sharpen-check.mjs
import assert from 'node:assert/strict';
import { mkdtempSync, readFileSync, writeFileSync } from 'node:fs';
import { tmpdir } from 'node:os';
import { join } from 'node:path';
import { fileURLToPath, pathToFileURL } from 'node:url';
import ts from 'typescript';
import CanvasKitInit from 'canvaskit-wasm/bin/full/canvaskit.js';

const transpile = (path) =>
  ts.transpileModule(readFileSync(new URL(path, import.meta.url), 'utf8'), {
    compilerOptions: { module: ts.ModuleKind.ESNext, target: ts.ScriptTarget.ES2022 },
  }).outputText;

const dir = mkdtempSync(join(tmpdir(), 'sharpen-check-'));
writeFileSync(join(dir, 'colorUtils.mjs'), transpile('../shared/utils/colorUtils.ts'));
writeFileSync(
  join(dir, 'toneShader.mjs'),
  transpile('../shared/utils/toneShader.ts').replace(
    /^import .*from ['"]\.\/colorUtils['"];$/m,
    'import { HSL_BANDS, hslBandGaps, isMonochromeBase } from "./colorUtils.mjs";',
  ),
);
const { SHARPEN_SKSL, SHARPEN_CORE, SHARPEN_MASK_LO, SHARPEN_MASK_HI } = await import(
  pathToFileURL(join(dir, 'toneShader.mjs')).href
);
const engine = readFileSync(new URL('../src/engine/exportEngine.ts', import.meta.url), 'utf8');

assert.match(engine, /Skia\.RuntimeEffect\.Make\(SHARPEN_SKSL\)/, 'SHARPEN_SKSL is not compiled any more');
assert.doesNotMatch(engine, /CLARITY_SKSL/, 'the unmasked kernel is still wired in somewhere');
assert.ok(
  SHARPEN_MASK_LO > 0 && SHARPEN_MASK_HI > SHARPEN_MASK_LO,
  `the doc's smoothstep(T, T + 0.1, G) is not a ramp (${SHARPEN_MASK_LO}..${SHARPEN_MASK_HI})`,
);
assert.ok(SHARPEN_CORE > 0, 'Detail coring is off, so a speckle is amplified again');

const CanvasKit = await CanvasKitInit({
  locateFile: () => fileURLToPath(new URL('../node_modules/canvaskit-wasm/bin/full/canvaskit.wasm', import.meta.url)),
});
const W = 16;
const H = 16;
const AMOUNT = 0.8; // the engine's own gain at SHARPENING 100: (100 / 10) * 0.8
const near = (a, b, why) => assert.ok(Math.abs(a - b) <= 2 / 255, `${why} (${a} vs ${b})`);

// One 8-bit RGBA image from a per-pixel grey level.
function imaged(grey) {
  const px = new Uint8Array(W * H * 4);
  for (let y = 0; y < H; y++) {
    for (let x = 0; x < W; x++) {
      const v = Math.round(Math.max(0, Math.min(1, grey(x, y))) * 255);
      const i = (y * W + x) * 4;
      px[i] = px[i + 1] = px[i + 2] = v;
      px[i + 3] = 255;
    }
  }
  return CanvasKit.MakeImage(
    {
      width: W, height: H,
      colorType: CanvasKit.ColorType.RGBA_8888,
      alphaType: CanvasKit.AlphaType.Unpremul,
      colorSpace: CanvasKit.ColorSpace.SRGB,
    },
    px,
    W * 4,
  );
}

function render(grey) {
  const effect = CanvasKit.RuntimeEffect.Make(SHARPEN_SKSL);
  assert.ok(effect, 'SHARPEN_SKSL does not compile');
  const src = imaged(grey);
  const child = src.makeShaderOptions(
    CanvasKit.TileMode.Clamp, CanvasKit.TileMode.Clamp, CanvasKit.FilterMode.Linear, CanvasKit.MipmapMode.None,
  );
  const shader = effect.makeShaderWithChildren([AMOUNT, 1, 1], [child]); // px = 1,1: 1:1 export canvas
  assert.ok(shader, 'the pass did not take the frame as its child');
  const out = CanvasKit.MakeSurface(W, H);
  const paint = new CanvasKit.Paint();
  paint.setShader(shader);
  out.getCanvas().drawPaint(paint);
  const bytes = out.makeImageSnapshot().readPixels(0, 0, {
    width: W, height: H, colorType: CanvasKit.ColorType.RGBA_8888,
    alphaType: CanvasKit.AlphaType.Unpremul, colorSpace: CanvasKit.ColorSpace.SRGB,
  });
  const at = (x, y) => bytes[(y * W + x) * 4] / 255;
  const values = [];
  for (let y = 0; y < H; y++) for (let x = 0; x < W; x++) values.push(at(x, y));
  const mean = values.reduce((a, b) => a + b, 0) / values.length;
  const std = Math.sqrt(values.reduce((a, b) => a + (b - mean) ** 2, 0) / values.length);
  return { at, mean, std };
}

// 1. A flat field: the Sobel magnitude is 0 and the high-pass is 0, so the whole
//    Mask is 0 and the frame is handed back exactly. The old kernel gained here.
const flat = render(() => 0.5);
near(flat.mean, 0.5, 'a flat field moved — Mask = 0 is not being honoured');
assert.ok(flat.std <= 2 / 255, `a flat field gained texture (std ${flat.std})`);

// 2. The same picture with grain on it: the noise is under the edge threshold, so
//    SHARPENING must not raise the frame's noise — the doc's §1 "sạn hạt cát".
let seed = 12345;
const rnd = () => ((seed = (seed * 1103515245 + 12345) & 0x7fffffff) / 0x7fffffff - 0.5);
const grain = new Float64Array(W * H);
for (let i = 0; i < grain.length; i++) grain[i] = 0.5 + rnd() * 0.04;
const grainy = render((x, y) => grain[y * W + x]);
const noiseIn = Math.sqrt(grain.reduce((a, b) => a + (b - 0.5) ** 2, 0) / grain.length);
assert.ok(
  grainy.std <= noiseIn + 2 / 255,
  `grain was amplified by SHARPENING (std ${grainy.std} for a noise of ${noiseIn})`,
);

// 3. A soft step, well under the edge threshold: Mask = 0, so it is not touched.
const soft = render((x) => (x < W / 2 ? 0.5 : 0.52));
near(soft.at(6, 8), 0.5, 'a sub-threshold step was sharpened on its dark side');
near(soft.at(9, 8), 0.52, 'a sub-threshold step was sharpened on its light side');

// 4. A hard step: Sobel saturates the mask, the high-pass is coring-open, and
//    both sides move apart. A pass that changed nothing would fail here.
const hard = render((x) => (x < W / 2 ? 0.25 : 0.75));
assert.ok(hard.at(7, 8) < 0.25 - 2 / 255, `the dark side of an edge did not move (${hard.at(7, 8)})`);
assert.ok(hard.at(8, 8) > 0.75 + 2 / 255, `the light side of an edge did not move (${hard.at(8, 8)})`);
// ...and only the two columns beside the edge: the flat halves keep Mask = 0.
near(hard.at(1, 8), 0.25, 'a flat half of the frame was sharpened');
near(hard.at(14, 8), 0.75, 'a flat half of the frame was sharpened');

console.log('sharpen ok: edges move, flat fields and grain do not');