import assert from 'node:assert/strict';
import fs from 'node:fs';
import vm from 'node:vm';

const viewSource = fs.readFileSync(new URL('../www/views/spectrogram.js', import.meta.url), 'utf8');
const timingSource = viewSource.match(/export function stepScrollAccumulator[\s\S]*?\n\}/)?.[0];
assert.ok(timingSource, 'stepScrollAccumulator must remain testable');
const timingContext = vm.createContext({ Number, Math });
vm.runInContext(timingSource.replace('export function', 'function'), timingContext);
const { stepScrollAccumulator } = timingContext;
const pixelsSource = viewSource.match(/export function spectrogramPixelsPerSourceFrame[\s\S]*?\n\}/)?.[0];
assert.ok(pixelsSource, 'spectrogramPixelsPerSourceFrame must remain testable');
timingContext.BASE_SCROLL_CSS_PX_PER_SECOND = 60;
vm.runInContext(pixelsSource.replace('export function', 'function'), timingContext);
const { spectrogramPixelsPerSourceFrame } = timingContext;

function emittedColumns(rate, frames, pixelScale = 1) {
  let accumulator = 0;
  let columns = 0;
  for (let frame = 0; frame < frames; frame++) {
    const step = stepScrollAccumulator(accumulator, rate * pixelScale, 1);
    accumulator = step.accumulator;
    columns += step.columns;
  }
  return columns;
}

assert.equal(emittedColumns(0.5, 20), 10, '0.5x must emit every second source frame');
assert.equal(emittedColumns(1, 20), 20);
assert.equal(emittedColumns(2, 20), 40);
assert.equal(emittedColumns(4, 20), 80);
assert.equal(emittedColumns(6, 20), 120);
assert.equal(emittedColumns(1, 10, 1.7), 17, 'DPR scaling must preserve CSS scroll speed');

function emittedInOneSecond(rate, fftSize) {
  const sampleRate = 48000;
  const hop = Math.max(128, Math.floor(fftSize / 8));
  const sourceFrames = sampleRate / hop;
  const pixelsPerFrame = spectrogramPixelsPerSourceFrame(rate, sampleRate, fftSize);
  return emittedColumns(pixelsPerFrame, sourceFrames);
}

assert.equal(emittedInOneSecond(0.5, 4096), 30);
assert.equal(emittedInOneSecond(1, 4096), 60);
assert.equal(emittedInOneSecond(1, 8192), 60, 'FFT size must not alter real-time scroll speed');
assert.equal(emittedInOneSecond(2, 8192), 120);
assert.equal(emittedInOneSecond(4, 8192), 240);
assert.equal(emittedInOneSecond(6, 8192), 360);

const messages = [];
const calls = { drawImage: 0, putImageData: [] };
const context2d = {
  imageSmoothingEnabled: true,
  globalCompositeOperation: 'source-over',
  fillStyle: '#000',
  save() {},
  restore() {},
  fillRect() {},
  drawImage() { calls.drawImage += 1; },
  createImageData(width, height) {
    return { width, height, data: new Uint8ClampedArray(width * height * 4) };
  },
  putImageData(image, x, y) { calls.putImageData.push({ image, x, y }); },
};
const canvas = {
  width: 0,
  height: 0,
  getContext() { return context2d; },
};
const workerContext = vm.createContext({
  self: {},
  postMessage(message) { messages.push(message); },
  performance: { now: (() => { let now = 0; return () => ++now; })() },
  Float32Array,
  Uint8ClampedArray,
  Number,
  Math,
});
const workerSource = fs.readFileSync(new URL('../www/workers/spectrogram.worker.js', import.meta.url), 'utf8');
vm.runInContext(workerSource, workerContext, { filename: 'spectrogram.worker.js' });

workerContext.self.onmessage({
  data: { type: 'init', canvas, width: 8, height: 4, topDb: 0, bottomDb: -80, gamma: 1 },
});
assert.equal(messages.at(-1)?.type, 'ready');

workerContext.self.onmessage({
  data: { type: 'column', id: 7, repeat: 2, data: new Float32Array([-80, -40, -20, 0]) },
});
const ack = messages.at(-1);
assert.equal(ack.type, 'drawn');
assert.equal(ack.id, 7);
assert.equal(ack.repeat, 2);
assert.equal(calls.drawImage, 1, 'existing canvas should be shifted once');
assert.equal(calls.putImageData.length, 1, 'only the new stripe should be uploaded');
assert.equal(calls.putImageData[0].image.width, 2);
assert.equal(calls.putImageData[0].x, 6);

// Roughly ten minutes at 100 source columns/s. The worker has no history or
// pending-message collection that can grow with runtime.
messages.length = 0;
context2d.putImageData = () => {};
const longRunColumn = new Float32Array([-80, -40, -20, 0]);
for (let index = 0; index < 60_000; index++) {
  workerContext.self.onmessage({
    data: { type: 'column', id: 100 + index, repeat: 1, data: longRunColumn },
  });
}
assert.equal(messages.length, 60_000);
assert.equal(messages.at(-1)?.type, 'drawn');
assert.equal(messages.at(-1)?.id, 60_099);

console.log('spectrogram timing and worker tests passed');