import assert from 'node:assert/strict';
// Two row delays plus three horizontal shift registers: valid 3x3, one channel.
export function streamWindows(pixels, width, stalls = new Set()) {
  const previous = Array(width).fill(0), older = Array(width).fill(0);
  const window = Array.from({length: 3}, () => Array(3).fill(0));
  const windows = []; let accepted = 0, cycles = 0;
  while (accepted < pixels.length) {
    if (stalls.has(cycles++)) continue;
    const row = Math.floor(accepted / width), col = accepted % width;
    if (col === 0) window.forEach(r => r.fill(0));
    const current = pixels[accepted];
    [older[col], previous[col], current].forEach((v, r) => {window[r].shift(); window[r].push(v);});
    older[col] = previous[col]; previous[col] = current;
    if (row >= 2 && col >= 2) windows.push({acceptedIndex: accepted, cycle: cycles - 1, values: window.flat()});
    accepted++;
  }
  return {windows, accepted, cycles, storageSamples: 2 * width + 9};
}
const pixels = Array.from({length: 16}, (_, i) => i + 1);
const normal = streamWindows(pixels, 4);
const paused = streamWindows(pixels, 4, new Set([2, 3, 12]));
assert.deepEqual(normal.windows.map(w => w.acceptedIndex), [10, 11, 14, 15]);
assert.deepEqual(normal.windows[0].values, [1, 2, 3, 5, 6, 7, 9, 10, 11]);
assert.deepEqual(paused.windows.map(w => w.values), normal.windows.map(w => w.values));
assert.equal(paused.cycles, 19);
console.log(JSON.stringify({normal, paused}));