(function () {
  'use strict';

  const root = window.PixelIslandModules ||= {};

  function clonePixels(pixels) {
    return Array.isArray(pixels) ? [...pixels] : [];
  }

  function floodFill(sourcePixels, size, x, y, colorCode) {
    const pixels = clonePixels(sourcePixels);
    const target = pixels[y * size + x] || null;
    const replacement = colorCode || null;
    if (target === replacement) return { pixels, changed: false, count: 0, cells: [] };

    const stack = [[x, y]];
    const cells = [];
    while (stack.length) {
      const [cx, cy] = stack.pop();
      if (cx < 0 || cy < 0 || cx >= size || cy >= size) continue;
      const index = cy * size + cx;
      if ((pixels[index] || null) !== target) continue;
      pixels[index] = replacement;
      cells.push({ x: cx, y: cy });
      stack.push([cx + 1, cy], [cx - 1, cy], [cx, cy + 1], [cx, cy - 1]);
    }
    return { pixels, changed: cells.length > 0, count: cells.length, cells };
  }

  function pickColor(sourcePixels, size, x, y) {
    if (!Array.isArray(sourcePixels)) return null;
    if (x < 0 || y < 0 || x >= size || y >= size) return null;
    return sourcePixels[y * size + x] || null;
  }

  root.EditorActions = {
    clonePixels,
    floodFill,
    pickColor,
    apply(snapshot, pushHistory, mutate) {
      pushHistory(snapshot());
      mutate();
    }
  };
})();