export type ImageSizePreset = {
  label: string;
  width: number;
  height: number;
  paper?: "a4";
};

// A4 is 70:99, not 3:4. These dimensions keep reference-image generation
// below the 2048² pixel budget. This is a generation preset, not print export.
export const imageSizePresets: ImageSizePreset[] = [
  { label: "1:1", width: 2048, height: 2048 },
  { label: "4:3", width: 2304, height: 1728 },
  { label: "3:4", width: 1728, height: 2304 },
  { label: "16:9", width: 2560, height: 1440 },
  { label: "9:16", width: 1440, height: 2560 },
  { label: "A4 竖版", width: 1680, height: 2376, paper: "a4" },
  { label: "A4 横版", width: 2376, height: 1680, paper: "a4" }
];

export function imageDimensionsForEngine(size: Pick<ImageSizePreset, "width" | "height">, engine: string) {
  // EvoLink ignores resolution for explicit pixels. Stay within its existing
  // 1K budget and align to 16px; the resulting A4 ratio differs by < 0.06%.
  if (engine === "evolink") {
    if (size.width === 1680 && size.height === 2376) return { width: 848, height: 1200 };
    if (size.width === 2376 && size.height === 1680) return { width: 1200, height: 848 };
  }
  return { width: size.width, height: size.height };
}

export function imageSizePresetFromDimensions(width?: number, height?: number) {
  return imageSizePresets.find((size) => {
    const evo = imageDimensionsForEngine(size, "evolink");
    return size.width === width && size.height === height || evo.width === width && evo.height === height;
  });
}