const OPENAI_SIZE_TO_ASPECT_RATIO: Record<string, string> = {
  "256x256": "1:1",
  "512x512": "1:1",
  "1024x1024": "1:1",
  "1792x1024": "16:9",
  "1024x1792": "9:16",
  "1536x1024": "3:2",
  "1024x1536": "2:3",
};

// Supports direct aspect ratios (e.g. "16:9")
const ASPECT_RATIO_PASSTHROUGH = /^\d+:\d+$/;

export function mapImageSize(sizeParam?: string | null): string {
  if (!sizeParam) return "1:1"; // default

  // Native aspect ratio (e.g. "16:9") — pass-through
  if (ASPECT_RATIO_PASSTHROUGH.test(sizeParam)) return sizeParam;

  // Map OpenAI sizes to aspect ratios
  return OPENAI_SIZE_TO_ASPECT_RATIO[sizeParam] ?? "1:1";
}