/** Downscale an image file to a JPEG data URL so uploads and AI calls stay fast. */
export async function fileToCompressedDataUrl(file: File, maxSize = 900): Promise<string> {
  const bitmap = await createImageBitmap(file);
  const scale = Math.min(1, maxSize / Math.max(bitmap.width, bitmap.height));
  const canvas = document.createElement("canvas");
  canvas.width = Math.round(bitmap.width * scale);
  canvas.height = Math.round(bitmap.height * scale);
  const ctx = canvas.getContext("2d");
  if (!ctx) throw new Error("Could not read that image.");
  ctx.drawImage(bitmap, 0, 0, canvas.width, canvas.height);
  bitmap.close();
  return canvas.toDataURL("image/jpeg", 0.85);
}

export function dataUrlToBlob(dataUrl: string): Blob {
  const parts = dataUrl.split(",");
  const mime = (parts[0] ?? "").match(/:(.*?);/)?.[1] ?? "image/jpeg";
  const binary = atob(parts[1] ?? "");
  const bytes = new Uint8Array(binary.length);
  for (let i = 0; i < binary.length; i += 1) bytes[i] = binary.charCodeAt(i);
  return new Blob([bytes], { type: mime });
}