import sharp from "sharp";

// This is the provider's per-reference limit, separate from our 20 MiB upload limit.
export const VIP98K_REFERENCE_MAX_BYTES = 10 * 1024 * 1024;

export function isVip98kReferenceSizeAllowed(bytes: number) {
  return Number.isFinite(bytes) && bytes > 0 && bytes <= VIP98K_REFERENCE_MAX_BYTES;
}

export async function normalizeVip98kReferenceImage(buffer: Buffer) {
  for (const quality of [92, 82, 70]) {
    const normalized = await sharp(buffer, { failOn: "none" })
      .rotate()
      .resize(1920, 1920, { fit: "inside", withoutEnlargement: true })
      .flatten({ background: "#ffffff" })
      .jpeg({ quality, chromaSubsampling: "4:4:4", mozjpeg: true })
      .toBuffer();
    if (isVip98kReferenceSizeAllowed(normalized.byteLength)) {
      return { buffer: normalized, extension: "jpg" };
    }
  }
  throw new Error("参考图压缩后仍超过服务商单张 10 MiB 限制，请缩小图片后重试");
}