import sharp from "sharp";
import type { ProductTemplate } from "./products";

export interface ProcessedImage {
  buffer: Buffer;
  format: "png" | "tiff";
  widthPx: number;
  heightPx: number;
  dpi: number;
  sizeBytes: number;
}

/**
 * Process an uploaded image for a given product template.
 * Resizes to fit the print area at the correct DPI, converts to PNG with
 * proper density metadata.
 */
export async function processImage(
  inputBuffer: Buffer,
  product: ProductTemplate
): Promise<ProcessedImage> {
  const targetWidth = product.widthPx;
  const targetHeight = product.heightPx;

  const result = await sharp(inputBuffer)
    .resize(targetWidth, targetHeight, {
      fit: "contain",
      background: { r: 255, g: 255, b: 255, alpha: 0 },
    })
    .withMetadata({ density: product.dpi })
    .png()
    .toBuffer();

  return {
    buffer: result,
    format: "png",
    widthPx: targetWidth,
    heightPx: targetHeight,
    dpi: product.dpi,
    sizeBytes: result.length,
  };
}