import imageCompression from "browser-image-compression";

interface ImageSizeVariant {
  size: "original" | "medium" | "thumbnail";
  maxWidth: number;
  quality: number;
  suffix: string;
}

const IMAGE_VARIANTS: ImageSizeVariant[] = [
  { size: "thumbnail", maxWidth: 200, quality: 0.8, suffix: "_th" },
  { size: "medium", maxWidth: 800, quality: 0.8, suffix: "_md" },
  { size: "original", maxWidth: 4096, quality: 0.9, suffix: "" },
];

interface ResizedImage {
  variant: ImageSizeVariant;
  file: File;
}

/**
 * Resize an image to all size variants (thumbnail, medium, original)
 * Returns array of resized File objects
 */
export async function resizeImage(file: File): Promise<ResizedImage[]> {
  const results: ResizedImage[] = [];

  for (const variant of IMAGE_VARIANTS) {
    const options = {
      maxWidthOrHeight: variant.maxWidth,
      useWebWorker: true,
      initialQuality: variant.quality,
      fileType: "image/jpeg" as const,
    };

    try {
      const compressedFile = await imageCompression(file, options);

      // Create new File with variant-specific name
      const variantFile = new File(
        [compressedFile],
        generateVariantFilename(file.name, variant.suffix),
        { type: "image/jpeg" }
      );

      results.push({
        variant,
        file: variantFile,
      });
    } catch (error) {
      console.error(`Failed to resize image for ${variant.size}:`, error);
      throw error;
    }
  }

  return results;
}

/**
 * Generate filename with variant suffix
 * e.g., "photo.png" + "_th" => "photo_th.jpg"
 */
function generateVariantFilename(
  originalName: string,
  suffix: string
): string {
  const lastDot = originalName.lastIndexOf(".");
  const baseName = lastDot === -1 ? originalName : originalName.substring(0, lastDot);
  return `${baseName}${suffix}.jpg`;
}

/**
 * Derive S3 key for a specific variant from the base key
 * e.g., "items/uuid.jpg" + "_th" => "items/uuid_th.jpg"
 */
export function getVariantKey(baseKey: string, suffix: string): string {
  if (!suffix) return baseKey;
  const lastDot = baseKey.lastIndexOf(".");
  if (lastDot === -1) return `${baseKey}${suffix}`;
  return `${baseKey.substring(0, lastDot)}${suffix}${baseKey.substring(lastDot)}`;
}

/**
 * Get the suffix for a given size
 */
export function getSizeSuffix(
  size: "thumbnail" | "medium" | "original"
): string {
  const variant = IMAGE_VARIANTS.find((v) => v.size === size);
  return variant?.suffix || "";
}