import sharp from 'sharp';
import { join, parse } from 'path';
import { UPLOADS_DIR } from './middleware/upload.js';

interface VariantSpec {
  suffix: string;
  maxDimension: number;
}

const VARIANTS: VariantSpec[] = [
  { suffix: '_thumb', maxDimension: 300 },
  { suffix: '_medium', maxDimension: 768 },
  { suffix: '_large', maxDimension: 1920 },
];

const RESIZABLE_MIMES = new Set([
  'image/jpeg', 'image/png', 'image/webp', 'image/heic',
]);

export function isResizable(mimeType: string): boolean {
  return RESIZABLE_MIMES.has(mimeType);
}

export async function generateVariants(storedName: string): Promise<void> {
  const { name, ext } = parse(storedName);
  const sourcePath = join(UPLOADS_DIR, storedName);

  for (const variant of VARIANTS) {
    const outPath = join(UPLOADS_DIR, `${name}${variant.suffix}${ext}`);
    await sharp(sourcePath)
      .resize(variant.maxDimension, variant.maxDimension, {
        fit: 'inside',
        withoutEnlargement: true,
      })
      .toFile(outPath);
  }
}

export function getVariantFilenames(storedName: string): string[] {
  const { name, ext } = parse(storedName);
  return VARIANTS.map(v => `${name}${v.suffix}${ext}`);
}