import sharp from 'sharp';
import { readdir, stat, rename } from 'node:fs/promises';
import { join, extname, basename } from 'node:path';

const MAX_WIDTH = 1600;
const MIN_BYTES_TO_OPTIMISE = 250 * 1024;

const dirs = ['src/lib/images', 'static/images'];

async function optimiseFile(file) {
  const ext = extname(file).toLowerCase();
  const input = await sharp(file, { failOn: 'none' }).rotate();
  const meta = await input.metadata();
  const width = meta.width ?? 0;
  const targetWidth = width > MAX_WIDTH ? MAX_WIDTH : width;
  const pipeline = sharp(file, { failOn: 'none' })
    .rotate()
    .resize({ width: targetWidth, withoutEnlargement: true });

  let buf;
  if (ext === '.png') {
    if (meta.hasAlpha) {
      buf = await pipeline
        .png({ palette: true, quality: 88, compressionLevel: 9, effort: 10 })
        .toBuffer();
    } else {
      buf = await pipeline
        .png({ palette: true, quality: 82, compressionLevel: 9, effort: 10 })
        .toBuffer();
    }
  } else if (ext === '.jpg' || ext === '.jpeg') {
    buf = await pipeline.jpeg({ quality: 82, mozjpeg: true }).toBuffer();
  } else if (ext === '.webp') {
    buf = await pipeline.webp({ quality: 80, effort: 6 }).toBuffer();
  } else {
    return null;
  }

  const original = (await stat(file)).size;
  if (buf.length >= original) return { file, original, optimised: original, skipped: true };

  const tmp = file + '.opt.tmp';
  await sharp(buf).toFile(tmp);
  await rename(tmp, file);
  return { file, original, optimised: buf.length, skipped: false };
}

let totalOrig = 0;
let totalNew = 0;
for (const dir of dirs) {
  const entries = await readdir(dir);
  for (const name of entries) {
    if (!/\.(png|jpe?g|webp)$/i.test(name)) continue;
    const file = join(dir, name);
    const s = await stat(file);
    if (s.size < MIN_BYTES_TO_OPTIMISE) continue;
    try {
      const res = await optimiseFile(file);
      if (!res) continue;
      totalOrig += res.original;
      totalNew += res.optimised;
      const pct = ((1 - res.optimised / res.original) * 100).toFixed(0);
      const flag = res.skipped ? ' (skipped: no gain)' : '';
      console.log(
        `${basename(file).padEnd(58)} ${(res.original / 1024).toFixed(0).padStart(5)}KB → ${(res.optimised / 1024).toFixed(0).padStart(5)}KB  (-${pct}%)${flag}`
      );
    } catch (err) {
      console.error('FAILED', file, err.message);
    }
  }
}
console.log(`\nTotal: ${(totalOrig / 1024 / 1024).toFixed(2)} MB → ${(totalNew / 1024 / 1024).toFixed(2)} MB`);