import { promises as fs } from 'node:fs';
import path from 'node:path';
import sharp from 'sharp';

const ROOT = path.resolve('public');
// Files NOT to touch
const SKIP = new Set(['favicon.ico', 'apple-touch-icon.png', 'icon.png', 'apple-icon.png']);
const SKIP_EXACT_PATHS = new Set([
  'public/favicon.ico',
  'public/apple-touch-icon.png',
]);

const exts = new Set(['.jpg', '.jpeg', '.png', '.gif']);
const results = { converted: 0, savedBytes: 0, skipped: 0, failed: 0 };

async function walk(dir) {
  const entries = await fs.readdir(dir, { withFileTypes: true });
  for (const e of entries) {
    const p = path.join(dir, e.name);
    if (e.isDirectory()) {
      await walk(p);
    } else if (exts.has(path.extname(p).toLowerCase())) {
      await convert(p);
    }
  }
}

async function convert(input) {
  const ext = path.extname(input).toLowerCase();
  const base = input.slice(0, -ext.length);
  const output = base + '.webp';
  const relRoot = path.relative(process.cwd(), input).split(path.sep).join('/');
  if (SKIP.has(path.basename(input)) || SKIP_EXACT_PATHS.has(relRoot)) {
    results.skipped++;
    console.log(`SKIP   ${relRoot}`);
    return;
  }
  try {
    const stIn = await fs.stat(input);
    // Output options per type
    const isPng = ext === '.png';
    const isGif = ext === '.gif';
    const opts = isPng
      ? { quality: 86, alphaQuality: 90, effort: 5, nearLossless: false }
      : isGif
      ? { quality: 80, effort: 5, loop: 0 } // animated -> animated webp
      : { quality: 82, effort: 5 };
    let pipeline = sharp(input, { animated: isGif });
    await pipeline.webp(opts).toFile(output);
    const stOut = await fs.stat(output);
    if (stOut.size >= stIn.size) {
      // worse than original — keep original, remove webp
      await fs.unlink(output);
      results.skipped++;
      console.log(`KEEP   ${relRoot}  (webp larger: ${stOut.size} vs ${stIn.size})`);
      return;
    }
    await fs.unlink(input);
    results.converted++;
    results.savedBytes += stIn.size - stOut.size;
    const inKB = (stIn.size / 1024).toFixed(0);
    const outKB = (stOut.size / 1024).toFixed(0);
    console.log(`OK     ${relRoot}  ${inKB}KB -> ${outKB}KB`);
  } catch (err) {
    results.failed++;
    console.log(`FAIL   ${relRoot}: ${err.message}`);
  }
}

await walk(ROOT);
const savedMB = (results.savedBytes / 1024 / 1024).toFixed(2);
console.log('\n---');
console.log(`converted: ${results.converted}  skipped: ${results.skipped}  failed: ${results.failed}`);
console.log(`saved: ${savedMB} MB`);