#!/usr/bin/env node
const fs = require('fs');
const path = require('path');
const { PNG } = require('pngjs');
let pixelmatch = require('pixelmatch');
if (pixelmatch && typeof pixelmatch !== 'function' && pixelmatch.default && typeof pixelmatch.default === 'function') pixelmatch = pixelmatch.default;

const names = ['video_preview','mic_status','controls','form'];
const out = [];
for (const n of names) {
  const base = `/tmp/baseline_prejoin_region_${n}.png`;
  const cur = `/tmp/prejoin_region_${n}.png`;
  if (!fs.existsSync(base) && !fs.existsSync(cur)) {
    out.push({ region: n, foundBaseline: false, foundCurrent: false });
    continue;
  }
  if (!fs.existsSync(base)) {
    out.push({ region: n, foundBaseline: false, foundCurrent: true, current: cur });
    continue;
  }
  if (!fs.existsSync(cur)) {
    out.push({ region: n, foundBaseline: true, foundCurrent: false, baseline: base });
    continue;
  }
  try {
    const A = PNG.sync.read(fs.readFileSync(base));
    const B = PNG.sync.read(fs.readFileSync(cur));
    if (A.width !== B.width || A.height !== B.height) {
      out.push({ region: n, error: 'dim_mismatch', baseline: base, current: cur, baseSize: [A.width,A.height], curSize: [B.width,B.height] });
      continue;
    }
    const diff = new PNG({ width: A.width, height: A.height });
    const mismatched = pixelmatch(A.data, B.data, diff.data, A.width, A.height, { threshold: 0.1 });
    const diffPath = `/tmp/prejoin_region_diff_${n}.png`;
    fs.writeFileSync(diffPath, PNG.sync.write(diff));
    out.push({ region: n, baseline: base, current: cur, diff: diffPath, mismatched, total: A.width*A.height, ratio: mismatched/(A.width*A.height) });
  } catch (e) {
    out.push({ region: n, error: String(e) });
  }
}
const report = { generatedAt: new Date().toISOString(), report: out };
fs.writeFileSync('/tmp/prejoin_regions_compare_report.json', JSON.stringify(report, null, 2));
console.log('Wrote /tmp/prejoin_regions_compare_report.json');
console.log(JSON.stringify(report, null, 2));