#!/usr/bin/env node
// Pre-deploy syntax guard for the served HTML pages.
//
// WHY: our pages carry large INLINE <script> blocks. A single JavaScript syntax error in one block makes the
// WHOLE block fail to parse — every function/handler it defines becomes undefined. That is exactly what caused
// an app-wide login outage (home.html's `callConnected` listener was missing one `}`: the boot code never ran,
// so after login the splash spun forever). The browser catches it instantly; our deploy did not. This script
// turns that class of bug into a FAILED BUILD (exit 1) instead of a production outage.
//
// It parses — but never executes — every inline <script> in server/public/*.html with Node's `vm`, so it only
// checks SYNTAX (browser globals like `document` are irrelevant to parsing). Runs in the Docker build (see
// Dockerfile, right after `COPY server/ ./`) and locally from redeploy.sh for fast feedback.
const fs = require('fs');
const path = require('path');
const vm = require('vm');

const dir = path.join(__dirname, '..', 'public');
let files;
try {
  files = fs.readdirSync(dir).filter((f) => f.toLowerCase().endsWith('.html'));
} catch (e) {
  console.error('[check-syntax] cannot read ' + dir + ': ' + e.message);
  process.exit(1);
}

// Inline <script> … </script> (skip ones with a src= attribute — those are external files, nothing inline).
const re = /<script\b([^>]*)>([\s\S]*?)<\/script\s*>/gi;
let errors = 0;
let blocks = 0;

for (const f of files) {
  const html = fs.readFileSync(path.join(dir, f), 'utf8');
  re.lastIndex = 0;
  let m;
  while ((m = re.exec(html))) {
    if (/\bsrc\s*=/i.test(m[1] || '')) continue; // external script
    blocks++;
    const code = m[2];
    // File line where this block's body starts, so the reported line is file-relative (not block-relative).
    const openTagEnd = m.index + m[0].indexOf('>') + 1;
    const startLine = html.slice(0, openTagEnd).split('\n').length - 1; // 0-indexed offset
    try {
      new vm.Script(code, { filename: f, lineOffset: startLine });
    } catch (e) {
      errors++;
      const loc = (String(e.stack || '').split('\n')[0] || '').trim(); // e.g. "home.html:4398"
      console.error('[check-syntax] ' + f + ' — ' + (e.message || 'syntax error') +
        (loc && /:\d+$/.test(loc) ? ('  @ ' + loc) : ('  (inline <script> near line ' + (startLine + 1) + ')')));
    }
  }
}

if (errors) {
  console.error('[check-syntax] FAILED: ' + errors + ' inline <script> block(s) with syntax errors. Aborting deploy.');
  process.exit(1);
}
console.log('[check-syntax] OK: ' + blocks + ' inline <script> block(s) parsed across ' + files.length + ' HTML file(s).');
process.exit(0);