'use strict';

const fs = require('node:fs');
const path = require('node:path');
const { execFileSync } = require('node:child_process');

const isGitRevision = value => typeof value === 'string' && value.length === 40 && /^[0-9a-f]{40}$/.test(value);

function getBuildId(root) {
  // The image's baked revision is authoritative; never accept arbitrary HTML/header text.
  try {
    const baked = fs.readFileSync(path.join(root, 'BUILD_ID'), 'utf8').trim();
    return isGitRevision(baked) ? baked : 'unknown';
  } catch (_) {}
  // Require this checkout's marker, not an unrelated ancestor repository.
  if (!fs.existsSync(path.join(root, '.git'))) return 'unknown';
  try {
    const revision = execFileSync('git', ['-C', root, 'rev-parse', '--verify', 'HEAD^{commit}'], {
      encoding: 'utf8', timeout: 5000, stdio: ['ignore', 'pipe', 'ignore'],
      env: Object.fromEntries(Object.entries(process.env).filter(([key]) => !key.startsWith('GIT_'))),
    }).trim();
    return isGitRevision(revision) ? revision : 'unknown';
  } catch (_) {
    return 'unknown';
  }
}

module.exports = { getBuildId, isGitRevision };