#!/usr/bin/env node

import { spawnSync } from 'node:child_process';

import { deriveHistoryBoundary } from './gate-history.mjs';

const candidateKind = process.argv[2];
const root = process.cwd();
const boundary = deriveHistoryBoundary(root);

function revParse(revision) {
  const result = spawnSync('git', ['rev-parse', revision], {
    cwd: root,
    encoding: 'utf8',
  });
  if (result.status !== 0) {
    process.stderr.write(`history boundary control could not resolve ${revision}\n`);
    process.exit(2);
  }
  return result.stdout.trim();
}

const candidates = {
  head: revParse('HEAD'),
  parent: revParse('HEAD^'),
  introduction: boundary.introductionCommit,
};
if (!Object.hasOwn(candidates, candidateKind)) {
  process.stderr.write(`unknown history boundary candidate ${String(candidateKind)}\n`);
  process.exit(2);
}
const candidate = candidates[candidateKind];
if (candidate === boundary.activationCommit) {
  process.stdout.write(`history boundary candidate ${candidateKind} matched derived activation\n`);
  process.exit(0);
}
process.stderr.write(
  `history boundary candidate ${candidateKind} rejected: derived activation is parent of registry introduction\n`,
);
process.exit(1);