// The consensus page's central result as a file a program can read.
//
// Raft's rule is that a leader may count replicas toward committing an entry only
// if the entry is from the leader's own term. The page removes that clause, searches
// every reachable state of three servers through four terms, and finds the shortest
// run in which two servers disagree about a committed entry. This writes that run,
// the bounds, the state counts under each rule and the engine's file hash to JSON,
// so a reader can replay it without opening the page.
//
//   node scripts/consensus-counterexample.mjs            write tests/fixtures/consensus-counterexample.json
//   node scripts/consensus-counterexample.mjs --check    regenerate and compare, write nothing
import { readFileSync, writeFileSync } from 'node:fs';
import { createHash } from 'node:crypto';
import { fileURLToPath } from 'node:url';
import { dirname, join } from 'node:path';

const ROOT = join(dirname(fileURLToPath(import.meta.url)), '..');
const SRC = readFileSync(join(ROOT, 'site/js/consensus.js'), 'utf8');
const window = {};
new Function('window', SRC)(window);
const C = window.Consensus;

const test = readFileSync(join(ROOT, 'tests/consensus.test.mjs'), 'utf8');
const box = test.match(/const BOX = (\{[^}]*\})/);
if (!box) throw new Error('tests/consensus.test.mjs no longer defines BOX: the bounds below would be a guess');
const BOX = new Function(`return ${box[1]}`)();

const raft = C.check({ ...BOX, rule: 'raft' });
const majority = C.check({ ...BOX, rule: 'majority' });
const lower = C.check({ ...BOX, maxTerm: 3, rule: 'majority' });
const out = {
  what: 'Raft with the current-term clause removed (rule "majority"), searched exhaustively inside the bounds given. The trace is the shortest run that breaks a safety property.',
  engine: 'site/js/consensus.js',
  engine_sha256: createHash('sha256').update(SRC).digest('hex'),
  bounds: BOX,
  states: { raft: raft.states, majority: majority.states, majority_with_terms_to_3: lower.states },
  raft_fails: !!raft.failed,
  majority_fails: !!majority.failed,
  majority_with_terms_to_3_fails: !!lower.failed,
  trace_length: majority.trace ? majority.trace.length : null,
  trace: majority.trace || null,
  failure: majority.failed || null,
};
const text = JSON.stringify(out, null, 2) + '\n';
const path = join(ROOT, 'tests/fixtures/consensus-counterexample.json');
if (process.argv.includes('--check')) {
  const have = readFileSync(path, 'utf8');
  if (have !== text) { console.error('consensus-counterexample.json is stale: rerun without --check'); process.exit(1); }
  console.log('consensus-counterexample.json is current');
} else {
  writeFileSync(path, text);
  console.log(`wrote ${path}: trace of ${out.trace_length} steps, ${out.states.majority} states searched`);
}