#!/usr/bin/env node
/**
 * append-team-log.js — concurrency-safe append tool for the team log
 * (lives in 91-team-tools/; team-skeleton spec §4 optional enhancement,
 *  wired into the modpack since v0.4.0)
 *
 * WHY THIS EXISTS (real production lesson from the source team, sanitized):
 * a dozen-plus agents all editing the top of the same team-log file with no
 * lock corrupted 5 entries in real use — one harness's concurrent appends
 * interleaved with another session's and glued entries together (signature
 * headers swallowed mid-line). "Everyone edits the top of the same file"
 * does not survive the concurrent-session era. This tool fixes it for good:
 * lock-file queueing + atomic replace + read-back verification.
 * That is also why the team constitution (team-root ARCHITECTURE.md §2.1)
 * says: when the team ships this tool, ALWAYS write through it — never edit
 * the log head by hand.
 *
 * USAGE (three ways, pick one):
 *   1) argv, direct (fine in bash-like shells; avoid in Windows PowerShell 5.1 —
 *      its legacy codepage mangles non-ASCII argv):
 *      node append-team-log.js "- 【2026-01-01】@builder: did X → conclusion (path)"
 *   2) file (PowerShell users / long entries; UTF-8, BOM tolerated):
 *      node append-team-log.js --file C:\path\entry.txt
 *   3) stdin (pipe):
 *      cat entry.txt | node append-team-log.js --stdin
 *
 * BEHAVIOR:
 *   - The entry must match the team log's format contract
 *     `- 【YYYY-MM-DD】@name: …` — anything else is rejected up front
 *     (foolproofing; if your team relaxes the format, adjust validate()).
 *   - Takes the lock by atomically creating `<log>.lock`; if someone else holds
 *     it, retries once per second, up to 30 times.
 *   - A lock older than 30s counts as a crash leftover and is force-cleared
 *     (deadlock self-healing).
 *   - With the lock held: read file → insert right below the append anchor
 *     (the `▼▼▼` comment line the log template ships with), or below the title
 *     line when no anchor exists → write temp file → atomic rename → read back
 *     and verify the entry actually landed.
 *   - Any failure: non-zero exit + a stderr explanation. No silent failure.
 *
 * SECOND LESSON kept in code (also sanitized): an earlier version hardcoded
 * "line 0 is the title line". The day a YAML frontmatter block was added to
 * the log file, every append that day (6 out of 6) inserted INTO the
 * frontmatter and repeatedly broke the file structure. computeInsertIndex()
 * now probes for the frontmatter block first — that is why it looks more
 * paranoid than the job sounds.
 *
 * The lock/atomic-write helpers below were inlined from the source team's
 * shared file-lock module so this ships as ONE dependency-free file (Node
 * standard library only, no npm install).
 */
'use strict';
const fs = require('fs');
const path = require('path');

// Default target: this script lives in <team-root>/91-team-tools/, the log in
// <team-root>/02-shared-knowledge/. TEAMLOG_PATH env var overrides (tests only;
// don't set it in daily use).
const LOG = process.env.TEAMLOG_PATH
  || path.join(__dirname, '..', '02-shared-knowledge', 'team-log.md');
const LOCK = LOG + '.lock';

// die() throws instead of process.exit(): exit() would skip the finally-block
// lock release and leave a stale lock behind on validation failures (a real
// bug class the source team hit — "read-back verification failed after taking
// the lock" used to strand the lock and stall every other writer for 30s).
class DieError extends Error {
  constructor(msg, code) { super(msg); this.name = 'DieError'; this.exitCode = code || 1; }
}
function die(msg, code) { throw new DieError(msg, code); }

/* ------------------------------------------------------------------ *
 * Inlined lock helpers (single source: keep them in this file only)  *
 * ------------------------------------------------------------------ */

class LockError extends Error {
  constructor(message, code) {
    super(message);
    this.name = 'LockError';
    this.code = code || 'LOCK_ERROR';
  }
}

/** Synchronous sleep without busy-waiting (Atomics.wait blocks, no CPU spin). */
function sleepSync(ms) {
  Atomics.wait(new Int32Array(new SharedArrayBuffer(4)), 0, 0, ms);
}

/**
 * Queue on the lock file (atomic create). An existing lock older than staleMs
 * is treated as a crash leftover and force-cleared.
 */
function acquireLockSync(lockPath, opts) {
  opts = opts || {};
  const staleMs = opts.staleMs != null ? opts.staleMs : 30 * 1000;
  const retryMax = opts.retryMax != null ? opts.retryMax : 30;
  const retryIntervalMs = opts.retryIntervalMs != null ? opts.retryIntervalMs : 1000;
  let transientWithoutPathRetries = 0;

  for (let i = 0; i < retryMax; i++) {
    try {
      fs.writeFileSync(lockPath, process.pid + ' ' + new Date().toISOString(), { flag: 'wx' });
      return; // got the lock
    } catch (e) {
      let contended = e.code === 'EEXIST';
      if (!contended && (e.code === 'EPERM' || e.code === 'EACCES' || e.code === 'EBUSY')) {
        // On Windows, high-frequency create/delete on the same path sometimes
        // surfaces real contention as a transient EPERM instead of EEXIST.
        // If the path exists, treat it as contention; if not, probe briefly
        // (3x) before letting the genuine permission error through.
        if (fs.existsSync(lockPath)) {
          contended = true;
        } else if (transientWithoutPathRetries < 3) {
          transientWithoutPathRetries++;
          sleepSync(Math.min(retryIntervalMs, 20));
          continue;
        }
      }
      if (!contended) throw new LockError('Failed to create lock file: ' + e.message, 'LOCK_CREATE_FAIL');
      try {
        const age = Date.now() - fs.statSync(lockPath).mtimeMs;
        if (age > staleMs) {
          fs.unlinkSync(lockPath); // stale leftover — clear it and retry next round
          if (opts.onStaleClear) opts.onStaleClear(age);
          continue;
        }
      } catch (e2) {
        /* lock was released right under us — next round takes it */
      }
      if (i === 0 && opts.onWait) opts.onWait();
      sleepSync(retryIntervalMs);
    }
  }
  throw new LockError(
    'Still could not take the lock after queueing ' + retryMax + ' s. If you are '
    + 'sure nobody is writing, delete ' + lockPath + ' by hand and retry.',
    'LOCK_TIMEOUT');
}

/**
 * Release the lock. Missing file = idempotent success; any other unlink error
 * is retried briefly, then MUST fail loudly — never report a stranded lock as
 * released.
 */
function releaseLockFile(lockPath, opts) {
  opts = opts || {};
  const retryMax = opts.retryMax != null ? opts.retryMax : 5;
  const retryIntervalMs = opts.retryIntervalMs != null ? opts.retryIntervalMs : 20;

  for (let i = 0; i < retryMax; i++) {
    try {
      fs.unlinkSync(lockPath);
      return { released: true, existed: true };
    } catch (e) {
      if (e.code === 'ENOENT') return { released: false, existed: false };
      if (i < retryMax - 1) {
        sleepSync(retryIntervalMs);
        continue;
      }
      throw new LockError(
        'Failed to release the lock file; it may still be stranded: '
        + lockPath + ' (' + e.message + ')', 'LOCK_RELEASE_FAIL');
    }
  }
  throw new LockError('Failed to release the lock file: ' + lockPath, 'LOCK_RELEASE_FAIL');
}

/**
 * Sweep stale atomic-write temp files for the same target. Only this module's
 * strict naming pattern, only regular files older than the threshold — a fresh
 * temp may belong to a writer that is still running and must be kept.
 */
function cleanupStaleAtomicTempsSync(targetPath, opts) {
  opts = opts || {};
  const staleTempMs = opts.staleTempMs != null ? opts.staleTempMs : 5 * 60 * 1000;
  const dir = path.dirname(targetPath);
  const namePrefix = path.basename(targetPath) + '.tmp_';
  const removed = [];
  const kept = [];
  let entries;

  try {
    entries = fs.readdirSync(dir, { withFileTypes: true });
  } catch (e) {
    if (e.code === 'ENOENT') return { removed, kept };
    throw e;
  }

  for (const entry of entries) {
    if (!entry.isFile() || !entry.name.startsWith(namePrefix)) continue;
    const suffix = entry.name.slice(namePrefix.length);
    if (!/^\d+_\d+$/.test(suffix)) continue;
    const candidate = path.join(dir, entry.name);
    let age;
    try {
      age = Date.now() - fs.statSync(candidate).mtimeMs;
    } catch (e) {
      if (e.code === 'ENOENT') continue;
      throw e;
    }
    if (age <= staleTempMs) {
      kept.push(candidate);
      continue;
    }
    let removedThis = false;
    for (let i = 0; i < 5; i++) {
      try {
        fs.unlinkSync(candidate);
        removedThis = true;
        break;
      } catch (e) {
        if (e.code === 'ENOENT') { removedThis = true; break; }
        if (i < 4) { sleepSync(20); continue; }
        throw new LockError(
          'Failed to sweep a stale atomic-write temp file: ' + candidate
          + ' (' + e.message + ')', 'ATOMIC_TEMP_CLEANUP_FAIL');
      }
    }
    if (removedThis) removed.push(candidate);
  }
  return { removed, kept };
}

/** Temp file + rename = atomic replace (Windows Node rename overwrites). UTF-8, no BOM. */
function atomicWriteSync(targetPath, content, opts) {
  cleanupStaleAtomicTempsSync(targetPath, opts);
  const tmp = targetPath + '.tmp_' + process.pid + '_' + Date.now();
  try {
    fs.writeFileSync(tmp, content, 'utf8');
    fs.renameSync(tmp, targetPath);
  } catch (e) {
    try {
      fs.unlinkSync(tmp);
    } catch (cleanupError) {
      if (cleanupError.code !== 'ENOENT') e.cleanupError = cleanupError;
    }
    throw e;
  }
}

/* ------------------------------------------------------------------ *
 * Tool body                                                          *
 * ------------------------------------------------------------------ */

function readEntry() {
  const args = process.argv.slice(2);
  if (args[0] === '--file') {
    if (!args[1]) die('--file needs a file path after it');
    if (!fs.existsSync(args[1])) die('Entry file does not exist: ' + args[1]);
    let t = fs.readFileSync(args[1], 'utf8');
    if (t.charCodeAt(0) === 0xFEFF) t = t.slice(1); // tolerate BOM
    return t.trim();
  }
  if (args[0] === '--stdin') {
    try {
      return fs.readFileSync(0, 'utf8').trim();
    } catch (e) {
      die('Failed to read stdin: ' + e.message);
    }
  }
  if (args.length === 0) die('No entry given. See the usage block in this file header (argv / --file / --stdin).');
  return args.join(' ').trim();
}

function validate(entry) {
  if (!/^- 【\d{4}-\d{2}-\d{2}】@\S+[：:]/.test(entry)) {
    die('Entry format mismatch. It must start with `- 【YYYY-MM-DD】@name: ` '
      + '(the team log format contract); got: ' + entry.slice(0, 50) + '…');
  }
  if (entry.includes('\n')) {
    // One entry = one line (the log convention); newlines break diffs and entry counting.
    entry = entry.split('\n').map(s => s.trim()).filter(Boolean).join(' ');
  }
  return entry;
}

function acquireLock() {
  try {
    acquireLockSync(LOCK, {
      onWait: () => process.stderr.write('[append-team-log] Someone is writing the log; queueing…\n'),
      onStaleClear: (age) =>
        process.stderr.write(
          '[append-team-log] Cleared a stale lock from ' + Math.round(age / 1000)
          + 's ago (its holder likely crashed)\n'
        ),
    });
  } catch (e) {
    if (e instanceof LockError) {
      die(e.message, e.code === 'LOCK_TIMEOUT' ? 2 : 1);
    }
    die('Error taking the lock: ' + e.message);
  }
}

function releaseLock() {
  releaseLockFile(LOCK);
}

/**
 * Insert-point computation, in priority order:
 *   1. Append anchor — the log template ships a `▼▼▼` comment line reading
 *      "append the newest entry directly below this line"; if present, insert
 *      right below it (newest-on-top stays true by construction).
 *   2. No anchor: skip a YAML frontmatter block if the file starts with one
 *      (`---` … `---`), find the first non-blank line (the title), insert after
 *      it (and after one following blank line, keeping "title, blank, newest").
 * An unterminated frontmatter block (no second `---`) is conservatively treated
 * as "no frontmatter" — no guessing, no full-file scanning, so a stray `---`
 * divider deep in the body can never be misread as a frontmatter fence.
 */
function computeInsertIndex(lines) {
  // 1. anchor line
  for (let i = 0; i < lines.length; i++) {
    if (lines[i].includes('▼▼▼')) return i + 1;
  }
  // 2. frontmatter-aware title fallback
  let bodyStart = 0;
  if (lines[0] !== undefined && lines[0].trim() === '---') {
    let fmEnd = -1;
    for (let i = 1; i < lines.length; i++) {
      if (lines[i].trim() === '---') { fmEnd = i; break; }
    }
    if (fmEnd !== -1) bodyStart = fmEnd + 1;
  }
  let titleAt = bodyStart;
  while (lines[titleAt] !== undefined && lines[titleAt].trim() === '') titleAt++;
  let insertAt = titleAt + 1;
  if (lines[insertAt] !== undefined && lines[insertAt].trim() === '') insertAt++;
  return insertAt;
}

function main() {
  const entry = validate(readEntry());
  if (!fs.existsSync(LOG)) die('Team log file does not exist: ' + LOG);

  acquireLock();
  try {
    const before = fs.readFileSync(LOG, 'utf8');
    const lines = before.split('\n');
    const insertAt = computeInsertIndex(lines);
    lines.splice(insertAt, 0, entry);
    const after = lines.join('\n');

    // Atomic replace: temp file + rename.
    atomicWriteSync(LOG, after);

    // Read-back verification ("probed" is not "landed": trust disk, not memory).
    const verify = fs.readFileSync(LOG, 'utf8');
    if (!verify.includes(entry)) die('Read-back after writing did not find the new entry — the file may have been corrupted by a concurrent writer. Inspect it by hand!', 3);
    const nBefore = before.split('\n').filter(l => l.startsWith('- 【')).length;
    const nAfter = verify.split('\n').filter(l => l.startsWith('- 【')).length;
    if (nAfter !== nBefore + 1) die('Entry count anomaly: ' + nBefore + ' before, ' + nAfter + ' after (expected +1) — inspect the file by hand!', 3);

    process.stdout.write('[append-team-log] OK, appended (' + nAfter + ' entries now): ' + entry.slice(0, 60) + '…\n');

    // Soft reminders (all non-blocking; this tool never auto-rotates — stable beats clever)
    const nLines = verify.split(/\r\n|\r|\n/).length;
    if (nLines > 400) {
      process.stderr.write('[append-team-log] Note: the log is ' + nLines + ' lines now (>400). Consider moving old months into 98-archive/ to keep the head light.\n');
    }
    if (entry.length > 600) {
      process.stderr.write('[append-team-log] Note: this entry is ' + entry.length + ' chars (>600 suggested) — one line says it, details belong in an artifact file.\n');
    }
    const oldestMonths = new Set((verify.match(/^- 【(\d{4}-\d{2})/gm) || []).map(s => s.slice(3)));
    if (oldestMonths.size > 2) {
      process.stderr.write('[append-team-log] Note: the log now spans ' + oldestMonths.size + ' months — consider archiving the older months into 98-archive/.\n');
    }
  } finally {
    releaseLock();
  }
}

if (require.main === module) {
  // Runtime version gate (a guardrail, not a gate): if run directly on Node < 18, print a
  // note; skipped when require()'d, so module.exports stays unaffected.
  if (parseInt(process.versions.node.split('.')[0], 10) < 18) {
    process.stderr.write('[append-team-log] Note: Node ' + process.versions.node + ' detected; 18+ recommended. Older versions may hit newer-syntax errors; please upgrade Node.\n');
  }
  try {
    main();
  } catch (e) {
    if (e instanceof DieError) {
      process.stderr.write('[append-team-log] FAILED: ' + e.message + '\n');
    } else {
      process.stderr.write('[append-team-log] Unexpected error: ' + ((e && e.stack) || e) + '\n');
    }
    process.exitCode = (e && e.exitCode) || 1;
  }
}

module.exports = { computeInsertIndex, validate };