#!/usr/bin/env node
/**
 * session-stop.js — Nomad Stop hook (portable port of production
 * `hooks-core/flush-reminder-core.js`, parameterized per team-skeleton.md §3/§5).
 *
 * Reminds the agent to flush its progress (own memory files + team log) at
 * close-out, in a way that is safe against looping — per-session state file
 * tracks (transcript byte length, memory dir newest mtime) so it only reminds
 * when there's plausible new, unflushed work.
 *
 * Same four-branch decide() logic as the production original:
 *   - no state file yet (first Stop this session) → remind
 *   - memory dir's newest mtime is newer than last recorded → memory was
 *     already updated since last check → don't remind, advance the baseline
 *   - otherwise: transcript grew by more than the threshold since the last
 *     baseline → remind, advance the baseline
 *   - otherwise → don't remind, leave the baseline untouched (keep accumulating)
 *
 * On remind=false this script emits nothing on stdout at all (no payload =
 * let the session end) — same "silence means proceed" contract as the
 * production original and as Cursor's followup_message being optional.
 *
 * Also releases the cross-session soft lock acquired by session-start.js
 * (see lib/session-lock.js) — symmetric acquire/release, best-effort, never
 * blocks close-out if it fails.
 *
 * Usage: node session-stop.js [--platform claude|codex|cursor]
 *   stdin: hook input JSON (session_id/cwd/transcript_path). No session_id → proceed silently.
 */
'use strict';
const fs = require('fs');
const path = require('path');
const os = require('os');
const emit = require('./lib/emit');
const cfg = require('./lib/config');
const sessionLock = require('./lib/session-lock');
const messages = require('./lib/messages');

const STALE_THRESHOLD_BYTES = 9000;
const STATE_FILE_PREFIX = 'nomad_stop_';

/**
 * Recursively find the newest mtimeMs among all files under dirPath. Returns 0
 * if the directory is missing/empty. Never throws.
 * Rounds down with Math.floor — Node's fs.Stats.mtimeMs often carries a
 * sub-millisecond fraction; if stored as-is in the state file and read back
 * with parseInt, the fraction gets truncated and "current mtime (with
 * fraction) > last-recorded (truncated)" becomes permanently true, falsely
 * reading as "memory was just updated" on every check (a real bug the
 * production port hit and fixed — millisecond precision is all this needs).
 */
function newestMtimeMs(dirPath) {
  let newest = 0;
  function walk(dir) {
    let entries;
    try {
      entries = fs.readdirSync(dir, { withFileTypes: true });
    } catch (e) {
      return;
    }
    for (const ent of entries) {
      const full = path.join(dir, ent.name);
      try {
        if (ent.isDirectory()) {
          walk(full);
        } else if (ent.isFile()) {
          const mt = Math.floor(fs.statSync(full).mtimeMs);
          if (mt > newest) newest = mt;
        }
      } catch (e) {
        /* one bad entry shouldn't sink the rest */
      }
    }
  }
  try {
    if (fs.existsSync(dirPath)) walk(dirPath);
  } catch (e) {
    /* ignore */
  }
  return newest;
}

function fileSizeBytes(filePath) {
  try {
    if (filePath && fs.existsSync(filePath)) return fs.statSync(filePath).size;
  } catch (e) {
    /* ignore */
  }
  return 0;
}

/**
 * Core decision logic (pure function — no filesystem access, directly unit-testable).
 * @param {{exists:boolean,lastT:number,lastM:number}} prevState
 * @param {number} tlen current transcript byte size
 * @param {number} memNewest current memory dir newest mtimeMs
 * @returns {{remind:boolean,newT:number,newM:number}}
 */
function decide(prevState, tlen, memNewest) {
  if (!prevState.exists) {
    return { remind: true, newT: tlen, newM: memNewest };
  }
  const lastT = prevState.lastT || 0;
  const lastM = prevState.lastM || 0;
  if (memNewest > lastM) {
    return { remind: false, newT: tlen, newM: memNewest };
  }
  if (tlen - lastT > STALE_THRESHOLD_BYTES) {
    return { remind: true, newT: tlen, newM: memNewest };
  }
  return { remind: false, newT: lastT, newM: lastM };
}

function readPrevState(stateFile) {
  if (!fs.existsSync(stateFile)) return { exists: false, lastT: 0, lastM: 0 };
  try {
    const raw = fs.readFileSync(stateFile, 'utf8');
    const parts = raw.split('|');
    const lastT = parts.length >= 1 ? parseInt(parts[0], 10) : NaN;
    const lastM = parts.length >= 2 ? parseInt(parts[1], 10) : NaN;
    return { exists: true, lastT: Number.isFinite(lastT) ? lastT : 0, lastM: Number.isFinite(lastM) ? lastM : 0 };
  } catch (e) {
    return { exists: false, lastT: 0, lastM: 0 };
  }
}

function writeState(stateFile, newT, newM) {
  fs.writeFileSync(stateFile, String(newT) + '|' + String(newM), 'utf8');
}

/** Build the append-log.js CLI hint shown in the reminder text, resolved against this team's actual team_log path. */
function buildAppendLogHint(teamRoot, config) {
  const appendLogScript = path.join(__dirname, 'append-log.js');
  const teamLogPath = cfg.resolveSharedPath(teamRoot, config, 'team_log');
  const target = teamLogPath || '<team_log path from team-config.json shared_paths.team_log>';
  return 'node "' + appendLogScript + '" "- <your entry>" --target "' + target + '"';
}

async function main() {
  const platform = emit.getPlatform();
  try {
    const raw = await emit.readStdin();
    let j = {};
    try {
      j = raw && raw.trim() ? JSON.parse(raw) : {};
    } catch (e) {
      j = {};
    }
    const sid = typeof j.session_id === 'string' ? j.session_id : '';
    if (!sid) {
      process.exit(0);
      return;
    }

    if (emit.isDuplicateInvocation('Stop', sid)) {
      process.exit(0);
      return;
    }

    const cwd = emit.resolveCwd(raw, platform);
    const tp = typeof j.transcript_path === 'string' ? j.transcript_path : '';

    const agentHome = cfg.resolveAgentHome(cwd);
    const memDir = agentHome ? cfg.firstExisting(agentHome, ['记忆', 'memory']) : null;
    const memNewest = memDir ? newestMtimeMs(memDir) : 0;
    const tlen = fileSizeBytes(tp);

    const key = sid.replace(/[^A-Za-z0-9]/g, '');
    const stateFile = path.join(os.tmpdir(), STATE_FILE_PREFIX + key + '.txt');

    const prevState = readPrevState(stateFile);
    const result = decide(prevState, tlen, memNewest);
    // writeState was the ONE bare filesystem write left in main() — every other
    // write call in this file already carries its own try/catch. If it threw
    // (tmpdir unwritable, disk full, EPERM under a locked-down profile), control
    // jumped straight to the outer catch and the `sessionLock.release()` below
    // was skipped — leaving `.session_lock.json` behind, so every subsequent
    // start falsely reported "another session is already running". The state
    // file is a best-effort reminder heuristic; failing to persist it must never
    // cost the lock release, which is the part with cross-session consequences.
    try {
      writeState(stateFile, result.newT, result.newM);
    } catch (e) {
      process.stderr.write('[session-stop] could not persist reminder state (non-fatal, ' +
        'lock release continues): ' + ((e && e.message) || e) + '\n');
    }

    if (result.remind) {
      const teamRoot = cfg.resolveTeamRoot(cwd || process.cwd());
      const config = cfg.loadTeamConfig(teamRoot);
      const lang = cfg.resolveLanguage(config);
      const msg = messages.get(lang);
      const reason = msg.stopReason(buildAppendLogHint(teamRoot, config));
      emit.writeJson(emit.buildStopBlockPayload(reason, platform));
    }
    // remind=false: emit nothing (matches production original — silence = proceed).

    if (agentHome) {
      try {
        sessionLock.release(agentHome);
      } catch (e) {
        /* best-effort — never block close-out on lock release failure */
      }
    }
  } catch (e) {
    // Never block close-out: emit nothing on stdout (silence = proceed). But
    // surface an unexpected exception on stderr instead of swallowing it
    // silently — stderr does not affect the "silence means let the session end"
    // contract, it just gives an operator a trace when something genuinely broke.
    process.stderr.write('[session-stop] non-fatal error, no reminder emitted (close-out not blocked): ' + ((e && e.stack) || e) + '\n');
  }
  process.exit(0);
}

if (require.main === module) {
  main();
}

module.exports = {
  decide,
  newestMtimeMs,
  fileSizeBytes,
  readPrevState,
  writeState,
  buildAppendLogHint,
  STALE_THRESHOLD_BYTES,
};