#!/usr/bin/env node
// session-title.mjs — UserPromptSubmit hook (CC v2.1.94+)
//
// Sets a sessionTitle when the user invokes one of the four voyage commands,
// so multi-session headless runs are easy to identify in process lists and
// session pickers.
//
// Title format: voyage:<command>:<slug>
//   - <command> ∈ {brief, research, plan, execute, review}
//   - <slug>    ∈ first 30 chars of project slug, or "ad-hoc" when no
//                  --project / --brief context is detected
//
// Fail-open invariant: any error → exit 0 with no output. We never block
// the user's prompt.

import { stdin } from 'node:process';
import { resolve, basename } from 'node:path';

const COMMANDS = {
  '/trekbrief': 'brief',
  '/trekresearch': 'research',
  '/trekplan': 'plan',
  '/trekexecute': 'execute',
  '/trekreview': 'review',
  '/trekcontinue': 'continue',
  '/trekendsession': 'endsession',
};

function slugify(s) {
  return String(s)
    .toLowerCase()
    .replace(/[^a-z0-9]+/g, '-')
    .replace(/^-+|-+$/g, '')
    .slice(0, 30) || 'ad-hoc';
}

function detectSlug(prompt) {
  const projectMatch = prompt.match(/--project[=\s]+(\S+)/);
  if (projectMatch) {
    const dir = projectMatch[1].replace(/['"]/g, '');
    const base = basename(resolve(dir));
    const dateStripped = base.replace(/^\d{4}-\d{2}-\d{2}-/, '');
    return slugify(dateStripped);
  }
  const briefMatch = prompt.match(/--brief[=\s]+(\S+)/);
  if (briefMatch) {
    const file = briefMatch[1].replace(/['"]/g, '');
    return slugify(basename(file, '.md'));
  }
  return 'ad-hoc';
}

async function readStdin() {
  let data = '';
  for await (const chunk of stdin) data += chunk;
  return data;
}

(async () => {
  try {
    const raw = await readStdin();
    if (!raw.trim()) return;
    const payload = JSON.parse(raw);
    const prompt = String(payload.prompt || '').trim();
    if (!prompt) return;

    let matchedCmd = null;
    for (const [cmd, short] of Object.entries(COMMANDS)) {
      if (prompt.startsWith(cmd)) {
        matchedCmd = short;
        break;
      }
    }
    if (!matchedCmd) return;

    const slug = detectSlug(prompt);
    const title = `voyage:${matchedCmd}:${slug}`;

    const out = {
      hookSpecificOutput: {
        hookEventName: 'UserPromptSubmit',
        sessionTitle: title,
      },
    };
    process.stdout.write(JSON.stringify(out) + '\n');
  } catch {
    // fail open
  }
})();