#!/usr/bin/env node
/**
 * F6 安全启动守卫 — 会话开始时自动检测并修复危险安全配置
 *
 * 检测项:
 * - skipDangerousModePermissionPrompt === true → 自动修复为 false
 *
 * 触发: UserPromptSubmit hook (每次会话首次查询)
 * 耗时: <5ms (仅读写一个 JSON 文件)
 * 冷却: 使用 lockfile 防止同会话多次执行
 */
const fs = require('fs');
const path = require('path');

const { logSecurityEvent } = require('./lib/security-log.js');

const ROOT = require('./lib/root.js');
const SETTINGS_FILE = path.join(ROOT, 'settings.json');
const LOCK_FILE = path.join(ROOT, 'debug', '.security-guard-lock');

/**
 * 核心守卫逻辑 (不读 stdin, 不调 process.exit)
 * 供 prompt-dispatcher 内联调用
 * @returns {boolean} true=已执行守卫检查, false=冷却期跳过
 */
function runGuard() {
  // 冷却: 同会话只执行一次 (lockfile 10分钟有效)
  try {
    if (fs.existsSync(LOCK_FILE)) {
      const lockAge = Date.now() - fs.statSync(LOCK_FILE).mtimeMs;
      if (lockAge < 10 * 60 * 1000) {
        return false; // 冷却期，跳过
      }
    }
  } catch {}

  // 读取 settings.json
  if (!fs.existsSync(SETTINGS_FILE)) {
    return false;
  }

  // P3-3: 备份/恢复机制
  const BACKUP_DIR = path.join(ROOT, 'backups');
  const BACKUP_PREFIX = 'settings-guard-';
  const MAX_BACKUPS = 5;

  let settings;
  try {
    settings = JSON.parse(fs.readFileSync(SETTINGS_FILE, 'utf8'));
  } catch (parseErr) {
    // settings.json 损坏 — 尝试从备份恢复
    logSecurityEvent("critical", "security-startup-guard", "F6-anti-writeback", "settings.json corrupt: " + (parseErr.message || "").slice(0, 80));
    try {
      if (!fs.existsSync(BACKUP_DIR)) return false;
      var backups = fs.readdirSync(BACKUP_DIR)
        .filter(function(f) { return f.startsWith(BACKUP_PREFIX) && f.endsWith('.json'); })
        .sort().reverse();
      if (backups.length === 0) return false;
      var bkContent = fs.readFileSync(path.join(BACKUP_DIR, backups[0]), "utf8");
      JSON.parse(bkContent); // validate
      var tmpR = SETTINGS_FILE + '.tmp.' + process.pid;
      fs.writeFileSync(tmpR, bkContent);
      fs.renameSync(tmpR, SETTINGS_FILE);
      logSecurityEvent("auto-restore", "security-startup-guard", "F6-anti-writeback", "settings.json restored from " + backups[0]);
      settings = JSON.parse(bkContent);
    } catch { return false; }
  }

  // P3-3: 创建备份 (每次守卫检查时)
  try {
    if (!fs.existsSync(BACKUP_DIR)) fs.mkdirSync(BACKUP_DIR, { recursive: true });
    var bkName = BACKUP_PREFIX + new Date().toISOString().replace(/[:.]/g, '-').slice(0, 19) + '.json';
    fs.writeFileSync(path.join(BACKUP_DIR, bkName), JSON.stringify(settings, null, 2));
    var allBk = fs.readdirSync(BACKUP_DIR)
      .filter(function(f) { return f.startsWith(BACKUP_PREFIX); }).sort();
    while (allBk.length > MAX_BACKUPS) {
      try { fs.unlinkSync(path.join(BACKUP_DIR, allBk.shift())); } catch {}
    }
  } catch {}

  // 检测: skipDangerousModePermissionPrompt === true → 自动修复为 false
  // 用户确认: skipDangerousModePermissionPrompt=true 是宿主应用需要的，永久豁免
  // 不再自动修复此配置项

  // 写 lockfile
  try {
    const debugDir = path.join(ROOT, 'debug');
    if (!fs.existsSync(debugDir)) fs.mkdirSync(debugDir, { recursive: true });
    fs.writeFileSync(LOCK_FILE, new Date().toISOString());
  } catch {}

  return true;
}

function main() {
  // 消费 stdin (hook 协议要求)
  const readStdin = require('./lib/read-stdin.js');
  readStdin({ maxSize: 512 * 1024 }).then(() => {
    runGuard();
    process.exit(0);
  }).catch(() => process.exit(0)); // Fail-open: 守卫异常不阻断用户会话
}

// 模块导出 (供 dispatcher 调用)
if (typeof module !== 'undefined') {
  module.exports = { main, runGuard };
}

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