#!/usr/bin/env node
/** L4: 状态文件 HMAC 完整性模块 (v1.2 — 随机密钥 + Markdown + sanitization) */
const fs = require('fs');
const path = require('path');
const crypto = require('crypto');
const os = require('os');
const SALT = 'bookworm-state-integrity-v1';

// R5: HMAC 密钥改为随机生成，首次运行时持久化到 .hmac-key (权限 600)
// 回退: 密钥文件不可用时仍使用 hostname+username 派生 (向后兼容)
var _keyFile = path.join(os.homedir(), '.claude', '.hmac-key');

function deriveKey() {
  // 优先使用随机密钥文件
  try {
    if (fs.existsSync(_keyFile)) {
      return Buffer.from(fs.readFileSync(_keyFile, 'utf8').trim(), 'hex');
    }
    // 首次运行: 生成 32 字节随机密钥
    var key = crypto.randomBytes(32);
    var dir = path.dirname(_keyFile);
    if (!fs.existsSync(dir)) fs.mkdirSync(dir, { recursive: true });
    fs.writeFileSync(_keyFile, key.toString('hex') + '\n', { mode: 0o600 });
    return key;
  } catch {
    // 回退: 可预测密钥 (向后兼容)
    return crypto.createHash('sha256')
      .update(os.hostname() + ':' + os.userInfo().username + ':' + SALT)
      .digest();
  }
}

function computeHMAC(content) {
  return crypto.createHmac('sha256', deriveKey()).update(content).digest('hex');
}

function sigPath(fp) { return fp + '.sig'; }

// ─── JSON 文件签名读写 ──────────────────────────────────

function writeWithSignature(filePath, data) {
  var json = JSON.stringify(data, null, 2) + '\n';
  var tmp = filePath + '.tmp.' + process.pid;
  fs.writeFileSync(tmp, json);
  fs.renameSync(tmp, filePath);
  fs.writeFileSync(sigPath(filePath), computeHMAC(json) + '\n');
}

function readWithVerification(filePath, opts) {
  opts = opts || {};
  try {
    var raw = fs.readFileSync(filePath, 'utf8');
    var sp = sigPath(filePath);
    if (!fs.existsSync(sp)) {
      return { data: JSON.parse(raw), verified: false, error: 'sig-missing' };
    }
    var expected = fs.readFileSync(sp, 'utf8').trim();
    var actual = computeHMAC(raw);
    if (expected !== actual) {
      if (opts.strict) return { data: null, verified: false, error: 'sig-mismatch' };
      return { data: JSON.parse(raw), verified: false, error: 'sig-mismatch' };
    }
    return { data: JSON.parse(raw), verified: true, error: null };
  } catch (e) {
    return { data: null, verified: false, error: e.message };
  }
}

// ─── 通用文件原子写入 + 签名 (支持任意文本文件) ──────────

/**
 * 原子写入文本文件 + HMAC 签名
 * @param {string} filePath - 目标文件路径
 * @param {string} content - 文本内容
 */
function writeTextWithSignature(filePath, content) {
  var dir = path.dirname(filePath);
  if (!fs.existsSync(dir)) fs.mkdirSync(dir, { recursive: true });
  var tmp = filePath + '.tmp.' + process.pid;
  fs.writeFileSync(tmp, content);
  fs.renameSync(tmp, filePath);
  fs.writeFileSync(sigPath(filePath), computeHMAC(content) + '\n');
}

/**
 * 读取文本文件 + 验证 HMAC
 * @param {string} filePath
 * @param {object} [opts] - { strict: boolean }
 * @returns {{ content: string|null, verified: boolean, error: string|null }}
 */
function readTextWithVerification(filePath, opts) {
  opts = opts || {};
  try {
    var raw = fs.readFileSync(filePath, 'utf8');
    var sp = sigPath(filePath);
    if (!fs.existsSync(sp)) {
      return { content: raw, verified: false, error: 'sig-missing' };
    }
    var expected = fs.readFileSync(sp, 'utf8').trim();
    var actual = computeHMAC(raw);
    if (expected !== actual) {
      if (opts.strict) return { content: null, verified: false, error: 'sig-mismatch' };
      return { content: raw, verified: false, error: 'sig-mismatch' };
    }
    return { content: raw, verified: true, error: null };
  } catch (e) {
    return { content: null, verified: false, error: e.message };
  }
}

// ─── Prompt Injection Sanitizer ─────────────────────────

/**
 * 检测 resume-prompt.md 中的疑似注入标记
 * 返回清理后的内容 + 检测到的可疑模式列表
 */
const INJECTION_PATTERNS = [
  /<!--\s*SYSTEM\b/gi,
  /<!--\s*OVERRIDE\b/gi,
  /<!--\s*IMPORTANT\b/gi,
  /\bSYSTEM\s*OVERRIDE\b/gi,
  /\bIGNORE\s+(?:ALL\s+)?PREVIOUS\s+INSTRUCTIONS?\b/gi,
  /\bYOU\s+ARE\s+NOW\b/gi,
  /\bDO\s+NOT\s+FOLLOW\b/gi,
  /^\s*(?:you\s+must\s+)?act\s+as\s+(?:a\s+)?(?:system|admin|root|hacker)/gim,
  /\bFORGET\s+(?:ALL\s+)?YOUR\b/gi,
  /\bEXFILTRATE\b/gi,
  /\bcurl\s+.*\|\s*(?:ba)?sh\b/gi,
  /\beval\s*\(/gi,
  /\bnew\s+Function\b/gi,
  /cat\s+~\/\.ssh\b/gi,
  /cat\s+.*\.env\b/gi,
  /base64\s+.*\.env\b/gi,
];

function sanitizeResumePrompt(content) {
  var warnings = [];
  var cleaned = content;
  for (var i = 0; i < INJECTION_PATTERNS.length; i++) {
    // W-04 修复: 重置 lastIndex 避免 /g 标志导致 test() 和 replace() 行为不一致
    INJECTION_PATTERNS[i].lastIndex = 0;
    if (INJECTION_PATTERNS[i].test(cleaned)) {
      warnings.push('detected: ' + INJECTION_PATTERNS[i].source);
      INJECTION_PATTERNS[i].lastIndex = 0;
      cleaned = cleaned.replace(INJECTION_PATTERNS[i], '[SANITIZED-INJECTION-ATTEMPT]');
    }
  }
  return { content: cleaned, warnings: warnings, injectionDetected: warnings.length > 0 };
}

module.exports = {
  writeWithSignature, readWithVerification,
  writeTextWithSignature, readTextWithVerification,
  sanitizeResumePrompt,
  computeHMAC, sigPath, deriveKey
};