'use strict';
/**
 * fast-cache.js — 启动期热数据快路径缓存 (P1-FAST-CACHE-V1)
 *
 * 通过 mtime 签名: 所有源文件未变 → 直接返回上次缓存。
 * 仅缓存只读字段子集，避免缓存整个大 JSON 文件。
 *
 * 借鉴: OpenClaw entry.version-fast-path.ts (零模块加载快退出)
 *
 * Usage:
 *   const { readFastCache } = require('./lib/fast-cache.js');
 *   const cache = readFastCache() || {};
 *   const skillCount = cache.skillCount || 0;
 */

const fs = require('fs');
const path = require('path');

const ROOT = path.join(__dirname, '..', '..');
const CACHE_FILE = path.join(ROOT, 'debug', '.hook-fast-cache.json');

const SOURCES = [
  { file: path.join(ROOT, 'stats-compiled.json'), fields: ['summary', 'version'] },
  // settings.json 不再读取 mcpServers (MCP 配置在 ~/.claude.json，由 stats 编译)
];

function readFastCache() {
  try {
    const mtimes = SOURCES.map(function(s) {
      try { return fs.statSync(s.file).mtimeMs; } catch (_) { return 0; }
    });
    const sig = mtimes.join(':');

    if (fs.existsSync(CACHE_FILE)) {
      try {
        const cache = JSON.parse(fs.readFileSync(CACHE_FILE, 'utf8'));
        if (cache && cache._sig === sig) return cache;
      } catch (_) { /* malformed cache, rebuild */ }
    }

    const rebuilt = { _sig: sig, _builtAt: Date.now() };
    for (let i = 0; i < SOURCES.length; i++) {
      const { file, fields } = SOURCES[i];
      try {
        const data = JSON.parse(fs.readFileSync(file, 'utf8'));
        for (let j = 0; j < fields.length; j++) {
          rebuilt[fields[j]] = data[fields[j]];
        }
      } catch (_) { /* missing file ok */ }
    }
    // P1-FAST-CACHE-V1-FIELDS-FIX: stats.summary 字段名修正
    const _sum = rebuilt.summary || {};
    rebuilt.skillCount = _sum.skills || 0;
    rebuilt.hookCount = _sum.hooks || 0;                  // 总数
    rebuilt.hookRegisteredCount = _sum.hooksRegistered || 0;
    rebuilt.agentCount = _sum.agents || 0;
    rebuilt.mcpCount = _sum.mcpTotal || _sum.mcp || 0;

    // 异步写回 (不阻塞主流程)
    setImmediate(function() {
      try {
        const cacheDir = path.dirname(CACHE_FILE);
        if (!fs.existsSync(cacheDir)) fs.mkdirSync(cacheDir, { recursive: true });
        const tmp = CACHE_FILE + '.tmp.' + process.pid;
        fs.writeFileSync(tmp, JSON.stringify(rebuilt));
        fs.renameSync(tmp, CACHE_FILE);
      } catch (_) { /* best effort */ }
    });

    return rebuilt;
  } catch (_) {
    return null;
  }
}

function enableCompileCacheBestEffort() {
  try {
    const mod = require('node:module');
    if (mod.enableCompileCache && !process.env.NODE_DISABLE_COMPILE_CACHE) {
      mod.enableCompileCache();
      return true;
    }
  } catch (_) { /* unsupported */ }
  return false;
}

module.exports = {
  readFastCache,
  enableCompileCacheBestEffort,
  __sentinel: 'P1-FAST-CACHE-V1',
};