"use strict";

/**
 * 巡检模块主进程存储适配器
 *
 * 使用 userData 目录下的 JSON 文件存储巡检相关数据（设备配置、告警规则、巡检结果等）。
 * 提供与 localStorage 类似的 key-value 接口，方便注入到 store 模块。
 */

const fs = require("node:fs");
const path = require("node:path");

const STORAGE_FILENAME = "inspection-data.json";
let _storageCache = null;
let _filePath = null;
let _dirty = false;
let _saveTimer = null;

function init(userDataDir) {
  _filePath = path.join(userDataDir, STORAGE_FILENAME);
  _loadFromDisk();
}

function _loadFromDisk() {
  if (!_filePath) {
    _storageCache = {};
    return;
  }
  try {
    if (fs.existsSync(_filePath)) {
      const raw = fs.readFileSync(_filePath, "utf-8");
      _storageCache = JSON.parse(raw);
    } else {
      _storageCache = {};
    }
  } catch (e) {
    console.error("[Inspection Storage] 加载失败:", e?.message);
    _storageCache = {};
  }
}

function _scheduleSave() {
  if (_saveTimer) return;
  _saveTimer = setTimeout(() => {
    _saveTimer = null;
    _flushToDisk();
  }, 200);
}

function _flushToDisk() {
  if (!_filePath || !_dirty) return;
  try {
    const dir = path.dirname(_filePath);
    if (!fs.existsSync(dir)) {
      fs.mkdirSync(dir, { recursive: true });
    }
    fs.writeFileSync(_filePath, JSON.stringify(_storageCache, null, 2), "utf-8");
    _dirty = false;
  } catch (e) {
    console.error("[Inspection Storage] 保存失败:", e?.message);
  }
}

function readStorage(key) {
  if (!_storageCache) _loadFromDisk();
  return _storageCache[key] ?? null;
}

function writeStorage(key, value) {
  if (!_storageCache) _loadFromDisk();
  if (value === null || value === undefined) {
    delete _storageCache[key];
  } else {
    _storageCache[key] = value;
  }
  _dirty = true;
  _scheduleSave();
}

function flushSync() {
  _flushToDisk();
}

function resetCache() {
  // 先确保内存中的修改已写到磁盘（200ms 异步保存可能还没触发）
  _flushToDisk();
  _storageCache = null;
  _loadFromDisk();
}

module.exports = {
  init,
  readStorage,
  writeStorage,
  flushSync,
  resetCache,
};