import assert from 'node:assert/strict';
import { createStateCache } from '../src/database/state-cache.mjs';

let loads = 0;
let release;
const gate = new Promise(resolve => { release = resolve; });
const coalesced = createStateCache({
  maxAgeMs: 30000,
  async load() {
    loads += 1;
    await gate;
    return { load: loads };
  }
});
const firstPending = coalesced.read();
const secondPending = coalesced.read();
release();
const [first, second] = await Promise.all([firstPending, secondPending]);
assert.equal(loads, 1, '并发冷读取应合并为一次全量加载');
assert.strictEqual(first, second, '并发读取应共享同一份快照');
assert.strictEqual(await coalesced.read(), first, '有效期内应直接复用内存快照');

coalesced.invalidate();
const afterInvalidation = await coalesced.read();
assert.equal(loads, 2, '应用写入失效后应重新加载');
assert.notStrictEqual(afterInvalidation, first, '失效后不得继续返回旧快照');

let version = 1;
let versionLoads = 0;
const versioned = createStateCache({
  version: () => version,
  load: () => ({ load: ++versionLoads })
});
const versionOne = await versioned.read();
assert.strictEqual(await versioned.read(), versionOne, '数据库版本未变化时应复用快照');
version += 1;
const versionTwo = await versioned.read();
assert.equal(versionLoads, 2, '外部数据库版本变化后应重新加载');
assert.notStrictEqual(versionTwo, versionOne, '外部写入后不得返回旧快照');

console.log('State cache tests passed');