/**
 * AriaEngine SSTable 缓存内存上限测试
 * @module tests/engine/aria-cache
 *
 * 验证 v0.2.6 修复：
 * 1. SSTable 缓存受 cacheLimitBytes 上限约束（LRU 裁剪）
 * 2. 缓存驱逐后所有读取路径（全表/范围/PK/索引）仍返回完整数据（prefetch 兜底）
 * 3. 写入路径不会导致缓存无限增长
 */
import { AriaEngine } from '../../src/engine/aria/index';
import { createSchema } from '../../src/table/schema';

import { installOPFSMock } from '../helpers/opfs-mock';

beforeEach(() => { installOPFSMock(new Map()); });

/** 构造小缓存 + 小 MemTable 阈值的引擎，快速产生多个 SSTable */
function createSmallCacheEngine(bufferPoolPages = 2) {
  return new AriaEngine({
    storageBackend: 'memory',
    memtableSizeThreshold: 2048, // ~2KB 阈值 → 300 行会产生多个 SSTable
    bufferPoolPages,
    checkpointInterval: 100000, // 关闭自动 checkpoint，避免干扰
    walSyncMode: 'none',
  } as any);
}

function makeRows(count: number): Record<string, unknown>[] {
  const rows: Record<string, unknown>[] = [];
  for (let i = 0; i < count; i++) {
    rows.push({ id: `u${i}`, name: `User${i}`, age: 20 + (i % 30) });
  }
  return rows;
}

describe('AriaEngine SSTable 缓存内存上限', () => {
  test('缓存大小受 cacheLimitBytes 约束', async () => {
    const engine = createSmallCacheEngine(2); // 2 * 4096 = 8KB 上限
    await engine.open('cache-limit-test', 1);
    await engine.createTable(createSchema('users', {
      id: { type: 'string', primaryKey: true },
      name: { type: 'string' },
      age: { type: 'number', index: true },
    }));

    await engine.insert('users', makeRows(300));
    const lsm = (engine as any).lsm as {
      flush(): Promise<void>;
      getCacheSize(): number;
      getCacheLimit(): number;
      getStats(): { sstableCount: number };
    };
    // v0.6.1-perf: insert 不再隐式排空后台链（逐行 prefetchKeys 已移除），
    // 显式等待后台 flush 完成后再断言 SSTable 产物
    await lsm.flush();
    const stats = lsm.getStats();
    // 300 行 / 2KB 阈值 → 应产生多个 SSTable
    expect(stats.sstableCount).toBeGreaterThan(1);

    // 多轮查询后缓存仍受上限约束
    for (let round = 0; round < 5; round++) {
      const rows = await engine.find('users', { table: 'users', where: { age: 25 } });
      expect(rows.length).toBe(10);
      expect(lsm.cacheSize).toBeLessThanOrEqual(lsm.cacheLimitBytes);
    }

    await engine.close();
  });

  test('缓存驱逐后全表扫描仍返回完整数据（prefetch 兜底）', async () => {
    const engine = createSmallCacheEngine(1); // 4KB 上限，必然触发驱逐
    await engine.open('cache-evict-fullscan', 1);
    await engine.createTable(createSchema('users', {
      id: { type: 'string', primaryKey: true },
      name: { type: 'string' },
    }));

    const rows = makeRows(300);
    await engine.insert('users', rows);

    const all = await engine.find('users', { table: 'users' });
    expect(all.length).toBe(300);

    const lsm = (engine as any).lsm;
    expect(lsm.cacheSize).toBeLessThanOrEqual(lsm.cacheLimitBytes);
    await engine.close();
  });

  test('缓存驱逐后 PK 等值查询仍正确（prefetchKeys 兜底）', async () => {
    const engine = createSmallCacheEngine(1);
    await engine.open('cache-evict-pk', 1);
    await engine.createTable(createSchema('users', {
      id: { type: 'string', primaryKey: true },
      name: { type: 'string' },
    }));

    const rows = makeRows(300);
    await engine.insert('users', rows);

    // 分散查询多个 PK，每次都会经历 驱逐+重新加载
    for (let i = 0; i < 300; i += 11) {
      const found = await engine.find('users', { table: 'users', where: { id: `u${i}` } });
      expect(found.length).toBe(1);
      expect(found[0].name).toBe(`User${i}`);
    }

    await engine.close();
  });

  test('缓存驱逐后二级索引查询仍正确', async () => {
    const engine = createSmallCacheEngine(1);
    await engine.open('cache-evict-idx', 1);
    await engine.createTable(createSchema('users', {
      id: { type: 'string', primaryKey: true },
      name: { type: 'string' },
      age: { type: 'number', index: true },
    }));

    await engine.insert('users', makeRows(300));

    // 索引等值 + 范围查询
    const eq = await engine.find('users', { table: 'users', where: { age: 25 } });
    expect(eq.length).toBe(10);

    // age 范围 20-49，每个值 10 行
    const range = await engine.find('users', { table: 'users', where: { age: { $gte: 40 } } });
    expect(range.length).toBe(100);

    const range2 = await engine.find('users', { table: 'users', where: { age: { $gt: 45 } } });
    expect(range2.length).toBe(40);

    const inQuery = await engine.find('users', { table: 'users', where: { age: { $in: [21, 22] } } });
    expect(inQuery.length).toBe(20);

    await engine.close();
  });

  test('UPDATE/DELETE 在缓存驱逐后仍作用于全部行', async () => {
    const engine = createSmallCacheEngine(1);
    await engine.open('cache-evict-mutate', 1);
    await engine.createTable(createSchema('users', {
      id: { type: 'string', primaryKey: true },
      name: { type: 'string' },
      age: { type: 'number' },
    }));

    await engine.insert('users', makeRows(300));

    // 无条件更新 → 全表更新
    const updated = await engine.update('users', { table: 'users' }, { name: 'Renamed' });
    expect(updated).toBe(300);

    // age 20-49 每个值 10 行；$lt 25 → age 20-24 → 50 行
    const deleted = await engine.delete('users', { table: 'users', where: { age: { $lt: 25 } } });
    expect(deleted).toBe(50);

    const remaining = await engine.find('users', { table: 'users' });
    expect(remaining.length).toBe(250);
    expect(remaining.every((r) => r.name === 'Renamed')).toBe(true);

    await engine.close();
  });

  test('写入路径不突破缓存上限（flush 后立即裁剪）', async () => {
    const engine = createSmallCacheEngine(2);
    await engine.open('cache-write-bound', 1);
    await engine.createTable(createSchema('users', {
      id: { type: 'string', primaryKey: true },
      name: { type: 'string' },
    }));

    // 分批写入，每批都触发多次 flush
    for (let batch = 0; batch < 10; batch++) {
      await engine.insert('users', makeRows(30).map((r, i) => ({ ...r, id: `b${batch}_u${i}` })));
      const lsm = (engine as any).lsm;
      expect(lsm.cacheSize).toBeLessThanOrEqual(lsm.cacheLimitBytes);
    }

    const all = await engine.find('users', { table: 'users' });
    expect(all.length).toBe(300);

    await engine.close();
  });

  test('回归：主 LSM 与二级索引 LSM 的 SSTable 不互相覆盖（命名空间隔离）', async () => {
    const engine = createSmallCacheEngine(4);
    await engine.open('regression-ns', 1);
    await engine.createTable(createSchema('users', {
      id: { type: 'string', primaryKey: true },
      name: { type: 'string', index: true },
      age: { type: 'number', index: true },
    }));

    // 小阈值下 insert/update 会同时触发主 LSM 与两个索引 LSM 的多次 flush
    await engine.insert('users', makeRows(120));
    await engine.update('users', { table: 'users', where: { age: { $gte: 30 } } }, { name: 'Senior' });

    // 主数据完整且为最新值（age 20-49 每个值出现 4 次；$gte 30 → 20 个值 × 4 = 80 行）
    const all = await engine.find('users', { table: 'users' });
    expect(all.length).toBe(120);
    expect(all.filter((r) => r.name === 'Senior').length).toBe(80);

    // 二级索引等值查找仍正确（索引 LSM 数据未被覆盖）
    const byName = await engine.find('users', { table: 'users', where: { name: 'Senior' } });
    expect(byName.length).toBe(80);
    const byAge = await engine.find('users', { table: 'users', where: { age: 25 } });
    expect(byAge.length).toBe(4);

    await engine.close();
  });

  test('回归：同 key 跨多次 flush 更新后读到最新值（多版本语义）', async () => {
    const engine = createSmallCacheEngine(4);
    await engine.open('regression-versions', 1);
    await engine.createTable(createSchema('users', {
      id: { type: 'string', primaryKey: true },
      value: { type: 'number' },
    }));

    await engine.insert('users', [{ id: 'a', value: 1 }]);

    // 连续更新同一行 20 次，每次更新都经历 flush
    for (let v = 2; v <= 20; v++) {
      await engine.update('users', { table: 'users', where: { id: 'a' } }, { value: v });
    }

    const rows = await engine.find('users', { table: 'users', where: { id: 'a' } });
    expect(rows.length).toBe(1);
    expect(rows[0].value).toBe(20);

    // 全表扫描也应返回最新值
    const all = await engine.find('users', { table: 'users' });
    expect(all.length).toBe(1);
    expect(all[0].value).toBe(20);

    await engine.close();
  });

  test('回归：删除后 tombstone 跨 flush 仍生效（不残留旧数据）', async () => {
    const engine = createSmallCacheEngine(4);
    await engine.open('regression-tombstone', 1);
    await engine.createTable(createSchema('users', {
      id: { type: 'string', primaryKey: true },
      age: { type: 'number', index: true },
    }));

    await engine.insert('users', makeRows(120));

    // 分批删除，触发多次 flush
    for (let batch = 0; batch < 4; batch++) {
      const deleted = await engine.delete('users', { table: 'users', where: { age: { $gte: 20 + batch * 5, $lt: 25 + batch * 5 } } });
      expect(deleted).toBe(20);
    }

    const remaining = await engine.find('users', { table: 'users' });
    expect(remaining.length).toBe(40);

    // 索引查找也不应返回已删除行
    const ghost = await engine.find('users', { table: 'users', where: { age: 22 } });
    expect(ghost.length).toBe(0);

    await engine.close();
  });
});