/**
 * 介质：SharedMemoryBackend（跨实例共享，模拟磁盘持久化）
 */

import { KVStoreEngine } from '../../src/engine/kvstore_engine';
import { SharedMemoryBackend } from '../../src/engine/kvstore/shared_memory_medium';
import { createSchema } from '../../src/table/schema';

let dbCounter = 0;

describe('KVStoreEngine', () => {
  let engine: KVStoreEngine;
  let dbName: string;

  const userSchema = createSchema('users', {
    id: { type: 'string', primaryKey: true },
    name: { type: 'string', required: true },
    age: { type: 'number', default: 0 },
    email: { type: 'string', unique: true },
  });

  beforeEach(async () => {
    dbName = `test-kv-${++dbCounter}-${Math.random().toString(36).slice(2, 6)}`;
    engine = new KVStoreEngine(new SharedMemoryBackend());
    await engine.open(dbName, 1);
  });

  afterEach(async () => {
    if (engine.isOpen()) {
      await engine.close();
    }
  });

  // ---- 生命周期 ----

  describe('生命周期', () => {
    it('打开和关闭', async () => {
      expect(engine.isOpen()).toBe(true);
      await engine.close();
      expect(engine.isOpen()).toBe(false);
    });

    it('未打开时操作抛出错误', async () => {
      await engine.close();
      await expect(engine.count('users')).rejects.toThrow('not opened');
    });

    it('可以重新打开', async () => {
      await engine.close();
      await engine.open(dbName, 2);
      expect(engine.isOpen()).toBe(true);
    });
  });

  // ---- 表管理 ----

  describe('表管理', () => {
    it('创建表', async () => {
      await engine.createTable(userSchema);
      expect(await engine.hasTable('users')).toBe(true);
      const names = await engine.getTableNames();
      expect(names).toContain('users');
    });

    it('重复创建表抛错', async () => {
      await engine.createTable(userSchema);
      await expect(engine.createTable(userSchema)).rejects.toThrow('already exists');
    });

    it('删除表', async () => {
      await engine.createTable(userSchema);
      await engine.insert('users', [{ id: '1', name: 'Alice' }]);
      await engine.dropTable('users');
      expect(await engine.hasTable('users')).toBe(false);
      await expect(engine.count('users')).rejects.toThrow('does not exist');
    });

    it('获取表结构', async () => {
      await engine.createTable(userSchema);
      const schema = await engine.getTableSchema('users');
      expect(schema).not.toBeNull();
      expect(schema!.columns.id.primaryKey).toBe(true);
    });

    it('schema 持久化：重启后表结构保留', async () => {
      await engine.createTable(userSchema);
      await engine.close();

      const engine2 = new KVStoreEngine(new SharedMemoryBackend());
      await engine2.open(dbName, 1);
      expect(await engine2.hasTable('users')).toBe(true);
      const schema = await engine2.getTableSchema('users');
      expect(schema!.columns.email.unique).toBe(true);
      await engine2.close();
    });
  });

  // ---- 插入 ----

  describe('插入', () => {
    beforeEach(async () => { await engine.createTable(userSchema); });

    it('插入单行并返回主键', async () => {
      const pks = await engine.insert('users', [{ id: '1', name: 'Alice', age: 30 }]);
      expect(pks).toEqual(['1']);
      expect(await engine.count('users')).toBe(1);
    });

    it('默认值生效', async () => {
      await engine.insert('users', [{ id: '1', name: 'Alice' }]);
      const rows = await engine.find('users', { table: 'users' });
      expect(rows[0].age).toBe(0);
    });

    it('重复主键抛错', async () => {
      await engine.insert('users', [{ id: '1', name: 'A' }]);
      await expect(engine.insert('users', [{ id: '1', name: 'B' }])).rejects.toThrow('Duplicate primary key');
    });

    it('唯一约束冲突抛错', async () => {
      await engine.insert('users', [{ id: '1', name: 'A', email: 'a@x.com' }]);
      await expect(engine.insert('users', [{ id: '2', name: 'B', email: 'a@x.com' }]))
        .rejects.toThrow('Unique constraint violation');
    });

    it('必填字段校验', async () => {
      await expect(engine.insert('users', [{ id: '1' }])).rejects.toThrow('is required');
    });

    it('批量插入', async () => {
      const pks = await engine.insert('users', [
        { id: '1', name: 'A' }, { id: '2', name: 'B' }, { id: '3', name: 'C' },
      ]);
      expect(pks).toEqual(['1', '2', '3']);
    });
  });

  // ---- 查询 ----

  describe('查询', () => {
    beforeEach(async () => {
      await engine.createTable(userSchema);
      await engine.insert('users', [
        { id: '1', name: 'Alice', age: 30 },
        { id: '2', name: 'Bob', age: 25 },
        { id: '3', name: 'Carol', age: 35 },
      ]);
    });

    it('全表查询', async () => {
      const rows = await engine.find('users', { table: 'users' });
      expect(rows).toHaveLength(3);
    });

    it('WHERE 等值过滤', async () => {
      const rows = await engine.find('users', { table: 'users', where: { name: 'Bob' } });
      expect(rows).toHaveLength(1);
      expect(rows[0].id).toBe('2');
    });

    it('WHERE 操作符', async () => {
      const rows = await engine.find('users', { table: 'users', where: { age: { $gt: 26 } } });
      expect(rows.map((r) => r.id).sort()).toEqual(['1', '3']);
    });

    it('ORDER BY', async () => {
      const rows = await engine.find('users', { table: 'users', orderBy: [{ column: 'age', direction: 'desc' }] });
      expect(rows[0].id).toBe('3');
      expect(rows[2].id).toBe('2');
    });

    it('LIMIT / OFFSET', async () => {
      const rows = await engine.find('users', { table: 'users', limit: 2, offset: 1 });
      expect(rows).toHaveLength(2);
    });

    it('列投影', async () => {
      const rows = await engine.find('users', { table: 'users', columns: ['name'] });
      expect(Object.keys(rows[0])).toEqual(['name']);
    });
  });

  // ---- 更新 ----

  describe('更新', () => {
    beforeEach(async () => {
      await engine.createTable(userSchema);
      await engine.insert('users', [
        { id: '1', name: 'Alice', age: 30 },
        { id: '2', name: 'Bob', age: 25 },
      ]);
    });

    it('按条件更新', async () => {
      const count = await engine.update('users', { table: 'users', where: { id: '1' } }, { age: 31 });
      expect(count).toBe(1);
      const rows = await engine.find('users', { table: 'users', where: { id: '1' } });
      expect(rows[0].age).toBe(31);
    });

    it('无匹配行影响 0 行', async () => {
      const count = await engine.update('users', { table: 'users', where: { id: 'nope' } }, { age: 1 });
      expect(count).toBe(0);
    });

    it('更新主键（旧键删除 + 新键写入）', async () => {
      const count = await engine.update('users', { table: 'users', where: { id: '1' } }, { id: '10', age: 99 });
      expect(count).toBe(1);
      expect(await engine.count('users')).toBe(2);
      const rows = await engine.find('users', { table: 'users', where: { id: '10' } });
      expect(rows[0].age).toBe(99);
      expect(await engine.find('users', { table: 'users', where: { id: '1' } })).toHaveLength(0);
    });

    it('更新持久化：重启后保留', async () => {
      await engine.update('users', { table: 'users', where: { id: '1' } }, { age: 99 });
      await engine.close();

      const engine2 = new KVStoreEngine(new SharedMemoryBackend());
      await engine2.open(dbName, 1);
      const rows = await engine2.find('users', { table: 'users', where: { id: '1' } });
      expect(rows[0].age).toBe(99);
      await engine2.close();
    });
  });

  // ---- 删除 ----

  describe('删除', () => {
    beforeEach(async () => {
      await engine.createTable(userSchema);
      await engine.insert('users', [
        { id: '1', name: 'Alice' }, { id: '2', name: 'Bob' }, { id: '3', name: 'Carol' },
      ]);
    });

    it('按条件删除', async () => {
      const count = await engine.delete('users', { table: 'users', where: { id: '1' } });
      expect(count).toBe(1);
      expect(await engine.count('users')).toBe(2);
    });

    it('删除持久化：重启后保留', async () => {
      await engine.delete('users', { table: 'users', where: { id: '1' } });
      await engine.close();

      const engine2 = new KVStoreEngine(new SharedMemoryBackend());
      await engine2.open(dbName, 1);
      expect(await engine2.count('users')).toBe(2);
      await engine2.close();
    });

    it('级联删除（CASCADE）', async () => {
      const ordersSchema = createSchema('orders', {
        id: { type: 'string', primaryKey: true },
        user_id: { type: 'string', references: 'users.id', onDelete: 'CASCADE' },
      });
      await engine.createTable(ordersSchema);
      await engine.insert('orders', [{ id: 'o1', user_id: '1' }, { id: 'o2', user_id: '2' }]);

      await engine.delete('users', { table: 'users', where: { id: '1' } });
      // 级联：orders 中 user_id=1 的行被删
      expect(await engine.count('orders')).toBe(1);

      // 重启后级联结果持久化
      await engine.close();
      const engine2 = new KVStoreEngine(new SharedMemoryBackend());
      await engine2.open(dbName, 1);
      expect(await engine2.count('users')).toBe(2);
      expect(await engine2.count('orders')).toBe(1);
      await engine2.close();
    });
  });

  // ---- Count ----

  describe('Count', () => {
    beforeEach(async () => {
      await engine.createTable(userSchema);
      await engine.insert('users', [
        { id: '1', name: 'A', age: 10 }, { id: '2', name: 'B', age: 20 }, { id: '3', name: 'C', age: 30 },
      ]);
    });

    it('总数', async () => {
      expect(await engine.count('users')).toBe(3);
    });

    it('条件计数', async () => {
      expect(await engine.count('users', { table: 'users', where: { age: { $gte: 20 } } })).toBe(2);
    });
  });

  // ---- 事务 ----

  describe('事务', () => {
    beforeEach(async () => { await engine.createTable(userSchema); });

    it('commit 后数据可见且持久化', async () => {
      await engine.beginTransaction();
      await engine.insert('users', [{ id: '1', name: 'Alice' }]);
      await engine.commitTransaction();
      expect(await engine.count('users')).toBe(1);

      await engine.close();
      const engine2 = new KVStoreEngine(new SharedMemoryBackend());
      await engine2.open(dbName, 1);
      expect(await engine2.count('users')).toBe(1);
      await engine2.close();
    });

    it('rollback 后数据消失', async () => {
      await engine.beginTransaction();
      await engine.insert('users', [{ id: '1', name: 'Alice' }]);
      await engine.rollbackTransaction();
      expect(await engine.count('users')).toBe(0);
    });

    it('事务内读到自己写入的行', async () => {
      await engine.beginTransaction();
      await engine.insert('users', [{ id: '1', name: 'Alice' }]);
      const rows = await engine.find('users', { table: 'users' });
      expect(rows).toHaveLength(1);
      await engine.rollbackTransaction();
    });

    it('commit 多表原子（全部生效或全部不生效）', async () => {
      await engine.createTable(createSchema('orders', {
        id: { type: 'string', primaryKey: true },
        user_id: { type: 'string' },
      }));
      await engine.beginTransaction();
      await engine.insert('users', [{ id: '1', name: 'Alice' }]);
      await engine.insert('orders', [{ id: 'o1', user_id: '1' }]);
      await engine.commitTransaction();

      await engine.close();
      const engine2 = new KVStoreEngine(new SharedMemoryBackend());
      await engine2.open(dbName, 1);
      expect(await engine2.count('users')).toBe(1);
      expect(await engine2.count('orders')).toBe(1);
      await engine2.close();
    });

    it('事务中 DDL 支持（create/drop 随 commit 生效）', async () => {
      const txSchema = createSchema('tx_users', {
        id: { type: 'string', primaryKey: true },
        name: { type: 'string' },
      });
      await engine.beginTransaction();
      await engine.createTable(txSchema);
      await engine.insert('tx_users', [{ id: '1', name: 'A' }]);
      await engine.commitTransaction();
      expect(await engine.hasTable('tx_users')).toBe(true);
      expect(await engine.count('tx_users')).toBe(1);

      // 事务中 drop 表
      await engine.beginTransaction();
      await engine.dropTable('tx_users');
      await engine.commitTransaction();
      expect(await engine.hasTable('tx_users')).toBe(false);

      // 重启后 drop 生效（KV 残留清理）
      await engine.close();
      const engine2 = new KVStoreEngine(new SharedMemoryBackend());
      await engine2.open(dbName, 1);
      expect(await engine2.hasTable('tx_users')).toBe(false);
      await engine2.close();
    });
  });

  // ---- 持久化与崩溃恢复 ----

  describe('持久化与崩溃恢复', () => {
    it('未 checkpoint 数据重启后经日志重放恢复', async () => {
      await engine.createTable(userSchema);
      await engine.insert('users', [
        { id: '1', name: 'Alice', age: 30 },
        { id: '2', name: 'Bob', age: 25 },
      ]);
      await engine.close(); // 模拟"崩溃后重开"（未 checkpoint，数据在 KVStore 日志）

      const engine2 = new KVStoreEngine(new SharedMemoryBackend());
      await engine2.open(dbName, 1);
      expect(await engine2.count('users')).toBe(2);
      const rows = await engine2.find('users', { table: 'users' });
      expect(rows.map((r) => r.id).sort()).toEqual(['1', '2']);
      await engine2.close();
    });

    it('checkpoint 后重启（快照恢复）', async () => {
      await engine.createTable(userSchema);
      await engine.insert('users', [{ id: '1', name: 'Alice' }]);
      await (engine as any).kv.checkpoint();
      await engine.insert('users', [{ id: '2', name: 'Bob' }]);
      await engine.close();

      const engine2 = new KVStoreEngine(new SharedMemoryBackend());
      await engine2.open(dbName, 1);
      expect(await engine2.count('users')).toBe(2);
      await engine2.close();
    });

    it('索引列跨重启恢复（查询走索引）', async () => {
      const idxSchema = createSchema('items', {
        id: { type: 'string', primaryKey: true },
        tag: { type: 'string', index: true },
      });
      await engine.createTable(idxSchema);
      await engine.insert('items', [
        { id: '1', tag: 'a' }, { id: '2', tag: 'b' }, { id: '3', tag: 'a' },
      ]);
      await engine.close();

      const engine2 = new KVStoreEngine(new SharedMemoryBackend());
      await engine2.open(dbName, 1);
      const rows = await engine2.find('items', { table: 'items', where: { tag: 'a' } });
      expect(rows).toHaveLength(2);
      await engine2.close();
    });

    it('CREATE INDEX 持久化（重启后索引保留）', async () => {
      await engine.createTable(userSchema);
      await engine.insert('users', [{ id: '1', name: 'Alice', age: 30 }]);
      await engine.createIndex('users', 'name');
      await engine.close();

      const engine2 = new KVStoreEngine(new SharedMemoryBackend());
      await engine2.open(dbName, 1);
      const schema = await engine2.getTableSchema('users');
      expect(schema!.columns.name.index).toBe(true);
      const rows = await engine2.find('users', { table: 'users', where: { name: 'Alice' } });
      expect(rows).toHaveLength(1);
      await engine2.close();
    });

    it('ALTER TABLE ADD/DROP 持久化', async () => {
      await engine.createTable(userSchema);
      await engine.insert('users', [{ id: '1', name: 'Alice', age: 30 }]);
      await engine.alterTable('users', 'ADD', { name: 'phone', type: 'string' });
      await engine.alterTable('users', 'DROP', { name: 'age', type: 'number' });
      await engine.close();

      const engine2 = new KVStoreEngine(new SharedMemoryBackend());
      await engine2.open(dbName, 1);
      const schema = await engine2.getTableSchema('users');
      expect(schema!.columns.phone).toBeDefined();
      expect(schema!.columns.age).toBeUndefined();
      const rows = await engine2.find('users', { table: 'users' });
      expect(rows[0].phone).toBeUndefined();
      expect(rows[0].age).toBeUndefined();
      await engine2.close();
    });

    it('元数据 getMeta/setMeta 持久化', async () => {
      await engine.setMeta('__metona_version', '3');
      await engine.close();

      const engine2 = new KVStoreEngine(new SharedMemoryBackend());
      await engine2.open(dbName, 1);
      expect(await engine2.getMeta('__metona_version')).toBe('3');
      await engine2.close();
    });

    it('数据损坏自愈：日志损坏 → open 不崩，repair 截断', async () => {
      await engine.createTable(userSchema);
      await engine.insert('users', [{ id: '1', name: 'Alice' }]);
      await engine.close();

      // 篡改日志尾部 CRC（模拟最后一条记录写入中断）
      const medium = new SharedMemoryBackend();
      await medium.open(dbName);
      const log = await medium.read('__kv_log');
      expect(log).not.toBeNull();
      const corrupted = new Uint8Array(log as ArrayBuffer);
      corrupted[corrupted.byteLength - 5] ^= 0xff;
      await medium.write('__kv_log', corrupted.buffer as ArrayBuffer);

      const engine2 = new KVStoreEngine(new SharedMemoryBackend());
      await engine2.open(dbName, 1); // 损坏尾部截断，打开不崩
      expect(await engine2.hasTable('users')).toBe(true);
      await engine2.repair();
      expect(await engine2.hasTable('users')).toBe(true);
      // repair 后新写入正常
      await engine2.insert('users', [{ id: '2', name: 'Bob' }]);
      expect(await engine2.count('users')).toBeGreaterThanOrEqual(1);
      await engine2.close();
    });
  });

  // ---- 流式查询 ----

  describe('流式查询', () => {
    beforeEach(async () => {
      await engine.createTable(userSchema);
      await engine.insert('users', [
        { id: '1', name: 'A' }, { id: '2', name: 'B' }, { id: '3', name: 'C' },
      ]);
    });

    it('findStream 逐行回调', async () => {
      const rows: Record<string, unknown>[] = [];
      const count = await engine.findStream!('users', { table: 'users' }, (r) => rows.push(r));
      expect(count).toBe(3);
      expect(rows.map((r) => r.id).sort()).toEqual(['1', '2', '3']);
    });
  });
});