/**
 * AriaEngine ANALYZE / VACUUM / REINDEX + EXPLAIN 测试
 * 全部 MemoryBackend，零卡死
 */
import { AriaEngine } from '../../src/engine/aria/index';
import { createSchema } from '../../src/table/schema';
import { QueryExecutor } from '../../src/query/executor';
import { parse } from '../../src/sql/parser';

describe('AriaEngine — ANALYZE/VACUUM/REINDEX + EXPLAIN', () => {
  let engine: AriaEngine;

  beforeEach(async () => {
    engine = new AriaEngine({ storageBackend: 'memory' });
    await engine.open('maint-test', 1);
    await engine.createTable(createSchema('users', {
      id: { type: 'string', primaryKey: true },
      name: { type: 'string', index: true },
      age: { type: 'number', default: 0 },
    }));
    await engine.insert('users', [
      { id: '1', name: 'Alice', age: 30 },
      { id: '2', name: 'Bob', age: 25 },
      { id: '3', name: 'Charlie', age: 35 },
    ]);
  });

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

  // ---- ANALYZE ----
  it('ANALYZE 返回表统计信息', async () => {
    const stats = await (engine as any).analyzeTable('users');
    expect(stats.table).toBe('users');
    expect(stats.rowCount).toBe(3);
    expect(stats.avgRowSize).toBeGreaterThan(0);
    expect(stats.indexDepth).toBeGreaterThanOrEqual(0);
    expect(stats.sstableCount).toBeGreaterThanOrEqual(0);
  });

  it('ANALYZE 包含列基数统计', async () => {
    const stats = await (engine as any).analyzeTable('users');
    expect(stats.columnStats).toBeDefined();
    expect(stats.columnStats.name.distinctValues).toBe(3);
    expect(stats.columnStats.age.distinctValues).toBe(3);
  });

  it('ANALYZE 空表返回 rowCount=0', async () => {
    await engine.createTable(createSchema('empty', { id: { type: 'string', primaryKey: true } }));
    const stats = await (engine as any).analyzeTable('empty');
    expect(stats.rowCount).toBe(0);
  });

  // ---- REINDEX ----
  it('REINDEX 重建索引后查询正常', async () => {
    const count = await (engine as any).reindexTable('users');
    expect(count).toBeGreaterThanOrEqual(1);
    const rows = await engine.find('users', { table: 'users', where: { name: 'Alice' } });
    expect(rows).toHaveLength(1);
  });

  it('REINDEX 不存在的表抛出错误', async () => {
    await expect((engine as any).reindexTable('ghost')).rejects.toThrow('does not exist');
  });

  // ---- VACUUM ----
  it('VACUUM 返回压缩统计', async () => {
    const result = await (engine as any).vacuum();
    expect(result).toHaveProperty('compactedLevels');
    expect(result).toHaveProperty('gcVersions');
  });

  // ---- EXPLAIN ----
  it('EXPLAIN SELECT 输出查询计划', async () => {
    const executor = new QueryExecutor(engine);
    const selectStmt = parse('SELECT * FROM users WHERE id = \'1\'');
    const explainStmt: any = { type: 'EXPLAIN', query: selectStmt };
    const plan = await executor.execute(explainStmt);
    expect(plan.type).toBe('SELECT');
    expect(plan.table).toBe('users');
    expect(plan.usingIndex).toBeDefined();
    expect(plan.actualTimeMs).toBeGreaterThanOrEqual(0);
  });

  // ---- 查询优化器 ----
  it('estimateQueryCost PK 等值 → pk_lookup', () => {
    const cost = (engine as any).estimateQueryCost('users', { table: 'users', where: { id: '1' } });
    expect(cost.strategy).toBe('pk_lookup');
    expect(cost.estimatedRows).toBe(1);
  });

  it('estimateQueryCost 索引等值 → index_eq', () => {
    const cost = (engine as any).estimateQueryCost('users', { table: 'users', where: { name: 'Alice' } });
    expect(cost.strategy).toBe('index_eq:name');
  });

  it('estimateQueryCost 无索引 → full_scan', () => {
    const cost = (engine as any).estimateQueryCost('users', { table: 'users', where: { age: { $gt: 20 } } });
    expect(cost.strategy).toMatch(/index_range|full_scan/);
  });

  // ---- 在线备份 ----
  it('backup 导出全库一致性快照', async () => {
    const backup = await (engine as any).backup();
    expect(backup.users).toHaveLength(3);
    expect(backup.users[0]).toHaveProperty('id');
    expect(backup.users[0]).toHaveProperty('name');
  });
});