/**
 * 行所有权（row ownership）工具测试
 *
 * 背景（审计 A 类缺陷）：Memory/KVStore/Hybrid 曾把内部行对象直接交给调用方，
 * 调用方一次原地修改就能改写存储、让索引与行失配（改过的行再也查不出来）。
 * `cloneRow`/`cloneRows` 是这条不变量的唯一实现。
 *
 * v0.8.0 审查：这三个函数原本放在 `engine/interface.ts`（被描述为"纯类型、
 * 不纳入覆盖率"）→ 真实实现代码逃过覆盖率统计。搬到 `engine/row_clone.ts` 后
 * 覆盖率立刻暴露：退化路径（`cloneRowFallback`，即 `structuredClone` 不可用/
 * 抛错时的逐层复制）**从未被测试**。本文件补上这两条路径。
 */
import { describe, it, expect, afterEach } from '@jest/globals';
import { cloneRow, cloneRows } from '../../src/engine/row_clone';

const originalStructuredClone = (globalThis as { structuredClone?: unknown }).structuredClone;

afterEach(() => {
  (globalThis as { structuredClone?: unknown }).structuredClone = originalStructuredClone;
});

describe('cloneRow — structuredClone 可用', () => {
  it('深拷贝普通对象与嵌套结构，修改副本不影响源对象', () => {
    const source = { id: 'a', v: 1, nested: { deep: [1, 2, { x: true }] } };
    const copy = cloneRow(source);
    expect(copy).toEqual(source);
    expect(copy).not.toBe(source);
    expect(copy.nested).not.toBe(source.nested);
    copy.nested.deep.push(99);
    copy.v = 42;
    expect(source.v).toBe(1);
    expect(source.nested.deep).toHaveLength(3);
  });

  it('JSON 安全值深拷贝且逐层独立（行的实际契约）', () => {
    // 引擎的读路径只承载 validateRow 之后的 JSON 安全值 —— `date` 列在 schema 层
    // 就要求**字符串**（`src/table/validation.ts` 的 'date' 分支），因此行里不会
    // 出现 Date 实例。这里断言的是真实契约：值相等 + 逐层不共享引用。
    // （不在此处断言 Date 语义：jsdom 的 structuredClone 是 JSON 化的 polyfill，
    //   会把 Date 变成字符串；真实浏览器/Node 的 structuredClone 保留 Date，
    //   而退化路径的实现也显式保留 —— 见下方 fallback 用例。）
    const source = { id: 'a', when: '2026-09-15T00:00:00.000Z', nested: { k: [1, 2] } };
    const copy = cloneRow(source);
    expect(copy).toEqual(source);
    expect(copy.nested.k).not.toBe(source.nested.k);
    copy.nested.k.push(3);
    expect(source.nested.k).toEqual([1, 2]);
  });

  it('非对象输入原样返回（null / 数字 / 字符串不参与拷贝）', () => {
    expect(cloneRow(null as never)).toBeNull();
    expect(cloneRow(7 as never)).toBe(7);
    expect(cloneRow('x' as never)).toBe('x');
  });
});

describe('cloneRow — structuredClone 不可用（退化路径）', () => {
  it('无 structuredClone 时逐层复制：嵌套对象 / 数组 / Date / TypedArray / ArrayBuffer', () => {
    (globalThis as { structuredClone?: unknown }).structuredClone = undefined;
    const source = {
      id: 'a',
      nested: { list: [1, { k: 'v' }] },
      when: new Date('2026-01-02T03:04:05.000Z'),
      bytes: new Uint8Array([1, 2, 3]),
      raw: new Uint8Array([9, 8]).buffer,
      plain: 'str',
      num: 5,
      flag: false,
      nil: null,
    };
    const copy = cloneRow(source);

    expect(copy).toEqual(source);
    expect(copy).not.toBe(source);
    expect(copy.nested).not.toBe(source.nested);
    expect(copy.nested.list).not.toBe(source.nested.list);
    expect(copy.when).toBeInstanceOf(Date);
    expect(copy.when.getTime()).toBe(source.when.getTime());
    expect(copy.bytes).toBeInstanceOf(Uint8Array);
    expect(Array.from(copy.bytes)).toEqual([1, 2, 3]);
    expect(copy.bytes).not.toBe(source.bytes);
    expect(copy.raw).toBeInstanceOf(ArrayBuffer);
    expect(copy.raw).not.toBe(source.raw);
    expect(new Uint8Array(copy.raw as ArrayBuffer)).toEqual(new Uint8Array([9, 8]));

    // 深拷贝语义：改副本不影响源
    copy.nested.list.push({ k: 'mutated' });
    (copy.bytes as Uint8Array)[0] = 99;
    expect(source.nested.list).toHaveLength(2);
    expect(source.bytes[0]).toBe(1);
  });

  it('structuredClone 抛错（含不可克隆值）时也退化到逐层复制', () => {
    (globalThis as { structuredClone?: unknown }).structuredClone = () => {
      throw new Error('could not be cloned');
    };
    const fn = (): number => 1;
    const source = { id: 'a', fn, nested: { k: 1 } };
    const copy = cloneRow(source);
    expect(copy.id).toBe('a');
    expect(copy.fn).toBe(fn);              // 函数按引用保留（不可克隆值的合理退化）
    expect(copy.nested).toEqual({ k: 1 });
    expect(copy.nested).not.toBe(source.nested);
  });

  it('退化路径对原始值同样原样返回', () => {
    (globalThis as { structuredClone?: unknown }).structuredClone = undefined;
    expect(cloneRow(null as never)).toBeNull();
    expect(cloneRow(3 as never)).toBe(3);
  });
});

describe('cloneRows — 批量拷贝', () => {
  it('每行都是独立副本（改一行不影响其它行，也不影响源数组）', () => {
    const rows = [{ id: 'a', tags: ['x'] }, { id: 'b', tags: ['y'] }];
    const copies = cloneRows(rows);
    expect(copies).toEqual(rows);
    expect(copies).toHaveLength(2);
    copies[0].tags.push('mutated');
    expect(rows[0].tags).toEqual(['x']);
    expect(copies[0]).not.toBe(rows[0]);
    expect(copies[1]).not.toBe(rows[1]);
  });

  it('退化路径同样逐行深拷贝', () => {
    (globalThis as { structuredClone?: unknown }).structuredClone = undefined;
    const rows = [{ id: 'a', nested: { k: 1 } }];
    const copies = cloneRows(rows);
    copies[0].nested.k = 2;
    expect(rows[0].nested.k).toBe(1);
  });
});