/**
 * v0.4.4 回归测试 — SSTable 编码缺陷修复
 * 覆盖：
 * - P0: 大段中文内容（300KB）写入 aria → flush → close → reopen 数据完整（缓冲区低估越界）
 * - P0: >64KB value（u16 长度截断）
 * - P0: 大 value 超过块大小（4096）→ 单条独立成块读取正确
 * - P1: v1 旧格式文件兼容读取（旧库数据不丢）
 * - P1: 中文 key / 混合条目
 */

import { AriaEngine } from '../src/engine/aria/index';
import { createSchema } from '../src/table/schema';
import { SSTableBuilder } from '../src/engine/aria/index/sstable_builder';
import { SSTableReader } from '../src/engine/aria/index/sstable';
import type { SSTableMeta } from '../src/engine/aria/types';

import { resetOPFSMock } from './helpers/storage-harness';

beforeEach(() => { resetOPFSMock(); });

let idbCounter = 0;
function uniqueDB(): string {
  return `r45-${Date.now()}-${++idbCounter}-${Math.random().toString(36).slice(2, 8)}`;
}

const makeMeta = (data: Uint8Array): SSTableMeta => ({
  id: 1, level: 0, minKey: '', maxKey: '\uffff',
  blockCount: 1, totalSize: data.byteLength, bloomData: null,
});

/** 300KB 中文内容（模拟真实笔记/文档数据） */
function makeBigChineseContent(size = 300 * 1024): string {
  const chunk = '这是一段用于测试的中文内容。数据持久化必须正确处理 UTF-8 多字节编码！';
  return chunk.repeat(Math.ceil(size / chunk.length)).slice(0, size);
}

// ===================================================================
//  P0: 大内容编码（builder 字节估算）
// ===================================================================

describe('P0 — SSTable 编码：UTF-8 字节估算', () => {
  it('构建含 300KB 中文内容的 SSTable 不越界，可完整读回', () => {
    const builder = new SSTableBuilder(4096);
    const content = makeBigChineseContent();
    builder.add('note:1', { id: '1', title: '长文笔记', body: content });
    builder.add('note:2', { id: '2', body: '小内容' });
    const { sstableData } = builder.build();
    // 修复前：缓冲区低估 → build 抛 RangeError
    const reader = new SSTableReader(sstableData, makeMeta(sstableData));
    const note1 = reader.get('note:1');
    expect(note1).not.toBeNull();
    expect((note1 as any).body).toBe(content);
    expect((note1 as any).body.length).toBe(content.length);
  });

  it('构建含 >64KB value 的 SSTable（u32 长度字段，修复前 u16 截断）', () => {
    const builder = new SSTableBuilder(4096);
    const content = makeBigChineseContent(70 * 1024); // 70KB > 64KB
    builder.add('doc:big', { id: 'big', data: content });
    builder.add('doc:small', { id: 'small', data: 'x' });
    const { sstableData } = builder.build();
    const reader = new SSTableReader(sstableData, makeMeta(sstableData));
    const big = reader.get('doc:big');
    expect((big as any).data).toBe(content);
    expect((reader.get('doc:small') as any).data).toBe('x');
  });

  it('大 value（>4096 块大小）单条独立成块，scanAll/get 均正确', () => {
    const builder = new SSTableBuilder(64); // 极小块阈值
    const big = makeBigChineseContent(8 * 1024);
    for (let i = 0; i < 5; i++) {
      builder.add(`k-${i}`, { v: i, body: i === 2 ? big : 'small' });
    }
    const { sstableData, indexEntries } = builder.build();
    // 大条目独立成块（块数 > 1）
    expect(indexEntries.length).toBeGreaterThan(1);
    const reader = new SSTableReader(sstableData, makeMeta(sstableData));
    const collected: string[] = [];
    reader.scanAll((k) => collected.push(k));
    expect(collected).toEqual(['k-0', 'k-1', 'k-2', 'k-3', 'k-4']);
    expect((reader.get('k-2') as any).body).toBe(big);
  });

  it('中文 key（多字节）与混合条目', () => {
    const builder = new SSTableBuilder(4096);
    builder.add('表:笔记一', { 标题: '中文标题', 内容: '内容' });
    builder.add('表:笔记二', { 标题: '第二篇' });
    const { sstableData } = builder.build();
    const reader = new SSTableReader(sstableData, makeMeta(sstableData));
    expect((reader.get('表:笔记一') as any)['标题']).toBe('中文标题');
    expect((reader.get('表:笔记二') as any)['标题']).toBe('第二篇');
  });

  it('v2 魔数写入正确（SSTC）', () => {
    const builder = new SSTableBuilder(4096);
    builder.add('a', { v: 1 });
    const { sstableData } = builder.build();
    const magic = new DataView(sstableData.buffer, sstableData.byteOffset, sstableData.byteLength)
      .getUint32(sstableData.byteLength - 8, false);
    expect(magic).toBe(0x53535443); // "SSTC"
  });
});

// ===================================================================
//  P1: v1 旧格式兼容
// ===================================================================

describe('P1 — v1 旧格式兼容', () => {
  /** 手工构造 v1 格式（keyLen/valueLen u16 + magic SSTB） */
  function buildV1SSTable(entries: [string, Record<string, unknown>][]): Uint8Array {
    const enc = new TextEncoder();
    const encoded = entries.map(([k, v]) => ({ key: k, keyBytes: enc.encode(k), valueBytes: enc.encode(JSON.stringify(v)) }));
    // 块（全部放一个块）
    const entryCount = entries.length;
    let blockSize = 4;
    for (const e of encoded) blockSize += 2 + e.keyBytes.length + 2 + e.valueBytes.length;
    const indexSize = 4 + 2 + encoded[encoded.length - 1].keyBytes.length + 8;
    const _bloomSize = 0;
    const total = blockSize + indexSize + 32;
    const buf = new ArrayBuffer(total);
    const view = new DataView(buf);
    let offset = 0;
    view.setUint32(offset, entryCount, false); offset += 4;
    for (const e of encoded) {
      view.setUint16(offset, e.keyBytes.length, false); offset += 2;
      new Uint8Array(buf).set(e.keyBytes, offset); offset += e.keyBytes.length;
      view.setUint16(offset, e.valueBytes.length, false); offset += 2;
      new Uint8Array(buf).set(e.valueBytes, offset); offset += e.valueBytes.length;
    }
    const indexOffset = offset;
    view.setUint32(offset, 1, false); offset += 4;
    const last = encoded[encoded.length - 1];
    view.setUint16(offset, last.keyBytes.length, false); offset += 2;
    new Uint8Array(buf).set(last.keyBytes, offset); offset += last.keyBytes.length;
    view.setUint32(offset, 0, false); offset += 4;
    view.setUint32(offset, blockSize, false); offset += 4;
    const footer = offset;
    view.setUint32(footer, indexOffset, false);
    view.setUint32(footer + 4, indexSize, false);
    view.setUint32(footer + 8, 0, false);      // bloom_offset
    view.setUint32(footer + 12, 0, false);     // bloom_size
    view.setUint32(footer + 16, 0, false);     // hash_count
    view.setUint32(footer + 20, entryCount, false);
    view.setUint32(footer + 24, 0x53535442, false); // SSTB
    view.setUint32(footer + 28, 0, false);
    return new Uint8Array(buf);
  }

  it('v1 格式文件可读（旧库数据不丢）', () => {
    const v1 = buildV1SSTable([
      ['u:1', { name: 'Alice', age: 30 }],
      ['u:2', { name: 'Bob', age: 25 }],
    ]);
    const reader = new SSTableReader(v1, makeMeta(v1));
    expect((reader.get('u:1') as any).name).toBe('Alice');
    expect((reader.get('u:2') as any).name).toBe('Bob');
    const keys: string[] = [];
    reader.scanAll((k) => keys.push(k));
    expect(keys).toEqual(['u:1', 'u:2']);
  });
});

// ===================================================================
//  P0: 端到端 — 大内容跨重启（爸爸 Electron 冒烟场景）
// ===================================================================

describe('P0 — 大内容端到端（aria 模式）', () => {
  it('300KB 中文写入 → close → reopen 数据完整（修复前打开必崩）', async () => {
    const dbName = uniqueDB();
    const engine = new AriaEngine({ storageBackend: 'opfs', checkpointInterval: 100000 });
    await engine.open(dbName, 1);
    await engine.createTable(createSchema('notes', {
      id: { type: 'string', primaryKey: true },
      title: { type: 'string' },
      body: { type: 'string' },
    }));

    const content = makeBigChineseContent();
    await engine.insert('notes', [
      { id: 'n1', title: '长文', body: content },
      { id: 'n2', title: '短文', body: 'hello' },
    ]);
    // 强制落盘（修复前：flush 编码越界崩溃）
    await (engine as any).lsm.flush();
    await engine.close();

    // 修复前：打开解析半写文件 → ARIA_OPEN_ERROR
    const engine2 = new AriaEngine({ storageBackend: 'opfs', checkpointInterval: 100000 });
    await expect(engine2.open(dbName, 1)).resolves.toBeUndefined();
    const rows = await engine2.find('notes', { table: 'notes' });
    expect(rows).toHaveLength(2);
    const byId = Object.fromEntries(rows.map((r) => [r.id, r]));
    expect(byId['n1'].body).toBe(content);
    expect(byId['n1'].body.length).toBe(content.length);
    expect(byId['n2'].body).toBe('hello');
    await engine2.close();
  });

  it('多行 >64KB 内容批量写入重开完整（含索引列）', async () => {
    const dbName = uniqueDB();
    const engine = new AriaEngine({
      storageBackend: 'opfs',
      memtableSizeThreshold: 32 * 1024,
      checkpointInterval: 100000,
    });
    await engine.open(dbName, 1);
    await engine.createTable(createSchema('docs', {
      id: { type: 'string', primaryKey: true },
      tag: { type: 'string', index: true },
      body: { type: 'string' },
    }));
    const contents: string[] = [];
    for (let i = 0; i < 10; i++) {
      const c = makeBigChineseContent(70 * 1024 + i * 100);
      contents.push(c);
      await engine.insert('docs', [{ id: `d${i}`, tag: i % 2 === 0 ? 'even' : 'odd', body: c }]);
    }
    await engine.close();

    const engine2 = new AriaEngine({ storageBackend: 'opfs', checkpointInterval: 100000 });
    await engine2.open(dbName, 1);
    expect(await engine2.count('docs')).toBe(10);
    const evens = await engine2.find('docs', { table: 'docs', where: { tag: 'even' } });
    expect(evens).toHaveLength(5);
    for (let i = 0; i < 10; i++) {
      const rows = await engine2.find('docs', { table: 'docs', where: { id: `d${i}` } });
      expect(rows[0].body).toBe(contents[i]);
    }
    await engine2.close();
  });
});