/**
 * AriaEngine SSTable Builder + Reader 单元测试
 */
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';

// ===================================================================
//  SSTable Builder + Reader
// ===================================================================
describe('AriaEngine — SSTable Builder + Reader', () => {
  const makeMeta = (data: Uint8Array): SSTableMeta => ({
    id: 1, level: 0, minKey: '', maxKey: '\uffff',
    blockCount: 1, totalSize: data.byteLength, bloomData: null,
  });

  it('构建单条目 SSTable 并精确读取', () => {
    const builder = new SSTableBuilder(4096);
    builder.add('key1', { name: 'Alice', age: 30 });
    const { sstableData } = builder.build();

    const reader = new SSTableReader(sstableData, makeMeta(sstableData));
    const result = reader.get('key1');
    expect(result).not.toBeNull();
    expect(result!.name).toBe('Alice');
    expect(result!.age).toBe(30);
  });

  it('构建多条 SSTable 并全部读取', () => {
    const builder = new SSTableBuilder(4096);
    const items: [string, Record<string, unknown>][] = [];
    for (let i = 0; i < 100; i++) {
      const key = `user-${String(i).padStart(3, '0')}`;
      const value = { idx: i, name: `User${i}` };
      items.push([key, value]);
      builder.add(key, value);
    }
    const { sstableData } = builder.build();

    const reader = new SSTableReader(sstableData, makeMeta(sstableData));
    for (const [key, value] of items) {
      const result = reader.get(key);
      expect(result).not.toBeNull();
      expect(result!.idx).toBe(value.idx);
    }
  });

  it('get — 不存在的 key 返回 null', () => {
    const builder = new SSTableBuilder(4096);
    builder.add('a', { v: 1 });
    const { sstableData } = builder.build();

    const reader = new SSTableReader(sstableData, makeMeta(sstableData));
    expect(reader.get('nonexistent')).toBeNull();
  });

  it('rangeScan — 范围查询', () => {
    const builder = new SSTableBuilder(4096);
    for (let i = 0; i < 20; i++) {
      builder.add(`k-${String(i).padStart(2, '0')}`, { v: i });
    }
    const { sstableData } = builder.build();

    const reader = new SSTableReader(sstableData, makeMeta(sstableData));
    const results: [string, Record<string, unknown>][] = [];
    reader.rangeScan('k-05', 'k-10', (k, v) => results.push([k, v]));
    expect(results).toHaveLength(6);
    expect(results[0][0]).toBe('k-05');
    expect(results[results.length - 1][0]).toBe('k-10');
  });

  it('scanAll — 遍历所有条目', () => {
    const builder = new SSTableBuilder(4096);
    const count = 50;
    for (let i = 0; i < count; i++) {
      builder.add(`item-${i}`, { idx: i });
    }
    const { sstableData } = builder.build();

    const reader = new SSTableReader(sstableData, makeMeta(sstableData));
    const items: [string, Record<string, unknown>][] = [];
    reader.scanAll((k, v) => items.push([k, v]));
    expect(items).toHaveLength(count);
  });


  it('边界 — 空 SSTable 不抛异常', () => {
    const builder = new SSTableBuilder(4096);
    const { sstableData } = builder.build();

    const reader = new SSTableReader(sstableData, makeMeta(sstableData));
    expect(reader.get('any')).toBeNull();
    const results: [string, Record<string, unknown>][] = [];
    reader.scanAll((k, v) => results.push([k, v]));
    expect(results).toHaveLength(0);
  });

  it('带特殊字符的 key', () => {
    const builder = new SSTableBuilder(4096);
    // 必须按键排序添加（按 ASCII 排序：空格 < 短横 < 点号）
    builder.add('key with space', { v: 3 });
    builder.add('key-with-dash', { v: 1 });
    builder.add('key.with.dot', { v: 2 });
    const { sstableData } = builder.build();

    const reader = new SSTableReader(sstableData, makeMeta(sstableData));
    expect(reader.get('key-with-dash')!.v).toBe(1);
    expect(reader.get('key.with.dot')!.v).toBe(2);
    expect(reader.get('key with space')!.v).toBe(3);
  });

  it('getEntryCount 返回正确条目数', () => {
    const builder = new SSTableBuilder(4096);
    builder.add('a', { v: 1 });
    builder.add('b', { v: 2 });
    builder.add('c', { v: 3 });
    expect(builder.getEntryCount()).toBe(3);
  });
});

// ===================================================================
//  v0.4.5: 整文件 CRC-32 校验
// ===================================================================
describe('AriaEngine — SSTable CRC-32 校验', () => {
  const makeMeta = (data: Uint8Array): SSTableMeta => ({
    id: 1, level: 0, minKey: '', maxKey: '\uffff',
    blockCount: 1, totalSize: data.byteLength, bloomData: null,
  });

  it('新构建的 SSTable 写入真实非零 checksum', () => {
    const builder = new SSTableBuilder(4096);
    builder.add('key1', { name: 'Alice' });
    const { sstableData } = builder.build();

    const reader = new SSTableReader(sstableData, makeMeta(sstableData));
    // footer 最后 4 字节为真实 checksum（非 0）
    const stored = new DataView(sstableData.buffer, sstableData.byteOffset + sstableData.byteLength - 4, 4).getUint32(0, false);
    expect(stored).not.toBe(0);
    expect(reader.verifyChecksum()).toBe(true);
  });

  it('正常文件校验通过后可正常读取', () => {
    const builder = new SSTableBuilder(4096);
    for (let i = 0; i < 50; i++) builder.add(`k-${i}`, { v: i });
    const { sstableData } = builder.build();

    const reader = new SSTableReader(sstableData, makeMeta(sstableData));
    expect(reader.verifyChecksum()).toBe(true);
    expect(reader.get('k-30')).toEqual({ v: 30 });
  });

  it('数据块字节篡改 → 校验失败', () => {
    const builder = new SSTableBuilder(4096);
    for (let i = 0; i < 50; i++) builder.add(`k-${i}`, { v: i, pad: 'x'.repeat(64) });
    const { sstableData } = builder.build();

    // 篡改数据区中部一个字节（非 footer）
    const corrupted = new Uint8Array(sstableData);
    corrupted[Math.floor(corrupted.length / 2)] ^= 0xff;

    const reader = new SSTableReader(corrupted, makeMeta(corrupted));
    // 结构仍可解析（长度一致），但 CRC 必须失败
    const stored = new DataView(corrupted.buffer, corrupted.byteOffset + corrupted.byteLength - 4, 4).getUint32(0, false);
    expect(stored).not.toBe(0);
    expect(reader.verifyChecksum()).toBe(false);
  });

  it('索引块字节篡改 → 校验失败', () => {
    const builder = new SSTableBuilder(4096);
    for (let i = 0; i < 20; i++) builder.add(`k-${i}`, { v: i });
    const { sstableData } = builder.build();

    // 从 footer 反推索引块位置并篡改
    const footerOffset = sstableData.byteLength - 32;
    const view = new DataView(sstableData.buffer, sstableData.byteOffset, sstableData.byteLength);
    const indexOffset = view.getUint32(footerOffset, false);
    const corrupted = new Uint8Array(sstableData);
    corrupted[indexOffset + 8] ^= 0x01;

    const reader = new SSTableReader(corrupted, makeMeta(corrupted));
    expect(reader.verifyChecksum()).toBe(false);
  });

  it('旧版文件（checksum=0）跳过校验，保持兼容', () => {
    const builder = new SSTableBuilder(4096);
    builder.add('legacy', { v: 1 });
    const { sstableData } = builder.build();

    // 手工把 checksum 字段清零，模拟旧版写入产物
    const legacy = new Uint8Array(sstableData);
    new DataView(legacy.buffer).setUint32(legacy.byteLength - 4, 0, false);

    const reader = new SSTableReader(legacy, makeMeta(legacy));
    const stored = new DataView(legacy.buffer, legacy.byteOffset + legacy.byteLength - 4, 4).getUint32(0, false);
    expect(stored).toBe(0);
    expect(reader.verifyChecksum()).toBe(true); // 跳过校验
    expect(reader.get('legacy')).toEqual({ v: 1 }); // 数据仍可读
  });

  it('v1 旧格式文件（magic SSTB，checksum=0）校验通过且可读', () => {
    // 手工构造 v1 格式最小文件：单条记录 + 索引 + footer（magic SSTB, checksum 0）
    const encoder = new TextEncoder();
    const keyBytes = encoder.encode('old-key');
    const valBytes = encoder.encode(JSON.stringify({ v: 42 }));

    // data block: entryCount(u32)=1 + keyLen(u16)+key + valLen(u16)+val
    const block = new ArrayBuffer(4 + 2 + keyBytes.length + 2 + valBytes.length);
    const bv = new DataView(block);
    let off = 0;
    bv.setUint32(off, 1, false); off += 4;
    bv.setUint16(off, keyBytes.length, false); off += 2;
    new Uint8Array(block).set(keyBytes, off); off += keyBytes.length;
    bv.setUint16(off, valBytes.length, false); off += 2;
    new Uint8Array(block).set(valBytes, off); off += valBytes.length;

    // index block: entryCount(u32)=1 + keyLen(u16)+key + blockOffset(u32) + blockSize(u32)
    const blockSize = block.byteLength;
    const idxKey = encoder.encode('old-key');
    const idxBlock = new ArrayBuffer(4 + 2 + idxKey.length + 4 + 4);
    const iv = new DataView(idxBlock);
    let ioff = 0;
    iv.setUint32(ioff, 1, false); ioff += 4;
    iv.setUint16(ioff, idxKey.length, false); ioff += 2;
    new Uint8Array(idxBlock).set(idxKey, ioff); ioff += idxKey.length;
    iv.setUint32(ioff, 0, false); ioff += 4;      // blockOffset = 0
    iv.setUint32(ioff, blockSize, false); ioff += 4;

    const footerSize = 32;
    const total = block.byteLength + idxBlock.byteLength + footerSize;
    const file = new ArrayBuffer(total);
    const fv = new DataView(file);
    new Uint8Array(file).set(new Uint8Array(block), 0);
    new Uint8Array(file).set(new Uint8Array(idxBlock), block.byteLength);
    const fo = block.byteLength + idxBlock.byteLength;
    fv.setUint32(fo, block.byteLength, false);      // index_offset
    fv.setUint32(fo + 4, idxBlock.byteLength, false);
    fv.setUint32(fo + 8, 0, false);                 // bloom_offset
    fv.setUint32(fo + 12, 0, false);                // bloom_size
    fv.setUint32(fo + 16, 0, false);                // bloom_hash_count
    fv.setUint32(fo + 20, 1, false);                // entry_count
    fv.setUint32(fo + 24, 0x53535442, false);       // magic "SSTB" (v1)
    fv.setUint32(fo + 28, 0, false);                // checksum = 0（旧版无校验）

    const data = new Uint8Array(file);
    const reader = new SSTableReader(data, makeMeta(data));
    const stored = new DataView(data.buffer, data.byteOffset + data.byteLength - 4, 4).getUint32(0, false);
    expect(stored).toBe(0);
    expect(reader.verifyChecksum()).toBe(true);
    expect(reader.get('old-key')).toEqual({ v: 42 });
  });

  it('footer checksum 字段自身篡改 → 校验失败', () => {
    const builder = new SSTableBuilder(4096);
    builder.add('a', { v: 1 });
    const { sstableData } = builder.build();

    const tampered = new Uint8Array(sstableData);
    const view = new DataView(tampered.buffer);
    view.setUint32(tampered.byteLength - 4, view.getUint32(tampered.byteLength - 4, false) ^ 0x000000ff, false);

    const reader = new SSTableReader(tampered, makeMeta(tampered));
    expect(reader.verifyChecksum()).toBe(false);
  });
});