import { describe, it, expect } from 'vitest';
import { base64ToBytes, hexToBytes, BufferReader, BufferWriter } from '../src/parser';

describe('base64ToBytes', () => {
  it('decodes a simple base64 string', () => {
    const bytes = base64ToBytes('aGVsbG8=', 5); // "hello"
    expect(Array.from(bytes)).toEqual([104, 101, 108, 108, 111]);
  });

  it('handles empty string', () => {
    const bytes = base64ToBytes('', 0);
    expect(bytes).toBeInstanceOf(Uint8Array);
    expect(bytes.length).toBe(0);
  });
});

describe('BufferReader', () => {
  it('readByte and peekByte advance/inspect correctly', () => {
    const buf = new Uint8Array([1, 2, 3]);
    const r = new BufferReader(buf);
    expect(r.peekByte()).toBe(1);
    expect(r.readByte()).toBe(1);
    expect(r.peekByte()).toBe(2);
  });

  it('readBytes with and without length', () => {
    const buf = new Uint8Array([10, 11, 12, 13]);
    const r = new BufferReader(buf);
    const a = r.readBytes(2);
    expect(Array.from(a)).toEqual([10, 11]);
    const b = r.readBytes();
    expect(Array.from(b)).toEqual([12, 13]);
  });

  it('hasMore and remainingBytes reflect position', () => {
    const buf = new Uint8Array([5, 6]);
    const r = new BufferReader(buf);
    expect(r.hasMore()).toBe(true);
    expect(r.remainingBytes()).toBe(2);
    r.readByte();
    expect(r.remainingBytes()).toBe(1);
    r.readByte();
    expect(r.hasMore()).toBe(false);
  });

  it('reads little-endian unsigned ints', () => {
    const r16 = new BufferReader(new Uint8Array([0x34, 0x12]));
    expect(r16.readUint16LE()).toBe(0x1234);

    const r32 = new BufferReader(new Uint8Array([0x78, 0x56, 0x34, 0x12]));
    expect(r32.readUint32LE()).toBe(0x12345678);
  });

  it('reads signed ints with two/four bytes (negative)', () => {
    const r16 = new BufferReader(new Uint8Array([0xff, 0xff]));
    expect(r16.readInt16LE()).toBe(-1);

    const r32 = new BufferReader(new Uint8Array([0xff, 0xff, 0xff, 0xff]));
    expect(r32.readInt32LE()).toBe(-1);
  });

  it('readTimestamp returns Date with seconds->ms conversion', () => {
    const r = new BufferReader(new Uint8Array([0x01, 0x00, 0x00, 0x00]));
    const d = r.readTimestamp();
    expect(d.getTime()).toBe(1000);
  });
});
describe('sizedStringToBytes', () => {
  it('decodes hex string of correct length', () => {
    // 4 bytes = 8 hex chars
    const hex = 'deadbeef';
    const result = hexToBytes(hex, 4);
    expect(Array.from(result)).toEqual([0xde, 0xad, 0xbe, 0xef]);
  });

  it('decodes base64 string of correct length', () => {
    // 4 bytes = 8 hex chars, base64 for [0xde, 0xad, 0xbe, 0xef] is '3q2+7w=='
    const b64 = '3q2+7w==';
    const result = base64ToBytes(b64, 4);
    expect(Array.from(result)).toEqual([0xde, 0xad, 0xbe, 0xef]);
  });

  it('throws on invalid string length', () => {
    expect(() => hexToBytes('abc', 4)).toThrow();
    expect(() => hexToBytes('deadbeef00', 4)).toThrow();
  });
});

describe('BufferWriter', () => {
  it('writeByte and toBytes', () => {
    const w = new BufferWriter();
    w.writeByte(0x12);
    w.writeByte(0x34);
    expect(Array.from(w.toBytes())).toEqual([0x12, 0x34]);
  });

  it('writeBytes appends bytes', () => {
    const w = new BufferWriter();
    w.writeBytes(new Uint8Array([1, 2, 3]));
    expect(Array.from(w.toBytes())).toEqual([1, 2, 3]);
  });

  it('writeUint16LE writes little-endian', () => {
    const w = new BufferWriter();
    w.writeUint16LE(0x1234);
    expect(Array.from(w.toBytes())).toEqual([0x34, 0x12]);
  });

  it('writeUint32LE writes little-endian', () => {
    const w = new BufferWriter();
    w.writeUint32LE(0x12345678);
    expect(Array.from(w.toBytes())).toEqual([0x78, 0x56, 0x34, 0x12]);
  });

  it('writeInt16LE writes signed values', () => {
    const w = new BufferWriter();
    w.writeInt16LE(-1);
    expect(Array.from(w.toBytes())).toEqual([0xff, 0xff]);
    const w2 = new BufferWriter();
    w2.writeInt16LE(0x1234);
    expect(Array.from(w2.toBytes())).toEqual([0x34, 0x12]);
  });

  it('writeInt32LE writes signed values', () => {
    const w = new BufferWriter();
    w.writeInt32LE(-1);
    expect(Array.from(w.toBytes())).toEqual([0xff, 0xff, 0xff, 0xff]);
    const w2 = new BufferWriter();
    w2.writeInt32LE(0x12345678);
    expect(Array.from(w2.toBytes())).toEqual([0x78, 0x56, 0x34, 0x12]);
  });

  it('writeTimestamp writes seconds as uint32le', () => {
    const w = new BufferWriter();
    const date = new Date(1000); // 1 second
    w.writeTimestamp(date);
    expect(Array.from(w.toBytes())).toEqual([0x01, 0x00, 0x00, 0x00]);
  });

  it('BufferWriter output can be read back by BufferReader', () => {
    const w = new BufferWriter();
    w.writeByte(0x42);
    w.writeUint16LE(0x1234);
    w.writeInt16LE(-2);
    w.writeUint32LE(0xdeadbeef);
    w.writeInt32LE(-123456);
    w.writeBytes(new Uint8Array([0x01, 0x02]));
    const date = new Date(5000); // 5 seconds
    w.writeTimestamp(date);

    const bytes = w.toBytes();
    const r = new BufferReader(bytes);

    expect(r.readByte()).toBe(0x42);
    expect(r.readUint16LE()).toBe(0x1234);
    expect(r.readInt16LE()).toBe(-2);
    expect(r.readUint32LE()).toBe(0xdeadbeef);
    expect(r.readInt32LE()).toBe(-123456);
    expect(Array.from(r.readBytes(2))).toEqual([0x01, 0x02]);
    const readDate = r.readTimestamp();
    expect(readDate.getTime()).toBe(5000);
    expect(r.hasMore()).toBe(false);
  });

  it('BufferReader throws or returns undefined if reading past end', () => {
    const r = new BufferReader(new Uint8Array([1, 2]));
    r.readByte();
    r.readByte();
    expect(() => r.readByte()).toThrow();
  });

  it('BufferWriter handles multiple writeBytes calls', () => {
    const w = new BufferWriter();
    w.writeBytes(new Uint8Array([1, 2]));
    w.writeBytes(new Uint8Array([3, 4]));
    expect(Array.from(w.toBytes())).toEqual([1, 2, 3, 4]);
  });

  it('encodedStringToBytes decodes raw string', () => {
    const str = String.fromCharCode(0xde, 0xad, 0xbe, 0xef);
    const bytes = new Uint8Array(4);
    for (let i = 0; i < 4; i++) bytes[i] = str.charCodeAt(i) & 0xff;
    expect(Array.from(bytes)).toEqual([0xde, 0xad, 0xbe, 0xef]);
  });

  it('hexToBytes returns different length for wrong-size hex', () => {
    expect(() => hexToBytes('deadbe', 4)).toThrow();
  });

  it('base64ToBytes handles URL-safe base64', () => {
    // [0xde, 0xad, 0xbe, 0xef] in URL-safe base64: '3q2-7w=='
    const bytes = base64ToBytes('3q2-7w==', 4);
    expect(Array.from(bytes)).toEqual([0xde, 0xad, 0xbe, 0xef]);
  });
});