import { equalBytes } from "@noble/ciphers/utils.js";
import { bytesToHex, hexToBytes as nobleHexToBytes } from "@noble/hashes/utils.js";

export {
  bytesToHex,
  equalBytes
};

export const base64ToBytes = (base64: string, size?: number): Uint8Array => {
  // Normalize URL-safe base64 to standard base64
  let normalized = base64.replace(/-/g, '+').replace(/_/g, '/');
  // Add padding if missing
  while (normalized.length % 4 !== 0) {
    normalized += '=';
  }
  const binaryString = atob(normalized);
  const bytes = new Uint8Array(binaryString.length);
  for (let i = 0; i < binaryString.length; i++) {
    bytes[i] = binaryString.charCodeAt(i);
  }
  if (size !== undefined && bytes.length !== size) {
    throw new Error(`Invalid base64 length: expected ${size} bytes, got ${bytes.length}`);
  }
  return bytes;
}

// Note: encodedStringToBytes removed — prefer explicit parsers.
// Use `hexToBytes` for hex inputs and `base64ToBytes` for base64 inputs.

// Wrapper around @noble/hashes hexToBytes that optionally validates size.
export const hexToBytes = (hex: string, size?: number): Uint8Array => {
  const bytes = nobleHexToBytes(hex);
  if (size !== undefined && bytes.length !== size) {
    throw new Error(`Invalid hex length: expected ${size} bytes, got ${bytes.length}`);
  }
  return bytes;
};

export class BufferReader {
  private buffer: Uint8Array;
  private offset: number;

  constructor(buffer: Uint8Array) {
    this.buffer = buffer;
    this.offset = 0;
  }

  public readByte(): number {
    if (!this.hasMore()) throw new Error('read past end');
    return this.buffer[this.offset++];
  }

  public readBytes(length?: number): Uint8Array {
    if (length === undefined) {
      length = this.buffer.length - this.offset;
    }
    if (this.remainingBytes() < length) throw new Error('read past end');
    const bytes = this.buffer.slice(this.offset, this.offset + length);
    this.offset += length;
    return bytes;
}

  public hasMore(): boolean {
    return this.offset < this.buffer.length;
  }

  public remainingBytes(): number {
    return this.buffer.length - this.offset;
  }

  public peekByte(): number {
    if (!this.hasMore()) throw new Error('read past end');
    return this.buffer[this.offset];
  }

  public readUint16LE(): number {
    if (this.remainingBytes() < 2) throw new Error('read past end');
    const value = this.buffer[this.offset] | (this.buffer[this.offset + 1] << 8);
    this.offset += 2;
    return value;
  }

  public readUint32LE(): number {
    if (this.remainingBytes() < 4) throw new Error('read past end');
    const value = (this.buffer[this.offset] | (this.buffer[this.offset + 1] << 8) | (this.buffer[this.offset + 2] << 16) | (this.buffer[this.offset + 3] << 24)) >>> 0;
    this.offset += 4;
    return value;
  }

  public readInt16LE(): number {
    if (this.remainingBytes() < 2) throw new Error('read past end');
    const value = this.buffer[this.offset] | (this.buffer[this.offset + 1] << 8);
    this.offset += 2;
    return value < 0x8000 ? value : value - 0x10000;
  }

  public readInt32LE(): number {
    if (this.remainingBytes() < 4) throw new Error('read past end');
    const u = (this.buffer[this.offset] | (this.buffer[this.offset + 1] << 8) | (this.buffer[this.offset + 2] << 16) | (this.buffer[this.offset + 3] << 24)) >>> 0;
    this.offset += 4;
    return u < 0x80000000 ? u : u - 0x100000000;
  }

  public readTimestamp(): Date {
    const timestamp = this.readUint32LE();
    return new Date(timestamp * 1000);
  }
}

export class BufferWriter {
  private buffer: number[] = [];

  public writeByte(value: number): void {
    this.buffer.push(value & 0xFF);
  }

  public writeBytes(bytes: Uint8Array): void {
    this.buffer.push(...bytes);
  }

  public writeUint16LE(value: number): void {
    this.buffer.push(value & 0xFF, (value >> 8) & 0xFF);
  }

  public writeUint32LE(value: number): void {
    this.buffer.push(
      value & 0xFF,
      (value >> 8) & 0xFF,
      (value >> 16) & 0xFF,
      (value >> 24) & 0xFF
    );
  }

  public writeInt16LE(value: number): void {
    this.writeUint16LE(value < 0 ? value + 0x10000 : value);
  }

  public writeInt32LE(value: number): void {
    this.writeUint32LE(value < 0 ? value + 0x100000000 : value);
  }

  public writeTimestamp(date: Date): void {
    const timestamp = Math.floor(date.getTime() / 1000);
    this.writeUint32LE(timestamp);
  }

  public toBytes(): Uint8Array {
    return new Uint8Array(this.buffer);
  }
}