import { Buffer } from 'buffer';

export default class BitArray {
  private readonly byteArray: Uint8Array;

  constructor(input?: Buffer | number) {
    if (!input) {
      this.byteArray = new Uint8Array();
      return;
    }
    if (typeof input === 'number') {
      this.byteArray = new Uint8Array(input);
      return;
    }
    this.byteArray = new Uint8Array(input);
  }

  set(index: number, value?: number): void {
    const bytePosition = Math.floor(index / 8);
    const bitPosition = index % 8;
    // eslint-disable-next-line no-bitwise
    const byteMask = 128 >> bitPosition;
    const byteValue = this.byteArray[bytePosition];
    // eslint-disable-next-line no-bitwise
    this.byteArray[bytePosition] = byteMask | byteValue;
  }

  unset(index: number): void {
    const bytePosition = Math.floor(index / 8);
    const bitPosition = index % 8;
    const byteMask = 128 >> bitPosition;

    this.byteArray[bytePosition] = this.byteArray[bytePosition] & ~byteMask;
  }

  get(index: number): number {
    const bytePosition = Math.floor(index / 8);
    const bitPosition = index % 8;
    const byteValue = this.byteArray[bytePosition];
    const bit = byteValue.toString(2).padStart(8, '0').at(bitPosition);
    return parseInt(bit, 10);
  }

  toArray(): Uint8Array {
    return this.byteArray;
  }
}