export class BufferManager {

  private buffer: Buffer;

  constructor(
    private readonly maxBufferSize: number,
  ) {
    this.buffer = Buffer.alloc(0);
  }

  hasRoom(chunk: Buffer): boolean {
    return chunk.length + this.buffer.length <= this.maxBufferSize;
  }

  append(chunk: Buffer) {

    if (!this.hasRoom(chunk)) {
      throw new Error('Buffer overflow - data will be lost. Check hasRoom before calling');
    }

    this.buffer = Buffer.concat([this.buffer, chunk]);
  }

  appendAndGetCompletedBuffer(chunk: Buffer): Buffer {

    const fillSize = this.maxBufferSize - this.buffer.length;
    const completedBuffer = Buffer.concat([this.buffer, chunk.slice(0, fillSize)]);

    this.buffer = Buffer.from(chunk.slice(fillSize, chunk.length)); // ??? could be an issue

    return completedBuffer;
  }
}