const Buffer = require('safe-buffer').Buffer

module.exports = class BufferPipe {
  /**
   * Creates a new instance of a pipe
   * @param {Buffer} buf - an optional buffer to start with
   */
  constructor (buf = Buffer.from([])) {
    this.buffer = buf
  }

  /**
   * read `num` number of bytes from the pipe
   * @param {Number} num
   * @return {Buffer}
   */
  read (num) {
    const data = this.buffer.subarray(0, num)
    this.buffer = this.buffer.subarray(num)
    return data
  }

  /**
   * Wites a buffer to the pipe
   * @param {Buffer} buf
   */
  write (buf) {
    buf = Buffer.from(buf)
    this.buffer = Buffer.concat([this.buffer, buf])
  }

  /**
   * Whether or not there is more data to read from the buffer
   * returns {Boolean}
   */
  get end () {
    return !this.buffer.length
  }
}