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
    this._bytesRead = 0
    this._bytesWrote = 0
  }

  /**
   * read `num` number of bytes from the pipe
   * @param {Number} num
   * @return {Buffer}
   */
  read (num) {
    this._bytesRead += 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._bytesWrote += buf.length
    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
  }

  /**
   * returns the number of bytes read from the stream
   * @return {Integer}
   */
  get bytesRead () {
    return this._bytesRead
  }

  /**
   * returns the number of bytes wrote to the stream
   * @return {Integer}
   */
  get bytesWrote () {
    return this._bytesWrote
  }
}