f-hj/slsk-client

class Message {
  constructor (buffer) {
    if (buffer) {
      this.data = buffer
      this.write = false
    } else {
      this.data = Buffer.alloc(0)
      this.write = true
    }
    this.pointer = 0
  }

  int8 (val) {
    return this.write ? this.write8(val) : this.read8()
  }
  int32 (val) {
    return this.write ? this.write32(val) : this.read32()
  }
  str (val) {
    return this.write ? this.writeStr(val) : this.readStr()
  }
  rawHexStr (val) {
    return this.write ? this.writeRawHexStr(val) : this.readRawHexStr(val)
  }

  size () {
    return this.data.length
  }
  seek (val) {
    this.pointer += val
  }

  write8 (val) {
    let b = Buffer.alloc(1)
    b.writeUInt8(val, 0)
    this.data = Buffer.concat([this.data, b])
    this.pointer += 1
    return this
  }
  write32 (val) {
    let b = Buffer.alloc(4)
    b.writeUInt32LE(val, 0)
    this.data = Buffer.concat([this.data, b])
    this.pointer += 4
    return this
  }
  writeStr (val) {
    // convert to buff
    let b = Buffer.from(val, 'utf8')
    let s = Buffer.alloc(4)
    s.writeUInt32LE(b.length, 0)
    // write length
    b = Buffer.concat([s, b])
    // write text
    this.data = Buffer.concat([this.data, b])
    return this
  }

  writeRawHexStr (val) {
    let b = Buffer.from(val, 'hex')
    this.data = Buffer.concat([this.data, b])
    this.pointer += b.length
    return this
  }

  writeBuffer (buff) {
    this.data = Buffer.concat([this.data, buff])
    this.pointer += buff.length
    return this
  }

  read8 () {
    let val = this.data.readUInt8(this.pointer)
    this.pointer += 1
    return val
  }
  read32 () {
    let val = this.data.readUInt32LE(this.pointer)
    this.pointer += 4
    return val
  }
  readStr () {
    let size = this.data.readUInt32LE(this.pointer)
    this.pointer += 4
    let str = this.data.toString('utf8', this.pointer, this.pointer + size)
    this.pointer += size
    return str
  }

  readRawHexStr (size) {
    let str = this.data.toString('hex', this.pointer, this.pointer + size)
    this.pointer += size
    return str
  }

  getBuff () {
    let b = Buffer.alloc(4)
    b.writeUInt32LE(this.data.length, 0)
    this.data = Buffer.concat([b, this.data])
    this.write = false
    return this.data
  }
}

module.exports = Message