package main

import (
	"bytes"
	"encoding/binary"
	"encoding/gob"
	"io"
	"log"
	"net"

	"github.com/klauspost/compress/zstd"
)

func Compress(writer io.Writer, data [][]byte) {

	// encode gob
	enc := gob.NewEncoder(writer)

	err := enc.Encode(data)
	if err != nil {
		log.Panic(err)
	}

	// zstd compress
	zenc, err := zstd.NewWriter(writer)
	if err != nil {
		log.Panic(err)
	}
	err = zenc.Flush()
	if err != nil {
		log.Println(err)
	}

}

func Decompress(data []byte) (frames [][]byte) {
	var err error

	var buf = bytes.NewBuffer(data)
	var zdec *zstd.Decoder
	zdec, err = zstd.NewReader(buf)
	if err != nil {
		log.Panic(err)
	}
	zdec.Close()

	dec := gob.NewDecoder(buf)
	err = dec.Decode(&frames)
	if err != nil {
		log.Panic(err)
	}

	return
}

func SwapBytes(frame1 []byte, start1 int, frame2 []byte, start2 int, size int) {
	var temp []byte = make([]byte, size)
	copy(temp, frame1[start1:start1+size])
	copy(frame1[start1:start1+size], frame2[start2:start2+size])
	copy(frame2[start2:start2+size], temp)
}

type ARP []byte

func (arp ARP) Destination() net.HardwareAddr {
	return net.HardwareAddr(arp[:6])
}

func (arp ARP) Source() net.HardwareAddr {
	return net.HardwareAddr(arp[6:12])
}

func (arp ARP) Op() uint16 {
	return binary.BigEndian.Uint16(arp[20:22])
}

func (arp ARP) IPv4Source() net.IP {
	return net.IP(arp[28:32])
}

func (arp ARP) IPv4Destination() net.IP {
	return net.IP(arp[38:42])
}