package utils

import (
	"log"

	"github.com/google/gopacket"

	"saprusserver/structs"
)

func (c*SocketCall) BuildFileTransferPacket(Header structs.SaprusHeaderFrame,
				Data structs.SaprusFileTransfer) gopacket.SerializeBuffer {
        eth, ip, udp := basePacket(c)

	sapHeader := structs.SaprusHeaderFrame {
		PacketType:	Header.PacketType,
		Length:		c.saprusPayloadLength(Data.Bytes()),
		Payload:	Data.Bytes(),
	}

        buf := gopacket.NewSerializeBuffer()
        opts := gopacket.SerializeOptions {
                ComputeChecksums:       true,
                FixLengths:             true,
        }

        udp.SetNetworkLayerForChecksum(&ip)
	err := gopacket.SerializeLayers(buf, opts, &eth, &ip, &udp, gopacket.Payload(sapHeader.Bytes()))

	if err != nil {
		log.Panic(err)
	}

	return buf
}

func (c* SocketCall) FileTransferPacket(message string, seqNum uint16) gopacket.SerializeBuffer {
        sapFile := structs.SaprusFileTransfer {
                Flag:           [1]byte{0x11},
                Sequence:       [2]byte{byte(seqNum >> 8), byte(seqNum & 0xFF)},
                Checksum:       [2]byte{0x44, 0x44},
                Payload:        []byte(message),
        }

        sapHeader := structs.SaprusHeaderFrame {
                PacketType:     [2]byte{0x88, 0x88},
                Length:         c.saprusPayloadLength(sapFile.Bytes()),
                Payload:        sapFile.Bytes(),
        }

	buf := c.BuildFileTransferPacket(sapHeader, sapFile)

        return buf
}

func (c* SocketCall) InitFileTransferPacket() gopacket.SerializeBuffer {
	sapFile := structs.SaprusFileTransfer {
                Flag:           [1]byte{0x01},
                Sequence:       [2]byte{0x00, 0x00},
                Checksum:       [2]byte{0x00, 0x00},
                Payload:        []byte{},
	}

        sapHeader := structs.SaprusHeaderFrame {
                PacketType:     [2]byte{0x00, 0x00},
                Length:         c.saprusPayloadLength(sapFile.Bytes()),
                Payload:        sapFile.Bytes(),
        }

	buf := c.BuildFileTransferPacket(sapHeader, sapFile)

        return buf
}

func (c* SocketCall) EndFileTransferPacket() gopacket.SerializeBuffer {
	sapFile := structs.SaprusFileTransfer {
                Flag:           [1]byte{0x02},
                Sequence:       [2]byte{0x00, 0x00},
                Checksum:       [2]byte{0x00, 0x00},
                Payload:        []byte{},
	}

        sapHeader := structs.SaprusHeaderFrame {
                PacketType:     [2]byte{0x00, 0x00},
                Length:         c.saprusPayloadLength(sapFile.Bytes()),
                Payload:        sapFile.Bytes(),
        }

	buf := c.BuildFileTransferPacket(sapHeader, sapFile)

        return buf
}