package protocol

import (
	"encoding/binary"
	"io"

	"github.com/niko/qcc/pkg/types"
)

const MediaHeaderSize = 8 + 4 + 1 + 1 + 4

type MediaPacket struct {
	CallID    uint64
	SeqNum    uint32
	Codec     types.CodecType
	Flags     types.MediaFlags
	Timestamp uint32
	Payload   []byte
}

func MarshalMediaPacket(pkt *MediaPacket) []byte {
	size := MediaHeaderSize + len(pkt.Payload)
	buf := make([]byte, size)
	off := 0
	binary.BigEndian.PutUint64(buf[off:], pkt.CallID)
	off += 8
	binary.LittleEndian.PutUint32(buf[off:], pkt.SeqNum)
	off += 4
	buf[off] = byte(pkt.Codec)
	off++
	buf[off] = byte(pkt.Flags)
	off++
	binary.BigEndian.PutUint32(buf[off:], pkt.Timestamp)
	off += 4
	copy(buf[off:], pkt.Payload)
	return buf
}

func UnmarshalMediaPacket(data []byte) (*MediaPacket, bool) {
	if len(data) < MediaHeaderSize {
		return nil, false
	}
	pkt := &MediaPacket{}
	off := 0
	pkt.CallID = binary.BigEndian.Uint64(data[off:])
	off += 8
	pkt.SeqNum = binary.LittleEndian.Uint32(data[off:])
	off += 4
	pkt.Codec = types.CodecType(data[off])
	off++
	pkt.Flags = types.MediaFlags(data[off])
	off++
	pkt.Timestamp = binary.BigEndian.Uint32(data[off:])
	off += 4
	pkt.Payload = make([]byte, len(data)-off)
	copy(pkt.Payload, data[off:])
	return pkt, true
}

func ReadMediaPacket(r io.Reader) (*MediaPacket, error) {
	header := make([]byte, MediaHeaderSize)
	if _, err := io.ReadFull(r, header); err != nil {
		return nil, err
	}
	pkt := &MediaPacket{}
	off := 0
	pkt.CallID = binary.BigEndian.Uint64(header[off:])
	off += 8
	pkt.SeqNum = binary.LittleEndian.Uint32(header[off:])
	off += 4
	pkt.Codec = types.CodecType(header[off])
	off++
	pkt.Flags = types.MediaFlags(header[off])
	off++
	pkt.Timestamp = binary.BigEndian.Uint32(header[off:])
	payload, err := io.ReadAll(r)
	if err != nil {
		return nil, err
	}
	pkt.Payload = payload
	return pkt, nil
}