package transport

import (
	"encoding/binary"
	"net"
	"ripple/crypto"
	"ripple/state"
	"ripple/types"
	"ripple/udpr"
)

type UserTransport struct {
	st *state.State
	w  *senderWorker
}

func NewUserTransport(conn *udpr.UDPRConn, st *state.State) *UserTransport {
	return &UserTransport{
		st: st, 
		w: newSenderWorker(conn),
	}
}

func (t *UserTransport) Receive(data []byte, addr *net.UDPAddr) (types.UserRequest, error) {
	if len(data) < 6+32 {
		return types.UserRequest{}, errInvalidUserRequest
	}
	if !crypto.VerifySignature(data, t.st.Storage.User.SecretKey) {
		return types.UserRequest{}, errInvalidUserRequest
	}
	counter := binary.BigEndian.Uint32(data[1:5])
	if counter <= t.st.Storage.User.Counter {
		return types.UserRequest{}, errInvalidUserRequest
	}
	if err := t.st.SetUserCounter(counter); err != nil {
		return types.UserRequest{}, err
	}
	return types.UserRequest{
		Remote: types.ClientRemote{
			Addr:    addr,
			Counter: counter,
		},
		Instruction: types.Instruction{
			Command:   data[5],
			Arguments: data[6 : len(data)-32],
		},
	}, nil
}

func (t *UserTransport) Send(req types.UserRequest) {
	buf := make([]byte, 5+len(req.Instruction.Arguments))
	binary.BigEndian.PutUint32(buf[0:4], req.Remote.Counter)
	buf[4] = req.Instruction.Command
	copy(buf[5:], req.Instruction.Arguments)
	signed := crypto.SignData(buf, t.st.Storage.User.SecretKey)
	t.w.enqueue(sendRequest{
        data: signed,
        dest: req.Remote.Addr,
    })
}