package core

import (
	"net"
	"time"
)

// TCPConn abstracts a TCP connection comming from TUN. This connection
// should be handled by a registered TCP proxy handler. It's important
// to note that callback members are called from lwIP, they are already
// in the lwIP thread when they are called, that is, they are holding
// the lwipMutex.
type TCPConn interface {
	// Sent will be called when sent data has been acknowledged by peer.
	Sent(len uint16) error

	// Receive will be called when data arrives from TUN.
	Receive(data []byte) error

	// Err will be called when a fatal error has occurred on the connection.
	// The corresponding pcb is already freed when this callback is called
	Err(err error)

	// LocalClosed will be called when lwIP receives a FIN segment on a
	// connection.
	LocalClosed() error

	// Poll will be periodically called by TCP timers.
	Poll() error

	// RemoteAddr returns the destination network address.
	RemoteAddr() net.Addr

	// LocalAddr returns the local client network address.
	LocalAddr() net.Addr

	// Read reads data comming from TUN, note that it reads from an
	// underlying pipe that the writer writes in the lwip thread,
	// write op blocks until previous written data is consumed, one
	// should read out all data as soon as possible.
	Read(data []byte) (int, error)

	// Write writes data to TUN.
	Write(data []byte) (int, error)

	// Close closes the connection.
	Close() error

	// CloseWrite closes the writing side by sending a FIN
	// segment to local peer. That means we can write no further
	// data to TUN.
	CloseWrite() error

	// CloseRead closes the reading side. That means we can no longer
	// read more from TUN.
	CloseRead() error

	// Abort aborts the connection by sending a RST segment.
	Abort()

	SetDeadline(t time.Time) error
	SetReadDeadline(t time.Time) error
	SetWriteDeadline(t time.Time) error
}

// TCPConn abstracts a UDP connection comming from TUN. This connection
// should be handled by a registered UDP proxy handler.
type UDPConn interface {
	// LocalAddr returns the local client network address.
	LocalAddr() *net.UDPAddr

	// ReceiveTo will be called when data arrives from TUN, and the received
	// data should be sent to addr.
	ReceiveTo(data []byte, addr *net.UDPAddr) error

	// WriteFrom writes data to TUN, addr will be set as source address of
	// UDP packets that output to TUN.
	WriteFrom(data []byte, addr *net.UDPAddr) (int, error)

	// Close closes the connection.
	Close() error
}