//go:build windows
// +build windows

package quic

import (
	"errors"
	"fmt"
	"net"
	"syscall"

	"github.com/lucas-clemente/quic-go/internal/utils"
	"golang.org/x/sys/windows"
)

const (
	// same for both IPv4 and IPv6 on Windows
	// https://microsoft.github.io/windows-docs-rs/doc/windows/Win32/Networking/WinSock/constant.IP_DONTFRAG.html
	// https://microsoft.github.io/windows-docs-rs/doc/windows/Win32/Networking/WinSock/constant.IPV6_DONTFRAG.html
	IP_DONTFRAGMENT = 14
	IPV6_DONTFRAG   = 14
)

func newConn(c OOBCapablePacketConn) (connection, error) {
	rawConn, err := c.SyscallConn()
	if err != nil {
		return nil, fmt.Errorf("couldn't get syscall.RawConn: %w", err)
	}
	var errDFIPv4, errDFIPv6 error
	if err := rawConn.Control(func(fd uintptr) {
		errDFIPv4 = windows.SetsockoptInt(windows.Handle(fd), windows.IPPROTO_IP, IP_DONTFRAGMENT, 1)
		errDFIPv6 = windows.SetsockoptInt(windows.Handle(fd), windows.IPPROTO_IPV6, IPV6_DONTFRAG, 1)
	}); err != nil {
		return nil, err
	}
	switch {
	case errDFIPv4 == nil && errDFIPv6 == nil:
		utils.DefaultLogger.Debugf("Setting DF for IPv4 and IPv6.")
	case errDFIPv4 == nil && errDFIPv6 != nil:
		utils.DefaultLogger.Debugf("Setting DF for IPv4.")
	case errDFIPv4 != nil && errDFIPv6 == nil:
		utils.DefaultLogger.Debugf("Setting DF for IPv6.")
	case errDFIPv4 != nil && errDFIPv6 != nil:
		return nil, errors.New("setting Df failed for both IPv4 and IPv6")
	}
	return &basicConn{PacketConn: c}, nil
}

func inspectReadBuffer(c net.PacketConn) (int, error) {
	conn, ok := c.(interface {
		SyscallConn() (syscall.RawConn, error)
	})
	if !ok {
		return 0, errors.New("doesn't have a SyscallConn")
	}
	rawConn, err := conn.SyscallConn()
	if err != nil {
		return 0, fmt.Errorf("couldn't get syscall.RawConn: %w", err)
	}
	var size int
	var serr error
	if err := rawConn.Control(func(fd uintptr) {
		size, serr = windows.GetsockoptInt(windows.Handle(fd), windows.SOL_SOCKET, windows.SO_RCVBUF)
	}); err != nil {
		return 0, err
	}
	return size, serr
}

func (i *packetInfo) OOB() []byte { return nil }