package resources

import (
	"bytes"
	"fmt"
	"net"
	"unsafe"

	"golang.org/x/sys/unix"

	"github.com/canonical/lxd/shared/api"
)

type ethtoolReq struct {
	name [16]byte
	data uintptr
}

type ethtoolMode struct {
	bit  uint
	name string
}

var ethtoolModes = []ethtoolMode{
	{0, "10baseT/Half"},
	{1, "10baseT/Full"},
	{2, "100baseT/Half"},
	{3, "100baseT/Full"},
	{4, "1000baseT/Half"},
	{5, "1000baseT/Full"},
	{12, "10000baseT/Full"},
	{15, "2500baseX/Full"},
	{17, "1000baseKX/Full"},
	{18, "10000baseKX4/Full"},
	{19, "10000baseKR/Full"},
	{21, "20000baseMLD2/Full"},
	{22, "20000baseKR2/Full"},
	{23, "40000baseKR4/Full"},
	{24, "40000baseCR4/Full"},
	{25, "40000baseSR4/Full"},
	{26, "40000baseLR4/Full"},
	{27, "56000baseKR4/Full"},
	{28, "56000baseCR4/Full"},
	{29, "56000baseSR4/Full"},
	{30, "56000baseLR4/Full"},
	{31, "25000baseCR/Full"},
	{32, "25000baseKR/Full"},
	{33, "25000baseSR/Full"},
	{34, "50000baseCR2/Full"},
	{35, "50000baseKR2/Full"},
	{36, "100000baseKR4/Full"},
	{37, "100000baseSR4/Full"},
	{38, "100000baseCR4/Full"},
	{39, "100000baseLR4_ER4/Full"},
	{40, "50000baseSR2/Full"},
	{41, "1000baseX/Full"},
	{42, "10000baseCR/Full"},
	{43, "10000baseSR/Full"},
	{44, "10000baseLR/Full"},
	{45, "10000baseLRM/Full"},
	{46, "10000baseER/Full"},
	{47, "2500baseT/Full"},
	{48, "5000baseT/Full"},
}

var ethtoolPorts = []ethtoolMode{
	{7, "twisted pair"},
	{8, "AUI"},
	{9, "media-independent"},
	{10, "fibre"},
	{11, "BNC"},
	{16, "backplane"},
}

type ethtoolCmd struct {
	cmd           uint32
	supported     uint32
	advertising   uint32
	speed         uint16
	duplex        uint8
	port          uint8
	phyAddress    uint8
	transceiver   uint8
	autoneg       uint8
	mdioSupport   uint8
	maxtxpkt      uint32
	maxrxpkt      uint32
	speedHi       uint16
	ethTpMdix     uint8
	ethTpMdixCtrl uint8
	lpAdvertising uint32
	reserved      [2]uint32
}

type ethtoolDrvInfo struct {
	cmd         uint32
	driver      [32]byte
	version     [32]byte
	fwVersion   [32]byte
	busInfo     [32]byte
	reserved1   [32]byte
	reserved2   [16]byte
	nStats      uint32
	testinfoLen uint32
	eedumpLen   uint32
	regDumpLen  uint32
}

type ethtoolPermAddr struct {
	cmd  uint32
	size uint32
	data [32]byte
}

type ethtoolValue struct {
	cmd  uint32
	data uint32
}

const ethtoolLinkModeMaskMaxKernelNu32 = 127 // SCHAR_MAX
type ethtoolLinkSettings struct {
	cmd                 uint32
	speed               uint32
	duplex              uint8
	port                uint8
	phyAddress          uint8
	autoneg             uint8
	mdioSupport         uint8
	ethTpMdix           uint8
	ethTpMdixCtrl       uint8
	linkModeMasksNwords int8
	transceiver         uint8
	reserved1           [3]uint8
	reserved            [7]uint32
	linkModeMasks       [0]uint32
	linkModeData        [3 * ethtoolLinkModeMaskMaxKernelNu32]uint32
	// __u32 map_supported[link_mode_masks_nwords];
	// __u32 map_advertising[link_mode_masks_nwords];
	// __u32 map_lp_advertising[link_mode_masks_nwords];
}

type ethtoolLinkModeMaps struct {
	mapSupported     []uint32
	mapAdvertising   []uint32
	mapLpAdvertising []uint32
}

func ethtoolAddCardInfo(name string, info *api.ResourcesNetworkCard) error {
	// Open FD
	ethtoolFd, err := unix.Socket(unix.AF_INET, unix.SOCK_DGRAM, unix.IPPROTO_IP)
	if err != nil {
		return fmt.Errorf("Failed to open IPPROTO_IP socket: %w", err)
	}

	defer func() { _ = unix.Close(ethtoolFd) }()

	// Driver info
	ethDrvInfo := ethtoolDrvInfo{
		cmd: 0x00000003,
	}

	req := ethtoolReq{
		data: uintptr(unsafe.Pointer(&ethDrvInfo)),
	}

	copy(req.name[:], []byte(name))

	_, _, errno := unix.Syscall(unix.SYS_IOCTL, uintptr(ethtoolFd), unix.SIOCETHTOOL, uintptr(unsafe.Pointer(&req)))
	if errno != 0 {
		return fmt.Errorf("Failed to ETHTOOL_GDRVINFO: %w", unix.Errno(errno))
	}

	info.FirmwareVersion = string(bytes.Trim(ethDrvInfo.fwVersion[:], "\x00"))

	return unix.Close(ethtoolFd)
}

func ethtoolGset(ethtoolFd int, req *ethtoolReq, info *api.ResourcesNetworkCardPort) error {
	// Interface info
	ethCmd := ethtoolCmd{
		cmd: 0x00000001,
	}

	req.data = uintptr(unsafe.Pointer(&ethCmd))

	_, _, errno := unix.Syscall(unix.SYS_IOCTL, uintptr(ethtoolFd), unix.SIOCETHTOOL, uintptr(unsafe.Pointer(req)))
	if errno != 0 {
		if unix.Errno(errno) == unix.EOPNOTSUPP || unix.Errno(errno) == unix.ENODEV {
			// Driver doesn't support it, skip.
			return nil
		}

		return fmt.Errorf("Failed to ETHTOOL_GSET: %w", unix.Errno(errno))
	}

	// Link negotiation
	info.AutoNegotiation = ethCmd.autoneg == 1

	if info.LinkDetected {
		// Link duplex
		switch ethCmd.duplex {
		case 0x00:
			info.LinkDuplex = "half"
		case 0x01:
			info.LinkDuplex = "full"
		}

		// Link speed
		speed := uint64(uint32(ethCmd.speedHi)<<16 | uint32(ethCmd.speed))
		if speed != 65535 && speed != 4294967295 {
			info.LinkSpeed = speed
		}
	}

	// Transceiver
	switch ethCmd.transceiver {
	case 0x00:
		info.TransceiverType = "internal"
	case 0x01:
		info.TransceiverType = "external"
	}

	// Port
	switch ethCmd.port {
	case 0x00:
		info.PortType = "twisted pair"
	case 0x01:
		info.PortType = "AUI"
	case 0x02:
		info.PortType = "media-independent"
	case 0x03:
		info.PortType = "fibre"
	case 0x04:
		info.PortType = "BNC"
	case 0x05:
		info.PortType = "direct attach"
	case 0xef:
		info.PortType = "none"
	case 0xff:
		info.PortType = "other"
	}

	// Supported modes
	info.SupportedModes = []string{}
	for _, mode := range ethtoolModes {
		if hasBit(ethCmd.supported, mode.bit) {
			info.SupportedModes = append(info.SupportedModes, mode.name)
		}
	}

	// Supported ports
	info.SupportedPorts = []string{}
	for _, port := range ethtoolPorts {
		if hasBit(ethCmd.supported, port.bit) {
			info.SupportedPorts = append(info.SupportedPorts, port.name)
		}
	}

	return nil
}

func ethtoolLink(ethtoolFd int, req *ethtoolReq, info *api.ResourcesNetworkCardPort) error {
	// Interface info
	ethLinkSettings := ethtoolLinkSettings{
		cmd: 0x0000004c,
	}

	req.data = uintptr(unsafe.Pointer(&ethLinkSettings))

	// Retrieve size of masks
	_, _, errno := unix.Syscall(unix.SYS_IOCTL, uintptr(ethtoolFd), unix.SIOCETHTOOL, uintptr(unsafe.Pointer(req)))
	if errno != 0 {
		return fmt.Errorf("Failed to ETHTOOL_GLINKSETTINGS: %w", unix.Errno(errno))
	}

	// This insane interface gives us the size of the masks as a negative value.
	if ethLinkSettings.linkModeMasksNwords >= 0 || ethLinkSettings.cmd != 0x0000004c {
		return fmt.Errorf("Failed to ETHTOOL_GLINKSETTINGS: %w", unix.Errno(unix.EINVAL))
	}

	// Set the size of the masks we want to retrieve.
	ethLinkSettings.linkModeMasksNwords = -ethLinkSettings.linkModeMasksNwords
	_, _, errno = unix.Syscall(unix.SYS_IOCTL, uintptr(ethtoolFd), unix.SIOCETHTOOL, uintptr(unsafe.Pointer(req)))
	if errno != 0 {
		return fmt.Errorf("Failed to ETHTOOL_GLINKSETTINGS: %w", unix.Errno(errno))
	}

	if ethLinkSettings.linkModeMasksNwords <= 0 || ethLinkSettings.cmd != 0x0000004c {
		return fmt.Errorf("Failed to ETHTOOL_GLINKSETTINGS: %w", unix.Errno(unix.EINVAL))
	}

	// Copy the mode maps.
	ethLinkModeMap := ethtoolLinkModeMaps{}
	ethLinkModeMap.mapSupported = append(ethLinkModeMap.mapSupported, ethLinkSettings.linkModeData[:4*ethLinkSettings.linkModeMasksNwords]...)

	// Unused right now
	offset := ethLinkSettings.linkModeMasksNwords
	ethLinkModeMap.mapAdvertising = append(ethLinkModeMap.mapAdvertising, ethLinkSettings.linkModeData[offset:4*ethLinkSettings.linkModeMasksNwords]...)

	// Unused right now
	offset += ethLinkSettings.linkModeMasksNwords
	ethLinkModeMap.mapLpAdvertising = append(ethLinkModeMap.mapLpAdvertising, ethLinkSettings.linkModeData[offset:4*ethLinkSettings.linkModeMasksNwords]...)

	// Link negotiation
	info.AutoNegotiation = ethLinkSettings.autoneg == 1

	if info.LinkDetected {
		// Link duplex
		switch ethLinkSettings.duplex {
		case 0x00:
			info.LinkDuplex = "half"
		case 0x01:
			info.LinkDuplex = "full"
		}

		// Link speed
		speed := uint64(ethLinkSettings.speed)
		if speed < uint64(^uint32(0)) {
			info.LinkSpeed = speed
		}
	}

	// Transceiver
	switch ethLinkSettings.transceiver {
	case 0x00:
		info.TransceiverType = "internal"
	case 0x01:
		info.TransceiverType = "external"
	}

	// Port
	switch ethLinkSettings.port {
	case 0x00:
		info.PortType = "twisted pair"
	case 0x01:
		info.PortType = "AUI"
	case 0x02:
		info.PortType = "media-independent"
	case 0x03:
		info.PortType = "fibre"
	case 0x04:
		info.PortType = "BNC"
	case 0x05:
		info.PortType = "direct attach"
	case 0xef:
		info.PortType = "none"
	case 0xff:
		info.PortType = "other"
	}

	// Supported modes
	info.SupportedModes = []string{}
	for _, mode := range ethtoolModes {
		if hasBitField(ethLinkModeMap.mapSupported, mode.bit) {
			info.SupportedModes = append(info.SupportedModes, mode.name)
		}
	}

	// Supported ports
	info.SupportedPorts = []string{}
	for _, port := range ethtoolPorts {
		if hasBitField(ethLinkModeMap.mapSupported, port.bit) {
			info.SupportedPorts = append(info.SupportedPorts, port.name)
		}
	}

	return nil
}

func ethtoolAddPortInfo(info *api.ResourcesNetworkCardPort) error {
	// Open FD
	ethtoolFd, err := unix.Socket(unix.AF_INET, unix.SOCK_DGRAM, unix.IPPROTO_IP)
	if err != nil {
		return fmt.Errorf("Failed to open IPPROTO_IP socket: %w", err)
	}

	defer func() { _ = unix.Close(ethtoolFd) }()

	// Prepare the request struct
	req := ethtoolReq{}
	copy(req.name[:], []byte(info.ID))

	// Try to get MAC address
	ethPermaddr := ethtoolPermAddr{
		cmd:  0x00000020,
		size: 32,
	}

	req.data = uintptr(unsafe.Pointer(&ethPermaddr))

	_, _, errno := unix.Syscall(unix.SYS_IOCTL, uintptr(ethtoolFd), unix.SIOCETHTOOL, uintptr(unsafe.Pointer(&req)))
	if errno == 0 {
		hwaddr := net.HardwareAddr(ethPermaddr.data[0:ethPermaddr.size])
		info.Address = hwaddr.String()
	}

	// Link state
	ethGlink := ethtoolValue{
		cmd: 0x0000000a,
	}

	req.data = uintptr(unsafe.Pointer(&ethGlink))

	_, _, errno = unix.Syscall(unix.SYS_IOCTL, uintptr(ethtoolFd), unix.SIOCETHTOOL, uintptr(unsafe.Pointer(&req)))
	if errno != 0 {
		return fmt.Errorf("Failed to ETHTOOL_GLINK: %w", unix.Errno(errno))
	}

	info.LinkDetected = ethGlink.data == 1

	// Interface info
	err = ethtoolLink(ethtoolFd, &req, info)
	if err != nil {
		return ethtoolGset(ethtoolFd, &req, info)
	}

	return unix.Close(ethtoolFd)
}
