// SPDX-FileCopyrightText: 2023 The Pion community <https://pion.ly>
// SPDX-License-Identifier: MIT

package ice

import (
	"fmt"
	"net/netip"
	"strings"
)

const (
	udp  = "udp"
	tcp  = "tcp"
	udp4 = "udp4"
	udp6 = "udp6"
	tcp4 = "tcp4"
	tcp6 = "tcp6"
)

func supportedNetworkTypes() []NetworkType {
	return []NetworkType{
		NetworkTypeUDP4,
		NetworkTypeUDP6,
		NetworkTypeTCP4,
		NetworkTypeTCP6,
	}
}

// NetworkType represents the type of network.
type NetworkType int

const (
	// NetworkTypeUDP4 indicates UDP over IPv4.
	NetworkTypeUDP4 NetworkType = iota + 1

	// NetworkTypeUDP6 indicates UDP over IPv6.
	NetworkTypeUDP6

	// NetworkTypeTCP4 indicates TCP over IPv4.
	NetworkTypeTCP4

	// NetworkTypeTCP6 indicates TCP over IPv6.
	NetworkTypeTCP6
)

func (t NetworkType) String() string {
	switch t {
	case NetworkTypeUDP4:
		return udp4
	case NetworkTypeUDP6:
		return udp6
	case NetworkTypeTCP4:
		return tcp4
	case NetworkTypeTCP6:
		return tcp6
	default:
		return ErrUnknownType.Error()
	}
}

// IsUDP returns true when network is UDP4 or UDP6.
func (t NetworkType) IsUDP() bool {
	return t == NetworkTypeUDP4 || t == NetworkTypeUDP6
}

// IsTCP returns true when network is TCP4 or TCP6.
func (t NetworkType) IsTCP() bool {
	return t == NetworkTypeTCP4 || t == NetworkTypeTCP6
}

// NetworkShort returns the short network description.
func (t NetworkType) NetworkShort() string {
	switch t {
	case NetworkTypeUDP4, NetworkTypeUDP6:
		return udp
	case NetworkTypeTCP4, NetworkTypeTCP6:
		return tcp
	default:
		return ErrUnknownType.Error()
	}
}

// IsReliable returns true if the network is reliable.
func (t NetworkType) IsReliable() bool {
	switch t {
	case NetworkTypeUDP4, NetworkTypeUDP6:
		return false
	case NetworkTypeTCP4, NetworkTypeTCP6:
		return true
	}

	return false
}

// IsIPv4 returns whether the network type is IPv4 or not.
func (t NetworkType) IsIPv4() bool {
	switch t {
	case NetworkTypeUDP4, NetworkTypeTCP4:
		return true
	case NetworkTypeUDP6, NetworkTypeTCP6:
		return false
	}

	return false
}

// IsIPv6 returns whether the network type is IPv6 or not.
func (t NetworkType) IsIPv6() bool {
	switch t {
	case NetworkTypeUDP4, NetworkTypeTCP4:
		return false
	case NetworkTypeUDP6, NetworkTypeTCP6:
		return true
	}

	return false
}

// determineNetworkType determines the type of network based on
// the short network string and an IP address.
func determineNetworkType(network string, ip netip.Addr) (NetworkType, error) {
	// we'd rather have an IPv4-mapped IPv6 become IPv4 so that it is usable.
	ip = ip.Unmap()
	switch {
	case strings.HasPrefix(strings.ToLower(network), udp):
		if ip.Is4() {
			return NetworkTypeUDP4, nil
		}

		return NetworkTypeUDP6, nil

	case strings.HasPrefix(strings.ToLower(network), tcp):
		if ip.Is4() {
			return NetworkTypeTCP4, nil
		}

		return NetworkTypeTCP6, nil
	}

	return NetworkType(0), fmt.Errorf("%w from %s %s", ErrDetermineNetworkType, network, ip)
}