package logic

import (
	"errors"
	"fmt"
	"net"

	"github.com/google/uuid"
	"golang.org/x/exp/slog"

	"github.com/gravitl/netmaker/models"
)

const (
	IPv4Network = "0.0.0.0/0"
	IPv6Network = "::/0"
)

func ValidateInetGwReq(inetNode models.Node, req models.InetNodeReq, update bool) error {
	inetHost, err := GetHost(inetNode.HostID.String())
	if err != nil {
		return err
	}
	if inetHost.FirewallInUse == models.FIREWALL_NONE {
		return errors.New("iptables or nftables needs to be installed")
	}
	if inetNode.EgressDetails.InternetGwID != "" {
		return fmt.Errorf("node %s is using a internet gateway already", inetHost.Name)
	}
	if inetNode.IsRelayed {
		return fmt.Errorf("node %s is being relayed", inetHost.Name)
	}

	for _, clientNodeID := range req.InetNodeClientIDs {
		clientNode, err := GetNodeByID(clientNodeID)
		if err != nil {
			return err
		}
		if clientNode.IsFailOver {
			return errors.New("failover node cannot be set to use internet gateway")
		}
		clientHost, err := GetHost(clientNode.HostID.String())
		if err != nil {
			return err
		}
		if clientHost.IsDefault {
			return errors.New("default host cannot be set to use internet gateway")
		}
		if clientHost.OS != models.OS_Types.Linux && clientHost.OS != models.OS_Types.Windows {
			return errors.New("can only attach linux or windows machine to a internet gateway")
		}
		if clientNode.EgressDetails.IsInternetGateway {
			return fmt.Errorf("node %s acting as internet gateway cannot use another internet gateway", clientHost.Name)
		}
		if update {
			if clientNode.EgressDetails.InternetGwID != "" && clientNode.EgressDetails.InternetGwID != inetNode.ID.String() {
				return fmt.Errorf("node %s is already using a internet gateway", clientHost.Name)
			}
		} else {
			if clientNode.EgressDetails.InternetGwID != "" {
				return fmt.Errorf("node %s is already using a internet gateway", clientHost.Name)
			}
		}
		if clientNode.FailedOverBy != uuid.Nil {
			ResetFailedOverPeer(&clientNode)
		}

		if clientNode.IsRelayed && clientNode.RelayedBy != inetNode.ID.String() {
			return fmt.Errorf("node %s is being relayed", clientHost.Name)
		}

		for _, nodeID := range clientHost.Nodes {
			node, err := GetNodeByID(nodeID)
			if err != nil {
				continue
			}
			if node.EgressDetails.InternetGwID != "" && node.EgressDetails.InternetGwID != inetNode.ID.String() {
				return errors.New("nodes on same host cannot use different internet gateway")
			}

		}
	}
	return nil
}

// SetInternetGw - sets the node as internet gw based on flag bool
func SetInternetGw(node *models.Node, req models.InetNodeReq) {
	node.EgressDetails.IsInternetGateway = true
	node.EgressDetails.InetNodeReq = req
	for _, clientNodeID := range req.InetNodeClientIDs {
		clientNode, err := GetNodeByID(clientNodeID)
		if err != nil {
			continue
		}
		clientNode.EgressDetails.InternetGwID = node.ID.String()
		UpsertNode(&clientNode)
	}

}

func UnsetInternetGw(node *models.Node) {
	nodes, err := GetNetworkNodes(node.Network)
	if err != nil {
		slog.Error("failed to get network nodes", "network", node.Network, "error", err)
		return
	}
	for _, clientNode := range nodes {
		if node.ID.String() == clientNode.EgressDetails.InternetGwID {
			clientNode.EgressDetails.InternetGwID = ""
			UpsertNode(&clientNode)
		}

	}
	node.EgressDetails.IsInternetGateway = false
	node.EgressDetails.InetNodeReq = models.InetNodeReq{}

}

func SetDefaultGwForRelayedUpdate(relayed, relay models.Node, peerUpdate models.HostPeerUpdate) models.HostPeerUpdate {
	if relay.EgressDetails.InternetGwID != "" {
		relayedHost, err := GetHost(relayed.HostID.String())
		if err != nil {
			return peerUpdate
		}
		peerUpdate.ChangeDefaultGw = true
		peerUpdate.DefaultGwIp = relay.Address.IP
		if peerUpdate.DefaultGwIp == nil || relayedHost.EndpointIP == nil {
			peerUpdate.DefaultGwIp = relay.Address6.IP
		}

	}
	return peerUpdate
}

func SetDefaultGw(node models.Node, peerUpdate models.HostPeerUpdate) models.HostPeerUpdate {
	if node.EgressDetails.InternetGwID != "" {

		inetNode, err := GetNodeByID(node.EgressDetails.InternetGwID)
		if err != nil {
			return peerUpdate
		}
		host, err := GetHost(node.HostID.String())
		if err != nil {
			return peerUpdate
		}

		peerUpdate.ChangeDefaultGw = true
		peerUpdate.DefaultGwIp = inetNode.Address.IP
		if peerUpdate.DefaultGwIp == nil || host.EndpointIP == nil {
			peerUpdate.DefaultGwIp = inetNode.Address6.IP
		}
	}
	return peerUpdate
}

// GetAllowedIpForInetNodeClient - get inet cidr for node using a inet gw
func GetAllowedIpForInetNodeClient(node, peer *models.Node) []net.IPNet {
	var allowedips = []net.IPNet{}

	if peer.Address.IP != nil {
		_, ipnet, _ := net.ParseCIDR(IPv4Network)
		allowedips = append(allowedips, *ipnet)
	}

	if peer.Address6.IP != nil {
		_, ipnet, _ := net.ParseCIDR(IPv6Network)
		allowedips = append(allowedips, *ipnet)
	}

	return allowedips
}