package logic

import (
	"errors"
	"fmt"
	"log"
	"net"
	"strconv"
	"strings"
	"time"

	"github.com/c-robinson/iplib"
	"github.com/gravitl/netmaker/database"
	"github.com/gravitl/netmaker/logger"
	"github.com/gravitl/netmaker/logic/acls/nodeacls"
	"github.com/gravitl/netmaker/models"
	"github.com/gravitl/netmaker/netclient/ncutils"
	"github.com/gravitl/netmaker/servercfg"
	"golang.zx2c4.com/wireguard/wgctrl/wgtypes"
)

// GetPeerUpdate - gets a wireguard peer config for each peer of a node
func GetPeerUpdate(node *models.Node) (models.PeerUpdate, error) {
	var peerUpdate models.PeerUpdate
	var peers []wgtypes.PeerConfig
	var serverNodeAddresses = []models.ServerAddr{}
	currentPeers, err := GetNetworkNodes(node.Network)
	if err != nil {
		return models.PeerUpdate{}, err
	}
	if node.IsRelayed == "yes" {
		return GetPeerUpdateForRelayedNode(node)
	}

	// udppeers = the peers parsed from the local interface
	// gives us correct port to reach
	udppeers, errN := database.GetPeers(node.Network)
	if errN != nil {
		logger.Log(2, errN.Error())
	}

	// #1 Set Keepalive values: set_keepalive
	// #2 Set local address: set_local - could be a LOT BETTER and fix some bugs with additional logic
	// #3 Set allowedips: set_allowedips
	for _, peer := range currentPeers {

		// if the node is not a server, set the endpoint
		var setEndpoint = !(node.IsServer == "yes")

		if peer.ID == node.ID {
			//skip yourself
			continue
		}
		if peer.IsRelayed == "yes" {
			if !(node.IsRelay == "yes" && ncutils.StringSliceContains(node.RelayAddrs, peer.PrimaryAddress())) {
				//skip -- will be added to relay
				continue
			} else if node.IsRelay == "yes" && ncutils.StringSliceContains(node.RelayAddrs, peer.PrimaryAddress()) {
				// dont set peer endpoint if it's relayed by node
				setEndpoint = false
			}
		}
		if !nodeacls.AreNodesAllowed(nodeacls.NetworkID(node.Network), nodeacls.NodeID(node.ID), nodeacls.NodeID(peer.ID)) {
			//skip if not permitted by acl
			continue
		}
		pubkey, err := wgtypes.ParseKey(peer.PublicKey)
		if err != nil {
			return models.PeerUpdate{}, err
		}
		if node.Endpoint == peer.Endpoint {
			//peer is on same network
			// set_local
			if node.LocalAddress != peer.LocalAddress && peer.LocalAddress != "" {
				peer.Endpoint = peer.LocalAddress
				if peer.LocalListenPort != 0 {
					peer.ListenPort = peer.LocalListenPort
				}
			} else {
				continue
			}
		}

		// set address if setEndpoint is true
		// otherwise, will get inserted as empty value
		var address *net.UDPAddr

		// Sets ListenPort to UDP Hole Punching Port assuming:
		// - UDP Hole Punching is enabled
		// - udppeers retrieval did not return an error
		// - the endpoint is valid
		if setEndpoint {

			var setUDPPort = false
			if peer.UDPHolePunch == "yes" && errN == nil && CheckEndpoint(udppeers[peer.PublicKey]) {
				endpointstring := udppeers[peer.PublicKey]
				endpointarr := strings.Split(endpointstring, ":")
				if len(endpointarr) == 2 {
					port, err := strconv.Atoi(endpointarr[1])
					if err == nil {
						setUDPPort = true
						peer.ListenPort = int32(port)
					}
				}
			}
			// if udp hole punching is on, but udp hole punching did not set it, use the LocalListenPort instead
			// or, if port is for some reason zero use the LocalListenPort
			// but only do this if LocalListenPort is not zero
			if ((peer.UDPHolePunch == "yes" && !setUDPPort) || peer.ListenPort == 0) && peer.LocalListenPort != 0 {
				peer.ListenPort = peer.LocalListenPort
			}

			endpoint := peer.Endpoint + ":" + strconv.FormatInt(int64(peer.ListenPort), 10)
			address, err = net.ResolveUDPAddr("udp", endpoint)
			if err != nil {
				return models.PeerUpdate{}, err
			}
		}
		// set_allowedips
		allowedips := GetAllowedIPs(node, &peer)
		var keepalive time.Duration
		if node.PersistentKeepalive != 0 {
			// set_keepalive
			keepalive, _ = time.ParseDuration(strconv.FormatInt(int64(node.PersistentKeepalive), 10) + "s")
		}
		var peerData = wgtypes.PeerConfig{
			PublicKey:                   pubkey,
			Endpoint:                    address,
			ReplaceAllowedIPs:           true,
			AllowedIPs:                  allowedips,
			PersistentKeepaliveInterval: &keepalive,
		}

		peers = append(peers, peerData)
		if peer.IsServer == "yes" {
			serverNodeAddresses = append(serverNodeAddresses, models.ServerAddr{IsLeader: IsLeader(&peer), Address: peer.Address})
		}
	}
	if node.IsIngressGateway == "yes" {
		extPeers, err := getExtPeers(node)
		if err == nil {
			peers = append(peers, extPeers...)
		} else {
			log.Println("ERROR RETRIEVING EXTERNAL PEERS", err)
		}
	}

	peerUpdate.Network = node.Network
	peerUpdate.ServerVersion = servercfg.Version
	peerUpdate.Peers = peers
	peerUpdate.ServerAddrs = serverNodeAddresses
	peerUpdate.DNS = getPeerDNS(node.Network)
	return peerUpdate, nil
}

func getExtPeers(node *models.Node) ([]wgtypes.PeerConfig, error) {
	var peers []wgtypes.PeerConfig
	extPeers, err := GetExtPeersList(node)
	if err != nil {
		return peers, err
	}
	for _, extPeer := range extPeers {
		pubkey, err := wgtypes.ParseKey(extPeer.PublicKey)
		if err != nil {
			logger.Log(1, "error parsing ext pub key:", err.Error())
			continue
		}

		if node.PublicKey == extPeer.PublicKey {
			continue
		}

		var allowedips []net.IPNet
		var peer wgtypes.PeerConfig
		if extPeer.Address != "" {
			var peeraddr = net.IPNet{
				IP:   net.ParseIP(extPeer.Address),
				Mask: net.CIDRMask(32, 32),
			}
			if peeraddr.IP != nil && peeraddr.Mask != nil {
				allowedips = append(allowedips, peeraddr)
			}
		}

		if extPeer.Address6 != "" {
			var addr6 = net.IPNet{
				IP:   net.ParseIP(extPeer.Address6),
				Mask: net.CIDRMask(128, 128),
			}
			if addr6.IP != nil && addr6.Mask != nil {
				allowedips = append(allowedips, addr6)
			}
		}
		peer = wgtypes.PeerConfig{
			PublicKey:         pubkey,
			ReplaceAllowedIPs: true,
			AllowedIPs:        allowedips,
		}
		peers = append(peers, peer)
	}
	return peers, nil

}

// GetAllowedIPs - calculates the wireguard allowedip field for a peer of a node based on the peer and node settings
func GetAllowedIPs(node, peer *models.Node) []net.IPNet {
	var allowedips []net.IPNet

	if peer.Address != "" {
		var peeraddr = net.IPNet{
			IP:   net.ParseIP(peer.Address),
			Mask: net.CIDRMask(32, 32),
		}
		allowedips = append(allowedips, peeraddr)
	}

	if peer.Address6 != "" {
		var addr6 = net.IPNet{
			IP:   net.ParseIP(peer.Address6),
			Mask: net.CIDRMask(128, 128),
		}
		allowedips = append(allowedips, addr6)
	}
	// handle manually set peers
	for _, allowedIp := range peer.AllowedIPs {

		// parsing as a CIDR first. If valid CIDR, append
		if _, ipnet, err := net.ParseCIDR(allowedIp); err == nil {
			nodeEndpointArr := strings.Split(node.Endpoint, ":")
			if !ipnet.Contains(net.IP(nodeEndpointArr[0])) && ipnet.IP.String() != peer.Address { // don't need to add an allowed ip that already exists..
				allowedips = append(allowedips, *ipnet)
			}

		} else { // parsing as an IP second. If valid IP, check if ipv4 or ipv6, then append
			if iplib.Version(net.ParseIP(allowedIp)) == 4 && allowedIp != peer.Address {
				ipnet := net.IPNet{
					IP:   net.ParseIP(allowedIp),
					Mask: net.CIDRMask(32, 32),
				}
				allowedips = append(allowedips, ipnet)
			} else if iplib.Version(net.ParseIP(allowedIp)) == 6 && allowedIp != peer.Address6 {
				ipnet := net.IPNet{
					IP:   net.ParseIP(allowedIp),
					Mask: net.CIDRMask(128, 128),
				}
				allowedips = append(allowedips, ipnet)
			}
		}
	}
	// handle egress gateway peers
	if peer.IsEgressGateway == "yes" {
		//hasGateway = true
		ranges := peer.EgressGatewayRanges
		for _, iprange := range ranges { // go through each cidr for egress gateway
			_, ipnet, err := net.ParseCIDR(iprange) // confirming it's valid cidr
			if err != nil {
				logger.Log(1, "could not parse gateway IP range. Not adding ", iprange)
				continue // if can't parse CIDR
			}
			nodeEndpointArr := strings.Split(peer.Endpoint, ":") // getting the public ip of node
			if ipnet.Contains(net.ParseIP(nodeEndpointArr[0])) { // ensuring egress gateway range does not contain endpoint of node
				logger.Log(2, "egress IP range of ", iprange, " overlaps with ", node.Endpoint, ", omitting")
				continue // skip adding egress range if overlaps with node's ip
			}
			// TODO: Could put in a lot of great logic to avoid conflicts / bad routes
			if ipnet.Contains(net.ParseIP(node.LocalAddress)) { // ensuring egress gateway range does not contain public ip of node
				logger.Log(2, "egress IP range of ", iprange, " overlaps with ", node.LocalAddress, ", omitting")
				continue // skip adding egress range if overlaps with node's local ip
			}
			if err != nil {
				logger.Log(1, "error encountered when setting egress range", err.Error())
			} else {
				allowedips = append(allowedips, *ipnet)
			}
		}
	}
	// handle ingress gateway peers
	if peer.IsIngressGateway == "yes" {
		extPeers, err := getExtPeers(peer)
		if err != nil {
			logger.Log(2, "could not retrieve ext peers for ", peer.Name, err.Error())
		}
		for _, extPeer := range extPeers {
			allowedips = append(allowedips, extPeer.AllowedIPs...)
		}
	}
	// handle relay gateway peers
	if peer.IsRelay == "yes" {
		for _, ip := range peer.RelayAddrs {
			//find node ID of relayed peer
			relayedPeer, err := findNode(ip)
			if err != nil {
				logger.Log(0, "failed to find node for ip ", ip, err.Error())
				continue
			}
			if relayedPeer == nil {
				continue
			}
			if relayedPeer.ID == node.ID {
				//skip self
				continue
			}
			//check if acl permits comms
			if !nodeacls.AreNodesAllowed(nodeacls.NetworkID(node.Network), nodeacls.NodeID(node.ID), nodeacls.NodeID(relayedPeer.ID)) {
				continue
			}
			if iplib.Version(net.ParseIP(ip)) == 4 {
				relayAddr := net.IPNet{
					IP:   net.ParseIP(ip),
					Mask: net.CIDRMask(32, 32),
				}
				allowedips = append(allowedips, relayAddr)
			}
			if iplib.Version(net.ParseIP(ip)) == 6 {
				relayAddr := net.IPNet{
					IP:   net.ParseIP(ip),
					Mask: net.CIDRMask(128, 128),
				}
				allowedips = append(allowedips, relayAddr)
			}
		}
	}
	return allowedips
}

func getPeerDNS(network string) string {
	var dns string
	if nodes, err := GetNetworkNodes(network); err == nil {
		for i := range nodes {
			dns = dns + fmt.Sprintf("%s %s.%s\n", nodes[i].Address, nodes[i].Name, nodes[i].Network)
		}
	}

	if customDNSEntries, err := GetCustomDNS(network); err == nil {
		for _, entry := range customDNSEntries {
			// TODO - filter entries based on ACLs / given peers vs nodes in network
			dns = dns + fmt.Sprintf("%s %s.%s\n", entry.Address, entry.Name, entry.Network)
		}
	}
	return dns
}

// GetPeerUpdateForRelayedNode - calculates peer update for a relayed node by getting the relay
// copying the relay node's allowed ips and making appropriate substitutions
func GetPeerUpdateForRelayedNode(node *models.Node) (models.PeerUpdate, error) {
	var peerUpdate models.PeerUpdate
	var peers []wgtypes.PeerConfig
	var serverNodeAddresses = []models.ServerAddr{}
	var allowedips []net.IPNet
	//find node that is relaying us
	relay := FindRelay(node)
	if relay == nil {
		return models.PeerUpdate{}, errors.New("not found")
	}
	//add relay to lists of allowed ip
	if relay.Address != "" {
		relayIP := net.IPNet{
			IP:   net.ParseIP(relay.Address),
			Mask: net.CIDRMask(32, 32),
		}
		allowedips = append(allowedips, relayIP)
	}
	if relay.Address6 != "" {
		relayIP6 := net.IPNet{
			IP:   net.ParseIP(relay.Address6),
			Mask: net.CIDRMask(128, 128),
		}
		allowedips = append(allowedips, relayIP6)
	}
	//get PeerUpdate for relayed node
	relayPeerUpdate, err := GetPeerUpdate(relay)
	if err != nil {
		return models.PeerUpdate{}, err
	}
	//add the relays allowed ips from all of the relay's peers
	for _, peer := range relayPeerUpdate.Peers {
		allowedips = append(allowedips, peer.AllowedIPs...)
	}
	//delete any ips not permitted by acl
	for i, ip := range allowedips {
		target, err := findNode(ip.IP.String())
		if err != nil {
			logger.Log(0, "failed to find node for ip", ip.IP.String(), err.Error())
			continue
		}
		if target == nil {
			logger.Log(0, "failed to find node for ip", ip.IP.String())
			continue
		}
		if !nodeacls.AreNodesAllowed(nodeacls.NetworkID(node.Network), nodeacls.NodeID(node.ID), nodeacls.NodeID(target.ID)) {
			logger.Log(0, "deleting node from relayednode per acl", node.Name, target.Name)
			if i+1 == len(allowedips) {
				allowedips = allowedips[:i]
			} else {
				allowedips = append(allowedips[:i], allowedips[i+1:]...)
			}
		}
	}
	//delete self from allowed ips
	for i, ip := range allowedips {
		if ip.IP.String() == node.Address || ip.IP.String() == node.Address6 {
			if i+1 == len(allowedips) {
				allowedips = allowedips[:i]
			} else {
				allowedips = append(allowedips[:i], allowedips[i+1:]...)
			}
		}
	}

	pubkey, err := wgtypes.ParseKey(relay.PublicKey)
	if err != nil {
		return models.PeerUpdate{}, err
	}
	endpoint := relay.Endpoint + ":" + strconv.FormatInt(int64(relay.ListenPort), 10)
	address, err := net.ResolveUDPAddr("udp", endpoint)
	if err != nil {
		return models.PeerUpdate{}, err
	}
	var keepalive time.Duration
	if node.PersistentKeepalive != 0 {
		// set_keepalive
		keepalive, _ = time.ParseDuration(strconv.FormatInt(int64(node.PersistentKeepalive), 10) + "s")
	}
	var peerData = wgtypes.PeerConfig{
		PublicKey:                   pubkey,
		Endpoint:                    address,
		ReplaceAllowedIPs:           true,
		AllowedIPs:                  allowedips,
		PersistentKeepaliveInterval: &keepalive,
	}
	peers = append(peers, peerData)
	if relay.IsServer == "yes" {
		serverNodeAddresses = append(serverNodeAddresses, models.ServerAddr{IsLeader: IsLeader(relay), Address: relay.Address})
	}
	peerUpdate.Network = node.Network
	peerUpdate.ServerVersion = servercfg.Version
	peerUpdate.Peers = peers
	peerUpdate.ServerAddrs = serverNodeAddresses
	peerUpdate.DNS = getPeerDNS(node.Network)
	return peerUpdate, nil
}