package functions

import (
	"google.golang.org/grpc/credentials"
	"crypto/tls"
	"fmt"
	"errors"
	"context"
	"log"
	"net"
	"math/rand"
	"time"
        "github.com/gravitl/netmaker/netclient/config"
        "github.com/gravitl/netmaker/netclient/wireguard"
        "github.com/gravitl/netmaker/netclient/server"
        "github.com/gravitl/netmaker/netclient/local"
        nodepb "github.com/gravitl/netmaker/grpc"
	"golang.zx2c4.com/wireguard/wgctrl"
        "google.golang.org/grpc"
	"golang.zx2c4.com/wireguard/wgctrl/wgtypes"
	//homedir "github.com/mitchellh/go-homedir"
)

func JoinNetwork(cfg config.ClientConfig) error {

	hasnet := local.HasNetwork(cfg.Network)
	if hasnet {
		   err := errors.New("ALREADY_INSTALLED. Netclient appears to already be installed for " + cfg.Network + ". To re-install, please remove by executing 'sudo netclient leave -n " + cfg.Network + "'. Then re-run the install command.")
		return err
	}
	log.Println("attempting to join " + cfg.Network + " at " + cfg.Server.GRPCAddress)
	err := config.Write(&cfg, cfg.Network)
	if err != nil {
		return err
	}

        wgclient, err := wgctrl.New()
        if err != nil {
		return err
        }
        defer wgclient.Close()
	if cfg.Node.Network == "" {
		return errors.New("no network provided")
	}
	if cfg.Node.LocalRange != "" {
	if cfg.Node.LocalAddress == "" {
		log.Println("local vpn, getting local address from range: " + cfg.Node.LocalRange)
		ifaces, err := net.Interfaces()
                if err != nil {
                        return err
                }
		_, localrange, err := net.ParseCIDR(cfg.Node.LocalRange)
		if err != nil {
                        return err
                }

		var local string
		found := false
		for _, i := range ifaces {
			if i.Flags&net.FlagUp == 0 {
				continue // interface down
			}
			if i.Flags&net.FlagLoopback != 0 {
				continue // loopback interface
			}
			addrs, err := i.Addrs()
			if err != nil {
				return err
			}
			for _, addr := range addrs {
				var ip net.IP
				switch v := addr.(type) {
				case *net.IPNet:
					if !found {
						ip = v.IP
						local = ip.String()
						if cfg.Node.IsLocal == "yes" {
							found = localrange.Contains(ip)
						} else {
							found = true
						}
					}
				case *net.IPAddr:
					if  !found {
						ip = v.IP
						local = ip.String()
						if cfg.Node.IsLocal == "yes" {
							found = localrange.Contains(ip)

						} else {
							found = true
						}
					}
				}
			}
		}
		cfg.Node.LocalAddress = local
	}
	}
	if cfg.Node.Password == "" {
		cfg.Node.Password = GenPass()
	}
        if cfg.Node.Endpoint == "" {
		if cfg.Node.IsLocal == "yes" && cfg.Node.LocalAddress != "" {
			cfg.Node.Endpoint = cfg.Node.LocalAddress
		} else {

			cfg.Node.Endpoint, err = getPublicIP()
			if err != nil {
				fmt.Println("Error setting cfg.Node.Endpoint.")
				return err
			}
		}
        } else {
                cfg.Node.Endpoint = cfg.Node.Endpoint
        }
	if cfg.Node.PrivateKey == "" {
		privatekey, err := wgtypes.GeneratePrivateKey()
		if err != nil {
			log.Fatal(err)
		}
		cfg.Node.PrivateKey = privatekey.String()
		cfg.Node.PublicKey = privatekey.PublicKey().String()
	}

	if cfg.Node.MacAddress == "" {
		macs, err := getMacAddr()
		if err != nil {
			return err
		} else if len(macs) == 0 {
			log.Fatal()
		} else {
			cfg.Node.MacAddress  = macs[0]
		}
	}
	if cfg.Node.Port == 0 {
		cfg.Node.Port, err = GetFreePort(51821)
		if err != nil {
			fmt.Printf("Error retrieving port: %v", err)
		}
	}
	var wcclient nodepb.NodeServiceClient
	var requestOpts grpc.DialOption
	requestOpts = grpc.WithInsecure()
	if cfg.Server.GRPCSSL == "on" {
		h2creds := credentials.NewTLS(&tls.Config{NextProtos: []string{"h2"}})
		requestOpts = grpc.WithTransportCredentials(h2creds)
	}
	conn, err := grpc.Dial(cfg.Server.GRPCAddress, requestOpts)

        if err != nil {
                log.Fatalf("Unable to establish client connection to " + cfg.Server.GRPCAddress + ": %v", err)
        }

        wcclient = nodepb.NewNodeServiceClient(conn)

        postnode := &nodepb.Node{
                Password: cfg.Node.Password,
                Macaddress: cfg.Node.MacAddress,
                Accesskey: cfg.Server.AccessKey,
                Nodenetwork:  cfg.Network,
                Listenport: cfg.Node.Port,
                Postup: cfg.Node.PostUp,
                Postdown: cfg.Node.PostDown,
                Keepalive: cfg.Node.KeepAlive,
		Localaddress: cfg.Node.LocalAddress,
		Interface: cfg.Node.Interface,
                Publickey: cfg.Node.PublicKey,
                Name: cfg.Node.Name,
                Endpoint: cfg.Node.Endpoint,
        }
        err = config.ModConfig(postnode)
        if err != nil {
		return err
        }

        res, err := wcclient.CreateNode(
                context.TODO(),
                &nodepb.CreateNodeReq{
                        Node: postnode,
                },
        )
        if err != nil {
                return err
        }
        node := res.Node
        if err != nil {
                return err
        }

       if node.Dnsoff==true  {
		cfg.Node.DNS = "yes"
	}
	if !(cfg.Node.IsLocal == "yes") && node.Islocal && node.Localrange != "" {
		node.Localaddress, err = getLocalIP(node.Localrange)
		if err != nil {
			return err
		}
		node.Endpoint = node.Localaddress
	}
        err = config.ModConfig(node)
        if err != nil {
                return err
        }

	if node.Ispending {
		fmt.Println("Node is marked as PENDING.")
		fmt.Println("Awaiting approval from Admin before configuring WireGuard.")
	        if cfg.Daemon != "off" {
			err = local.ConfigureSystemD(cfg.Network)
			return err
		}
	}

	peers, hasGateway, gateways, err := server.GetPeers(node.Macaddress, cfg.Network, cfg.Server.GRPCAddress, node.Isdualstack, node.Isingressgateway)

	if err != nil {
                return err
        }
	err = wireguard.StorePrivKey(cfg.Node.PrivateKey, cfg.Network)
        if err != nil {
                return err
        }
	err = wireguard.InitWireguard(node, cfg.Node.PrivateKey, peers, hasGateway, gateways)
        if err != nil {
                return err
        }
	if cfg.Daemon != "off" {
		err = local.ConfigureSystemD(cfg.Network)
	}
        if err != nil {
                return err
        }

	return err
}

//generate an access key value
func GenPass() string {

        var seededRand *rand.Rand = rand.New(
                rand.NewSource(time.Now().UnixNano()))

        length := 16
        charset := "abcdefghijklmnopqrstuvwxyz" + "ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"

        b := make([]byte, length)
        for i := range b {
                b[i] = charset[seededRand.Intn(len(charset))]
        }
        return string(b)
}