package main

import (
	"flag"
	"io/ioutil"
	"math/rand"
	"net"
	"os"
	"time"

	"github.com/cloudflare/cfssl/config"
	"github.com/cloudflare/cfssl/signer/local"
	"github.com/golang/glog"
	"google.golang.org/grpc"
	"k8s.io/client-go/kubernetes"

	pb "code.hackerspace.pl/hscloud/cluster/prodvider/proto"
)

var (
	flagLDAPServer          string
	flagLDAPBindDN          string
	flagLDAPGroupSearchBase string
	flagListenAddress       string
	flagKubernetesHost      string

	flagCACertificatePath     string
	flagCAKeyPath             string
	flagKubeCACertificatePath string

	flagProdviderCN string
)

func init() {
	flag.Set("logtostderr", "true")
}

type prodvider struct {
	sign      *local.Signer
	k8s       *kubernetes.Clientset
	srv       *grpc.Server
	kubeCAPEM []byte
}

func newProdvider() *prodvider {
	policy := &config.Signing{
		Profiles: map[string]*config.SigningProfile{
			"server": &config.SigningProfile{
				Usage:        []string{"signing", "key encipherment", "server auth"},
				ExpiryString: "30d",
			},
			"client": &config.SigningProfile{
				Usage:        []string{"signing", "key encipherment", "client auth"},
				ExpiryString: "30d",
			},
			"client-server": &config.SigningProfile{
				Usage:        []string{"signing", "key encipherment", "server auth", "client auth"},
				ExpiryString: "30d",
			},
		},
		Default: config.DefaultConfig(),
	}

	sign, err := local.NewSignerFromFile(flagCACertificatePath, flagCAKeyPath, policy)
	if err != nil {
		glog.Exitf("Could not create signer: %v", err)
	}

	kubeCAPEM, err := ioutil.ReadFile(flagKubeCACertificatePath)
	if err != nil {
		glog.Exitf("Could not read kube CA cert path: %v")
	}

	return &prodvider{
		sign:      sign,
		kubeCAPEM: kubeCAPEM,
	}
}

// Timebomb restarts the prodvider after a deadline, usually 7 days +/- 4 days.
// This is to ensure we serve with up-to-date certificates and that the service
// can still come up after restart.
func timebomb(srv *grpc.Server) {
	deadline := time.Now()
	deadline = deadline.Add(3 * 24 * time.Hour)
	rand.Seed(time.Now().UnixNano())
	jitter := rand.Intn(8 * 24 * 60 * 60)
	deadline = deadline.Add(time.Duration(jitter) * time.Second)

	glog.Infof("Timebomb deadline set to %v", deadline)

	t := time.NewTicker(time.Minute)
	for {
		<-t.C
		if time.Now().After(deadline) {
			break
		}
	}

	// Start killing connections, and wait one minute...
	go srv.GracefulStop()
	<-t.C
	glog.Infof("Timebomb deadline exceeded, restarting.")
	os.Exit(0)
}

func main() {
	flag.StringVar(&flagLDAPServer, "ldap_server", "ldap.hackerspace.pl:636", "Address of LDAP server")
	flag.StringVar(&flagLDAPBindDN, "ldap_bind_dn", "uid=%s,ou=People,dc=hackerspace,dc=pl", "LDAP Bind DN")
	flag.StringVar(&flagLDAPGroupSearchBase, "ldap_group_search_base_dn", "ou=Group,dc=hackerspace,dc=pl", "LDAP Group Search Base DN")
	flag.StringVar(&flagListenAddress, "listen_address", "127.0.0.1:8080", "gRPC listen address")
	flag.StringVar(&flagKubernetesHost, "kubernetes_host", "k0.hswaw.net:4001", "Kubernetes API host")

	flag.StringVar(&flagCACertificatePath, "ca_certificate_path", "", "CA certificate path (for signer)")
	flag.StringVar(&flagCAKeyPath, "ca_key_path", "", "CA key path (for signer)")
	flag.StringVar(&flagKubeCACertificatePath, "kube_ca_certificate_path", "", "CA certificate path (for checking kube apiserver)")

	flag.StringVar(&flagProdviderCN, "prodvider_cn", "prodvider.hswaw.net", "CN of certificate that prodvider will use")
	flag.Parse()

	if flagCACertificatePath == "" || flagCAKeyPath == "" {
		glog.Exitf("CA certificate and key must be provided")
	}

	p := newProdvider()
	err := p.kubernetesConnect()
	if err != nil {
		glog.Exitf("Could not connect to kubernetes: %v", err)
	}
	creds := p.selfCreds()

	// Start serving gRPC
	grpcLis, err := net.Listen("tcp", flagListenAddress)
	if err != nil {
		glog.Exitf("Could not listen for gRPC on %q: %v", flagListenAddress, err)
	}

	glog.Infof("Starting gRPC on %q...", flagListenAddress)
	grpcSrv := grpc.NewServer(creds)

	pb.RegisterProdviderServer(grpcSrv, p)

	go timebomb(grpcSrv)

	err = grpcSrv.Serve(grpcLis)
	if err != nil {
		glog.Exitf("Could not serve gRPC: %v", err)
	}
}