package main

import (
	"crypto/ed25519"
	"crypto/rand"
	"crypto/tls"
	"crypto/x509"
	"crypto/x509/pkix"
	"encoding/pem"
	"fmt"
	"math/big"
	"net"
	"time"

	"github.com/golang/glog"
	"google.golang.org/grpc"
	"google.golang.org/grpc/credentials"
)

func serializeCert(der []byte) []byte {
	return pem.EncodeToMemory(&pem.Block{Type: "CERTIFICATE", Bytes: der})
}

func serializeKey(priv ed25519.PrivateKey) []byte {
	pkcs8, err := x509.MarshalPKCS8PrivateKey(priv)
	if err != nil {
		return nil
	}

	block := pem.EncodeToMemory(&pem.Block{Type: "PRIVATE KEY", Bytes: pkcs8})
	return block
}

func (p *prodvider) selfCreds() grpc.ServerOption {
	glog.Infof("Bootstrapping certificate for self (%q)...", flagProdviderCN)

	// Create a cert
	keyRaw, certRaw, err := p.makeSelfCertificate()
	if err != nil {
		glog.Exitf("Could not sign certificate for self: %v", err)
	}

	serverCert, err := tls.X509KeyPair(serializeCert(certRaw), serializeKey(keyRaw))
	if err != nil {
		glog.Exitf("Could not use gRPC certificate: %v", err)
	}

	serverCert.Certificate = append(serverCert.Certificate, p.intermediateCACert.Raw)

	return grpc.Creds(credentials.NewTLS(&tls.Config{
		Certificates: []tls.Certificate{serverCert},
	}))
}

func (p *prodvider) makeSelfCertificate() (ed25519.PrivateKey, []byte, error) {
	serialNumberLimit := new(big.Int).Lsh(big.NewInt(1), 127)
	serialNumber, err := rand.Int(rand.Reader, serialNumberLimit)
	if err != nil {
		return nil, nil, err
	}
	template := &x509.Certificate{
		Subject: pkix.Name{
			CommonName: flagProdviderCN,
		},
		NotBefore:    time.Now(),
		NotAfter:     time.Now().Add(30 * 24 * time.Hour),
		KeyUsage:     x509.KeyUsageDigitalSignature | x509.KeyUsageKeyEncipherment,
		ExtKeyUsage:  []x509.ExtKeyUsage{x509.ExtKeyUsageServerAuth},
		SerialNumber: serialNumber,
		DNSNames:     []string{flagProdviderCN},
		IPAddresses: []net.IP{
			{127, 0, 0, 1},
		},
	}

	pkey, skey, err := ed25519.GenerateKey(rand.Reader)
	if err != nil {
		return nil, nil, err
	}
	bytes, err := x509.CreateCertificate(rand.Reader, template, p.intermediateCACert, pkey, p.intermediateCAKey)
	if err != nil {
		return nil, nil, err
	}
	return skey, bytes, nil
}

func (p *prodvider) makeKubernetesCertificate(username, o string, notAfter time.Time) (ed25519.PrivateKey, []byte, error) {
	serialNumberLimit := new(big.Int).Lsh(big.NewInt(1), 127)
	serialNumber, err := rand.Int(rand.Reader, serialNumberLimit)
	if err != nil {
		return nil, nil, err
	}
	template := &x509.Certificate{
		Subject: pkix.Name{
			Organization:       []string{o},
			OrganizationalUnit: []string{fmt.Sprintf("Prodvider Kubernetes Cert for %s/%s", username, o)},
			CommonName:         username,
		},
		NotBefore:   time.Now(),
		NotAfter:    notAfter,
		KeyUsage:    x509.KeyUsageDigitalSignature | x509.KeyUsageKeyEncipherment,
		ExtKeyUsage: []x509.ExtKeyUsage{x509.ExtKeyUsageClientAuth},
		DNSNames: []string{
			username,
		},
		SerialNumber: serialNumber,
	}

	pkey, skey, err := ed25519.GenerateKey(rand.Reader)
	if err != nil {
		return nil, nil, err
	}
	bytes, err := x509.CreateCertificate(rand.Reader, template, p.intermediateCACert, pkey, p.intermediateCAKey)
	if err != nil {
		return nil, nil, err
	}
	return skey, bytes, nil
}