// nolint: gofmt, goimports

// Copyright 2009 The Go Authors. All rights reserved.
// Dehydrated certificate modifications Copyright 2015-2017 Jeremy Rand. All
// rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.


// Generate a self-signed X.509 certificate for a TLS server. Outputs to
// 'cert.pem' and 'key.pem' and will overwrite existing files.

// This code has been modified from the stock Go code to generate
// "dehydrated certificates", suitable for inclusion in a Namecoin name.

// Last rebased against Go 1.8.3.
// Future rebases need to rebase all of the main, parent, and falseHost flows.

package main

import (
	"crypto/ecdsa"
	"crypto/elliptic"
	"crypto/rand"
	//"crypto/rsa"
	"crypto/x509"
	"crypto/x509/pkix"
	"encoding/base64"
	"encoding/pem"
	//"flag"
	"fmt"
	"io/ioutil"
	"log"
	"math/big"
	//"net"
	"os"
	//"strings"
	"time"
)

//var (
//	host       = flag.String("host", "", "Comma-separated hostnames and IPs to generate a certificate for")
//	validFrom  = flag.String("start-date", "", "Creation date formatted as Jan 1 15:04:05 2011")
//	validFor   = flag.Duration("duration", 365*24*time.Hour, "Duration that certificate is valid for")
//	isCA       = flag.Bool("ca", false, "whether this cert should be its own Certificate Authority")
//	rsaBits    = flag.Int("rsa-bits", 2048, "Size of RSA key to generate. Ignored if --ecdsa-curve is set")
//	ecdsaCurve = flag.String("ecdsa-curve", "", "ECDSA curve to use to generate a key. Valid values are P224, P256, P384, P521")
//)

//func publicKey(priv interface{}) interface{} {
//	switch k := priv.(type) {
//	case *rsa.PrivateKey:
//		return &k.PublicKey
//	case *ecdsa.PrivateKey:
//		return &k.PublicKey
//	default:
//		return nil
//	}
//}

//func pemBlockForKey(priv interface{}) *pem.Block {
//	switch k := priv.(type) {
//	case *rsa.PrivateKey:
//		return &pem.Block{Type: "RSA PRIVATE KEY", Bytes: x509.MarshalPKCS1PrivateKey(k)}
//	case *ecdsa.PrivateKey:
//		b, err := x509.MarshalECPrivateKey(k)
//		if err != nil {
//			fmt.Fprintf(os.Stderr, "Unable to marshal ECDSA private key: %v", err)
//			os.Exit(2)
//		}
//		return &pem.Block{Type: "EC PRIVATE KEY", Bytes: b}
//	default:
//		return nil
//	}
//}

//func main() {
func getParent() (parentCert x509.Certificate, parentPriv interface{}) {
//	flag.Parse()

//	if len(*host) == 0 {
//		log.Fatalf("Missing required --host parameter")
//	}

	var priv interface{}
	var err error
	switch *ecdsaCurve {
	case "":
		//priv, err = rsa.GenerateKey(rand.Reader, *rsaBits)
		log.Fatalf("Missing required --ecdsa-curve parameter")
	case "P224": // nolint: goconst
		priv, err = ecdsa.GenerateKey(elliptic.P224(), rand.Reader)
	case "P256": // nolint: goconst
		priv, err = ecdsa.GenerateKey(elliptic.P256(), rand.Reader)
	case "P384": // nolint: goconst
		priv, err = ecdsa.GenerateKey(elliptic.P384(), rand.Reader)
	case "P521": // nolint: goconst
		priv, err = ecdsa.GenerateKey(elliptic.P521(), rand.Reader)
	default:
		fmt.Fprintf(os.Stderr, "Unrecognized elliptic curve: %q", *ecdsaCurve)
		os.Exit(1)
	}
	if err != nil {
		log.Fatalf("failed to generate private key: %s", err)
	}

	var privPEM []byte
	if *parentKey != "" {
		log.Print("Using existing CA private key")
		privPEM, err = ioutil.ReadFile(*parentKey)
		if err != nil {
			log.Fatalf("failed to read private key: %s", err)
		}
		privBlock, _ := pem.Decode(privPEM)
		priv, err = x509.ParseECPrivateKey(privBlock.Bytes)
		if err != nil {
			log.Fatalf("failed to parse private key: %s", err)
		}
	}

	var notBefore time.Time
	if len(*validFrom) == 0 {
		notBefore = time.Now()
	} else {
		notBefore, err = time.Parse("Jan 2 15:04:05 2006", *validFrom)
		if err != nil {
			fmt.Fprintf(os.Stderr, "Failed to parse creation date: %s\n", err)
			os.Exit(1)
		}
	}

	notAfter := notBefore.Add(*validFor)

	serialNumberLimit := new(big.Int).Lsh(big.NewInt(1), 128)
	serialNumber, err := rand.Int(rand.Reader, serialNumberLimit)
	if err != nil {
		log.Fatalf("failed to generate serial number: %s", err)
	}

	template := x509.Certificate{
		SerialNumber: serialNumber,
		Subject: pkix.Name{
			//Organization: []string{"Acme Co"},
			CommonName:   *host + " Domain CA",
			SerialNumber: "Namecoin TLS Certificate",
		},
		NotBefore: notBefore,
		NotAfter:  notAfter,

		IsCA: true,
		//KeyUsage:              x509.KeyUsageKeyEncipherment | x509.KeyUsageDigitalSignature,
		KeyUsage:              x509.KeyUsageCertSign,
		//ExtKeyUsage:           []x509.ExtKeyUsage{x509.ExtKeyUsageServerAuth},
		BasicConstraintsValid: true,

		PermittedDNSDomainsCritical: true,
		PermittedDNSDomains:         []string{*host},
	}

	//hosts := strings.Split(*host, ",")
	//for _, h := range hosts {
	//	if ip := net.ParseIP(h); ip != nil {
	//		template.IPAddresses = append(template.IPAddresses, ip)
	//	} else {
	//		template.DNSNames = append(template.DNSNames, h)
	//template.DNSNames = append(template.DNSNames, *falseHost)
	//	}
	//}

	//if *isCA {
	//	template.IsCA = true
	//	template.KeyUsage |= x509.KeyUsageCertSign
	//}

	//derBytes, err := x509.CreateCertificate(rand.Reader, &template, &template, publicKey(priv), priv)
	//if err != nil {
	//	log.Fatalf("Failed to create certificate: %s", err)
	//}

	//certOut, err := os.Create("cert.pem")
	//if err != nil {
	//	log.Fatalf("failed to open cert.pem for writing: %s", err)
	//}
	//pem.Encode(certOut, &pem.Block{Type: "CERTIFICATE", Bytes: derBytes})
	//certOut.Close()
	//log.Print("written cert.pem\n")

	pubBytes, err := x509.MarshalPKIXPublicKey(publicKey(priv))
	if err != nil {
		log.Print("failed to marshal CA public key:", err)
		return
	}
	pubB64 := base64.StdEncoding.EncodeToString(pubBytes)
	log.Printf("Your CA's \"tls\" record is: [2, 1, 0, \"%s\"]", pubB64)

	if *parentKey != "" {
		return template, priv
	}

	//keyOut, err := os.OpenFile("key.pem", os.O_WRONLY|os.O_CREATE|os.O_TRUNC, 0600)
	keyOut, err := os.OpenFile("caKey.pem", os.O_WRONLY|os.O_CREATE|os.O_TRUNC, 0600)
	if err != nil {
		//log.Print("failed to open key.pem for writing:", err)
		log.Print("failed to open caKey.pem for writing:", err)
		return
	}
	pem.Encode(keyOut, pemBlockForKey(priv))
	keyOut.Close()
	//log.Print("written key.pem\n")
	log.Print("written caKey.pem\n")

	return template, priv
}