package utility

import (
	"bytes"
	"crypto/rand"
	"crypto/rsa"
	"crypto/x509"
	"encoding/pem"
	"errors"
	"fmt"
	"os"
)

// GenerateRSAKeyPair generates an RSA keypair of 2048 bit size using the
// random source random (for example, crypto/rand.Reader) and returns the
// private and public keys
func GenerateRSAKeyPair() (string, string, error) {
	privatekey, err := rsa.GenerateKey(rand.Reader, 2048)
	if err != nil {
		return "", "", errors.New("Cannot generate RSA key\n")
	}

	publickey := &privatekey.PublicKey

	var privateKeyBytes []byte = x509.MarshalPKCS1PrivateKey(privatekey)
	privateKeyBlock := &pem.Block{
		Type:  "RSA PRIVATE KEY",
		Bytes: privateKeyBytes,
	}

	privatePem := bytes.NewBufferString("")
	err = pem.Encode(privatePem, privateKeyBlock)
	if err != nil {
		fmt.Printf("error when encode private pem: %s \n", err)
		os.Exit(1)
	}

	publicKeyBytes, err := x509.MarshalPKIXPublicKey(publickey)
	if err != nil {
		return "", "", fmt.Errorf("error when dumping publickey: %s \n", err)
	}

	publicKeyBlock := &pem.Block{
		Type:  "PUBLIC KEY",
		Bytes: publicKeyBytes,
	}

	publicPem := bytes.NewBufferString("")
	err = pem.Encode(publicPem, publicKeyBlock)
	if err != nil {
		fmt.Printf("error when encode public pem: %s \n", err)
		os.Exit(1)
	}

	return privatePem.String(), publicPem.String(), nil
}