package com.juick.server;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Component;
import org.springframework.util.Base64Utils;
import sun.security.x509.*;

import javax.annotation.PostConstruct;
import javax.net.ssl.KeyManagerFactory;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.math.BigInteger;
import java.security.*;
import java.security.cert.Certificate;
import java.security.cert.CertificateException;
import java.security.cert.X509Certificate;
import java.util.Date;

@Component
public class KeystoreManager {
    private static final Logger logger = LoggerFactory.getLogger("com.juick.server");
    @Value("${keystore:juick.p12}")
    private String keystore;
    @Value("${keystore_password:secret}")
    private String keystorePassword;

    private KeyStore ks;

    private KeyManagerFactory kmf;

    @PostConstruct
    public void init() throws GeneralSecurityException, IOException {
        try (InputStream ksIs = new FileInputStream(keystore)) {
            ks = KeyStore.getInstance("PKCS12");
            ks.load(ksIs, keystorePassword.toCharArray());
            kmf = KeyManagerFactory.getInstance(KeyManagerFactory
                    .getDefaultAlgorithm());
            kmf.init(ks, keystorePassword.toCharArray());
        } catch (IOException | KeyStoreException | NoSuchAlgorithmException | UnrecoverableKeyException | CertificateException e) {
            logger.warn("Keystore error, creating self-signed");
            KeyPairGenerator keyPairGenerator = KeyPairGenerator.getInstance("RSA");
            keyPairGenerator.initialize(4096);
            KeyPair keyPair = keyPairGenerator.generateKeyPair();

            Certificate[] chain = {generateCertificate("cn=localhost", keyPair, 365, "SHA256withRSA")};

            ks = KeyStore.getInstance(KeyStore.getDefaultType());
            ks.load(null, null);
            ks.setKeyEntry("1", keyPair.getPrivate(), keystorePassword.toCharArray(), chain);
            kmf = KeyManagerFactory.getInstance(KeyManagerFactory
                    .getDefaultAlgorithm());
            kmf.init(ks, keystorePassword.toCharArray());
        }
    }

    public KeyStore getKeystore() {
        return ks;
    }

    public KeyManagerFactory getKeymanagerFactory() {
        return kmf;
    }

    private KeyPair getKeyPair() {
        Key privateKey = null;
        try {
            privateKey = ks.getKey("1", keystorePassword.toCharArray());
            Certificate certificate = ks.getCertificate("1");
            return new KeyPair(certificate.getPublicKey(), (PrivateKey) privateKey);
        } catch (KeyStoreException | NoSuchAlgorithmException | UnrecoverableKeyException e) {
            e.printStackTrace();
        }
        return null;
    }
    public String getPublicKey() {
        return String.format("-----BEGIN RSA PUBLIC KEY-----\n%s\n-----END RSA PUBLIC KEY-----\n",
                new String(Base64Utils.encode(getKeyPair().getPublic().getEncoded())));
    }
    private X509Certificate generateCertificate(String dn, KeyPair keyPair, int validity, String sigAlgName) throws GeneralSecurityException, IOException {
        PrivateKey privateKey = keyPair.getPrivate();

        X509CertInfo info = new X509CertInfo();

        Date from = new Date();
        Date to = new Date(from.getTime() + validity * 1000L * 24L * 60L * 60L);

        CertificateValidity interval = new CertificateValidity(from, to);
        BigInteger serialNumber = new BigInteger(64, new SecureRandom());
        X500Name owner = new X500Name(dn);
        AlgorithmId sigAlgId = new AlgorithmId(AlgorithmId.sha256WithRSAEncryption_oid);

        info.set(X509CertInfo.VALIDITY, interval);
        info.set(X509CertInfo.SERIAL_NUMBER, new CertificateSerialNumber(serialNumber));
        info.set(X509CertInfo.SUBJECT, owner);
        info.set(X509CertInfo.ISSUER, owner);
        info.set(X509CertInfo.KEY, new CertificateX509Key(keyPair.getPublic()));
        info.set(X509CertInfo.VERSION, new CertificateVersion(CertificateVersion.V3));
        info.set(X509CertInfo.ALGORITHM_ID, new CertificateAlgorithmId(sigAlgId));

        // Sign the cert to identify the algorithm that's used.
        X509CertImpl certificate = new X509CertImpl(info);
        certificate.sign(privateKey, sigAlgName);

        // Update the algorith, and resign.
        sigAlgId = (AlgorithmId) certificate.get(X509CertImpl.SIG_ALG);
        info.set(CertificateAlgorithmId.NAME + "." + CertificateAlgorithmId.ALGORITHM, sigAlgId);
        certificate = new X509CertImpl(info);
        certificate.sign(privateKey, sigAlgName);

        return certificate;
    }
}