/*
 * ====================================================================
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 *
 */

package org.apache.hc.core5.http2.ssl;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.util.Set;
import java.util.concurrent.CopyOnWriteArraySet;

import javax.net.ssl.SSLEngine;
import javax.net.ssl.SSLParameters;

import org.apache.hc.core5.http2.HttpVersionPolicy;
import org.apache.hc.core5.net.NamedEndpoint;
import org.apache.hc.core5.reactor.ssl.SSLSessionInitializer;
import org.apache.hc.core5.ssl.ReflectionSupport;

public final class H2TlsSupport {

    private final static String[] PROTOCOL_BLACKLIST = {
            "TLSv1",
            "TLSv1.1"
    };

    private final static String[] CIPHER_BLACKLIST = {
            "TLS_NULL_WITH_NULL_NULL",
            "TLS_RSA_WITH_NULL_MD5",
            "TLS_RSA_WITH_NULL_SHA",
            "TLS_RSA_EXPORT_WITH_RC4_40_MD5",
            "TLS_RSA_WITH_RC4_128_MD5",
            "TLS_RSA_WITH_RC4_128_SHA",
            "TLS_RSA_EXPORT_WITH_RC2_CBC_40_MD5",
            "TLS_RSA_WITH_IDEA_CBC_SHA",
            "TLS_RSA_EXPORT_WITH_DES40_CBC_SHA",
            "TLS_RSA_WITH_DES_CBC_SHA",
            "TLS_RSA_WITH_3DES_EDE_CBC_SHA",
            "TLS_DH_DSS_EXPORT_WITH_DES40_CBC_SHA",
            "TLS_DH_DSS_WITH_DES_CBC_SHA",
            "TLS_DH_DSS_WITH_3DES_EDE_CBC_SHA",
            "TLS_DH_RSA_EXPORT_WITH_DES40_CBC_SHA",
            "TLS_DH_RSA_WITH_DES_CBC_SHA",
            "TLS_DH_RSA_WITH_3DES_EDE_CBC_SHA",
            "TLS_DHE_DSS_EXPORT_WITH_DES40_CBC_SHA",
            "TLS_DHE_DSS_WITH_DES_CBC_SHA",
            "TLS_DHE_DSS_WITH_3DES_EDE_CBC_SHA",
            "TLS_DHE_RSA_EXPORT_WITH_DES40_CBC_SHA",
            "TLS_DHE_RSA_WITH_DES_CBC_SHA",
            "TLS_DHE_RSA_WITH_3DES_EDE_CBC_SHA",
            "TLS_DH_anon_EXPORT_WITH_RC4_40_MD5",
            "TLS_DH_anon_WITH_RC4_128_MD5",
            "TLS_DH_anon_EXPORT_WITH_DES40_CBC_SHA",
            "TLS_DH_anon_WITH_DES_CBC_SHA",
            "TLS_DH_anon_WITH_3DES_EDE_CBC_SHA",
            "TLS_KRB5_WITH_DES_CBC_SHA",
            "TLS_KRB5_WITH_3DES_EDE_CBC_SHA",
            "TLS_KRB5_WITH_RC4_128_SHA",
            "TLS_KRB5_WITH_IDEA_CBC_SHA",
            "TLS_KRB5_WITH_DES_CBC_MD5",
            "TLS_KRB5_WITH_3DES_EDE_CBC_MD5",
            "TLS_KRB5_WITH_RC4_128_MD5",
            "TLS_KRB5_WITH_IDEA_CBC_MD5",
            "TLS_KRB5_EXPORT_WITH_DES_CBC_40_SHA",
            "TLS_KRB5_EXPORT_WITH_RC2_CBC_40_SHA",
            "TLS_KRB5_EXPORT_WITH_RC4_40_SHA",
            "TLS_KRB5_EXPORT_WITH_DES_CBC_40_MD5",
            "TLS_KRB5_EXPORT_WITH_RC2_CBC_40_MD5",
            "TLS_KRB5_EXPORT_WITH_RC4_40_MD5",
            "TLS_PSK_WITH_NULL_SHA",
            "TLS_DHE_PSK_WITH_NULL_SHA",
            "TLS_RSA_PSK_WITH_NULL_SHA",
            "TLS_RSA_WITH_AES_128_CBC_SHA",
            "TLS_DH_DSS_WITH_AES_128_CBC_SHA",
            "TLS_DH_RSA_WITH_AES_128_CBC_SHA",
            "TLS_DHE_DSS_WITH_AES_128_CBC_SHA",
            "TLS_DHE_RSA_WITH_AES_128_CBC_SHA",
            "TLS_DH_anon_WITH_AES_128_CBC_SHA",
            "TLS_RSA_WITH_AES_256_CBC_SHA",
            "TLS_DH_DSS_WITH_AES_256_CBC_SHA",
            "TLS_DH_RSA_WITH_AES_256_CBC_SHA",
            "TLS_DHE_DSS_WITH_AES_256_CBC_SHA",
            "TLS_DHE_RSA_WITH_AES_256_CBC_SHA",
            "TLS_DH_anon_WITH_AES_256_CBC_SHA",
            "TLS_RSA_WITH_NULL_SHA256",
            "TLS_RSA_WITH_AES_128_CBC_SHA256",
            "TLS_RSA_WITH_AES_256_CBC_SHA256",
            "TLS_DH_DSS_WITH_AES_128_CBC_SHA256",
            "TLS_DH_RSA_WITH_AES_128_CBC_SHA256",
            "TLS_DHE_DSS_WITH_AES_128_CBC_SHA256",
            "TLS_RSA_WITH_CAMELLIA_128_CBC_SHA",
            "TLS_DH_DSS_WITH_CAMELLIA_128_CBC_SHA",
            "TLS_DH_RSA_WITH_CAMELLIA_128_CBC_SHA",
            "TLS_DHE_DSS_WITH_CAMELLIA_128_CBC_SHA",
            "TLS_DHE_RSA_WITH_CAMELLIA_128_CBC_SHA",
            "TLS_DH_anon_WITH_CAMELLIA_128_CBC_SHA",
            "TLS_DHE_RSA_WITH_AES_128_CBC_SHA256",
            "TLS_DH_DSS_WITH_AES_256_CBC_SHA256",
            "TLS_DH_RSA_WITH_AES_256_CBC_SHA256",
            "TLS_DHE_DSS_WITH_AES_256_CBC_SHA256",
            "TLS_DHE_RSA_WITH_AES_256_CBC_SHA256",
            "TLS_DH_anon_WITH_AES_128_CBC_SHA256",
            "TLS_DH_anon_WITH_AES_256_CBC_SHA256",
            "TLS_RSA_WITH_CAMELLIA_256_CBC_SHA",
            "TLS_DH_DSS_WITH_CAMELLIA_256_CBC_SHA",
            "TLS_DH_RSA_WITH_CAMELLIA_256_CBC_SHA",
            "TLS_DHE_DSS_WITH_CAMELLIA_256_CBC_SHA",
            "TLS_DHE_RSA_WITH_CAMELLIA_256_CBC_SHA",
            "TLS_DH_anon_WITH_CAMELLIA_256_CBC_SHA",
            "TLS_PSK_WITH_RC4_128_SHA",
            "TLS_PSK_WITH_3DES_EDE_CBC_SHA",
            "TLS_PSK_WITH_AES_128_CBC_SHA",
            "TLS_PSK_WITH_AES_256_CBC_SHA",
            "TLS_DHE_PSK_WITH_RC4_128_SHA",
            "TLS_DHE_PSK_WITH_3DES_EDE_CBC_SHA",
            "TLS_DHE_PSK_WITH_AES_128_CBC_SHA",
            "TLS_DHE_PSK_WITH_AES_256_CBC_SHA",
            "TLS_RSA_PSK_WITH_RC4_128_SHA",
            "TLS_RSA_PSK_WITH_3DES_EDE_CBC_SHA",
            "TLS_RSA_PSK_WITH_AES_128_CBC_SHA",
            "TLS_RSA_PSK_WITH_AES_256_CBC_SHA",
            "TLS_RSA_WITH_SEED_CBC_SHA",
            "TLS_DH_DSS_WITH_SEED_CBC_SHA",
            "TLS_DH_RSA_WITH_SEED_CBC_SHA",
            "TLS_DHE_DSS_WITH_SEED_CBC_SHA",
            "TLS_DHE_RSA_WITH_SEED_CBC_SHA",
            "TLS_DH_anon_WITH_SEED_CBC_SHA",
            "TLS_RSA_WITH_AES_128_GCM_SHA256",
            "TLS_RSA_WITH_AES_256_GCM_SHA384",
            "TLS_DH_RSA_WITH_AES_128_GCM_SHA256",
            "TLS_DH_RSA_WITH_AES_256_GCM_SHA384",
            "TLS_DH_DSS_WITH_AES_128_GCM_SHA256",
            "TLS_DH_DSS_WITH_AES_256_GCM_SHA384",
            "TLS_DH_anon_WITH_AES_128_GCM_SHA256",
            "TLS_DH_anon_WITH_AES_256_GCM_SHA384",
            "TLS_PSK_WITH_AES_128_GCM_SHA256",
            "TLS_PSK_WITH_AES_256_GCM_SHA384",
            "TLS_RSA_PSK_WITH_AES_128_GCM_SHA256",
            "TLS_RSA_PSK_WITH_AES_256_GCM_SHA384",
            "TLS_PSK_WITH_AES_128_CBC_SHA256",
            "TLS_PSK_WITH_AES_256_CBC_SHA384",
            "TLS_PSK_WITH_NULL_SHA256",
            "TLS_PSK_WITH_NULL_SHA384",
            "TLS_DHE_PSK_WITH_AES_128_CBC_SHA256",
            "TLS_DHE_PSK_WITH_AES_256_CBC_SHA384",
            "TLS_DHE_PSK_WITH_NULL_SHA256",
            "TLS_DHE_PSK_WITH_NULL_SHA384",
            "TLS_RSA_PSK_WITH_AES_128_CBC_SHA256",
            "TLS_RSA_PSK_WITH_AES_256_CBC_SHA384",
            "TLS_RSA_PSK_WITH_NULL_SHA256",
            "TLS_RSA_PSK_WITH_NULL_SHA384",
            "TLS_RSA_WITH_CAMELLIA_128_CBC_SHA256",
            "TLS_DH_DSS_WITH_CAMELLIA_128_CBC_SHA256",
            "TLS_DH_RSA_WITH_CAMELLIA_128_CBC_SHA256",
            "TLS_DHE_DSS_WITH_CAMELLIA_128_CBC_SHA256",
            "TLS_DHE_RSA_WITH_CAMELLIA_128_CBC_SHA256",
            "TLS_DH_anon_WITH_CAMELLIA_128_CBC_SHA256",
            "TLS_RSA_WITH_CAMELLIA_256_CBC_SHA256",
            "TLS_DH_DSS_WITH_CAMELLIA_256_CBC_SHA256",
            "TLS_DH_RSA_WITH_CAMELLIA_256_CBC_SHA256",
            "TLS_DHE_DSS_WITH_CAMELLIA_256_CBC_SHA256",
            "TLS_DHE_RSA_WITH_CAMELLIA_256_CBC_SHA256",
            "TLS_DH_anon_WITH_CAMELLIA_256_CBC_SHA256",
            "TLS_EMPTY_RENEGOTIATION_INFO_SCSV",
            "TLS_ECDH_ECDSA_WITH_NULL_SHA",
            "TLS_ECDH_ECDSA_WITH_RC4_128_SHA",
            "TLS_ECDH_ECDSA_WITH_3DES_EDE_CBC_SHA",
            "TLS_ECDH_ECDSA_WITH_AES_128_CBC_SHA",
            "TLS_ECDH_ECDSA_WITH_AES_256_CBC_SHA",
            "TLS_ECDHE_ECDSA_WITH_NULL_SHA",
            "TLS_ECDHE_ECDSA_WITH_RC4_128_SHA",
            "TLS_ECDHE_ECDSA_WITH_3DES_EDE_CBC_SHA",
            "TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA",
            "TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA",
            "TLS_ECDH_RSA_WITH_NULL_SHA",
            "TLS_ECDH_RSA_WITH_RC4_128_SHA",
            "TLS_ECDH_RSA_WITH_3DES_EDE_CBC_SHA",
            "TLS_ECDH_RSA_WITH_AES_128_CBC_SHA",
            "TLS_ECDH_RSA_WITH_AES_256_CBC_SHA",
            "TLS_ECDHE_RSA_WITH_NULL_SHA",
            "TLS_ECDHE_RSA_WITH_RC4_128_SHA",
            "TLS_ECDHE_RSA_WITH_3DES_EDE_CBC_SHA",
            "TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA",
            "TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA",
            "TLS_ECDH_anon_WITH_NULL_SHA",
            "TLS_ECDH_anon_WITH_RC4_128_SHA",
            "TLS_ECDH_anon_WITH_3DES_EDE_CBC_SHA",
            "TLS_ECDH_anon_WITH_AES_128_CBC_SHA",
            "TLS_ECDH_anon_WITH_AES_256_CBC_SHA",
            "TLS_SRP_SHA_WITH_3DES_EDE_CBC_SHA",
            "TLS_SRP_SHA_RSA_WITH_3DES_EDE_CBC_SHA",
            "TLS_SRP_SHA_DSS_WITH_3DES_EDE_CBC_SHA",
            "TLS_SRP_SHA_WITH_AES_128_CBC_SHA",
            "TLS_SRP_SHA_RSA_WITH_AES_128_CBC_SHA",
            "TLS_SRP_SHA_DSS_WITH_AES_128_CBC_SHA",
            "TLS_SRP_SHA_WITH_AES_256_CBC_SHA",
            "TLS_SRP_SHA_RSA_WITH_AES_256_CBC_SHA",
            "TLS_SRP_SHA_DSS_WITH_AES_256_CBC_SHA",
            "TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA256",
            "TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA384",
            "TLS_ECDH_ECDSA_WITH_AES_128_CBC_SHA256",
            "TLS_ECDH_ECDSA_WITH_AES_256_CBC_SHA384",
            "TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256",
            "TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384",
            "TLS_ECDH_RSA_WITH_AES_128_CBC_SHA256",
            "TLS_ECDH_RSA_WITH_AES_256_CBC_SHA384",
            "TLS_ECDH_ECDSA_WITH_AES_128_GCM_SHA256",
            "TLS_ECDH_ECDSA_WITH_AES_256_GCM_SHA384",
            "TLS_ECDH_RSA_WITH_AES_128_GCM_SHA256",
            "TLS_ECDH_RSA_WITH_AES_256_GCM_SHA384",
            "TLS_ECDHE_PSK_WITH_RC4_128_SHA",
            "TLS_ECDHE_PSK_WITH_3DES_EDE_CBC_SHA",
            "TLS_ECDHE_PSK_WITH_AES_128_CBC_SHA",
            "TLS_ECDHE_PSK_WITH_AES_256_CBC_SHA",
            "TLS_ECDHE_PSK_WITH_AES_128_CBC_SHA256",
            "TLS_ECDHE_PSK_WITH_AES_256_CBC_SHA384",
            "TLS_ECDHE_PSK_WITH_NULL_SHA",
            "TLS_ECDHE_PSK_WITH_NULL_SHA256",
            "TLS_ECDHE_PSK_WITH_NULL_SHA384",
            "TLS_RSA_WITH_ARIA_128_CBC_SHA256",
            "TLS_RSA_WITH_ARIA_256_CBC_SHA384",
            "TLS_DH_DSS_WITH_ARIA_128_CBC_SHA256",
            "TLS_DH_DSS_WITH_ARIA_256_CBC_SHA384",
            "TLS_DH_RSA_WITH_ARIA_128_CBC_SHA256",
            "TLS_DH_RSA_WITH_ARIA_256_CBC_SHA384",
            "TLS_DHE_DSS_WITH_ARIA_128_CBC_SHA256",
            "TLS_DHE_DSS_WITH_ARIA_256_CBC_SHA384",
            "TLS_DHE_RSA_WITH_ARIA_128_CBC_SHA256",
            "TLS_DHE_RSA_WITH_ARIA_256_CBC_SHA384",
            "TLS_DH_anon_WITH_ARIA_128_CBC_SHA256",
            "TLS_DH_anon_WITH_ARIA_256_CBC_SHA384",
            "TLS_ECDHE_ECDSA_WITH_ARIA_128_CBC_SHA256",
            "TLS_ECDHE_ECDSA_WITH_ARIA_256_CBC_SHA384",
            "TLS_ECDH_ECDSA_WITH_ARIA_128_CBC_SHA256",
            "TLS_ECDH_ECDSA_WITH_ARIA_256_CBC_SHA384",
            "TLS_ECDHE_RSA_WITH_ARIA_128_CBC_SHA256",
            "TLS_ECDHE_RSA_WITH_ARIA_256_CBC_SHA384",
            "TLS_ECDH_RSA_WITH_ARIA_128_CBC_SHA256",
            "TLS_ECDH_RSA_WITH_ARIA_256_CBC_SHA384",
            "TLS_RSA_WITH_ARIA_128_GCM_SHA256",
            "TLS_RSA_WITH_ARIA_256_GCM_SHA384",
            "TLS_DH_RSA_WITH_ARIA_128_GCM_SHA256",
            "TLS_DH_RSA_WITH_ARIA_256_GCM_SHA384",
            "TLS_DH_DSS_WITH_ARIA_128_GCM_SHA256",
            "TLS_DH_DSS_WITH_ARIA_256_GCM_SHA384",
            "TLS_DH_anon_WITH_ARIA_128_GCM_SHA256",
            "TLS_DH_anon_WITH_ARIA_256_GCM_SHA384",
            "TLS_ECDH_ECDSA_WITH_ARIA_128_GCM_SHA256",
            "TLS_ECDH_ECDSA_WITH_ARIA_256_GCM_SHA384",
            "TLS_ECDH_RSA_WITH_ARIA_128_GCM_SHA256",
            "TLS_ECDH_RSA_WITH_ARIA_256_GCM_SHA384",
            "TLS_PSK_WITH_ARIA_128_CBC_SHA256",
            "TLS_PSK_WITH_ARIA_256_CBC_SHA384",
            "TLS_DHE_PSK_WITH_ARIA_128_CBC_SHA256",
            "TLS_DHE_PSK_WITH_ARIA_256_CBC_SHA384",
            "TLS_RSA_PSK_WITH_ARIA_128_CBC_SHA256",
            "TLS_RSA_PSK_WITH_ARIA_256_CBC_SHA384",
            "TLS_PSK_WITH_ARIA_128_GCM_SHA256",
            "TLS_PSK_WITH_ARIA_256_GCM_SHA384",
            "TLS_RSA_PSK_WITH_ARIA_128_GCM_SHA256",
            "TLS_RSA_PSK_WITH_ARIA_256_GCM_SHA384",
            "TLS_ECDHE_PSK_WITH_ARIA_128_CBC_SHA256",
            "TLS_ECDHE_PSK_WITH_ARIA_256_CBC_SHA384",
            "TLS_ECDHE_ECDSA_WITH_CAMELLIA_128_CBC_SHA256",
            "TLS_ECDHE_ECDSA_WITH_CAMELLIA_256_CBC_SHA384",
            "TLS_ECDH_ECDSA_WITH_CAMELLIA_128_CBC_SHA256",
            "TLS_ECDH_ECDSA_WITH_CAMELLIA_256_CBC_SHA384",
            "TLS_ECDHE_RSA_WITH_CAMELLIA_128_CBC_SHA256",
            "TLS_ECDHE_RSA_WITH_CAMELLIA_256_CBC_SHA384",
            "TLS_ECDH_RSA_WITH_CAMELLIA_128_CBC_SHA256",
            "TLS_ECDH_RSA_WITH_CAMELLIA_256_CBC_SHA384",
            "TLS_RSA_WITH_CAMELLIA_128_GCM_SHA256",
            "TLS_RSA_WITH_CAMELLIA_256_GCM_SHA384",
            "TLS_DH_RSA_WITH_CAMELLIA_128_GCM_SHA256",
            "TLS_DH_RSA_WITH_CAMELLIA_256_GCM_SHA384",
            "TLS_DH_DSS_WITH_CAMELLIA_128_GCM_SHA256",
            "TLS_DH_DSS_WITH_CAMELLIA_256_GCM_SHA384",
            "TLS_DH_anon_WITH_CAMELLIA_128_GCM_SHA256",
            "TLS_DH_anon_WITH_CAMELLIA_256_GCM_SHA384",
            "TLS_ECDH_ECDSA_WITH_CAMELLIA_128_GCM_SHA256",
            "TLS_ECDH_ECDSA_WITH_CAMELLIA_256_GCM_SHA384",
            "TLS_ECDH_RSA_WITH_CAMELLIA_128_GCM_SHA256",
            "TLS_ECDH_RSA_WITH_CAMELLIA_256_GCM_SHA384",
            "TLS_PSK_WITH_CAMELLIA_128_GCM_SHA256",
            "TLS_PSK_WITH_CAMELLIA_256_GCM_SHA384",
            "TLS_RSA_PSK_WITH_CAMELLIA_128_GCM_SHA256",
            "TLS_RSA_PSK_WITH_CAMELLIA_256_GCM_SHA384",
            "TLS_PSK_WITH_CAMELLIA_128_CBC_SHA256",
            "TLS_PSK_WITH_CAMELLIA_256_CBC_SHA384",
            "TLS_DHE_PSK_WITH_CAMELLIA_128_CBC_SHA256",
            "TLS_DHE_PSK_WITH_CAMELLIA_256_CBC_SHA384",
            "TLS_RSA_PSK_WITH_CAMELLIA_128_CBC_SHA256",
            "TLS_RSA_PSK_WITH_CAMELLIA_256_CBC_SHA384",
            "TLS_ECDHE_PSK_WITH_CAMELLIA_128_CBC_SHA256",
            "TLS_ECDHE_PSK_WITH_CAMELLIA_256_CBC_SHA384",
            "TLS_RSA_WITH_AES_128_CCM",
            "TLS_RSA_WITH_AES_256_CCM",
            "TLS_RSA_WITH_AES_128_CCM_8",
            "TLS_RSA_WITH_AES_256_CCM_8",
            "TLS_PSK_WITH_AES_128_CCM",
            "TLS_PSK_WITH_AES_256_CCM",
            "TLS_PSK_WITH_AES_128_CCM_8",
            "TLS_PSK_WITH_AES_256_CCM_8" };

    private final static Set<String> BLACKLISED_PROTOCOLS = new CopyOnWriteArraySet<>(Arrays.asList(PROTOCOL_BLACKLIST));
    private final static Set<String> BLACKLISED_CIPHERS = new CopyOnWriteArraySet<>(Arrays.asList(CIPHER_BLACKLIST));

    public static String[] excludeBlacklistedProtocols(final String[] protocols) {
        if (protocols == null) {
            return null;
        }
        List<String> enabledProtocols = null;
        for (final String protocol: protocols) {
            if (!protocol.startsWith("SSL") && !BLACKLISED_PROTOCOLS.contains(protocol)) {
                if (enabledProtocols == null) {
                    enabledProtocols = new ArrayList<>();
                }
                enabledProtocols.add(protocol);
            }
        }
        return enabledProtocols != null ? enabledProtocols.toArray(new String[enabledProtocols.size()]) : protocols;
    }

    public static String[] excludeBlacklistedCiphers(final String[] ciphers) {
        if (ciphers == null) {
            return null;
        }
        List<String> enabledCiphers = null;
        for (final String cipher: ciphers) {
            if (!BLACKLISED_CIPHERS.contains(cipher)) {
                if (enabledCiphers == null) {
                    enabledCiphers = new ArrayList<>();
                }
                enabledCiphers.add(cipher);
            }
        }
        return enabledCiphers != null ? enabledCiphers.toArray(new String[enabledCiphers.size()]) : ciphers;
    }

    public static void setEnableRetransmissions(final SSLParameters sslParameters, final boolean value) {
        ReflectionSupport.callSetter(sslParameters, "EnableRetransmissions", Boolean.TYPE, value);
    }

    public static void setApplicationProtocols(final SSLParameters sslParameters, final String[] values) {
        ReflectionSupport.callSetter(sslParameters, "ApplicationProtocols", String[].class, values);
    }

    public static SSLSessionInitializer enforceRequirements(
            final Object attachment,
            final SSLSessionInitializer initializer) {
        return new SSLSessionInitializer() {

            @Override
            public void initialize(final NamedEndpoint endpoint, final SSLEngine sslEngine) {
                final SSLParameters sslParameters = sslEngine.getSSLParameters();
                sslParameters.setProtocols(excludeBlacklistedProtocols(sslParameters.getProtocols()));
                sslParameters.setCipherSuites(excludeBlacklistedCiphers(sslParameters.getCipherSuites()));
                setEnableRetransmissions(sslParameters, false);
                final HttpVersionPolicy versionPolicy = attachment instanceof HttpVersionPolicy ?
                        (HttpVersionPolicy) attachment : HttpVersionPolicy.NEGOTIATE;
                final String[] appProtocols;
                switch (versionPolicy) {
                    case FORCE_HTTP_1:
                        appProtocols = new String[] { ApplicationProtocols.HTTP_1_1.id };
                        break;
                    case FORCE_HTTP_2:
                        appProtocols = new String[] { ApplicationProtocols.HTTP_2.id };
                        break;
                    default:
                        appProtocols = new String[] { ApplicationProtocols.HTTP_2.id, ApplicationProtocols.HTTP_1_1.id };
                        break;
                }
                setApplicationProtocols(sslParameters, appProtocols);
                sslEngine.setSSLParameters(sslParameters);
                if (initializer != null) {
                    initializer.initialize(endpoint, sslEngine);
                }
            }

        };
    }

}
