/*
 * Copyright 2014 The Netty Project
 *
 * The Netty Project 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:
 *
 *   https://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.
 */
package io.netty.handler.ssl;

import io.netty.util.internal.EmptyArrays;
import io.netty.util.internal.ObjectUtil;

import javax.net.ssl.SSLEngine;
import java.util.ArrayList;
import java.util.List;
import java.util.Set;

/**
 * This class will filter all requested ciphers out that are not supported by the current {@link SSLEngine}.
 */
public final class SupportedCipherSuiteFilter implements CipherSuiteFilter {
    public static final SupportedCipherSuiteFilter INSTANCE = new SupportedCipherSuiteFilter();

    private SupportedCipherSuiteFilter() { }

    @Override
    public String[] filterCipherSuites(Iterable<String> ciphers, List<String> defaultCiphers,
            Set<String> supportedCiphers) {
        ObjectUtil.checkNotNull(defaultCiphers, "defaultCiphers");
        ObjectUtil.checkNotNull(supportedCiphers, "supportedCiphers");

        final List<String> newCiphers;
        if (ciphers == null) {
            newCiphers = new ArrayList<String>(defaultCiphers.size());
            ciphers = defaultCiphers;
        } else {
            newCiphers = new ArrayList<String>(supportedCiphers.size());
        }
        for (String c : ciphers) {
            if (c == null) {
                break;
            }
            if (supportedCiphers.contains(c)) {
                newCiphers.add(c);
            }
        }
        return newCiphers.toArray(EmptyArrays.EMPTY_STRINGS);
    }

}
