/*
 * 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.
 */
package org.apache.geode.management.internal;

import java.security.NoSuchAlgorithmException;
import java.util.ArrayList;
import java.util.List;
import java.util.StringTokenizer;

import javax.net.ssl.SSLContext;

import org.apache.geode.internal.lang.StringUtils;

/**
 * 
 * @since GemFire 8.1
 */
public class SSLUtil {

  public static String getSSLAlgo(String[] protocols) {
    String c = null;

    if (protocols != null && protocols.length > 0) {
      for (String protocol : protocols) {
        if (!protocol.equals("any")) {
          try {
            SSLContext.getInstance(protocol);
            c = protocol;
            break;
          } catch (NoSuchAlgorithmException e) {
            // continue
          }
        }
      }
    }
    if (c != null) {
      return c;
    }
    // lookup known algorithms
    String[] knownAlgorithms = {"SSL", "SSLv2", "SSLv3", "TLS", "TLSv1", "TLSv1.1", "TLSv1.2"};
    for (String algo : knownAlgorithms) {
      try {
        SSLContext.getInstance(algo);
        c = algo;
        break;
      } catch (NoSuchAlgorithmException e) {
        // continue
      }
    }
    return c;
  }

  /** Read an array of values from a string, whitespace separated. */
  public static String[] readArray(String text) {
    if (StringUtils.isBlank(text)) {
      return null;
    }

    StringTokenizer st = new StringTokenizer(text);
    List<String> v = new ArrayList<String>();
    while (st.hasMoreTokens()) {
      v.add(st.nextToken());
    }
    return v.toArray(new String[v.size()]);
  }

}