/*
    * Copyright 2013-2019 the original author or authors.
    *
    * Licensed 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 org.springframework.security.oauth2.provider.token.store;
  
  import java.io.IOException;
  import java.io.InputStream;
  import java.security.KeyFactory;
  import java.security.KeyPair;
  import java.security.KeyStore;
  import java.security.PublicKey;
  import java.security.interfaces.RSAPrivateCrtKey;
  import java.security.spec.RSAPublicKeySpec;
  
  import org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogFactory;
  import org.springframework.core.io.Resource;
  
  /**
   * Factory for RSA key pairs from a JKS keystore file. User provides a {@link Resource} location of a keystore file and
   * the password to unlock it, and the factory grabs the keypairs from the store by name (and optionally password).
   * 
   * @author Dave Syer
   *
   */
  public class KeyStoreKeyFactory {
  	
  	private static final Log logger = LogFactory.getLog(KeyStoreKeyFactory.class);
  
  	private Resource resource;
  
  	private char[] password;
  
  	private KeyStore store;
  
  	private Object lock = new Object();
  
  	public KeyStoreKeyFactory(Resource resource, char[] password) {
  		this.resource = resource;
  		this.password = password;
  	}
  
  	public KeyPair getKeyPair(String alias) {
  		return getKeyPair(alias, password);
  	}
  
  	public KeyPair getKeyPair(String alias, char[] password) {
  		InputStream inputStream = null;
  		try {
  			synchronized (lock) {
  				if (store == null) {
  					synchronized (lock) {
  						store = KeyStore.getInstance("jks");
  						inputStream = resource.getInputStream();
  						store.load(inputStream, this.password);
  					}
  				}
  			}
  			RSAPrivateCrtKey key = (RSAPrivateCrtKey) store.getKey(alias, password);
  			RSAPublicKeySpec spec = new RSAPublicKeySpec(key.getModulus(), key.getPublicExponent());
  			PublicKey publicKey = KeyFactory.getInstance("RSA").generatePublic(spec);
  			return new KeyPair(publicKey, key);
  		}
  		catch (Exception e) {
  			throw new IllegalStateException("Cannot load keys from store: " + resource, e);
  		}
  		finally {
  			try {
  				if (inputStream != null) {
  					inputStream.close();
  				}
  			} 
  			catch (IOException e) {
  				logger.warn("Cannot close open stream: ", e);
  			}
  		}
  	}
  }