/**
    * Copyright 2010-2014 The Kuali Foundation
    *
    * Licensed under the Educational Community 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.opensource.org/licenses/ecl2.php
    *
   * 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.kuali.common.util.encrypt.provider;
  
  import static com.google.common.base.Optional.absent;
  import static com.google.common.collect.Lists.newArrayList;
  
  import java.util.List;
  
  import org.kuali.common.util.encrypt.EncryptionContext;
  
  import com.google.common.base.Optional;
  import com.google.common.collect.ImmutableList;
  
  public final class DefaultEncryptionContextProviderChain implements EncryptionContextProvider {
  
  	private static final String ENC_PASSWORD_KEY = "enc.password";
  	private static final String ENC_STRENGTH_KEY = "enc.strength";
  
  	// Need this key for backwards compatibility. "enc.password" contains a different password for some existing Maven processes
  	private static final String ENC_MAVEN_ALTERNATE_PASSWORD_KEY = "enc.pwd";
  
  	public DefaultEncryptionContextProviderChain() {
  		List<EncryptionContextProvider> providers = newArrayList();
  		providers.add(new SystemPropertiesEncryptionContextProvider(ENC_PASSWORD_KEY, ENC_STRENGTH_KEY));
  		providers.add(new EnvironmentVariableEncryptionContextProvider(toEnvKey(ENC_PASSWORD_KEY), toEnvKey(ENC_STRENGTH_KEY)));
  		providers.add(new FileEncryptionContextProvider());
  		providers.add(new MavenEncryptionContextProvider(ENC_MAVEN_ALTERNATE_PASSWORD_KEY, ENC_STRENGTH_KEY));
  		providers.add(new MavenEncryptionContextProvider(ENC_PASSWORD_KEY, ENC_STRENGTH_KEY));
  		this.providers = ImmutableList.copyOf(providers);
  	}
  
  	public DefaultEncryptionContextProviderChain(EncryptionContextProvider... providers) {
  		this(ImmutableList.copyOf(providers));
  	}
  
  	public DefaultEncryptionContextProviderChain(List<EncryptionContextProvider> providers) {
  		this.providers = ImmutableList.copyOf(providers);
  	}
  
  	private final List<EncryptionContextProvider> providers;
  
  	public List<EncryptionContextProvider> getProviders() {
  		return providers;
  	}
  
  	@Override
  	public Optional<EncryptionContext> getEncryptionContext() {
  		for (EncryptionContextProvider provider : providers) {
  			Optional<EncryptionContext> context = provider.getEncryptionContext();
  			if (context.isPresent()) {
  				return context;
  			}
  		}
  		return absent();
  	}
  
  	protected static String toEnvKey(String key) {
  		return key.replace('.', '_').toUpperCase();
  	}
  
  }