/**
    * 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.base.Optional.fromNullable;
  import static java.lang.String.format;
  import static org.apache.commons.lang3.StringUtils.trimToNull;
  import static org.kuali.common.util.base.Precondition.checkNotBlank;
  import static org.kuali.common.util.encrypt.EncryptionStrength.DEFAULT_ENCRYPTION_STRENGTH;
  import static org.kuali.common.util.log.Loggers.newLogger;
  
  import org.kuali.common.util.encrypt.EncryptionContext;
  import org.kuali.common.util.encrypt.EncryptionStrength;
  import org.slf4j.Logger;
  
  import com.google.common.base.Optional;
  
  public abstract class AbstractEncryptionContextProvider implements EncryptionContextProvider {
  
  	private static final Logger logger = newLogger();
  
  	public AbstractEncryptionContextProvider(String passwordKey, String strengthKey) {
  		this.passwordKey = checkNotBlank(passwordKey, "passwordKey");
  		this.strengthKey = checkNotBlank(strengthKey, "strengthKey");
  	}
  
  	private final String passwordKey;
  	private final String strengthKey;
  
  	@Override
  	public Optional<EncryptionContext> getEncryptionContext() {
  		Optional<String> password = getOptionalString(passwordKey);
  		if (!password.isPresent()) {
  			logger.debug(format("[%s, key=%s] encryption password not found", this.getClass().getSimpleName(), passwordKey));
  			return absent();
  		} else {
  			EncryptionStrength strength = getEncryptionStrength();
  			logger.debug(format("[%s, key=%s %s] encryption password located", this.getClass().getSimpleName(), passwordKey, strength));
  			return Optional.of(new EncryptionContext(password.get(), strength));
  		}
  	}
  
  	protected Optional<String> getOptionalString(String key) {
  		return fromNullable(trimToNull(getValueFromSource(key)));
  	}
  
  	protected abstract String getValueFromSource(String key);
  
  	protected EncryptionStrength getEncryptionStrength() {
  		Optional<String> optional = getOptionalString(strengthKey);
  		if (optional.isPresent()) {
  			return EncryptionStrength.valueOf(optional.get().toUpperCase());
  		} else {
  			return DEFAULT_ENCRYPTION_STRENGTH;
  		}
  	}
  
  }