/*
    * Copyright 2010 - org.tinyjee.maven
    *
    *    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
    *
    *        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.tinyjee.maven.dim.utils;
  
  import org.apache.maven.doxia.logging.Log;
  import org.tinyjee.maven.dim.spi.Globals;
  import org.tinyjee.maven.dim.spi.RequestParameterTransformer;
  
  import java.util.Map;
  
  import static org.tinyjee.maven.dim.IncludeMacroSignature.PARAM_SOURCE_CLASS;
  
  /**
   * Implements an handler that allows the definition of aliases for request parameters.
   */
  public abstract class AbstractAliasHandler implements RequestParameterTransformer {
  
  	final String triggerParameter, targetParameter, sourceClass;
  
  	/**
  	 * Constructs a new AbstractAliasHandler for the given values.
  	 *
  	 * @param triggerParameter the parameter to trigger.
  	 * @param targetParameter  the parameter to transfer the trigger value to.
  	 * @param sourceClass      the source class to set if the trigger was present.
  	 */
  	protected AbstractAliasHandler(String triggerParameter, String targetParameter, String sourceClass) {
  		this.triggerParameter = triggerParameter;
  		this.targetParameter = targetParameter;
  		this.sourceClass = sourceClass;
  	}
  
  	/**
  	 * {@inheritDoc}
  	 */
  	public void transformParameters(Map<String, Object> requestParams) {
  		Log logger = Globals.getLog();
  		Object parameterValue = requestParams.get(triggerParameter);
  		if (parameterValue != null) {
  			if (sourceClass != null) {
  				if (requestParams.containsKey(PARAM_SOURCE_CLASS)) {
  					logger.warn("The request parameter '" + PARAM_SOURCE_CLASS + "' is already set to '" +
  							requestParams.get(PARAM_SOURCE_CLASS) + "'. Will not set the parameter to '" + sourceClass + "' " +
  							"which may break subsequent template execution and may lead to unexpected results.");
  				} else
  					requestParams.put(PARAM_SOURCE_CLASS, sourceClass);
  			}
  
  			if (requestParams.containsKey(targetParameter)) {
  				logger.warn("The request parameter '" + targetParameter + "' is already set to '" +
  						requestParams.get(targetParameter) + "', overwriting it with '" + parameterValue + "'. " +
  						"This may may lead to unexpected results.");
  			}
  
  			requestParams.put(targetParameter, parameterValue);
  		}
  	}
  }