/*
 *  RapidMiner
 *
 *  Copyright (C) 2001-2011 by Rapid-I and the contributors
 *
 *  Complete list of developers available at our web site:
 *
 *       http://rapid-i.com
 *
 *  This program is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU Affero General Public License as published by
 *  the Free Software Foundation, either version 3 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU Affero General Public License for more details.
 *
 *  You should have received a copy of the GNU Affero General Public License
 *  along with this program.  If not, see http://www.gnu.org/licenses/.
 */
package com.rapidminer.operator;

import java.util.List;

import com.rapidminer.operator.meta.FeatureIterator;
import com.rapidminer.operator.ports.DummyPortPairExtender;
import com.rapidminer.operator.ports.PortPairExtender;
import com.rapidminer.parameter.ParameterType;
import com.rapidminer.parameter.ParameterTypeString;
import com.rapidminer.parameter.UndefinedParameterError;

/**
 * <p>(Re-)Define macros for the current process. Macros will be replaced in the value strings
 * of parameters by the macro values defined as a parameter of this operator.
 * In contrast to the usual MacroDefinitionOperator, this operator only supports the 
 * definition of a single macro and can hence be used inside of parameter iterations.</p>
 * 
 * <p>You have to define the macro name (without the enclosing brackets) and
 * the macro value. The defined macro can then be used in all succeeding operators as parameter
 * value. A macro must then be enclosed by "MACRO_START" and 
 * "MACRO_END".</p>
 *  
 * <p>There are several predefined macros:</p>
 * <ul>
 * <li>MACRO_STARTprocess_nameMACRO_END: will be replaced by the name of the process (without path and extension)</li>
 * <li>MACRO_STARTprocess_fileMACRO_END: will be replaced by the file name of the process (with extension)</li> 
 * <li>MACRO_STARTprocess_pathMACRO_END: will be replaced by the complete absolute path of the process file</li>
 * </ul>
 * 
 * <p>In addition to those the user might define arbitrary other macros which will be replaced
 * by arbitrary strings during the process run. Please note also that several other short macros
 * exist, e.g. MACRO_STARTaMACRO_END for the number of times the current operator was applied.
 * Please refer to the section about macros in the RapidMiner tutorial. Please note also that
 * other operators like the {@link FeatureIterator} also add specific macros.</p>
 *  
 * @author Ingo Mierswa
 */
public class SingleMacroDefinitionOperator extends Operator {

	/** The parameter name for "The values of the user defined macros." */
	public static final String PARAMETER_MACRO = "macro";
	public static final String PARAMETER_VALUE = "value";

	private PortPairExtender dummyPorts = new DummyPortPairExtender("through", getInputPorts(), getOutputPorts());

	public SingleMacroDefinitionOperator(OperatorDescription description) {
		super(description);

		dummyPorts.start();

		getTransformer().addRule(dummyPorts.makePassThroughRule());

		addValue(new ValueString("macro_name", "The name of the macro.") {
			@Override
			public String getStringValue() {
				try {
					return getParameterAsString(PARAMETER_MACRO);
				} catch (UndefinedParameterError e) {
					return null;
				}
			}        	
		});

		addValue(new ValueString("macro_value", "The value of the macro.") {
			@Override
			public String getStringValue() {
				try {
					return getParameterAsString(PARAMETER_VALUE);
				} catch (UndefinedParameterError e) {
					return null;
				}
			}        	
		});
	}

	@Override
	public void doWork() throws OperatorException {
		String macro = getParameterAsString(PARAMETER_MACRO);
		String value = getParameterAsString(PARAMETER_VALUE);
		getProcess().getMacroHandler().addMacro(macro, value);

		dummyPorts.passDataThrough();
	}

	@Override
	public List<ParameterType> getParameterTypes() {
		List<ParameterType> types = super.getParameterTypes();
		types.add(new ParameterTypeString(PARAMETER_MACRO, "The macro name defined by the user.", false, false));
		types.add(new ParameterTypeString(PARAMETER_VALUE, "The macro value defined by the user.", false, false));
		return types;
	}
}