/**
 * Copyright (C) 2001-2017 by RapidMiner and the contributors
 * 
 * Complete list of developers available at our web site:
 * 
 * http://rapidminer.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.execution;

import com.rapidminer.RapidMiner;
import com.rapidminer.example.ExampleSet;
import com.rapidminer.operator.IOObject;
import com.rapidminer.operator.ports.InputPort;
import com.rapidminer.tools.ParameterService;
import com.rapidminer.tools.parameter.ParameterChangeListener;


/**
 * Cleans up {@link ExampleSet}s between operators if possible.
 *
 * @author Gisa Schaefer
 * @since 7.3
 */
enum FlowCleaner {

	INSTANCE;

	/** the cleanup is only possible if beta features are activated */
	private boolean cleanupPossible = !Boolean
			.parseBoolean(ParameterService.getParameterValue(RapidMiner.PROPERTY_RAPIDMINER_SYSTEM_LEGACY_DATA_MGMT));

	private FlowCleaner() {
		// register listener for (de)activation of beta features
		ParameterService.registerParameterChangeListener(new ParameterChangeListener() {

			@Override
			public void informParameterSaved() {
				// not necessary
			}

			@Override
			public void informParameterChanged(String key, String value) {
				if (RapidMiner.PROPERTY_RAPIDMINER_SYSTEM_LEGACY_DATA_MGMT.equals(key)) {
					cleanupPossible = !Boolean.parseBoolean(value);
				}
			}
		});
	}

	/**
	 * Checks if the data is a {@link ExampleSet} that can be cleaned via
	 * {@link ExampleSet#cleanup()}. Does the cleanup if it is necessary.
	 *
	 * @param data
	 *            the current data at the inputPort
	 * @param inputPort
	 *            the input port to which the data belongs
	 * @return the cleaned up data or the unchanged data
	 */
	IOObject checkCleanup(IOObject data, InputPort inputPort) {
		if (cleanupPossible && data instanceof ExampleSet) {
			ExampleSet exampleSet = (ExampleSet) data;
			// do cleanup if there are unused columns
			if (exampleSet.getAttributes().allSize() < exampleSet.getExampleTable().getAttributeCount()) {
				ExampleSet clone = (ExampleSet) exampleSet.clone();
				String source = exampleSet.getSource();
				if (source != null && !source.isEmpty()) {
					clone.setSource(source);
				}
				clone.cleanup();
				inputPort.receive(clone);
				return clone;
			}
		}
		return data;
	}

}