/*
 *  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.ports.metadata;

import java.util.Collection;

import com.rapidminer.operator.ports.InputPort;


/** Checks whether a given port receives an object of a desired class. 
 *  If more checks are desired, override {@link #makeAdditionalChecks}. 
 *  
 *  @author Simon Fischer
 *  
 *  */
public class SimplePrecondition extends AbstractPrecondition {

	private final MetaData desiredMetaData;
	private final boolean mandatory;

	public SimplePrecondition(InputPort inputPort, MetaData desiredMetaData) {
		this(inputPort, desiredMetaData, true);
	}
	
	public SimplePrecondition(InputPort inputPort, MetaData desiredMetaData, boolean mandatory) {		
		super(inputPort);
		this.desiredMetaData = desiredMetaData;
		this.mandatory = mandatory;
	}

	@Override
	public final void check(MetaData metaData) {	
		InputPort inputPort = getInputPort();	
		if (metaData == null) {
			if (isMandatory()) {
				inputPort.addError(new InputMissingMetaDataError(inputPort, desiredMetaData.getObjectClass(), null));
			}
		} else {
			if (desiredMetaData != null) {
				Collection<MetaDataError> errors = desiredMetaData.getErrorsForInput(inputPort, metaData, CompatibilityLevel.VERSION_5);
				for (MetaDataError error : errors) {				
					inputPort.addError(error);
				}
			}
			makeAdditionalChecks(metaData);
		}		
	}

	@Override
	public String getDescription() {		 
		return (isMandatory() ? "<em>expects:</em> " : "<em>optional:</em> ") + desiredMetaData;
	}
	
	/** Override this method to make additional checks. The default implementation does nothing. */
	public void makeAdditionalChecks(MetaData received) {		
	}

	@Override
	public boolean isCompatible(MetaData input, CompatibilityLevel level) {
		if (desiredMetaData != null) {
			return desiredMetaData.isCompatible(input, level);
		} else {
			return true;
		}
	}

	@Override
	public void assumeSatisfied() {
		if (mandatory && (desiredMetaData != null)) {
			getInputPort().receiveMD(desiredMetaData.clone());
		}
	}

	protected boolean isMandatory() {
		return mandatory;
	}

	@Override
	public MetaData getExpectedMetaData() {
		return desiredMetaData;
	}	
}