/*
 *  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.LinkedList;
import java.util.logging.Level;

import com.rapidminer.operator.IOObject;
import com.rapidminer.operator.Operator;
import com.rapidminer.operator.SimpleProcessSetupError;
import com.rapidminer.operator.ProcessSetupError.Severity;
import com.rapidminer.operator.ports.InputPort;
import com.rapidminer.operator.ports.OutputPort;

/** This class mirrors the behavior of an Operator's apply-method with respect to the 
 *  I/O meta data. This functionality is performed by a class of its own (rather than another
 *  method in Operator) to keep Operator lean and since it is assumed that most meta data
 *  transformations can be handled by a small set of standard rules. 
 *  
 *  The general rule is that methods of this package should not throw exceptions but rather
 *  register possible errors with the ports if preconditions are not satisfied etc.
 *  
 *  @author Simon Fischer
 *  */
public class MDTransformer {

	private final LinkedList<MDTransformationRule> transformationRules = new LinkedList<MDTransformationRule>();
	private final Operator operator;
	
	public MDTransformer(Operator op) {
		this.operator = op;
	}
	
	/** Executes all rules added by {@link #addRule}. */
	public void transformMetaData() {
		for (MDTransformationRule rule : transformationRules) {
			try {
				rule.transformMD();
			} catch (Exception e) {
				operator.getLogger().log(Level.WARNING, "Error during meta data transformation: "+e, e);
				operator.addError(new SimpleProcessSetupError(Severity.WARNING, operator.getPortOwner(), "exception_transforming_metadata", e.toString()));			
			}
		}
	}

	public void addRule(MDTransformationRule rule) {
		transformationRules.add(rule);		
	}

	/** Convenience method to generate a {@link PassThroughRule}. */
	public void addPassThroughRule(InputPort input, OutputPort output) {
		addRule(new PassThroughRule(input, output, false));		
	}
	
	/** Convenience method to generate a {@link GenerateNewMDRule}. */
	public void addGenerationRule(OutputPort output, Class<? extends IOObject> clazz) {
		addRule(new GenerateNewMDRule(output, clazz));		
	}

	public void clearRules() {
		transformationRules.clear();
	}

	public void addRuleAtBeginning(MDTransformationRule mdTransformationRule) {
		transformationRules.addFirst(mdTransformationRule);		
	}	

}