/**
 * 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.generator;

import com.rapidminer.example.Attribute;
import com.rapidminer.operator.ports.metadata.ExampleSetMetaData;
import com.rapidminer.tools.RandomGenerator;


/**
 * A target function which is used for the {@link ExampleSetGenerator} operator. All target function
 * will need an empty constructor since they are initialized via reflection.
 * 
 * @author Ingo Mierswa
 */
public interface TargetFunction {

	/**
	 * Will be thrown if an error occurs during the calculation of the target function.
	 */
	public static class FunctionException extends Exception {

		private static final long serialVersionUID = -990633489806141677L;

		private String functionName;

		public FunctionException(String functionName, String message) {
			super(message);
			this.functionName = functionName;
		}

		public String getFunctionName() {
			return functionName;
		}
	}

	/** Should be called before the data is created. */
	public void init(RandomGenerator random);

	/** Calculates the target function on arguments. */
	public double calculate(double[] args) throws FunctionException;

	/** Returns the label attribute. */
	public Attribute getLabel();

	/** Creates and returns a number of arguments. */
	public double[] createArguments(int dimension, RandomGenerator random) throws FunctionException;

	/** Sets the lower bound for the arguments. */
	public void setLowerArgumentBound(double lower);

	/** Sets the upper bound for the arguments. */
	public void setUpperArgumentBound(double upper);

	/**
	 * Sets the maximal number of examples. This might be used by some target functions in order to
	 * create proper arguments.
	 */
	public void setTotalNumberOfExamples(int number);

	/**
	 * Sets the maximal number of attributes. This might be used by some target functions in order
	 * to create proper arguments.
	 */
	public void setTotalNumberOfAttributes(int number);

	/**
	 * This method returns the meta data of the generated data.
	 */
	public ExampleSetMetaData getGeneratedMetaData();

	/**
	 * @return The minimum number of attributes this functions must produce
	 */
	public int getMinNumberOfAttributes();

	/**
	 * @return The maximum number of attributes this functions can produce
	 */
	public int getMaxNumberOfAttributes();
}