/*
 *  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.preprocessing.filter.attributes;

import java.util.ArrayList;
import java.util.LinkedList;
import java.util.List;

import com.rapidminer.example.Attribute;
import com.rapidminer.example.Example;
import com.rapidminer.example.set.ConditionCreationException;
import com.rapidminer.operator.Operator;
import com.rapidminer.operator.UserError;
import com.rapidminer.operator.ports.InputPort;
import com.rapidminer.operator.ports.metadata.AttributeMetaData;
import com.rapidminer.operator.ports.metadata.MetaDataInfo;
import com.rapidminer.parameter.ParameterHandler;
import com.rapidminer.parameter.ParameterType;
import com.rapidminer.parameter.ParameterTypeString;

/**
 * This class implements a condition for the AttributeFilter operator. 
 * It provides the possibility to check if all values of a numerical attribute
 * match a condition. This conditions might be specified by != or <>, =, <, <=, >, >= 
 * followed by a value. For example like this: "> 6.5" would keep all attributes having only values
 * greater 6.5. 
 * This single conditions might be combined by || or && but not mixed. Example: "> 6.5 && < 11" would keep
 * all attributes containing only values between 6.5 and 11.
 * 
 * @author Sebastian Land, Ingo Mierswa
 */
public class NumericValueAttributeFilter extends AbstractAttributeFilterCondition {

	public static String PARAMETER_NUMERIC_CONDITION = "numeric_condition";

	private Attribute lastCheckedAttribute = null;

	private ArrayList<Condition> conditions;

	private boolean keep = true;

	private boolean conjunctiveMode;

	private static class Condition {

		private int condition;

		private double value;

		public Condition(String condition, String value) {
			this.value = Double.parseDouble(value);
			if (condition.equals("<>") || condition.equals("!=")) {
				this.condition = 1;
			} else if (condition.equals("<=")) {
				this.condition = 2;
			} else if (condition.equals("<")) {
				this.condition = 3;
			} else if (condition.equals(">=")) {
				this.condition = 4;
			} else if (condition.equals(">")) {
				this.condition = 5;
			} else if (condition.equals("=")) {
				this.condition = 0;
			}
		}

		public boolean check(double value) {
			if (Double.isNaN(value))
				return true;

			switch (condition) {
			case 0: return (value == this.value);
			case 1: return (value != this.value);
			case 2: return (value <= this.value);
			case 3: return (value < this.value);
			case 4: return (value >= this.value);
			case 5: return (value > this.value);
			}
			return false;
		}
	}


	@Override
	public void init(ParameterHandler parameterHandler) throws UserError, ConditionCreationException {
		String conditionString = parameterHandler.getParameterAsString(PARAMETER_NUMERIC_CONDITION);
		Operator operator = null;
		if (parameterHandler instanceof Operator)
			operator = (Operator) parameterHandler;
		
		if ((conditionString == null) || (conditionString.length() == 0))
			throw new UserError(operator, 904, "The condition for numerical values needs a parameter string.");
		// testing if not allowed combination of and and or
		if (conditionString.contains("||") && conditionString.contains("&&")) {
			throw new UserError(operator, 904, "|| and && not allowed in one condition");
		}
		this.conjunctiveMode = conditionString.contains("&&");
		conditions = new ArrayList<Condition>();
		for (String conditionSubString: conditionString.split("[|&]{2}")) {
			String[] parts = conditionSubString.trim().split("\\s+");
			if (parts.length != 2) {
				throw new UserError(operator, 904, "number of condition arguments not correct");
			} else {
				conditions.add(new Condition(parts[0], parts[1]));
			}
		}
	}

	@Override
	public MetaDataInfo isFilteredOutMetaData(AttributeMetaData attribute, ParameterHandler handler) {
		//TODO: If some infos over the value range are available: Use them to decide if possible
		return MetaDataInfo.UNKNOWN;
	}

	@Override
	public boolean isNeedingScan() {
		return true;
	}

	/**
	 * Don't remove any attribute without checking values
	 */
	public ScanResult beforeScanCheck(Attribute attribute) throws UserError {
		return ScanResult.UNCHECKED;
	}

	@Override
	public ScanResult check(Attribute attribute, Example example) {
		if (lastCheckedAttribute != attribute)
			keep = true;
		if (attribute.isNumerical()) {
			boolean exampleResult;
			double checkValue = example.getValue(attribute);

			if (conjunctiveMode) {
				exampleResult = true;
				for(Condition condition : conditions) {
					exampleResult &= condition.check(checkValue);
				}
			} else {
				exampleResult = false;
				for (Condition condition : conditions) {
					exampleResult |= condition.check(checkValue);
				}	
			}
			keep &= exampleResult;
		}
		if ((!keep) && attribute.isNumerical())
			return ScanResult.REMOVE;
		else
			return ScanResult.UNCHECKED;
	}

	@Override
	public List<ParameterType> getParameterTypes(ParameterHandler operator, InputPort inPort, int...valueTypes) {
		LinkedList<ParameterType> types = new LinkedList<ParameterType>();
		types.add(new ParameterTypeString(PARAMETER_NUMERIC_CONDITION, "Parameter string for the condition, e.g. '>= 5'", true, false));
		return types;
	}

}