/*
 *  Licensed to the Apache Software Foundation (ASF) under one or more
 *  contributor license agreements.  See the NOTICE file distributed with
 *  this work for additional information regarding copyright ownership.
 *  The ASF licenses this file to You under the Apache License, Version 2.0
 *  (the "License"); you may not use this file except in compliance with
 *  the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 */
package org.apache.commons.collections.functors;

import java.io.Serializable;
import java.util.Collection;

import org.apache.commons.collections.Predicate;

/**
 * Predicate implementation that returns true if only one of the
 * predicates return true.
 * If the array of predicates is empty, then this predicate returns false.
 * <p>
 * NOTE: In versions prior to 3.2 an array size of zero or one
 * threw an exception.
 *
 * @since Commons Collections 3.0
 * @version $Revision: 646777 $ $Date: 2008-04-10 13:33:15 +0100 (Thu, 10 Apr 2008) $
 *
 * @author Stephen Colebourne
 * @author Matt Benson
 */
public final class OnePredicate implements Predicate, PredicateDecorator, Serializable {

    /** Serial version UID */
    private static final long serialVersionUID = -8125389089924745785L;
    
    /** The array of predicates to call */
    private final Predicate[] iPredicates;
    
    /**
     * Factory to create the predicate.
     * <p>
     * If the array is size zero, the predicate always returns false.
     * If the array is size one, then that predicate is returned.
     *
     * @param predicates  the predicates to check, cloned, not null
     * @return the <code>any</code> predicate
     * @throws IllegalArgumentException if the predicates array is null
     * @throws IllegalArgumentException if any predicate in the array is null
     */
    public static Predicate getInstance(Predicate[] predicates) {
        FunctorUtils.validate(predicates);
        if (predicates.length == 0) {
            return FalsePredicate.INSTANCE;
        }
        if (predicates.length == 1) {
            return predicates[0];
        }
        predicates = FunctorUtils.copy(predicates);
        return new OnePredicate(predicates);
    }

    /**
     * Factory to create the predicate.
     *
     * @param predicates  the predicates to check, cloned, not null
     * @return the <code>one</code> predicate
     * @throws IllegalArgumentException if the predicates array is null
     * @throws IllegalArgumentException if any predicate in the array is null
     */
    public static Predicate getInstance(Collection predicates) {
        Predicate[] preds = FunctorUtils.validate(predicates);
        return new OnePredicate(preds);
    }

    /**
     * Constructor that performs no validation.
     * Use <code>getInstance</code> if you want that.
     * 
     * @param predicates  the predicates to check, not cloned, not null
     */
    public OnePredicate(Predicate[] predicates) {
        super();
        iPredicates = predicates;
    }

    /**
     * Evaluates the predicate returning true if only one decorated predicate
     * returns true.
     * 
     * @param object  the input object
     * @return true if only one decorated predicate returns true
     */
    public boolean evaluate(Object object) {
        boolean match = false;
        for (int i = 0; i < iPredicates.length; i++) {
            if (iPredicates[i].evaluate(object)) {
                if (match) {
                    return false;
                }
                match = true;
            }
        }
        return match;
    }

    /**
     * Gets the predicates, do not modify the array.
     * 
     * @return the predicates
     * @since Commons Collections 3.1
     */
    public Predicate[] getPredicates() {
        return iPredicates;
    }

}
