/*
 * ModeShape (http://www.modeshape.org)
 * See the COPYRIGHT.txt file distributed with this work for information
 * regarding copyright ownership.  Some portions may be licensed
 * to Red Hat, Inc. under one or more contributor license agreements.
 * See the AUTHORS.txt file in the distribution for a full listing of 
 * individual contributors.
 *
 * ModeShape is free software. Unless otherwise indicated, all code in ModeShape
 * is licensed to you under the terms of the GNU Lesser General Public License as
 * published by the Free Software Foundation; either version 2.1 of
 * the License, or (at your option) any later version.
 * 
 * ModeShape 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this software; if not, write to the Free
 * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
 * 02110-1301 USA, or see the FSF site: http://www.fsf.org.
 */
package org.modeshape.jcr.cache.document;

import java.util.Collection;
import java.util.Iterator;
import java.util.NoSuchElementException;
import java.util.regex.Pattern;

/**
 * A base class for an {@link Iterator} implementation that exposes values from another iterator that match at least one of the
 * supplied patterns.
 * 
 * @param <Type> the type of values
 */
abstract class PatternIterator<Type> extends DelegatingIterator<Type> {

    private final Collection<?> patterns;
    private Type last;

    protected PatternIterator( Iterator<Type> delegate,
                               Collection<?> patterns ) {
        super(delegate);
        this.patterns = patterns;
    }

    @Override
    public boolean hasNext() {
        if (last != null) {
            return true;
        }
        while (super.hasNext()) {
            last = super.next();
            String childName = matchable(last);
            for (Object pattern : patterns) {
                if (pattern instanceof String) {
                    // Check for an exact match ...
                    if (childName.equals(pattern)) return true;
                } else {
                    Pattern p = (Pattern)pattern;
                    if (p.matcher(childName).matches()) return true;
                }
            }
        }
        last = null;
        return false;
    }

    @Override
    public Type next() {
        try {
            if (last == null) {
                if (!hasNext()) {
                    throw new NoSuchElementException();
                }
            }
            if (last != null) {
                return last;
            }
        } finally {
            last = null;
        }
        throw new NoSuchElementException();
    }

    protected abstract String matchable( Type value );
}
