// ========================================================================
// Copyright 2007 Mort Bay Consulting Pty. Ltd.
// ------------------------------------------------------------------------
// Licensed 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.mortbay.cometd.filter;

import java.lang.reflect.Array;
import java.util.regex.Pattern;


/**
 * @author gregw
 *
 */
public class RegexFilter extends JSONDataFilter
{
    String[] _templates;
    String[] _replaces;
    
    transient Pattern[] _patterns;
    
    /**
     * Assumes the init object is an Array of 2 element Arrays:  [regex,replacement].
     * if the regex replacement string is null, then an IllegalStateException is thrown if
     * the pattern matches.
     */
    public void init(Object init)
    {
        super.init(init);
        
        _templates=new String[Array.getLength(init)];
        _replaces=new String[_templates.length];

        for (int i=0;i<_templates.length;i++)
        {
            Object entry = Array.get(init,i);
            _templates[i]=(String)Array.get(entry,0);
            _replaces[i]=(String)Array.get(entry,1);
        }
        
        checkPatterns();
    }
    
    private void checkPatterns()
    {
        // TODO replace this check with a terracotta transient init clause
        synchronized(this)
        {
            if (_patterns==null)
            {
                _patterns=new Pattern[_templates.length];
                for (int i=0;i<_patterns.length;i++)
                {
                    _patterns[i]=Pattern.compile(_templates[i]);
                }
            }
        }
    }

    protected Object filterString(String string)
    {
        checkPatterns();
        
        for (int i=0;i<_patterns.length;i++)
        {
            if (_replaces[i]!=null)
                string=_patterns[i].matcher(string).replaceAll(_replaces[i]);
            else if (_patterns[i].matcher(string).matches())
                throw new IllegalStateException("matched "+_patterns[i]+" in "+string);
        }
        return string;
    }
}
