/*
 * ====================================================================
 *
 * The Apache Software License, Version 1.1
 *
 * Copyright (c) 1999-2002 The Apache Software Foundation.  All rights
 * reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
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 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
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 * 3. The end-user documentation included with the redistribution, if
 *    any, must include the following acknowlegement:
 *       "This product includes software developed by the
 *        Apache Software Foundation (http://www.apache.org/)."
 *    Alternately, this acknowlegement may appear in the software itself,
 *    if and wherever such third-party acknowlegements normally appear.
 *
 * 4. The names "The Jakarta Project", "Commons", and "Apache Software
 *    Foundation" must not be used to endorse or promote products derived
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 * 5. Products derived from this software may not be called "Apache"
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 * SUCH DAMAGE.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
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 */

package org.apache.commons.discovery.resource.names;

import java.util.Hashtable;

import org.apache.commons.discovery.ResourceNameDiscover;
import org.apache.commons.discovery.ResourceNameIterator;
import org.apache.commons.discovery.log.DiscoveryLogFactory;
import org.apache.commons.logging.Log;


/**
 * Recover resource name from Managed Properties,
 * using OLD property names.
 * 
 * This class maintains a mapping between old names and
 * (new) the class names they represent.  The discovery
 * mechanism uses the class names as property names.
 * 
 * @see org.apache.commons.discovery.tools.ManagedProperties
 * 
 * @author Richard A. Sitze
 */
public class DiscoverMappedNames
    extends ResourceNameDiscoverImpl
    implements ResourceNameDiscover
{
    private static Log log = DiscoveryLogFactory.newLog(DiscoverMappedNames.class);
    public static void setLog(Log _log) {
        log = _log;
    }
    
    private Hashtable mapping = new Hashtable();  // String name ==> String[] newNames
    
    /** Construct a new resource discoverer
     */
    public DiscoverMappedNames() {
    }
    
    public void map(String fromName, String toName) {
        mapping.put(fromName, toName);
    }
    
    public void map(String fromName, String [] toNames) {
        mapping.put(fromName, toNames);
    }

    /**
     * @return Enumeration of ResourceInfo
     */
    public ResourceNameIterator findResourceNames(final String resourceName) {
        if (log.isDebugEnabled()) {
            log.debug("find: resourceName='" + resourceName + "', mapping to constants");
        }
        
        final Object obj = mapping.get(resourceName);

        final String[] names;
        if (obj instanceof String) {
            names = new String[] { (String)obj };
        } else if (obj instanceof String[]) {
            names = (String[])obj;
        } else {
            names = null;
        }
        
        return new ResourceNameIterator() {

            private int idx = 0;
            
            public boolean hasNext() {
                if (names != null) {
                    while (idx < names.length  &&  names[idx] == null) {
                        idx++;
                    }
                    return idx < names.length;
                }
                return false;
            }
            
            public String nextResourceName() {
                return hasNext() ? names[idx++] : null;
            }
        };
    }
}