/*****************************************************************************
 *                                                                           *
 *  This file is part of the BeanShell Java Scripting distribution.          *
 *  Documentation and updates may be found at http://www.beanshell.org/      *
 *                                                                           *
 *  Sun Public License Notice:                                               *
 *                                                                           *
 *  The contents of this file are subject to the Sun Public License Version  *
 *  1.0 (the "License"); you may not use this file except in compliance with *
 *  the License. A copy of the License is available at http://www.sun.com    *
 *                                                                           *
 *  The Original Code is BeanShell. The Initial Developer of the Original    *
 *  Code is Pat Niemeyer. Portions created by Pat Niemeyer are Copyright     *
 *  (C) 2000.  All Rights Reserved.                                          *
 *                                                                           *
 *  GNU Public License Notice:                                               *
 *                                                                           *
 *  Alternatively, the contents of this file may be used under the terms of  *
 *  the GNU Lesser General Public License (the "LGPL"), in which case the    *
 *  provisions of LGPL are applicable instead of those above. If you wish to *
 *  allow use of your version of this file only under the  terms of the LGPL *
 *  and not to allow others to use your version of this file under the SPL,  *
 *  indicate your decision by deleting the provisions above and replace      *
 *  them with the notice and other provisions required by the LGPL.  If you  *
 *  do not delete the provisions above, a recipient may use your version of  *
 *  this file under either the SPL or the LGPL.                              *
 *                                                                           *
 *  Patrick Niemeyer (pat@pat.net)                                           *
 *  Author of Learning Java, O'Reilly & Associates                           *
 *  http://www.pat.net/~pat/                                                 *
 *                                                                           *
 *****************************************************************************/

package org.gjt.sp.jedit.bsh;

import java.util.Enumeration;
import java.util.Vector;
import java.util.Hashtable;
import java.lang.reflect.Array;

/**
    The default CollectionManager (which remains Java 1.1 compatible)
    supports iteration over objects of type:
    Enumeration, Vector, String, StringBuffer and array.
    The dynamically loaded CollectionManagerImpl supports additional types when
    it is present.
*/
public class CollectionManager
{
    private static CollectionManager manager;

    public synchronized static CollectionManager getCollectionManager()
    {
        if ( manager == null
            && Capabilities.classExists("java.util.Collection") )
        {
            Class clas;
            try {
                clas = Class.forName( "org.gjt.sp.jedit.bsh.collection.CollectionManagerImpl" );
                manager = (CollectionManager)clas.newInstance();
            } catch ( Exception e ) {
                Interpreter.debug("unable to load CollectionManagerImpl: "+e);
            }
        }

        if ( manager == null )
            manager = new CollectionManager(); // default impl

        return manager;
    }

    /**
    */
    public boolean isBshIterable( Object obj )
    {
        // This could be smarter...
        try {
            getBshIterator( obj );
            return true;
        } catch( IllegalArgumentException e ) {
            return false;
        }
    }

    public BshIterator getBshIterator( Object obj )
        throws IllegalArgumentException
    {
        return new BasicBshIterator( obj );
    }

    public boolean isMap( Object obj ) {
        return obj instanceof Hashtable;
    }

    public Object getFromMap( Object map, Object key ) {
        return ((Hashtable)map).get(key);
    }

    public Object putInMap( Object map, Object key, Object value )
    {
        return ((Hashtable)map).put(key, value);
    }

    /**
        Determine dynamically if the target is an iterator by the presence of a
        pair of next() and hasNext() methods.
    public static boolean isIterator() { }
    */

    /**
     * An implementation that works with JDK 1.1
     */
    public static class BasicBshIterator implements BshIterator
    {
        Enumeration enumeration;

        /**
         * Construct a basic BasicBshIterator
         *
         * @param iterateOverMe The object over which we are iterating
         *
         * @throws java.lang.IllegalArgumentException If the argument is not a
         * supported (i.e. iterable) type.
         *
         * @throws java.lang.NullPointerException If the argument is null
         */
        public BasicBshIterator(Object iterateOverMe) {
            enumeration = createEnumeration(iterateOverMe);
        }

        /**
         * Create an enumeration over the given object
         *
         * @param iterateOverMe Object of type Enumeration, Vector, String,
         *                      StringBuffer or an array
         *
         * @return an enumeration
         *
         * @throws java.lang.IllegalArgumentException If the argument is not a
         * supported (i.e. iterable) type.
         *
         * @throws java.lang.NullPointerException If the argument is null
         */
        protected Enumeration createEnumeration( Object iterateOverMe )
        {
            if(iterateOverMe==null)
                throw new NullPointerException("Object arguments passed to " +
                    "the BasicBshIterator constructor cannot be null.");

            if (iterateOverMe instanceof Enumeration)
                return (Enumeration)iterateOverMe;

            if (iterateOverMe instanceof Vector)
                return ((Vector)iterateOverMe).elements();

            if (iterateOverMe.getClass().isArray()) {
                final Object array = iterateOverMe;
                return new Enumeration() {
                    int index = 0, length = Array.getLength(array);
                    public Object nextElement() {
                        return Array.get(array, index++);
                    }
                    public boolean hasMoreElements() { return index<length; }
                };
            }

            if (iterateOverMe instanceof String)
                return createEnumeration(((String)iterateOverMe).toCharArray());

            if (iterateOverMe instanceof StringBuffer)
                return createEnumeration(
                    iterateOverMe.toString().toCharArray());

            throw new IllegalArgumentException(
                "Cannot enumerate object of type "+iterateOverMe.getClass());
        }

        /**
         * Fetch the next object in the iteration
         *
         * @return The next object
         */
        public Object next() {
            return 	enumeration.nextElement();
        }

        /**
         * Returns true if and only if there are more objects available
         * via the <code>next()</code> method
         *
         * @return The next object
         */
        public boolean hasNext() {
            return enumeration.hasMoreElements();
        }
    }
}
