/*
 * Copyright (c) 2001 Sun Microsystems, Inc.  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.
 *
 * 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.
 *
 * 3. The end-user documentation included with the redistribution,
 *    if any, must include the following acknowledgment:
 *       "This product includes software developed by the
 *       Sun Microsystems, Inc. for Project JXTA."
 *    Alternately, this acknowledgment may appear in the software itself,
 *    if and wherever such third-party acknowledgments normally appear.
 *
 * 4. The names "Sun", "Sun Microsystems, Inc.", "JXTA" and "Project JXTA" must
 *    not be used to endorse or promote products derived from this
 *    software without prior written permission. For written
 *    permission, please contact Project JXTA at http://www.jxta.org.
 *
 * 5. Products derived from this software may not be called "JXTA",
 *    nor may "JXTA" appear in their name, without prior written
 *    permission of Sun.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED.  IN NO EVENT SHALL SUN MICROSYSTEMS OR
 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of Project JXTA.  For more
 * information on Project JXTA, please see
 * <http://www.jxta.org/>.
 *
 * This license is based on the BSD license adopted by the Apache Foundation.
 *
 * $Id: ShellEnv.java,v 1.13 2007/05/30 21:23:47 bondolo Exp $
 */

package net.jxta.impl.shell;

import java.util.*;
import java.util.concurrent.atomic.AtomicInteger;

/**
 * Manages environment variables for a shell application.
 */
public final class ShellEnv {

    /**
     * Variables stored in this environment.
     */
    private final Map<String, ShellObject<? extends Object>> vars = new HashMap<String, ShellObject<? extends Object>>();
    
    /**
     *  The next value to use for automatically generated env variables.
     */
    private final AtomicInteger next;

    public ShellEnv() {
        next = new AtomicInteger(0);
    }

    public ShellEnv(ShellEnv srcEnv) {
        vars.putAll(srcEnv.vars);
        next = new AtomicInteger(srcEnv.next.get());
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public String toString() {
        return vars.toString();
    }

    public synchronized String createName() {
        return "env" + Integer.toString(next.incrementAndGet());
    }

    public synchronized void clear() {
        vars.clear();
    }

    public synchronized ShellObject add(ShellObject<? extends Object> obj) {
        return add(createName(), obj);
    }

    public synchronized ShellObject<? extends Object> add(String name, ShellObject<? extends Object> obj) {
        if (obj == null)
            return null;

        if (name == null) {
            name = createName();
        }

        return (ShellObject<? extends Object>) vars.put(name, obj);
    }

    public synchronized ShellObject<?> get(String name) {
        if (name == null)
            return null;

        return (ShellObject<? extends Object>) vars.get(name);
    }

    public synchronized boolean contains(String name) {
        return vars.containsKey(name);
    }

    public synchronized boolean contains(ShellObject<? extends Object> obj) {
        return vars.containsValue(obj);
    }

    public synchronized boolean rename(String oldName, String newName) {
        if (contains(newName)) {
            return false;
        }
        if (contains(oldName)) {
            ShellObject<? extends Object> obj = vars.remove(oldName);

            vars.put(newName, obj);
            return true;
        } else {
            return false;
        }
    }

    public synchronized boolean remove(String name) {
        return vars.remove(name) != null;
    }

    public synchronized boolean remove(ShellObject<? extends Object> obj) {
        boolean removed = false;

        Iterator<ShellObject<? extends Object>> eachValue = vars.values().iterator();

        while (eachValue.hasNext()) {
            if (eachValue.next() == obj) {
                eachValue.remove();
                removed = true;
            }
        }

        return removed;
    }

    public synchronized Enumeration<String> elements() {
        List<String> asList = new ArrayList<String>(vars.keySet());

        return Collections.enumeration(asList);
    }
}