/*

 * Copyright (c) 2005, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * This code 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 General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 */

package javax.script;

import java.util.Map;

import java.util.HashMap;

import java.util.Collection;

import java.util.Set;

/**

 * A simple implementation of Bindings backed by

 * a <code>HashMap</code> or some other specified <code>Map</code>.

 *

 * @author Mike Grogan

 * @since 1.6

 */

public class SimpleBindings implements Bindings {

    /**

     * The <code>Map</code> field stores the attributes.

     */

    private Map<String,Object> map;

    /**

     * Constructor uses an existing <code>Map</code> to store the values.

     * @param m The <code>Map</code> backing this <code>SimpleBindings</code>.

     * @throws NullPointerException if m is null

     */

    public SimpleBindings(Map<String,Object> m) {

        if (m == null) {

            throw new NullPointerException();

        }

        this.map = m;

    }

    /**

     * Default constructor uses a <code>HashMap</code>.

     */

    public SimpleBindings() {

        this(new HashMap<String,Object>());

    }

    /**

     * Sets the specified key/value in the underlying <code>map</code> field.

     *

     * @param name Name of value

     * @param value Value to set.

     *

     * @return Previous value for the specified key.  Returns null if key was previously

     * unset.

     *

     * @throws NullPointerException if the name is null.

     * @throws IllegalArgumentException if the name is empty.

     */

    public Object put(String name, Object value) {

        checkKey(name);

        return map.put(name,value);

    }

    /**

     * <code>putAll</code> is implemented using <code>Map.putAll</code>.

     *

     * @param toMerge The <code>Map</code> of values to add.

     *

     * @throws NullPointerException

     *         if toMerge map is null or if some key in the map is null.

     * @throws IllegalArgumentException

     *         if some key in the map is an empty String.

     */

    public void putAll(Map<? extends String, ? extends Object> toMerge) {

        if (toMerge == null) {

            throw new NullPointerException("toMerge map is null");

        }

        for (Map.Entry<? extends String, ? extends Object> entry : toMerge.entrySet()) {

            String key = entry.getKey();

            checkKey(key);

            put(key, entry.getValue());

        }

    }

    /** {@inheritDoc} */

    public void clear() {

        map.clear();

    }

    /**

     * Returns <tt>true</tt> if this map contains a mapping for the specified

     * key.  More formally, returns <tt>true</tt> if and only if

     * this map contains a mapping for a key <tt>k</tt> such that

     * <tt>(key==null ? k==null : key.equals(k))</tt>.  (There can be

     * at most one such mapping.)

     *

     * @param key key whose presence in this map is to be tested.

     * @return <tt>true</tt> if this map contains a mapping for the specified

     *         key.

     *

     * @throws NullPointerException if key is null

     * @throws ClassCastException if key is not String

     * @throws IllegalArgumentException if key is empty String

     */

    public boolean containsKey(Object key) {

        checkKey(key);

        return map.containsKey(key);

    }

    /** {@inheritDoc} */

    public boolean containsValue(Object value) {

        return map.containsValue(value);

    }

    /** {@inheritDoc} */

    public Set<Map.Entry<String, Object>> entrySet() {

        return map.entrySet();

    }

    /**

     * Returns the value to which this map maps the specified key.  Returns

     * <tt>null</tt> if the map contains no mapping for this key.  A return

     * value of <tt>null</tt> does not <i>necessarily</i> indicate that the

     * map contains no mapping for the key; it's also possible that the map

     * explicitly maps the key to <tt>null</tt>.  The <tt>containsKey</tt>

     * operation may be used to distinguish these two cases.

     *

     * <p>More formally, if this map contains a mapping from a key

     * <tt>k</tt> to a value <tt>v</tt> such that <tt>(key==null ? k==null :

     * key.equals(k))</tt>, then this method returns <tt>v</tt>; otherwise

     * it returns <tt>null</tt>.  (There can be at most one such mapping.)

     *

     * @param key key whose associated value is to be returned.

     * @return the value to which this map maps the specified key, or

     *         <tt>null</tt> if the map contains no mapping for this key.

     *

     * @throws NullPointerException if key is null

     * @throws ClassCastException if key is not String

     * @throws IllegalArgumentException if key is empty String

     */

    public Object get(Object key) {

        checkKey(key);

        return map.get(key);

    }

    /** {@inheritDoc} */

    public boolean isEmpty() {

        return map.isEmpty();

    }

    /** {@inheritDoc} */

    public Set<String> keySet() {

        return map.keySet();

    }

    /**

     * Removes the mapping for this key from this map if it is present

     * (optional operation).   More formally, if this map contains a mapping

     * from key <tt>k</tt> to value <tt>v</tt> such that

     * <code>(key==null ?  k==null : key.equals(k))</code>, that mapping

     * is removed.  (The map can contain at most one such mapping.)

     *

     * <p>Returns the value to which the map previously associated the key, or

     * <tt>null</tt> if the map contained no mapping for this key.  (A

     * <tt>null</tt> return can also indicate that the map previously

     * associated <tt>null</tt> with the specified key if the implementation

     * supports <tt>null</tt> values.)  The map will not contain a mapping for

     * the specified  key once the call returns.

     *

     * @param key key whose mapping is to be removed from the map.

     * @return previous value associated with specified key, or <tt>null</tt>

     *         if there was no mapping for key.

     *

     * @throws NullPointerException if key is null

     * @throws ClassCastException if key is not String

     * @throws IllegalArgumentException if key is empty String

     */

    public Object remove(Object key) {

        checkKey(key);

        return map.remove(key);

    }

    /** {@inheritDoc} */

    public int size() {

        return map.size();

    }

    /** {@inheritDoc} */

    public Collection<Object> values() {

        return map.values();

    }

    private void checkKey(Object key) {

        if (key == null) {

            throw new NullPointerException("key can not be null");

        }

        if (!(key instanceof String)) {

            throw new ClassCastException("key should be a String");

        }

        if (key.equals("")) {

            throw new IllegalArgumentException("key can not be empty");

        }

    }

}