/*
 * 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} or some other specified {@code Map}.
 *
 * @author Mike Grogan
 * @since 1.6
 */
public class SimpleBindings implements Bindings {

 /**
 * The {@code Map} field stores the attributes.
 */
 private Map<String,Object> map;

 /**
 * Constructor uses an existing {@code Map} to store the values.
 * @param m The {@code Map} backing this {@code SimpleBindings}.
 * @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}.
 */
 public SimpleBindings() {
 this(new HashMap<String,Object>());
 }

 /**
 * Sets the specified key/value in the underlying {@code map} 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} is implemented using {@code Map.putAll}.
 *
 * @param toMerge The {@code Map} 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 {@code true} if this map contains a mapping for the specified
 * key. More formally, returns {@code true} if and only if
 * this map contains a mapping for a key {@code k} such that
 * {@code (key==null ? k==null : key.equals(k))}. (There can be
 * at most one such mapping.)
 *
 * @param key key whose presence in this map is to be tested.
 * @return {@code true} 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
 * {@code null} if the map contains no mapping for this key. A return
 * value of {@code null} 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 {@code null}. The {@code containsKey}
 * operation may be used to distinguish these two cases.
 *
 * <p>More formally, if this map contains a mapping from a key
 * {@code k} to a value {@code v} such that
 * {@code (key==null ? k==null : key.equals(k))},
 * then this method returns {@code v}; otherwise
 * it returns {@code null}. (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
 * {@code null} 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 {@code k} to value {@code v} such that
 * {@code (key==null ? k==null : key.equals(k))}, 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
 * {@code null} if the map contained no mapping for this key. (A
 * {@code null} return can also indicate that the map previously
 * associated {@code null} with the specified key if the implementation
 * supports {@code null} 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 {@code null}
 * 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");
 }
 }
}