/*
 *  Licensed to the Apache Software Foundation (ASF) under one or more
 *  contributor license agreements.  See the NOTICE file distributed with
 *  this work for additional information regarding copyright ownership.
 *  The ASF licenses this file to You under the Apache License, Version 2.0
 *  (the "License"); you may not use this file except in compliance with
 *  the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 */

package org.apache.harmony.javax.security.auth.kerberos;

import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.ObjectStreamField;
import java.io.Serializable;
import java.security.Permission;
import java.security.PermissionCollection;
import java.util.Enumeration;
import java.util.NoSuchElementException;
import java.util.Vector;

import org.apache.harmony.auth.internal.nls.Messages;

/**
 * Specific PermissionCollection for storing ServicePermissions
 * 
 */

final class KrbServicePermissionCollection extends PermissionCollection
		implements Serializable {

	private static final long serialVersionUID = -4118834211490102011L;

	private static final ObjectStreamField[] serialPersistentFields = { new ObjectStreamField(
			"permissions", Vector.class) }; //$NON-NLS-1$

	private transient ServicePermission[] items = new ServicePermission[10];

	private transient int offset;

	// initialization of a collection
	KrbServicePermissionCollection() {
	}

	/**
	 * Adds a ServicePermission to the collection.
	 */
	@Override
	public void add(Permission permission) {

		if (isReadOnly()) {
			throw new SecurityException(Messages.getString("auth.21")); //$NON-NLS-1$
		}

		if (permission == null || !(permission instanceof ServicePermission)) {
			throw new IllegalArgumentException(Messages.getString(
					"auth.22", permission)); //$NON-NLS-1$
		}
		synchronized (this) {
			if (offset == items.length) {
				final ServicePermission[] sp = new ServicePermission[items.length * 2];
				System.arraycopy(items, 0, sp, 0, offset);
				items = sp;
			}
			items[offset++] = (ServicePermission) permission;
		}
	}

	/**
	 * Returns enumeration of the collection.
	 */
	@Override
	public Enumeration<Permission> elements() {
		return new Enumeration<Permission>() {
			private int index = 0;

			@Override
			public boolean hasMoreElements() {
				return index < offset;
			}

			@Override
			public Permission nextElement() {
				if (index == offset) {
					throw new NoSuchElementException();
				}
				return items[index++];
			}
		};
	}

	/**
	 * Returns true if this collection implies the specified permission.
	 */
	@Override
	public boolean implies(Permission permission) {

		if (permission == null || !(permission instanceof ServicePermission)) {
			return false;
		}

		synchronized (this) {
			for (int i = 0; i < offset; i++) {
				if (items[i].implies(permission)) {
					return true;
				}
			}
		}

		return false;
	}

	// read collection from stream
	private void readObject(java.io.ObjectInputStream in) throws IOException,
			ClassNotFoundException {
		final ObjectInputStream.GetField fields = in.readFields();
		final Vector<?> permissions = (Vector<?>) fields.get(
				"permissions", null); //$NON-NLS-1$
		items = new ServicePermission[permissions.size() * 2];
		for (offset = 0; offset < items.length / 2;) {
			final Object obj = permissions.get(offset);
			if (obj == null || !(obj instanceof ServicePermission)) {
				throw new IllegalArgumentException(Messages.getString(
						"auth.22", obj)); //$NON-NLS-1$
			}
			items[offset++] = (ServicePermission) obj;
		}
	}

	// white collection to stream
	private void writeObject(java.io.ObjectOutputStream out) throws IOException {
		Vector<ServicePermission> permissions;
		permissions = new Vector<ServicePermission>(offset);
		for (int i = 0; i < offset; permissions.add(items[i++])) {
		}
		final ObjectOutputStream.PutField fields = out.putFields();
		fields.put("permissions", permissions); //$NON-NLS-1$
		out.writeFields();
	}
}