/**
 *
 * Copyright the original author or authors
 *
 * Licensed 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.jivesoftware.smackx.pubsub;

import java.util.List;

import org.jivesoftware.smack.packet.ExtensionElement;

/**
 * This class is used to for multiple purposes.  
 * <li>It can represent an event containing a list of items that have been published
 * <li>It can represent an event containing a list of retracted (deleted) items.
 * <li>It can represent a request to delete a list of items.
 * <li>It can represent a request to get existing items.
 * 
 * <p><b>Please note, this class is used for internal purposes, and is not required for usage of 
 * pubsub functionality.</b>
 * 
 * @author Robin Collier
 */
public class ItemsExtension extends NodeExtension implements EmbeddedPacketExtension
{
        protected ItemsElementType type;
        protected Boolean notify;
        protected List<? extends ExtensionElement> items;

        public enum ItemsElementType
        {
                /** An items element, which has an optional <b>max_items</b> attribute when requesting items */
                items(PubSubElementType.ITEMS, "max_items"),
                
                /** A retract element, which has an optional <b>notify</b> attribute when publishing deletions */
                retract(PubSubElementType.RETRACT, "notify");
                
                private PubSubElementType elem;
                private String att;
                
                private ItemsElementType(PubSubElementType nodeElement, String attribute)
                {
                        elem = nodeElement;
                        att = attribute;
                }
                
                public PubSubElementType getNodeElement()
                {
                        return elem;
                }

                public String getElementAttribute()
                {
                        return att;
                }
        }

        /**
         * Construct an instance with a list representing items that have been published or deleted.
         * 
         * <p>Valid scenarios are:
         * <li>Request items from node - itemsType = {@link ItemsElementType#items}, items = list of {@link Item} and an
         * optional value for the <b>max_items</b> attribute.
         * <li>Request to delete items - itemsType = {@link ItemsElementType#retract}, items = list of {@link Item} containing
         * only id's and an optional value for the <b>notify</b> attribute.
         * <li>Items published event - itemsType = {@link ItemsElementType#items}, items = list of {@link Item} and 
         * attributeValue = <code>null</code>
         * <li>Items deleted event -  itemsType = {@link ItemsElementType#items}, items = list of {@link RetractItem} and 
         * attributeValue = <code>null</code> 
         * 
         * @param itemsType Type of representation
         * @param nodeId The node to which the items are being sent or deleted
         * @param items The list of {@link Item} or {@link RetractItem}
         */
        public ItemsExtension(ItemsElementType itemsType, String nodeId, List<? extends ExtensionElement> items)
        {
                super(itemsType.getNodeElement(), nodeId);
                type = itemsType;
                this.items = items;
        }
        
        /**
         * Construct an instance with a list representing items that have been published or deleted.
         * 
         * <p>Valid scenarios are:
         * <li>Request items from node - itemsType = {@link ItemsElementType#items}, items = list of {@link Item} and an
         * optional value for the <b>max_items</b> attribute.
         * <li>Request to delete items - itemsType = {@link ItemsElementType#retract}, items = list of {@link Item} containing
         * only id's and an optional value for the <b>notify</b> attribute.
         * <li>Items published event - itemsType = {@link ItemsElementType#items}, items = list of {@link Item} and 
         * attributeValue = <code>null</code>
         * <li>Items deleted event -  itemsType = {@link ItemsElementType#items}, items = list of {@link RetractItem} and 
         * attributeValue = <code>null</code> 
         * 
         * @param nodeId The node to which the items are being sent or deleted
         * @param items The list of {@link Item} or {@link RetractItem}
         */
        public ItemsExtension(String nodeId, List<? extends ExtensionElement> items, boolean notify)
        {
                super(ItemsElementType.retract.getNodeElement(), nodeId);
                type = ItemsElementType.retract;
                this.items = items; 
                this.notify = notify;
        }
        
        /**
         * Get the type of element
         * 
         * @return The element type
         */
        public ItemsElementType getItemsElementType()
        {
                return type;
        }
        
        @SuppressWarnings("unchecked")
        public List<ExtensionElement> getExtensions()
        {
                return (List<ExtensionElement>)getItems();
        }
        
        /**
         * Gets the items related to the type of request or event.
         * 
         * return List of {@link Item}, {@link RetractItem}, or null
         */
        public List<? extends ExtensionElement> getItems()
        {
                return items;
        }

        /**
         * Gets the value of the optional attribute related to the {@link ItemsElementType}.
         * 
         * @return The attribute value
         */
        public boolean getNotify()
        {
                return notify;
        }
        
        @Override
        public CharSequence toXML()
        {
                if ((items == null) || (items.size() == 0))
                {
                        return super.toXML();
                }
                else
                {
                        StringBuilder builder = new StringBuilder("<");
                        builder.append(getElementName());
                        builder.append(" node='");
                        builder.append(getNode());
                        
                        if (notify != null)
                        {
                                builder.append("' ");
                                builder.append(type.getElementAttribute());
                                builder.append("='");
                                builder.append(notify.equals(Boolean.TRUE) ? 1 : 0);
                                builder.append("'>");
                        }
                        else
                        {
                                builder.append("'>");
                                for (ExtensionElement item : items)
                                {
                                        builder.append(item.toXML());
                                }
                        }
                        
                        builder.append("</");
                        builder.append(getElementName());
                        builder.append(">");
                        return builder.toString();
                }
        }

        @Override
        public String toString()
        {
                return getClass().getName() + "Content [" + toXML() + "]";
        }

}