/**
 * Copyright (c) 2015-2017 by the respective copyright holders.
 *
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 */
package org.openhab.core.items;

import java.util.Collection;

/**
 * The ItemRegistry is the central place, where items are kept in memory and their state
 * is permanently tracked. So any code that requires the current state of items should use
 * this service (instead of trying to keep their own local copy of the items).
 *
 * Items are registered by {@link ItemProvider}s, which can provision them from any source
 * they like and also dynamically remove or add items.
 *
 * @author Kai Kreuzer
 * @since 0.1.0
 *
 */
public interface ItemRegistry {

    /**
     * This method retrieves a single item from the registry.
     *
     * @param name the item name
     * @return the uniquely identified item
     * @throws ItemNotFoundException if no item matches the input
     */
    public Item getItem(String name) throws ItemNotFoundException;

    /**
     * This method retrieves a single item from the registry.
     * Search patterns and shortened versions are supported, if they uniquely identify an item
     *
     * @param name the item name, a part of the item name or a search pattern
     * @return the uniquely identified item
     * @throws ItemNotFoundException if no item matches the input
     * @throws ItemNotUniqueException if multiply items match the input
     */
    public Item getItemByPattern(String name) throws ItemNotFoundException, ItemNotUniqueException;

    /**
     * This method retrieves all items that are currently available in the registry
     *
     * @return a collection of all available items
     */
    public Collection<Item> getItems();

    /**
     * This method retrieves all items that match a given search pattern
     *
     * @return a collection of all items matching the search pattern
     */
    public Collection<Item> getItems(String pattern);

    /**
     * Checks whether itemName matches the item name conventions.
     * Item names must only consist out of alpha-numerical characters and
     * underscores (_).
     *
     * @param itemName the item name to validate
     * @return true, if the name is valid
     */
    public boolean isValidItemName(String itemName);

    public void addItemRegistryChangeListener(ItemRegistryChangeListener listener);

    public void removeItemRegistryChangeListener(ItemRegistryChangeListener listener);

}
