/**
 * @author Hyacinthe MENIET
 * Created on 21 août 07
 */
package net.dotmyself.weatherws;

import java.util.HashMap;
import java.util.Map;

/**
 * Data Access Object which allows to Create, Retrieve, Update and Delete {@link City}.
 */
public class CityMemory {
	
	private Map<Long, City> mapCities = new HashMap<Long, City>();
    private long nextId = 0;
    
    /**
     * Inserts the given {@link City}.
     * @param item 
     * 	The {@link City} to insert.
     * @return 
     * 	The key associated with the {@link City}.
     */
    public Long create(City item) {
    	Long key = nextKey();
    	item.setId(key);
    	mapCities.put(key, item);
        return key;
    }
    /**
     * Gets a {@link City}.
     * @param key 
     * 	The key associated with the {@link City}.
     * @return 
     * 	The {@link City} or <code>null</code> if
     * 	no {@link City} could be found.
     */
    public City retrieve(Long key) {
        return mapCities.get(key);
    }
    /**
     * Updates an existing {@link City}.
     * @param key 
     * 	The key associated with the {@link City}.
     * @param item 
     * 	The {@link City}.
     */
    public void update(Long key,City item) {
        if (mapCities.containsKey(key)) {
        	item.setId(key);
        	mapCities.put(key, item);
        } else {
            throw new IllegalArgumentException("There is no City with key=" + key);
        }
    }
    /**
     * Removes the {@link City} for this key if present.
     * @param key 
     * 	The key associated with the {@link City}.
     */
    public void delete(Long key) {
    	mapCities.remove(key);
    }
    /**
     * Searches for the given {@link City}, testing for equality using the equals method.
     * @param item 
     * 	The {@link City}.
     * @return 
     * 	The key or <code>null</code> if no key could be found.
     */
    public Long getKey(City item) {
        for (Map.Entry<Long, City> entry : mapCities.entrySet()) {
            if (entry.getValue().equals(item)) {
                return entry.getKey();
            }
        }
        return null;
    }
    /**
     * Returns the next key available.
     * @return 
     * 	The next key available.
     */
    protected Long nextKey() {
        return new Long(++nextId);
    }

}