package student.web;

import java.io.File;


// -------------------------------------------------------------------------
/**
 * This class represents a {@link PersistentMap} whose contents are
 * <b>shared</b> only by separate executions of a single program. In the
 * constructor, you provide a unique "application identifier" as a string, and
 * the persistent values stored in this map will only be accessible to other
 * <code>ApplicationPersistentMap</code> instances that were created with the
 * same application identifier.
 * <p>
 * In other respects, an <code>ApplicationPersistentMap</code> works just like a
 * {@link SharedPersistentMap}. Read the documentation for that class, and for
 * the {@link PersistentMap} interface, to learn how to use this class.
 * </p>
 * 
 * @param <T>
 *            The type of objects to store in the map
 * 
 * @author Mike Woods
 * @author Last changed by $Author: mwoodsvt $
 * @version $Revision: 1.5 $, $Date: 2011/06/21 14:57:28 $
 */
public class ApplicationPersistentMap<T> extends AbstractPersistentMap<T>
{
    // ~ Instance/static variables .............................................

    public static final String APP_STORE = "app-store";

    private static final String APP = "app";


    // ~ Constructor ...........................................................

    // ----------------------------------------------------------
    /**
     * Create a new map that associates keys with values of the specified class.
     * Initially, the map will contain all of the key/value associations that
     * have been previously stored in other instances of this class using the
     * same application identifier,.
     * <p>
     * Typical usage: if you want an application persistent map that stores
     * objects of class <code>Widget</code>, then:
     * </p>
     * 
     * <pre>
     * ApplicationPersistentMap<Widget> map = new ApplicationPersistentMap<Widget>( Widget.class );
     * </pre>
     * 
     * @param applicationIdentifier
     *            A non-null, non-empty string used to uniquely identify the
     *            application using this map. All instances created with the
     *            same application identifier will "share" the same set of
     *            key/value mappings.
     * @param genericClass
     *            The {@link Class} object that represents the generic type
     *            <code>T</code>, the type of values stored in this map.
     */
    public ApplicationPersistentMap(
        String applicationIdentifier,
        Class<T> genericClass )
    {
        super(applicationIdentifier, APP + File.separator + checkId( applicationIdentifier ),genericClass );
    }
    /**
     * NOT FOR STUDENT USE.  ONLY USE IF YOU KNOW WHAT YOU ARE DOING!
     * 
     * @param genericClass Class type
     * @param loader custom class loader to use to load classes
     */
    public ApplicationPersistentMap(
        String applicationIdentifier,
        Class<T> genericClass, ClassLoader loader)
    {
        super(applicationIdentifier, APP + File.separator + checkId( applicationIdentifier ),genericClass, loader);
    }


    private static final String checkId( String applicationIdentifier )
    {
        assert applicationIdentifier != null : "The applicationIdentifier passed into the "
            + "ApplicationPersistentMap constructor cannot be null";
        assert applicationIdentifier.length() > 0 : "The applicationIdentifier passed into the "
            + "ApplicationPersistentMap constructor cannot be an empty string";
        return applicationIdentifier;
    }


    @Override
    protected String getCacheId(String uniqueId)
    {
        return APP_STORE+"-"+uniqueId;
    }
    public static String findIdentifier( String contextMap )
    {
        return contextMap.substring( APP_STORE.length()+1 );
    }
}