AbstractEMFModel.java

/**
 * (C) Copyright 2013 Jabylon (http://www.jabylon.org) and others.
 *
 * 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.jabylon.rest.ui.model;

import java.io.Serializable;

import org.apache.wicket.model.IModel;
import org.eclipse.emf.cdo.CDOObject;
import org.eclipse.emf.cdo.common.id.CDOID;
import org.eclipse.emf.cdo.common.id.CDOIDUtil;
import org.jabylon.rest.ui.Activator;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import com.google.common.base.Function;
import com.google.common.base.Supplier;
import com.google.common.base.Suppliers;


public abstract class AbstractEMFModel<T extends CDOObject, R>
    implements IModel<R>
{

    private static final long serialVersionUID = 1L;

    private static final Logger LOGGER = LoggerFactory.getLogger(AbstractEMFModel.class);
    
    protected Supplier<T> modelSupplier;
    protected long id;

    public AbstractEMFModel(T model)
    {
        super();
        id=CDOIDUtil.getLong(model.cdoID());
        this.modelSupplier = Suppliers.memoize(new LoadingSupplier<T>(model));
    }


    protected T getDomainObject()
    {
        T t = modelSupplier.get();
        if(t==null) {
        	LOGGER.warn("Lost for some reason the model supplier. Trying to recover");
        	modelSupplier = Suppliers.memoize(new LoadingSupplier<T>(id));
        	t = modelSupplier.get();
        	LOGGER.warn("Recovered to "+t);
        }
        return t;
    }

    protected void setDomainObject(T domainObject) {
        this.modelSupplier = Suppliers.memoize(Suppliers.ofInstance(domainObject));
    }


    @Override
    public void detach()
    {
    	modelSupplier = Suppliers.memoize(new LoadingSupplier<T>(id));

    }

    private static final class LookupFunction<X> implements Serializable, Function<Long, X>
    {

        /** field <code>serialVersionUID</code> */
        private static final long serialVersionUID = -7243181664341900603L;

        @SuppressWarnings("unchecked")
        @Override
        public X apply(Long from)
        {
        	CDOID id = CDOIDUtil.createLong(from);
            CDOObject cdoObject = Activator.getDefault().getRepositoryLookup().resolve(id);
            return (X)cdoObject;
        }
    }


    private static final class LoadingSupplier<T> implements Supplier<T>, Serializable {

        private static final long serialVersionUID = 1L;
        private transient T instance;
        private LookupFunction<T> function;
        private long id;



        public LoadingSupplier(T instance) {
            super();
            this.instance = instance;
            function = new LookupFunction<T>();
        }
        
        public LoadingSupplier(long id) {
            super();
            this.instance = null;
            this.id = id;
            function = new LookupFunction<T>();
        }



        @Override
        public T get() {
            if(instance==null)
                instance = function.apply(id);
            return instance;
        }

    }

    @SuppressWarnings("rawtypes")
    @Override
    public boolean equals(Object obj) {
        if (obj instanceof AbstractEMFModel) {
            AbstractEMFModel other = (AbstractEMFModel) obj;
            return other.id ==  id;
        }
        return false;
    }

    @Override
    public int hashCode() {
        return (int)id;
    }
}