/*

 * All Sigmah code is released under the GNU General Public License v3

 * See COPYRIGHT.txt and LICENSE.txt.

 */



package org.sigmah;







import javax.persistence.Id;



import org.sigmah.shared.dao.DAO;



import java.lang.reflect.*;

import java.util.ArrayList;

import java.util.List;



public class MockDb {



    private List entities = new ArrayList(0);



    public MockDb() {



    }



    public Object findById(Class entityClass, Object primaryKey) {

        if (primaryKey == null) {

            return null;

        }



        for (Object entity : entities) {

            if (entity.getClass().equals(entityClass) && primaryKey.equals(getId(entity))) {

                return entity;

            }

        }

        return null;

    }



    public void persist(Object entity) {

        entities.add(entity);

    }



    private Object getId(Object t) {

        for (Method method : t.getClass().getMethods()) {

            if (method.getAnnotation(Id.class) != null) {

                try {

                    return method.invoke(t);

                } catch (Exception e) {

                    throw new RuntimeException(e);

                }

            }

        }

        throw new RuntimeException("No @Id field!");

    }



    public <S extends DAO> S getDAO(Class<S> daoSubClass) {

        ClassLoader cl = daoSubClass.getClassLoader();

        Type daoClass = daoSubClass.getGenericInterfaces()[0];

        Class persistentClass = (Class)((ParameterizedType) daoClass).getActualTypeArguments()[0];

        return (S) Proxy.newProxyInstance(cl, new Class[]{daoSubClass}, new Handler(persistentClass));

    }





    public class Handler implements InvocationHandler {



        private final Class persistentClass;



        public Handler(Class persistentClass) {

            this.persistentClass = persistentClass;

        }



        @Override

        public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {



            if (method.getName().equals("findById")) {

                return findById(persistentClass, args[0]);

            } else if (method.getName().equals("persist")) {

                persist(args[0]);

            } else if (method.getReturnType().equals(Boolean.TYPE)) {

                return false;

            }

            return null;

        }

    }



}