# ApplicationEventFactoryService.java

    /*
     * Copyright 2009-2010 Rickard Öberg AB
     *
     * Licensed under the Apache License, Version 2.0 (the "License");
     * you may not use this file except in compliance with the License.
     * You may obtain a copy of the License at
     *
     *     http://www.apache.org/licenses/LICENSE-2.0
     *
     * Unless required by applicable law or agreed to in writing, software
     * distributed under the License is distributed on an "AS IS" BASIS,
     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     * See the License for the specific language governing permissions and
     * limitations under the License.
     */

    package org.qi4j.library.eventsourcing.application.factory;

    import org.json.JSONException;
    import org.json.JSONObject;
    import org.json.JSONStringer;
    import org.json.JSONWriter;
    import org.qi4j.api.concern.Concerns;
    import org.qi4j.api.entity.IdentityGenerator;
    import org.qi4j.api.injection.scope.Service;
    import org.qi4j.api.injection.scope.Structure;
    import org.qi4j.api.mixin.Mixins;
    import org.qi4j.api.service.ServiceComposite;
    import org.qi4j.api.structure.Application;
    import org.qi4j.api.unitofwork.UnitOfWork;
    import org.qi4j.api.unitofwork.UnitOfWorkFactory;
    import org.qi4j.api.value.ValueBuilder;
    import org.qi4j.api.value.ValueBuilderFactory;
    import org.qi4j.library.eventsourcing.application.api.ApplicationEvent;
    import org.qi4j.library.eventsourcing.domain.spi.CurrentUser;

    import java.util.Date;

    /**
     * DomainEventValue factory
     */
    @Concerns(TransactionNotificationConcern.class)
    @Mixins(ApplicationEventFactoryService.Mixin.class)
    public interface ApplicationEventFactoryService
            extends ApplicationEventFactory, ServiceComposite
    {
        class Mixin
                implements ApplicationEventFactory
        {
            @Structure
            UnitOfWorkFactory uowf;

            @Structure
            ValueBuilderFactory vbf;

            @Service
            IdentityGenerator idGenerator;

            @Service
            CurrentUser currentUser;

            String version;

            public void init( @Structure Application application )
            {
                version = application.version();
            }

            @Override
            public ApplicationEvent createEvent( String name, Object[] args )
            {
                ValueBuilder<ApplicationEvent> builder = vbf.newValueBuilder( ApplicationEvent.class );

                ApplicationEvent prototype = builder.prototype();
                prototype.name().set( name );
                prototype.on().set( new Date() );

                prototype.identity().set( idGenerator.generate( ApplicationEvent.class ) );

                UnitOfWork uow = uowf.currentUnitOfWork();
                prototype.usecase().set( uow.usecase().name() );
                prototype.version().set( version );

                // JSON-ify parameters
                JSONStringer json = new JSONStringer();
                try
                {
                    JSONWriter params = json.object();
                    for (int i = 1; i < args.length; i++)
                    {
                        params.key( "param" + i );
                        if (args[i] == null)
                            params.value( JSONObject.NULL );
                        else
                            params.value( args[i] );
                    }
                    json.endObject();
                } catch (JSONException e)
                {
                    throw new IllegalArgumentException( "Could not create event", e );
                }

                prototype.parameters().set( json.toString() );

                ApplicationEvent event = builder.newInstance();

                return event;
            }
        }
    }