# ActivatorModel.java

    /*
     * Copyright (c) 2014, Paul Merlin. All Rights Reserved.
     *
     * 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.runtime.activation;

    import org.qi4j.api.activation.Activator;
    import org.qi4j.api.activation.ActivatorDescriptor;
    import org.qi4j.api.common.ConstructionException;
    import org.qi4j.functional.HierarchicalVisitor;
    import org.qi4j.functional.VisitableHierarchy;
    import org.qi4j.runtime.composite.ConstructorsModel;
    import org.qi4j.runtime.injection.InjectedFieldsModel;
    import org.qi4j.runtime.injection.InjectedMethodsModel;
    import org.qi4j.runtime.injection.InjectionContext;

    /**
     * Model for a single Activator.
     *
     * @param <ActivateeType> Type of the activation target
     */
    public class ActivatorModel<ActivateeType>
        implements ActivatorDescriptor, VisitableHierarchy<Object, Object>
    {
        private final Class<? extends Activator<ActivateeType>> activatorType;
        private final ConstructorsModel constructorsModel;
        private final InjectedFieldsModel injectedFieldsModel;
        private final InjectedMethodsModel injectedMethodsModel;

        public ActivatorModel( Class<? extends Activator<ActivateeType>> activatorType )
        {
            this.activatorType = activatorType;
            this.constructorsModel = new ConstructorsModel( activatorType );
            this.injectedFieldsModel = new InjectedFieldsModel( activatorType );
            this.injectedMethodsModel = new InjectedMethodsModel( activatorType );
        }

        @Override
        public <ThrowableType extends Throwable> boolean accept( HierarchicalVisitor<? super Object, ? super Object, ThrowableType> visitor )
            throws ThrowableType
        {
            if( visitor.visitEnter( this ) )
            {
                if( constructorsModel.accept( visitor ) )
                {
                    if( injectedFieldsModel.accept( visitor ) )
                    {
                        injectedMethodsModel.accept( visitor );
                    }
                }
            }
            return visitor.visitLeave( this );
        }

        public Activator<ActivateeType> newInstance()
        {
            try
            {
                return activatorType.newInstance();
            }
            catch( InstantiationException | IllegalAccessException ex )
            {
                throw new ConstructionException( "Could not instantiate " + activatorType.getName(), ex );
            }
        }

        @SuppressWarnings( "unchecked" )
        public Activator<ActivateeType> newInstance( InjectionContext injectionContext )
        {
            try
            {
                Activator<ActivateeType> instance = (Activator<ActivateeType>) constructorsModel.newInstance( injectionContext );
                injectionContext = new InjectionContext( injectionContext.module(), injectionContext.uses(), instance );
                inject( injectionContext, instance );
                return instance;
            }
            catch( Exception ex )
            {
                throw new ConstructionException( "Could not instantiate " + activatorType.getName(), ex );
            }
        }

        public void inject( InjectionContext injectionContext, Activator<ActivateeType> instance )
        {
            injectedFieldsModel.inject( injectionContext, instance );
            injectedMethodsModel.inject( injectionContext, instance );
        }

        @Override
        public String toString()
        {
            return activatorType.getName();
        }

    }