# EntityStateInstance.java

    /*
     * Copyright (c) 2008-2011, Rickard Öberg. All Rights Reserved.
     * Copyright (c) 2008-2013, Niclas Hedhman. All Rights Reserved.
     * 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.entity;

    import java.lang.reflect.AccessibleObject;
    import java.lang.reflect.Type;
    import java.util.HashMap;
    import java.util.Map;
    import org.qi4j.api.association.Association;
    import org.qi4j.api.association.AssociationDescriptor;
    import org.qi4j.api.association.AssociationStateHolder;
    import org.qi4j.api.association.ManyAssociation;
    import org.qi4j.api.association.NamedAssociation;
    import org.qi4j.api.entity.EntityReference;
    import org.qi4j.api.property.Property;
    import org.qi4j.api.property.PropertyDescriptor;
    import org.qi4j.api.unitofwork.UnitOfWork;
    import org.qi4j.api.util.Classes;
    import org.qi4j.functional.Function;
    import org.qi4j.functional.Function2;
    import org.qi4j.functional.Iterables;
    import org.qi4j.runtime.association.AssociationInstance;
    import org.qi4j.runtime.association.AssociationModel;
    import org.qi4j.runtime.association.ManyAssociationInstance;
    import org.qi4j.runtime.association.ManyAssociationModel;
    import org.qi4j.runtime.association.NamedAssociationInstance;
    import org.qi4j.runtime.association.NamedAssociationModel;
    import org.qi4j.runtime.composite.ConstraintsCheck;
    import org.qi4j.runtime.property.PropertyModel;
    import org.qi4j.runtime.unitofwork.BuilderEntityState;
    import org.qi4j.spi.entity.EntityState;

    /**
     * TODO
     */
    public final class EntityStateInstance
        implements AssociationStateHolder
    {
        private Map<AccessibleObject, Object> state;

        private final EntityStateModel stateModel;
        private EntityState entityState;
        private final Function2<EntityReference, Type, Object> entityFunction;

        public EntityStateInstance( EntityStateModel stateModel, final UnitOfWork uow, EntityState entityState )
        {
            this.stateModel = stateModel;
            this.entityState = entityState;

            entityFunction = new Function2<EntityReference, Type, Object>()
            {
                @Override
                public Object map( EntityReference entityReference, Type type )
                {
                    return uow.get( Classes.RAW_CLASS.map( type ), entityReference.identity() );
                }
            };
        }

        @Override
        @SuppressWarnings( "unchecked" )
        public <T> Property<T> propertyFor( AccessibleObject accessor )
            throws IllegalArgumentException
        {
            Map<AccessibleObject, Object> state = state();

            Property<T> property = (Property<T>) state.get( accessor );

            if( property == null )
            {
                PropertyModel entityPropertyModel = stateModel.propertyModelFor( accessor );
                property = new EntityPropertyInstance<>(
                    entityState instanceof BuilderEntityState
                    ? entityPropertyModel.getBuilderInfo()
                    : entityPropertyModel,
                    entityState );
                state.put( accessor, property );
            }

            return property;
        }

        @Override
        public Iterable<Property<?>> properties()
        {
            return Iterables.map( new Function<PropertyDescriptor, Property<?>>()
            {
                @Override
                public Property<?> map( PropertyDescriptor propertyDescriptor )
                {
                    return propertyFor( propertyDescriptor.accessor() );
                }
            }, stateModel.properties() );
        }

        @Override
        @SuppressWarnings( "unchecked" )
        public <T> Association<T> associationFor( AccessibleObject accessor )
            throws IllegalArgumentException
        {
            Map<AccessibleObject, Object> state = state();
            Association<T> association = (Association<T>) state.get( accessor );

            if( association == null )
            {
                final AssociationModel associationModel = stateModel.getAssociation( accessor );
                association = new AssociationInstance<>(
                    entityState instanceof BuilderEntityState
                    ? associationModel.getBuilderInfo()
                    : associationModel,
                    entityFunction,
                    new Property<EntityReference>()
                {
                    @Override
                    public EntityReference get()
                    {
                        return entityState.associationValueOf( associationModel.qualifiedName() );
                    }

                    @Override
                    public void set( EntityReference newValue )
                        throws IllegalArgumentException, IllegalStateException
                    {
                        entityState.setAssociationValue( associationModel.qualifiedName(), newValue );
                    }
                } );
                state.put( accessor, association );
            }

            return association;
        }

        @Override
        public Iterable<Association<?>> allAssociations()
        {
            return Iterables.map( new Function<AssociationDescriptor, Association<?>>()
            {
                @Override
                public Association<?> map( AssociationDescriptor associationDescriptor )
                {
                    return associationFor( associationDescriptor.accessor() );
                }
            }, stateModel.associations() );
        }

        @Override
        @SuppressWarnings( "unchecked" )
        public <T> ManyAssociation<T> manyAssociationFor( AccessibleObject accessor )
        {
            Map<AccessibleObject, Object> state = state();

            ManyAssociation<T> manyAssociation = (ManyAssociation<T>) state.get( accessor );

            if( manyAssociation == null )
            {
                ManyAssociationModel associationModel = stateModel.getManyAssociation( accessor );
                manyAssociation = new ManyAssociationInstance<>(
                    entityState instanceof BuilderEntityState
                    ? associationModel.getBuilderInfo()
                    : associationModel,
                    entityFunction,
                    entityState.manyAssociationValueOf( associationModel.qualifiedName() ) );
                state.put( accessor, manyAssociation );
            }

            return manyAssociation;
        }

        @Override
        public Iterable<ManyAssociation<?>> allManyAssociations()
        {
            return Iterables.map( new Function<AssociationDescriptor, ManyAssociation<?>>()
            {
                @Override
                public ManyAssociation<?> map( AssociationDescriptor associationDescriptor )
                {
                    return manyAssociationFor( associationDescriptor.accessor() );
                }
            }, stateModel.manyAssociations() );
        }

        @Override
        @SuppressWarnings( "unchecked" )
        public <T> NamedAssociation<T> namedAssociationFor( AccessibleObject accessor )
        {
            Map<AccessibleObject, Object> state = state();

            NamedAssociation<T> namedAssociation = (NamedAssociation<T>) state.get( accessor );

            if( namedAssociation == null )
            {
                NamedAssociationModel associationModel = stateModel.getNamedAssociation( accessor );
                namedAssociation = new NamedAssociationInstance<>(
                    entityState instanceof BuilderEntityState
                    ? associationModel.getBuilderInfo()
                    : associationModel,
                    entityFunction,
                    entityState.namedAssociationValueOf( associationModel.qualifiedName() ) );
                state.put( accessor, namedAssociation );
            }

            return namedAssociation;
        }

        @Override
        public Iterable<? extends NamedAssociation<?>> allNamedAssociations()
        {
            return Iterables.map( new Function<AssociationDescriptor, NamedAssociation<?>>()
            {
                @Override
                public NamedAssociation<?> map( AssociationDescriptor associationDescriptor )
                {
                    return namedAssociationFor( associationDescriptor.accessor() );
                }
            }, stateModel.namedAssociations() );
        }

        public void checkConstraints()
        {
            for( PropertyDescriptor propertyDescriptor : stateModel.properties() )
            {
                ConstraintsCheck constraints = (ConstraintsCheck) propertyDescriptor;
                Property<Object> property = this.propertyFor( propertyDescriptor.accessor() );
                constraints.checkConstraints( property.get() );
            }

            for( AssociationDescriptor associationDescriptor : stateModel.associations() )
            {
                ConstraintsCheck constraints = (ConstraintsCheck) associationDescriptor;
                Association<Object> association = this.associationFor( associationDescriptor.accessor() );
                constraints.checkConstraints( association.get() );
            }

            // TODO Should ManyAssociations and NamedAssociations be checked too?
        }

        private Map<AccessibleObject, Object> state()
        {
            if( state == null )
            {
                state = new HashMap<>();
            }

            return state;
        }
    }