# ManyAssociationInstance.java

    /*
     * Licensed to the Apache Software Foundation (ASF) under one
     * or more contributor license agreements.  See the NOTICE file
     * distributed with this work for additional information
     * regarding copyright ownership.  The ASF licenses this file
     * to you 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.association;

    import java.lang.reflect.Type;
    import java.util.ArrayList;
    import java.util.HashSet;
    import java.util.Iterator;
    import java.util.List;
    import java.util.Set;
    import org.qi4j.api.association.AssociationDescriptor;
    import org.qi4j.api.association.ManyAssociation;
    import org.qi4j.api.association.ManyAssociationWrapper;
    import org.qi4j.api.entity.EntityReference;
    import org.qi4j.api.entity.Identity;
    import org.qi4j.api.util.NullArgumentException;
    import org.qi4j.functional.Function2;
    import org.qi4j.functional.Iterables;
    import org.qi4j.spi.entity.ManyAssociationState;

    /**
     * JAVADOC
     */
    public class ManyAssociationInstance<T>
        extends AbstractAssociationInstance<T>
        implements ManyAssociation<T>
    {
        private ManyAssociationState manyAssociationState;

        public ManyAssociationInstance( AssociationInfo associationInfo,
                                        Function2<EntityReference, Type, Object> associationFunction,
                                        ManyAssociationState manyAssociationState
        )
        {
            super( associationInfo, associationFunction );
            this.manyAssociationState = manyAssociationState;
        }

        @Override
        public int count()
        {
            return manyAssociationState.count();
        }

        @Override
        public boolean contains( T entity )
        {
            return manyAssociationState.contains( getEntityReference( entity ) );
        }

        @Override
        public boolean add( int i, T entity )
        {
            NullArgumentException.validateNotNull( "entity", entity );
            checkImmutable();
            checkType( entity );
            associationInfo.checkConstraints( entity );
            return manyAssociationState.add( i, new EntityReference( ( (Identity) entity ).identity().get() ) );
        }

        @Override
        public boolean add( T entity )
        {
            return add( manyAssociationState.count(), entity );
        }

        @Override
        public boolean remove( T entity )
        {
            NullArgumentException.validateNotNull( "entity", entity );
            checkImmutable();
            checkType( entity );

            return manyAssociationState.remove( new EntityReference( ( (Identity) entity ).identity().get() ) );
        }

        @Override
        public T get( int i )
        {
            return getEntity( manyAssociationState.get( i ) );
        }

        @Override
        public List<T> toList()
        {
            ArrayList<T> list = new ArrayList<>();
            for( EntityReference entityReference : manyAssociationState )
            {
                list.add( getEntity( entityReference ) );
            }

            return list;
        }

        @Override
        public Set<T> toSet()
        {
            Set<T> set = new HashSet<>();
            for( EntityReference entityReference : manyAssociationState )
            {
                set.add( getEntity( entityReference ) );
            }

            return set;
        }

        @Override
        public Iterable<EntityReference> references()
        {
            return Iterables.toList( manyAssociationState );
        }

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

        @Override
        public Iterator<T> iterator()
        {
            return new ManyAssociationIterator( manyAssociationState.iterator() );
        }

        @Override
        public boolean equals( Object o )
        {
            if( this == o )
            {
                return true;
            }
            if( o == null || getClass() != o.getClass() )
            {
                return false;
            }
            ManyAssociation<?> that = (ManyAssociation) o;
            // Unwrap if needed
            while( that instanceof ManyAssociationWrapper )
            {
                that = ( (ManyAssociationWrapper) that ).next();
            }
            // Descriptor equality
            ManyAssociationInstance<?> thatInstance = (ManyAssociationInstance) that;
            AssociationDescriptor thatDescriptor = (AssociationDescriptor) thatInstance.associationInfo();
            if( !associationInfo.equals( thatDescriptor ) )
            {
                return false;
            }
            // State equality
            if( manyAssociationState.count() != thatInstance.manyAssociationState.count() )
            {
                return false;
            }
            for( EntityReference ref : manyAssociationState )
            {
                if( !thatInstance.manyAssociationState.contains( ref ) )
                {
                    return false;
                }
            }
            return true;
        }

        @Override
        public int hashCode()
        {
            int hash = associationInfo.hashCode() * 31; // Descriptor
            for( EntityReference ref : manyAssociationState )
            {
                hash += ref.hashCode() * 7; // State
            }
            return hash;
        }

        public ManyAssociationState getManyAssociationState()
        {
            return manyAssociationState;
        }

        protected class ManyAssociationIterator
            implements Iterator<T>
        {
            private final Iterator<EntityReference> idIterator;

            public ManyAssociationIterator( Iterator<EntityReference> idIterator )
            {
                this.idIterator = idIterator;
            }

            @Override
            public boolean hasNext()
            {
                return idIterator.hasNext();
            }

            @Override
            public T next()
            {
                return getEntity( idIterator.next() );
            }

            @Override
            public void remove()
            {
                checkImmutable();
                idIterator.remove();
            }
        }
    }