# MixinsModel.java

    /*
     * Copyright (c) 2008, Rickard Öberg. 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.composite;

    import java.lang.reflect.Method;
    import java.lang.reflect.Type;
    import java.util.ArrayList;
    import java.util.Collection;
    import java.util.HashMap;
    import java.util.LinkedHashSet;
    import java.util.List;
    import java.util.Map;
    import java.util.Set;
    import org.qi4j.api.util.Classes;
    import org.qi4j.bootstrap.BindingException;
    import org.qi4j.functional.Function;
    import org.qi4j.functional.HierarchicalVisitor;
    import org.qi4j.functional.HierarchicalVisitorAdapter;
    import org.qi4j.functional.Specification;
    import org.qi4j.functional.VisitableHierarchy;
    import org.qi4j.runtime.injection.DependencyModel;
    import org.qi4j.runtime.injection.InjectedFieldModel;
    import org.qi4j.runtime.model.Binder;
    import org.qi4j.runtime.model.Resolution;

    import static org.qi4j.api.util.Classes.interfacesOf;
    import static org.qi4j.functional.Iterables.filter;
    import static org.qi4j.functional.Iterables.flattenIterables;
    import static org.qi4j.functional.Iterables.map;

    /**
     * Base implementation of model for mixins. This records the mapping between methods in the Composite
     * and mixin implementations.
     */
    public class MixinsModel
        implements Binder, VisitableHierarchy<Object, Object>
    {
        protected final Map<Method, MixinModel> methodImplementation = new HashMap<Method, MixinModel>();
        protected final Map<Method, Integer> methodIndex = new HashMap<Method, Integer>();
        protected List<MixinModel> mixinModels = new ArrayList<MixinModel>();

        private final Map<Class, Integer> mixinIndex = new HashMap<Class, Integer>();
        private final Set<Class<?>> mixinTypes = new LinkedHashSet<Class<?>>();

        public Iterable<Class<?>> mixinTypes()
        {
            return mixinTypes;
        }

        public <T> boolean isImplemented( Class<T> mixinType )
        {
            return mixinTypes.contains( mixinType );
        }

        public List<MixinModel> mixinModels()
        {
            return mixinModels;
        }

        public MixinModel mixinFor( Method method )
        {
            return methodImplementation.get( method );
        }

        public MixinModel getMixinModel( Class mixinClass )
        {
            for( MixinModel mixinModel : mixinModels )
            {
                if( mixinModel.mixinClass().equals( mixinClass ) )
                {
                    return mixinModel;
                }
            }
            return null;
        }

        public void addMixinType( Class mixinType )
        {
            for( Type type : interfacesOf( mixinType ) )
            {
                mixinTypes.add( Classes.RAW_CLASS.map( type ) );
            }
        }

        public void addMixinModel( MixinModel mixinModel )
        {
            mixinModels.add( mixinModel );
        }

        public void addMethodMixin( Method method, MixinModel mixinModel )
        {
            methodImplementation.put( method, mixinModel );
        }

        @Override
        public <ThrowableType extends Throwable> boolean accept( HierarchicalVisitor<? super Object, ? super Object, ThrowableType> visitor )
            throws ThrowableType
        {
            if( visitor.visitEnter( this ) )
            {
                for( MixinModel mixinModel : mixinModels )
                {
                    mixinModel.accept( visitor );
                }
            }
            return visitor.visitLeave( this );
        }

        // Binding
        @Override
        public void bind( final Resolution resolution )
            throws BindingException
        {
            // Order mixins based on @This usages
            UsageGraph<MixinModel> deps = new UsageGraph<MixinModel>( mixinModels, new Uses(), true );
            mixinModels = deps.resolveOrder();

            // Populate mappings
            for( int i = 0; i < mixinModels.size(); i++ )
            {
                MixinModel mixinModel = mixinModels.get( i );
                mixinIndex.put( mixinModel.mixinClass(), i );
            }

            for( Map.Entry<Method, MixinModel> methodClassEntry : methodImplementation.entrySet() )
            {
                methodIndex.put( methodClassEntry.getKey(), mixinIndex.get( methodClassEntry.getValue().mixinClass() ) );
            }

            for( MixinModel mixinModel : mixinModels )
            {
                mixinModel.accept( new HierarchicalVisitorAdapter<Object, Object, BindingException>()
                {
                    @Override
                    public boolean visitEnter( Object visited )
                        throws BindingException
                    {
                        if( visited instanceof InjectedFieldModel )
                        {
                            InjectedFieldModel fieldModel = (InjectedFieldModel) visited;
                            fieldModel.bind( resolution.forField( fieldModel.field() ) );
                            return false;
                        }
                        else if( visited instanceof Binder )
                        {
                            Binder constructorsModel = (Binder) visited;
                            constructorsModel.bind( resolution );

                            return false;
                        }
                        return true;
                    }

                    @Override
                    public boolean visit( Object visited )
                        throws BindingException
                    {
                        if( visited instanceof Binder )
                        {
                            ( (Binder) visited ).bind( resolution );
                        }
                        return true;
                    }
                } );
            }
        }

        // Context

        public Object[] newMixinHolder()
        {
            return new Object[ mixinIndex.size() ];
        }

        public FragmentInvocationHandler newInvocationHandler( final Method method )
        {
            return mixinFor( method ).newInvocationHandler( method );
        }

        public Iterable<DependencyModel> dependencies()
        {
            return flattenIterables( map( new Function<MixinModel, Iterable<DependencyModel>>()
            {
                @Override
                public Iterable<DependencyModel> map( MixinModel mixinModel )
                {
                    return mixinModel.dependencies();
                }
            }, mixinModels ) );
        }

        public Iterable<Method> invocationsFor( final Class<?> mixinClass )
        {
            return map( new Function<Map.Entry<Method, MixinModel>, Method>()
            {
                @Override
                public Method map( Map.Entry<Method, MixinModel> entry )
                {
                    return entry.getKey();
                }
            }, filter( new Specification<Map.Entry<Method, MixinModel>>()
            {
                @Override
                public boolean satisfiedBy( Map.Entry<Method, MixinModel> item )
                {
                    MixinModel model = item.getValue();
                    return model.mixinClass().equals( mixinClass );
                }
            }, methodImplementation.entrySet() ) );
        }

        private class Uses
            implements UsageGraph.Use<MixinModel>
        {
            @Override
            public Collection<MixinModel> uses( MixinModel source )
            {
                Iterable<Class<?>> thisMixinTypes = source.thisMixinTypes();
                List<MixinModel> usedMixinClasses = new ArrayList<MixinModel>();
                for( Class thisMixinType : thisMixinTypes )
                {
                    for( Method method : thisMixinType.getMethods() )
                    {
                        usedMixinClasses.add( methodImplementation.get( method ) );
                    }
                }
                return usedMixinClasses;
            }
        }
    }