# LayeredLayerAssembler.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.bootstrap.layered;

    import java.lang.reflect.Constructor;
    import java.util.HashMap;
    import org.qi4j.bootstrap.LayerAssembly;
    import org.qi4j.bootstrap.ModuleAssembly;

    public abstract class LayeredLayerAssembler
        implements LayerAssembler
    {
        private HashMap<Class<? extends ModuleAssembler>, ModuleAssembler> assemblers = new HashMap<>();

        protected ModuleAssembly createModule( LayerAssembly layer, Class<? extends ModuleAssembler> modulerAssemblerClass )
        {
            try
            {
                ModuleAssembler moduleAssembler = instantiateAssembler( layer, modulerAssemblerClass );
                String moduleName = createModuleName( modulerAssemblerClass );
                LayeredApplicationAssembler.setNameIfPresent( modulerAssemblerClass, moduleName );
                ModuleAssembly module = layer.module( moduleName );
                assemblers.put( modulerAssemblerClass, moduleAssembler );
                ModuleAssembly assembly = moduleAssembler.assemble( layer, module );
                if( assembly == null )
                {
                    return module;
                }
                return assembly;
            }
            catch( Exception e )
            {
                throw new IllegalArgumentException( "Unable to instantiate module with " + modulerAssemblerClass.getSimpleName(), e );
            }
        }

        protected String createModuleName( Class<? extends ModuleAssembler> modulerAssemblerClass )
        {
            String moduleName = modulerAssemblerClass.getSimpleName();
            if( moduleName.endsWith( "Module" ) )
            {
                moduleName = moduleName.substring( 0, moduleName.length() - 6 ) + " Module";
            }
            return moduleName;
        }

        private ModuleAssembler instantiateAssembler( LayerAssembly layer,
                                                      Class<? extends ModuleAssembler> modulerAssemblerClass
        )
            throws InstantiationException, IllegalAccessException, java.lang.reflect.InvocationTargetException
        {
            ModuleAssembler moduleAssembler;
            try
            {
                Constructor<? extends ModuleAssembler> assemblyConstructor = modulerAssemblerClass.getConstructor( ModuleAssembly.class );
                moduleAssembler = assemblyConstructor.newInstance( layer );
            }
            catch( NoSuchMethodException e )
            {
                moduleAssembler = modulerAssemblerClass.newInstance();
            }
            return moduleAssembler;
        }

        @SuppressWarnings( "unchecked" )
        protected <T extends ModuleAssembler> T assemblerOf( Class<T> moduleAssemblerType )
        {
            return (T) assemblers.get( moduleAssemblerType );
        }
    }