/*
 * 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.apache.tuscany.sca.implementation.java.introspect.impl;

import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
import java.util.logging.Logger;
import org.apache.tuscany.sca.assembly.AssemblyFactory;
import org.apache.tuscany.sca.assembly.Service;
import org.apache.tuscany.sca.implementation.java.IntrospectionException;
import org.apache.tuscany.sca.implementation.java.JavaImplementation;
import org.apache.tuscany.sca.implementation.java.impl.JavaElementImpl;
import org.apache.tuscany.sca.interfacedef.InvalidInterfaceException;
import org.apache.tuscany.sca.interfacedef.java.JavaInterface;
import org.apache.tuscany.sca.interfacedef.java.JavaInterfaceContract;
import org.apache.tuscany.sca.interfacedef.java.JavaInterfaceFactory;

/**
 * Processes an {@link org.osoa.sca.annotations.Service} annotation and updates
 * the component type with corresponding {@link Service}s. Also processes
 * related {@link org.osoa.sca.annotations.Callback} annotations.
 * 
 * @version $$
 */
public class ConsumerProcessor extends BaseJavaClassVisitor {
	@SuppressWarnings("unused")
    private static final Logger logger = Logger.getLogger(ConsumerProcessor.class.getName());

    private JavaInterfaceFactory javaFactory;
    
    public ConsumerProcessor(AssemblyFactory assemblyFactory, JavaInterfaceFactory javaFactory) {
        super(assemblyFactory);
        this.javaFactory = javaFactory;
    }
    
    @Override
    public void visitMethod(Method method, JavaImplementation type) throws IntrospectionException {

    	org.osoa.sca.annotations.Consumer annotation = method.getAnnotation(org.osoa.sca.annotations.Consumer.class);
        if (annotation == null) {
            return;
        }
        if(Modifier.isPrivate(method.getModifiers())) {
            throw new IllegalConsumerException("Illegal annotation @Consumer found on "+method, method);
        }
        if (method.getParameterTypes().length != 1) {
            throw new IllegalConsumerException("Consumer must have one parameter", method);
        }
        JavaElementImpl element = new JavaElementImpl(method.getDeclaringClass());
        try {
			createConsumer(type, element, annotation.name(), method);
		} catch (InvalidInterfaceException e) {
			throw new IntrospectionException(e);
		}
    }

    /**
     * Creates or updates a Consumer 
     * @param type - the JavaImplementation to which the consumer applies
     * @param element - the Java class implementing the consumer
     * @param consumerName - the Name of the consumer
     * @param operationName - the Name of the operation (ie Method) annotated with @Consumer
     * @throws IllegalConsumerException
     */
    private void createConsumer(JavaImplementation type, JavaElementImpl element, 
    		                    String consumerName, Method method )
        throws IllegalConsumerException, InvalidInterfaceException {
    	
    	// First, see if the Consumer already exists
    	org.apache.tuscany.sca.assembly.Consumer consumer = findConsumerByName( type, consumerName ); 
    	
    	if( consumer == null ) {
    		// Create the consumer object and add it to the JavaImplementation
	        Class<?> consumerClass = element.getType();
	        
	        consumer = assemblyFactory.createConsumer();
	        JavaInterfaceContract interfaceContract = javaFactory.createJavaInterfaceContract();
	        consumer.setInterfaceContract(interfaceContract);
	        consumer.setName(consumerName);       
	        JavaInterface consumerInterface = javaFactory.createJavaInterface();
	        consumerInterface.setRemotable(true);
	        javaFactory.createJavaInterface(consumerInterface, consumerClass);
	        consumer.getInterfaceContract().setInterface(consumerInterface);

	        type.getConsumers().add(consumer);
    	} // end if 
    	
    	// Add the operation to the consumer
    	consumer.addOperation(method.getName(), getOperationEventTypes(method) );
    	
    } // end method createConsumer
    
    private static String getOperationEventTypes( Method method ) {
    	// 1) If the method is annotated with @EventTypes, extract the supported event types from the annotation
    	org.osoa.sca.annotations.EventTypes annotation = method.getAnnotation(org.osoa.sca.annotations.EventTypes.class);
        if (annotation != null) {
            return annotation.value();
        } // end if 

    	// 2) If the method has a parameter that is NOT java.lang.Object, return its event type or its base Java type
        Class<?> parameter = method.getParameterTypes()[0];
        String className = parameter.getCanonicalName();
        if( !className.equals("java.lang.Object")) {
        	org.osoa.sca.annotations.EventType eventType = parameter.getAnnotation(org.osoa.sca.annotations.EventType.class);
            if (eventType != null) {
                return eventType.name();
            } else { 
            	return className;
            }// end if 
        } // end if
        
    	// 3) Else, return "null" meaning that the method supports "any event type"
    	return null;
    } // end getOperationEventTypes
    
    /**
     * Finds a Consumer within a Java implementation by the name of the consumer
     * @param impl - the Java implementation
     * @param name - the consumer name
     * @return - the Consumer with the specified name, or null if it does not exist
     */
    private static org.apache.tuscany.sca.assembly.Consumer findConsumerByName( JavaImplementation impl, String name ) {
    	for( org.apache.tuscany.sca.assembly.Consumer consumer : impl.getConsumers() ) {
    		if( name.equals(consumer.getName()) ) return consumer;
    	} // end for
    	return null;
    } // end method findConsumerByName
    

}