/*
 * 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.core.invocation.impl;

import java.io.Serializable;
import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;
import java.util.IdentityHashMap;
import java.util.List;
import java.util.Map;

import org.apache.tuscany.sca.assembly.Endpoint;
import org.apache.tuscany.sca.context.ThreadMessageContext;
import org.apache.tuscany.sca.core.context.ServiceReferenceExt;
import org.apache.tuscany.sca.interfacedef.DataType;
import org.apache.tuscany.sca.interfacedef.Operation;
import org.apache.tuscany.sca.interfacedef.java.JavaOperation;
import org.apache.tuscany.sca.invocation.InvocationChain;
import org.apache.tuscany.sca.invocation.Invoker;
import org.apache.tuscany.sca.invocation.Message;
import org.apache.tuscany.sca.invocation.MessageFactory;
import org.apache.tuscany.sca.runtime.Invocable;
import org.apache.tuscany.sca.runtime.RuntimeEndpointReference;
import org.oasisopen.sca.ServiceReference;
import org.oasisopen.sca.ServiceRuntimeException;

/**
 * @version $Rev$ $Date$
 */
public class JDKInvocationHandler implements InvocationHandler, Serializable {
    private static final long serialVersionUID = -3366410500152201371L;

    protected boolean conversational;
    protected MessageFactory messageFactory;
    protected Endpoint target;
    protected RuntimeEndpointReference source;
    protected ServiceReferenceExt<?> callableReference;
    protected Class<?> businessInterface;

    protected boolean fixedWire = true;

    protected transient Map<Method, InvocationChain> chains = new IdentityHashMap<Method, InvocationChain>();

    public JDKInvocationHandler(MessageFactory messageFactory, Class<?> businessInterface, RuntimeEndpointReference source) {
        this.messageFactory = messageFactory;
        this.source = source;
        this.businessInterface = businessInterface;
    }

    public JDKInvocationHandler(MessageFactory messageFactory, ServiceReference<?> callableReference) {
        this.messageFactory = messageFactory;
        this.callableReference = (ServiceReferenceExt<?>)callableReference;
        if (callableReference != null) {
            this.businessInterface = callableReference.getBusinessInterface();
            this.source = (RuntimeEndpointReference) this.callableReference.getEndpointReference();
        }
    }


    public Class<?> getBusinessInterface() {
        return businessInterface;
    }
    
    protected Object getCallbackID() {
            return null;
    }

    public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
        if (Object.class == method.getDeclaringClass()) {
            return invokeObjectMethod(method, args);
        }
        if (source == null) {
            throw new ServiceRuntimeException("No runtime source is available");
        }
        
        if (source.isOutOfDate()) {
            source.rebuild();
            chains.clear();
        }
        
        InvocationChain chain = getInvocationChain(method, source);
        
        if (chain == null) {
            throw new IllegalArgumentException("No matching operation is found: " + method);
        }
        
        // send the invocation down the source
        Object result = invoke(chain, args, source);

        return result;
    }

    /**
     * Handle the methods on the Object.class
     * @param method
     * @param args
     */
    protected Object invokeObjectMethod(Method method, Object[] args) throws Throwable {
        String name = method.getName();
        if ("toString".equals(name)) {
            return "[Proxy - " + toString() + "]";
        } else if ("equals".equals(name)) {
            Object obj = args[0];
            if (obj == null) {
                return false;
            }
            if (!Proxy.isProxyClass(obj.getClass())) {
                return false;
            }
            return equals(Proxy.getInvocationHandler(obj));
        } else if ("hashCode".equals(name)) {
            return hashCode();
        } else {
            return method.invoke(this);
        }
    }

    /**
     * Determines if the given operation matches the given method
     * 
     * @return true if the operation matches, false if does not
     */
    // FIXME: Should it be in the InterfaceContractMapper?
    @SuppressWarnings("unchecked")
    private static boolean match(Operation operation, Method method) {
        if (operation instanceof JavaOperation) {
            JavaOperation javaOp = (JavaOperation)operation;
            Method m = javaOp.getJavaMethod();
            if (!method.getName().equals(m.getName())) {
                return false;
            }
            if (method.equals(m)) {
                return true;
            }
        } else {
            if (!method.getName().equals(operation.getName())) {
                return false;
            }
        }

        // For remotable interface, operation is not overloaded. 
        if (operation.getInterface().isRemotable()) {
            return true;
        }

        Class<?>[] params = method.getParameterTypes();

        DataType<List<DataType>> inputType = null;
        if (operation.isWrapperStyle()) {
            inputType = operation.getWrapper().getUnwrappedInputType();
        } else {
            inputType = operation.getInputType();
        }
        List<DataType> types = inputType.getLogical();
        boolean matched = true;
        if (types.size() == params.length && method.getName().equals(operation.getName())) {
            for (int i = 0; i < params.length; i++) {
                Class<?> clazz = params[i];
                Class<?> type = types.get(i).getPhysical();
                // Object.class.isAssignableFrom(int.class) returns false
                if (type != Object.class && (!type.isAssignableFrom(clazz))) {
                    matched = false;
                }
            }
        } else {
            matched = false;
        }
        return matched;

    }

    protected synchronized InvocationChain getInvocationChain(Method method, Invocable source) {
        if (fixedWire && chains.containsKey(method)) {
            return chains.get(method);
        }
        InvocationChain found = null;
        for (InvocationChain chain : source.getInvocationChains()) {
            Operation operation = chain.getSourceOperation();
            if (operation.isDynamic()) {
                operation.setName(method.getName());
                found = chain;
                break;
            } else if (match(operation, method)) {
                found = chain;
                break;
            }
        }
        if (fixedWire) {
            chains.put(method, found);
        }
        return found;
    }

    protected void setEndpoint(Endpoint endpoint) {
        this.target = endpoint;
    }

    protected Object invoke(InvocationChain chain, Object[] args, RuntimeEndpointReference source)
                         throws Throwable {
        Message msg = messageFactory.createMessage();
        msg.setFrom(source);
        if (target != null) {
            msg.setTo(target);
        } else {
            msg.setTo(source.getTargetEndpoint());
        }
        Invoker headInvoker = chain.getHeadInvoker();
        Operation operation = chain.getTargetOperation();
        msg.setOperation(operation);
        msg.setBody(args);

        Message msgContext = ThreadMessageContext.getMessageContext();
        
        ThreadMessageContext.setMessageContext(msg);

        try {
            // dispatch the source down the chain and get the response
            Message resp = headInvoker.invoke(msg);
            Object body = resp.getBody();
            if (resp.isFault()) {
                throw (Throwable)body;
            }
            return body;
        } finally {
            //conversationPostInvoke(msg, source, abnormalEndConversation);
            ThreadMessageContext.setMessageContext(msgContext);
        }
    }

    /**
     * @return the callableReference
     */
    public ServiceReference<?> getCallableReference() {
        return callableReference;
    }

    /**
     * @param callableReference the callableReference to set
     */
    public void setCallableReference(ServiceReference<?> callableReference) {
        this.callableReference = (ServiceReferenceExt<?>)callableReference;
    }

}