/*
 * Copyright (c) 2010-2016. Axon Framework
 *
 * 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.axonframework.commandhandling.model.inspection;

import org.axonframework.commandhandling.CommandHandler;
import org.axonframework.commandhandling.CommandMessage;
import org.axonframework.common.AxonConfigurationException;
import org.axonframework.messaging.Message;
import org.axonframework.messaging.annotation.HandlerEnhancerDefinition;
import org.axonframework.messaging.annotation.MessageHandlingMember;
import org.axonframework.messaging.annotation.WrappedMessageHandlingMember;

import java.lang.reflect.Constructor;
import java.lang.reflect.Executable;
import java.util.Map;

/**
 * Implementation of a {@link HandlerEnhancerDefinition} that is used for {@link CommandHandler} annotated methods.
 */
public class MethodCommandHandlerDefinition implements HandlerEnhancerDefinition {

    @SuppressWarnings("unchecked")
    @Override
    public <T> MessageHandlingMember<T> wrapHandler(MessageHandlingMember<T> original) {
        return original.annotationAttributes(CommandHandler.class)
                .map(attr -> (MessageHandlingMember<T>) new MethodCommandMessageHandlingMember(original, attr))
                .orElse(original);
    }

    private static class MethodCommandMessageHandlingMember<T> extends WrappedMessageHandlingMember<T> implements
            CommandMessageHandlingMember<T> {

        private final String commandName;
        private final boolean isFactoryHandler;
        private final String routingKey;

        private MethodCommandMessageHandlingMember(MessageHandlingMember<T> delegate,
                                                   Map<String, Object> annotationAttributes) {
            super(delegate);
            this.routingKey = "".equals(annotationAttributes.get("routingKey")) ? null :
                    (String) annotationAttributes.get("routingKey");
            Executable executable = delegate.unwrap(Executable.class).orElseThrow(() -> new AxonConfigurationException(
                    "The @CommandHandler annotation must be put on an Executable (either directly or as Meta " +
                            "Annotation)"));
            if ("".equals(annotationAttributes.get("commandName"))) {
                commandName = delegate.payloadType().getName();
            } else {
                commandName = (String) annotationAttributes.get("commandName");
            }
            isFactoryHandler = (executable instanceof Constructor);
        }

        @Override
        public boolean canHandle(Message<?> message) {
            return super.canHandle(message) && commandName.equals(((CommandMessage) message).getCommandName());
        }

        @Override
        public String routingKey() {
            return routingKey;
        }

        @Override
        public String commandName() {
            return commandName;
        }

        @Override
        public boolean isFactoryHandler() {
            return isFactoryHandler;
        }

    }
}