//

// 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 com.cloud.resource;

import java.text.MessageFormat;

import java.util.Hashtable;

import java.util.Set;

import org.apache.log4j.Logger;

import com.cloud.agent.api.Answer;

import com.cloud.agent.api.Command;

public abstract class RequestWrapper {

static public class CommandNotSupported extends NullPointerException {

public CommandNotSupported(String msg) {

super(msg);

}

public CommandNotSupported(String msg, Throwable cause) {

super(msg);

initCause(cause);

}

}

private static final Logger s_logger = Logger.getLogger(RequestWrapper.class);

@SuppressWarnings("rawtypes")

protected Hashtable<Class<? extends ServerResource>, Hashtable<Class<? extends Command>, CommandWrapper>> resources = new Hashtable<Class<? extends ServerResource>, Hashtable<Class<? extends Command>, CommandWrapper>>();

/**

* @param command to be executed.

* @return an Answer for the executed command.

*/

public abstract Answer execute(Command command, ServerResource serverResource);

@SuppressWarnings({ "rawtypes", "unchecked" })

protected Hashtable<Class<? extends Command>, CommandWrapper> retrieveResource(final Command command, final Class<? extends ServerResource> resourceClass) {

Class<? extends ServerResource> keepResourceClass = resourceClass;

Hashtable<Class<? extends Command>, CommandWrapper> resource = resources.get(keepResourceClass);

while (resource == null) {

try {

final Class<? extends ServerResource> keepResourceClass2 = (Class<? extends ServerResource>) keepResourceClass.getSuperclass();

resource = resources.get(keepResourceClass2);

keepResourceClass = keepResourceClass2;

} catch (final ClassCastException e) {

throw new CommandNotSupported("No key found for '" + command.getClass() + "' in the Map!");

}

}

return resource;

}

@SuppressWarnings({ "rawtypes", "unchecked" })

protected CommandWrapper<Command, Answer, ServerResource> retrieveCommands(final Class<? extends Command> commandClass,

final Hashtable<Class<? extends Command>, CommandWrapper> resourceCommands) {

Class<? extends Command> keepCommandClass = commandClass;

CommandWrapper<Command, Answer, ServerResource> commandWrapper = resourceCommands.get(keepCommandClass);

while (commandWrapper == null) {

try {

final Class<? extends Command> commandClass2 = (Class<? extends Command>) keepCommandClass.getSuperclass();

if (commandClass2 == null) {

throw new CommandNotSupported("All the COMMAND hierarchy tree has been visited but no compliant key has been found for '" + commandClass + "'.");

}

commandWrapper = resourceCommands.get(commandClass2);

keepCommandClass = commandClass2;

} catch (final ClassCastException e) {

throw new CommandNotSupported("No key found for '" + keepCommandClass.getClass() + "' in the Map!");

} catch (final NullPointerException e) {

// Will now traverse all the resource hierarchy. Returning null

// is not a problem.

// It is all being nicely checked and in case we do not have a

// resource, an Unsupported answer will be thrown by the base

// class.

return null;

}

}

return commandWrapper;

}

@SuppressWarnings({ "rawtypes", "unchecked" })

protected CommandWrapper<Command, Answer, ServerResource> retryWhenAllFails(final Command command, final Class<? extends ServerResource> resourceClass,

final Hashtable<Class<? extends Command>, CommandWrapper> resourceCommands) {

Class<? extends ServerResource> keepResourceClass = resourceClass;

CommandWrapper<Command, Answer, ServerResource> commandWrapper = resourceCommands.get(command.getClass());

while (commandWrapper == null) {

// Could not find the command in the given resource, will traverse

// the family tree.

try {

final Class<? extends ServerResource> resourceClass2 = (Class<? extends ServerResource>) keepResourceClass.getSuperclass();

if (resourceClass2 == null) {

throw new CommandNotSupported("All the SERVER-RESOURCE hierarchy tree has been visited but no compliant key has been found for '" + command.getClass() + "'.");

}

final Hashtable<Class<? extends Command>, CommandWrapper> resourceCommands2 = retrieveResource(command,

(Class<? extends ServerResource>) keepResourceClass.getSuperclass());

keepResourceClass = resourceClass2;

commandWrapper = retrieveCommands(command.getClass(), resourceCommands2);

} catch (final ClassCastException | NullPointerException e) {

throw new CommandNotSupported("No key found for '" + command.getClass() + "' in the Map!", e);

}

}

return commandWrapper;

}

@SuppressWarnings("rawtypes")

protected Hashtable<Class<? extends Command>, CommandWrapper> processAnnotations(final Set<Class<? extends CommandWrapper>> wrappers) {

final String errorMessage = "Error when adding Xen command to map ==> '{0}'. CommandWrapper class is ==> '{1}'";

final Hashtable<Class<? extends Command>, CommandWrapper> commands = new Hashtable<Class<? extends Command>, CommandWrapper>();

for (final Class<? extends CommandWrapper> wrapper : wrappers) {

final ResourceWrapper annotation = wrapper.getAnnotation(ResourceWrapper.class);

if (annotation == null) {

// Just in case people add classes without the annotation in the package and we don't see it.

continue;

}

try {

commands.put(annotation.handles(), wrapper.newInstance());

} catch (final InstantiationException e) {

s_logger.warn(MessageFormat.format(errorMessage, e.getLocalizedMessage(), wrapper.toString()));

} catch (final IllegalAccessException e) {

s_logger.warn(MessageFormat.format(errorMessage, e.getLocalizedMessage(), wrapper.toString()));

}

}

return commands;

}

}