package org.argeo.slc.jms;

import java.net.InetAddress;
import java.net.UnknownHostException;
import java.util.ArrayList;
import java.util.List;
import java.util.UUID;

import javax.jms.Destination;
import javax.jms.JMSException;
import javax.jms.Message;
import javax.jms.MessageListener;
import javax.jms.TextMessage;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.argeo.slc.SlcException;
import org.argeo.slc.core.runtime.AbstractAgent;
import org.argeo.slc.execution.ExecutionModule;
import org.argeo.slc.execution.ExecutionModuleDescriptor;
import org.argeo.slc.msg.ExecutionAnswer;
import org.argeo.slc.process.SlcExecution;
import org.argeo.slc.runtime.SlcAgent;
import org.argeo.slc.runtime.SlcAgentDescriptor;
import org.springframework.beans.factory.DisposableBean;
import org.springframework.beans.factory.InitializingBean;
import org.springframework.jms.core.JmsTemplate;
import org.springframework.jms.core.MessagePostProcessor;

/** JMS based implementation of SLC Agent. */
public class JmsAgent extends AbstractAgent implements SlcAgent,
		InitializingBean, DisposableBean, MessageListener {
	public final static String PROPERTY_QUERY = "query";
	public final static String PROPERTY_SLC_AGENT_ID = "slc_agentId";

	private final static Log log = LogFactory.getLog(JmsAgent.class);

	private final SlcAgentDescriptor agentDescriptor;
	private JmsTemplate jmsTemplate;
	private Destination agentRegister;
	private Destination agentUnregister;

	private Destination responseDestination;

	public JmsAgent() {
		try {
			agentDescriptor = new SlcAgentDescriptor();
			agentDescriptor.setUuid(UUID.randomUUID().toString());
			agentDescriptor.setHost(InetAddress.getLocalHost().getHostName());
		} catch (UnknownHostException e) {
			throw new SlcException("Unable to create agent descriptor.", e);
		}
	}

	public void afterPropertiesSet() throws Exception {
		jmsTemplate.convertAndSend(agentRegister, agentDescriptor);
		log.info("Agent #" + agentDescriptor.getUuid() + " registered to "
				+ agentRegister);
	}

	public void destroy() throws Exception {
		jmsTemplate.convertAndSend(agentUnregister, agentDescriptor);
		log.info("Agent #" + agentDescriptor.getUuid() + " unregistered from "
				+ agentUnregister);
	}

	public void setAgentRegister(Destination agentRegister) {
		this.agentRegister = agentRegister;
	}

	public void setAgentUnregister(Destination agentUnregister) {
		this.agentUnregister = agentUnregister;
	}

	public String getMessageSelector() {
		String messageSelector = "slc_agentId='" + agentDescriptor.getUuid()
				+ "'";
		// if (log.isDebugEnabled())
		// log.debug("Message selector: " + messageSelector);
		return messageSelector;
	}

	public ExecutionModuleDescriptor getExecutionModuleDescriptor(
			String moduleName, String version) {
		return getModulesManager().getExecutionModuleDescriptor(moduleName,
				version);
	}

	public List<ExecutionModuleDescriptor> listExecutionModuleDescriptors() {
		List<ExecutionModule> modules = getModulesManager()
				.listExecutionModules();

		List<ExecutionModuleDescriptor> descriptors = new ArrayList<ExecutionModuleDescriptor>();
		for (ExecutionModule module : modules) {
			ExecutionModuleDescriptor md = new ExecutionModuleDescriptor();
			md.setName(module.getName());
			md.setVersion(module.getVersion());
			descriptors.add(md);
		}
		return descriptors;
	}

	public boolean ping() {
		return true;
	}

	public void onMessage(final Message message) {
		final String query;
		final String correlationId;
		try {
			query = message.getStringProperty(PROPERTY_QUERY);
			correlationId = message.getJMSCorrelationID();
		} catch (JMSException e1) {
			throw new SlcException("Cannot analyze incoming message " + message);
		}

		final Object response = process(query, message);

		new Thread() {
			public void run() {
				// Send response
				jmsTemplate.convertAndSend(responseDestination, response,
						new MessagePostProcessor() {
							public Message postProcessMessage(
									Message messageToSend) throws JMSException {
								messageToSend
										.setStringProperty(
												PROPERTY_QUERY,
												message
														.getStringProperty(PROPERTY_QUERY));
								messageToSend.setStringProperty(
										PROPERTY_SLC_AGENT_ID, agentDescriptor
												.getUuid());
								messageToSend.setJMSCorrelationID(message
										.getJMSCorrelationID());
								return messageToSend;
							}
						});
				if (log.isDebugEnabled())
					log.debug("Sent response to query " + query
							+ " with correlationId " + correlationId);
			}
		}.start();

	}

	/** @return response */
	public Object process(String query, Message message) {
		try {
			if ("getExecutionModuleDescriptor".equals(query)) {
				String moduleName = message.getStringProperty("moduleName");
				String version = message.getStringProperty("version");
				return getExecutionModuleDescriptor(moduleName, version);
			} else if ("listExecutionModuleDescriptors".equals(query)) {

				List<ExecutionModuleDescriptor> lst = listExecutionModuleDescriptors();
				SlcAgentDescriptor agentDescriptorToSend = new SlcAgentDescriptor(
						agentDescriptor);
				agentDescriptorToSend.setModuleDescriptors(lst);
				return agentDescriptorToSend;
			} else if ("runSlcExecution".equals(query)) {
				SlcExecution slcExecution = (SlcExecution) convertFrom(message);
				runSlcExecution(slcExecution);
				return ExecutionAnswer.ok("Execution started on agent "
						+ agentDescriptor.getUuid());
			} else if ("ping".equals(query)) {
				return ExecutionAnswer.ok("Agent " + agentDescriptor.getUuid()
						+ " is alive.");
			} else {
				throw new SlcException("Unsupported query " + query);
			}
		} catch (Exception e) {
			log.error("Processing of query " + query + " failed", e);
			return ExecutionAnswer.error(e);
		}
	}

	protected Object convertFrom(Message message) throws JMSException {
		return jmsTemplate.getMessageConverter().fromMessage(message);
	}

	public void setResponseDestination(Destination responseDestination) {
		this.responseDestination = responseDestination;
	}

	public void setJmsTemplate(JmsTemplate jmsTemplate) {
		this.jmsTemplate = jmsTemplate;
	}

}