/*
 * Copyright 2012 LinkedIn, Inc
 * 
 * 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 azkaban.webapp;

import java.io.File;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.OutputStream;
import java.util.Arrays;
import java.util.HashMap;
import java.util.Map;
import java.util.TimeZone;

import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.log4j.Logger;
import org.codehaus.jackson.map.ObjectMapper;
import org.joda.time.DateTimeZone;
import org.mortbay.jetty.Server;
import org.mortbay.jetty.servlet.Context;
import org.mortbay.jetty.servlet.ServletHolder;
import org.mortbay.thread.QueuedThreadPool;

import azkaban.executor.ExecutableFlow;
import azkaban.executor.ExecutorManagerException;
import azkaban.executor.FlowRunnerManager;
import azkaban.utils.Mailman;
import azkaban.utils.Props;
import azkaban.utils.Utils;
import azkaban.webapp.servlet.AzkabanServletContextListener;

import joptsimple.OptionParser;
import joptsimple.OptionSet;
import joptsimple.OptionSpec;

public class AzkabanExecutorServer {
	private static final Logger logger = Logger.getLogger(AzkabanExecutorServer.class);

	public static final String AZKABAN_HOME = "AZKABAN_HOME";
	public static final String DEFAULT_CONF_PATH = "conf";
	public static final String AZKABAN_PROPERTIES_FILE = "azkaban.properties";
	public static final int DEFAULT_PORT_NUMBER = 12321;
	
	private static final String DEFAULT_TIMEZONE_ID = "default.timezone.id";
	private static final int DEFAULT_THREAD_NUMBER = 50;

	private static AzkabanExecutorServer app;
	
	private final Mailman mailer;
	
	private FlowRunnerManager runnerManager;
	private Props props;
	private File tempDir;
	private Server server;
	

	/**
	 * Constructor
	 * 
	 * @throws Exception
	 */
	public AzkabanExecutorServer(Props props) throws Exception {
		this.props = props;

		int portNumber = props.getInt("executor.port", DEFAULT_PORT_NUMBER);
		int maxThreads = props.getInt("executor.maxThreads", DEFAULT_THREAD_NUMBER);

		Server server = new Server(portNumber);
		QueuedThreadPool httpThreadPool = new QueuedThreadPool(maxThreads);
		server.setThreadPool(httpThreadPool);

		Context root = new Context(server, "/", Context.SESSIONS);
		String sharedToken = props.getString("executor.shared.token", "");

		ServletHolder executorHolder = new ServletHolder(new ExecutorServlet(sharedToken));
		root.addServlet(executorHolder, "/executor");
		root.setAttribute(AzkabanServletContextListener.AZKABAN_SERVLET_CONTEXT_KEY, this);
		mailer = new Mailman(
				props.getString("mail.host", "localhost"),
				props.getString("mail.user", ""), 
				props.getString("mail.password", ""),
				props.getString("mail.sender", ""));

		runnerManager = new FlowRunnerManager(props, mailer);

		try {
			server.start();
		} 
		catch (Exception e) {
			logger.warn(e);
			Utils.croak(e.getMessage(), 1);
		}
		
		logger.info("Azkaban Executor Server started on port " + portNumber);

		tempDir = new File(props.getString("azkaban.temp.dir", "temp"));
	}

	public void stopServer() throws Exception {
		server.stop();
		server.destroy();
	}

	/**
	 * Returns the global azkaban properties
	 * 
	 * @return
	 */
	public Props getAzkabanProps() {
		return props;
	}

	/**
	 * Azkaban using Jetty
	 * 
	 * @param args
	 * @throws IOException
	 */
	public static void main(String[] args) throws Exception {
		OptionParser parser = new OptionParser();

		OptionSpec<String> configDirectory = parser
				.acceptsAll(Arrays.asList("c", "conf"),
						"The conf directory for Azkaban.").withRequiredArg()
				.describedAs("conf").ofType(String.class);

		logger.error("Starting Jetty Azkaban Executor...");

		// Grabbing the azkaban settings from the conf directory.
		Props azkabanSettings = null;
		OptionSet options = parser.parse(args);
		if (options.has(configDirectory)) {
			String path = options.valueOf(configDirectory);
			logger.info("Loading azkaban settings file from " + path);
			File file = new File(path, AZKABAN_PROPERTIES_FILE);
			if (!file.exists() || file.isDirectory() || !file.canRead()) {
				logger.error("Cannot read file " + file);
			}

			azkabanSettings = loadAzkabanConfiguration(file.getPath());
		} else {
			logger.info("Conf parameter not set, attempting to get value from AZKABAN_HOME env.");
			azkabanSettings = loadConfigurationFromAzkabanHome();
		}

		if (azkabanSettings == null) {
			logger.error("Azkaban Properties not loaded.");
			logger.error("Exiting Azkaban Executor Server...");
			return;
		}

		// Setup time zone
		if (azkabanSettings.containsKey(DEFAULT_TIMEZONE_ID)) {
			String timezone = azkabanSettings.getString(DEFAULT_TIMEZONE_ID);
			TimeZone.setDefault(TimeZone.getTimeZone(timezone));
			DateTimeZone.setDefault(DateTimeZone.forID(timezone));

			logger.info("Setting timezone to " + timezone);
		}

		app = new AzkabanExecutorServer(azkabanSettings);

		Runtime.getRuntime().addShutdownHook(new Thread() {

			public void run() {
				logger.info("Shutting down http server...");
				try {
					app.stopServer();
				} catch (Exception e) {
					logger.error("Error while shutting down http server.", e);
				}
				logger.info("kk thx bye.");
			}
		});
	}

	/**
	 * Loads the Azkaban property file from the AZKABAN_HOME conf directory
	 * 
	 * @return
	 */
	private static Props loadConfigurationFromAzkabanHome() {
		String azkabanHome = System.getenv("AZKABAN_HOME");

		if (azkabanHome == null) {
			logger.error("AZKABAN_HOME not set. Will try default.");
			return null;
		}

		if (!new File(azkabanHome).isDirectory()
				|| !new File(azkabanHome).canRead()) {
			logger.error(azkabanHome + " is not a readable directory.");
			return null;
		}

		File confPath = new File(azkabanHome, DEFAULT_CONF_PATH);
		if (!confPath.exists() || !confPath.isDirectory()
				|| !confPath.canRead()) {
			logger.error(azkabanHome
					+ " does not contain a readable conf directory.");
			return null;
		}

		File confFile = new File(confPath, AZKABAN_PROPERTIES_FILE);
		if (!confFile.exists() || confFile.isDirectory() || !confPath.canRead()) {
			logger.error(confFile + " does not contain a readable azkaban.properties file.");
			return null;
		}

		return loadAzkabanConfiguration(confFile.getPath());
	}

	public FlowRunnerManager getFlowRunnerManager() {
		return runnerManager;
	}
	
	/**
	 * Returns the set temp dir
	 * 
	 * @return
	 */
	public File getTempDirectory() {
		return tempDir;
	}

	/**
	 * Loads the Azkaban conf file int a Props object
	 * 
	 * @param path
	 * @return
	 */
	private static Props loadAzkabanConfiguration(String path) {
		try {
			return new Props(null, path);
		} catch (FileNotFoundException e) {
			logger.error("File not found. Could not load azkaban config file "
					+ path);
		} catch (IOException e) {
			logger.error("File found, but error reading. Could not load azkaban config file "
					+ path);
		}

		return null;
	}
	
	public static class ExecutorServlet extends HttpServlet {
		private static final Logger logger = Logger.getLogger(ExecutorServlet.class.getName());
		public static final String JSON_MIME_TYPE = "application/json";
		
		public enum State {
			FAILED, SUCCEEDED, RUNNING, WAITING, IGNORED, READY
		}
		private String sharedToken;
		private AzkabanExecutorServer application;
		private FlowRunnerManager flowRunnerManager;
		
		public ExecutorServlet(String token) {
			super();
			sharedToken = token;
		}
		
		@Override
		public void init(ServletConfig config) throws ServletException {
			application = (AzkabanExecutorServer) config.getServletContext().getAttribute(AzkabanServletContextListener.AZKABAN_SERVLET_CONTEXT_KEY);

			if (application == null) {
				throw new IllegalStateException(
						"No batch application is defined in the servlet context!");
			}

			flowRunnerManager = application.getFlowRunnerManager();
		}

		
		protected void writeJSON(HttpServletResponse resp, Object obj) throws IOException {
			resp.setContentType(JSON_MIME_TYPE);
			ObjectMapper mapper = new ObjectMapper();
			OutputStream stream = resp.getOutputStream();
			mapper.writeValue(stream, obj);
		}

		@Override
		public void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
			HashMap<String,Object> respMap= new HashMap<String,Object>();
			
			String token = getParam(req, "sharedToken");
			if (!token.equals(sharedToken)) {
				respMap.put("error", "Mismatched token. Will not run.");
			}
			else if (!hasParam(req, "action")) {
				respMap.put("error", "Parameter action not set");
			}
			else if (!hasParam(req, "execid")) {
				respMap.put("error", "Parameter execid not set.");
			}
			else {
				String action = getParam(req, "action");
				String execid = getParam(req, "execid");
				
				// Handle execute
				if (action.equals("execute")) {
					handleAjaxExecute(req, respMap, execid);
				}
				// Handle Status
				else if (action.equals("status")) {
					handleAjaxFlowStatus(respMap, execid);
				}
				else if (action.equals("cancel")) {
					String user = getParam(req, "user");
					logger.info("Cancel called.");
					handleAjaxCancel(respMap, execid, user);
				}
				else if (action.equals("pause")) {
					String user = getParam(req, "user");
					logger.info("Paused called.");
					handleAjaxPause(respMap, execid, user);
				}
				else if (action.equals("resume")) {
					String user = getParam(req, "user");
					logger.info("Resume called.");
					handleAjaxResume(respMap, execid, user);
				}
			}

			writeJSON(resp, respMap);
			resp.flushBuffer();
		}
		
		private void handleAjaxExecute(HttpServletRequest req, Map<String, Object> respMap, String execid) throws ServletException {
			String execpath = getParam(req, "execpath");
			logger.info("Submitted " + execid + " with " + execpath);
			try {
				flowRunnerManager.submitFlow(execid, execpath);
				respMap.put("status", "success");
			} catch (ExecutorManagerException e) {
				e.printStackTrace();
				respMap.put("error", e.getMessage());
			}
		}
		
		private void handleAjaxFlowStatus(Map<String, Object> respMap, String execid) {
			ExecutableFlow flow = flowRunnerManager.getExecutableFlow(execid);
			if (flow == null) {
				respMap.put("status", "notfound");
			}
			else {
				respMap.put("status", flow.getStatus().toString());
			}
		}
		
		private void handleAjaxPause(Map<String, Object> respMap, String execid, String user) throws ServletException {

			try {
				flowRunnerManager.pauseFlow(execid, user);
				respMap.put("status", "success");
			} catch (ExecutorManagerException e) {
				e.printStackTrace();
				respMap.put("error", e.getMessage());
			}
		}
		
		private void handleAjaxResume(Map<String, Object> respMap, String execid, String user) throws ServletException {
			try {
				flowRunnerManager.resumeFlow(execid, user);
				respMap.put("status", "success");
			} catch (ExecutorManagerException e) {
				e.printStackTrace();
				respMap.put("error", e.getMessage());
			}
		}
		
		private void handleAjaxCancel(Map<String, Object> respMap, String execid, String user) throws ServletException {
			try {
				flowRunnerManager.cancelFlow(execid, user);
				respMap.put("status", "success");
			} catch (ExecutorManagerException e) {
				e.printStackTrace();
				respMap.put("error", e.getMessage());
			}
		}
		
		@Override
		public void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
			
		}
		
		/**
		 * Duplicated code with AbstractAzkabanServlet, but ne
		 */
		public boolean hasParam(HttpServletRequest request, String param) {
			return request.getParameter(param) != null;
		}

		public String getParam(HttpServletRequest request, String name)
				throws ServletException {
			String p = request.getParameter(name);
			if (p == null)
				throw new ServletException("Missing required parameter '" + name + "'.");
			else
				return p;
		}
	}

}
