/*
 * The MIT License (MIT)
 *
 * Copyright (c) 2015 Ziver Koc
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */

package zutil.net.http;

import zutil.StringUtil;
import zutil.log.LogUtil;
import zutil.net.threaded.ThreadedTCPNetworkServer;
import zutil.net.threaded.ThreadedTCPNetworkServerThread;

import java.io.*;
import java.net.Socket;
import java.util.*;
import java.util.concurrent.ConcurrentHashMap;
import java.util.logging.Level;
import java.util.logging.Logger;


/**
 * A simple web server that handles both cookies and
 * sessions for all the clients
 * 
 * @author Ziver
 */
public class HttpServer extends ThreadedTCPNetworkServer{
	private static final Logger logger = LogUtil.getLogger();

	public static final String SESSION_ID_KEY = "session_id";
	public static final String SESSION_TTL_KEY = "session_ttl";
	public static final String SERVER_VERSION = "Zutil HttpServer";
	public static final int SESSION_TTL = 10*60*1000; // in milliseconds


	private Map<String,HttpPage> pages;
	private HttpPage defaultPage;
	private Map<Integer,Map<String,Object>> sessions;
	private int nextSessionId;

	/**
	 * Creates a new instance of the sever
	 *
	 * @param   port    The port that the server should listen to
	 */
	public HttpServer(int port){
		this(port, null, null);
	}


	/**
	 * Creates a new instance of the sever
	 *
	 * @param   port            The port that the server should listen to
	 * @param   keyStore        If this is not null then the server will use SSL connection with this keyStore file path
	 * @param   keyStorePass    If this is not null then the server will use a SSL connection with the given certificate
	 */
	public HttpServer(int port, File keyStore, String keyStorePass){
		super( port, keyStore, keyStorePass );

		pages = new ConcurrentHashMap<>();
		sessions = new ConcurrentHashMap<>();
		nextSessionId = 0;

		Timer timer = new Timer();
		timer.schedule(new SessionGarbageCollector(), 10000, SESSION_TTL / 2);

		logger.info("HTTP"+(keyStore==null?"":"S")+" Server ready!");
	}

	/**
	 * This class acts as an garbage collector that 
	 * removes old sessions from the session HashMap
	 * 
	 * @author Ziver
	 */
	private class SessionGarbageCollector extends TimerTask {
		public void run(){
			Object[] keys = sessions.keySet().toArray();
			for(Object key : keys){
				Map<String,Object> session = sessions.get(key);

				// Check if session is still valid
				if((Long)session.get(SESSION_TTL_KEY) < System.currentTimeMillis()){
					sessions.remove(key);
					logger.fine("Removing Session: "+key);
				}
			}
		}
	}

	/**
	 * Add a HttpPage to a specific URL
	 * 
	 * @param   name    The URL or name of the page
	 * @param   page    The page itself
	 */
	public void setPage(String name, HttpPage page){
		if(name.charAt(0) != '/')
			name = "/"+name;
		pages.put(name, page);
	}

	/**
	 * This is a default page that will be shown
	 * if there is no other matching page,
	 * 
	 * @param   page    The HttpPage that will be shown
	 */
	public void setDefaultPage(HttpPage page){
		defaultPage = page;
	}

	protected ThreadedTCPNetworkServerThread getThreadInstance( Socket s ){
		try {
			return new HttpServerThread( s );
		} catch (IOException e) {
			logger.log(Level.SEVERE, "Could not start new Thread", e);
		}
		return null;
	}

    private static int noOfConnections = 0;
	/**
	 * Internal class that handles all the requests
	 * 
	 * @author Ziver
	 *
	 */
	protected class HttpServerThread implements ThreadedTCPNetworkServerThread{
		private HttpPrintStream out;
		private BufferedInputStream in;
		private Socket socket;

		public HttpServerThread(Socket socket) throws IOException{
			out = new HttpPrintStream(socket.getOutputStream());
			in = new BufferedInputStream(socket.getInputStream());
			this.socket = socket;
		}

		public void run(){
			//logger.finest("New Connection: "+socket.getInetAddress()+" (Ongoing connections: "+(++noOfConnections)+")");

			try {
                //**************************** PARSE REQUEST *********************************
                long time = System.currentTimeMillis();
                HttpHeaderParser headerParser = new HttpHeaderParser(in);
                HttpHeader header = headerParser.read();
                if (header == null) {
                    logger.finer("No header received");
                    return;
                }
                String tmp = null;

                //******* Read in the post data if available
                if (header.getHeader("Content-Length") != null &&
						header.getHeader("Content-Type") != null &&
						header.getHeader("Content-Type").contains("application/x-www-form-urlencoded")) {
                    // Reads the post data size
                    int post_data_length = Integer.parseInt(header.getHeader("Content-Length"));
                    // read the data
                    StringBuilder tmpBuff = new StringBuilder();
                    // read the data
                    for (int i = 0; i < post_data_length; i++) {
                        tmpBuff.append((char) in.read());
                    }
					// get the variables
					HttpHeaderParser.parseURLParameters(header, tmpBuff.toString());
                }

                //****************************  HANDLE REQUEST *********************************
                // Get the client session or create one
                Map<String, Object> session;
                long ttlTime = System.currentTimeMillis() + SESSION_TTL;
                String sessionCookie = header.getCookie(SESSION_ID_KEY);
                if (sessionCookie != null && sessions.containsKey(sessionCookie) &&
                        (Long) sessions.get(sessionCookie).get(SESSION_TTL_KEY) < System.currentTimeMillis()) { // Check if session is still valid

                    session = sessions.get(sessionCookie);
                    // renew the session TTL
                    session.put(SESSION_TTL_KEY, ttlTime);
                } else {
                    session = Collections.synchronizedMap(new HashMap<String, Object>());
                    session.put(SESSION_ID_KEY, nextSessionId);
                    session.put(SESSION_TTL_KEY, ttlTime);
                    sessions.put(nextSessionId, session);
                    ++nextSessionId;
                }

                //****************************  RESPONSE  ************************************
                out.setHttpVersion("1.0");
                out.setStatusCode(200);
                out.setHeader("Server", SERVER_VERSION);
                out.setHeader("Content-Type", "text/html");
                //out.setHeader("Connection", "keep-alive");
                out.setCookie(SESSION_ID_KEY, "" + session.get(SESSION_ID_KEY));

                if (header.getRequestURL() != null && pages.containsKey(header.getRequestURL())) {
                    HttpPage page = pages.get(header.getRequestURL());
                    page.respond(out, header, session, header.getCookieMap(), header.getUrlAttributeMap());
                    if (LogUtil.isLoggable(page.getClass(), Level.FINER))
                        logRequest(header, session, time);
                } else if (header.getRequestURL() != null && defaultPage != null) {
                    defaultPage.respond(out, header, session, header.getCookieMap(), header.getUrlAttributeMap());
                    if (LogUtil.isLoggable(defaultPage.getClass(), Level.FINER))
                        logRequest(header, session, time);
                } else {
                    out.setStatusCode(404);
                    out.println("404 Page Not Found: " + header.getRequestURL());
                    logger.warning("Page not defined: " + header.getRequestURL());
                    }
				//********************************************************************************
			} catch (Exception e) {
				logger.log(Level.SEVERE, "500 Internal Server Error", e);
				try {
					if (!out.isHeaderSent())
						out.setStatusCode(500);
					if (e.getMessage() != null)
						out.println("500 Internal Server Error: " + e.getMessage());
					else if (e.getCause() != null) {
						out.println("500 Internal Server Error: " + e.getCause().getMessage());
					} else {
						out.println("500 Internal Server Error: " + e);
					}
				}catch(IOException ioe){
					logger.log(Level.SEVERE, null, ioe);
				}
			}
            finally {
                try{
                    out.close();
                    in.close();
                    socket.close();
                    //logger.finest("Connection Closed: "+socket.getInetAddress()+" (Ongoing connections: "+(--noOfConnections)+")");
                } catch( Exception e ) {
                    logger.log(Level.WARNING, "Could not close connection", e);
                }
            }
		}
	}


    protected static void logRequest(HttpHeader header,
                                   Map<String,Object> session,
                                   long time){
        // Debug
        if(logger.isLoggable(Level.FINEST) ){
            StringBuilder buff = new StringBuilder();
            buff.append("Received request: ").append(header.getRequestURL());
            buff.append(", (");
            buff.append("request: ").append(header.toStringAttributes());
            buff.append(", cookies: ").append(header.toStringCookies());
            buff.append(", session: ").append(session);
            buff.append(")");
            buff.append(", time: "+ StringUtil.formatTimeToString(System.currentTimeMillis() - time));

            logger.finer(buff.toString());
        } else if(logger.isLoggable(Level.FINER)){
            logger.finer(
                    "Received request: " + header.getRequestURL()
                            + ", time: "+ StringUtil.formatTimeToString(System.currentTimeMillis() - time));
        }
    }
}