package de.tudarmstadt.informatik.hostage.protocol;

import java.security.SecureRandom;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Calendar;
import java.util.List;
import java.util.Locale;
import java.util.TimeZone;

import de.tudarmstadt.informatik.hostage.commons.HelperUtils;
import de.tudarmstadt.informatik.hostage.wrapper.Packet;


/**
 * HTTP protocol.
 * Implementation of RFC document 1945.
 * It can handle the following requests: GET, HEAD, TRACE, POST, DELETE.
 * For all other requests '400 Bad Request' will be replied.
 * @author Wulf Pfeiffer
 */
public class HTTP implements Protocol {
	
	@Override
	public int getDefaultPort() {
		return 80;
	}

	@Override
	public TALK_FIRST whoTalksFirst() {
		return TALK_FIRST.CLIENT;
	}
	
	@Override
	public List<Packet> processMessage(Packet requestPacket) {
		String request = null;
		if (requestPacket != null) {
			request = requestPacket.toString();
		}
		List<Packet> responsePackets = new ArrayList<Packet>();
		this.request = request;

		if(!request.contains(httpVersion)){
			responsePackets.add(buildPacket(STATUS_CODE_505, ""));
		} else if(request.contains(GET)) {
			responsePackets.add(buildPacket(STATUS_CODE_200, GET));
		} else if(request.contains(HEAD)) {
			responsePackets.add(buildPacket(STATUS_CODE_200, HEAD));
		} else if(request.contains(TRACE)){
			responsePackets.add(buildPacket(STATUS_CODE_200, TRACE));
		} else if(request.contains(OPTIONS)){
			responsePackets.add(buildPacket(STATUS_CODE_400, OPTIONS));
		} else if(request.contains(POST)){
			responsePackets.add(buildPacket(STATUS_CODE_200, POST));
		} else if(request.contains(PUT)){
			responsePackets.add(buildPacket(STATUS_CODE_400, PUT));
		} else if(request.contains(DELETE)){
			responsePackets.add(buildPacket(STATUS_CODE_200, DELETE));
		} else if(request.contains(CONNECT)){
			responsePackets.add(buildPacket(STATUS_CODE_400, CONNECT));
		} else {
			responsePackets.add(buildPacket(STATUS_CODE_400, ""));
		}
		return responsePackets;
	}

	@Override
	public boolean isClosed() {
		return true;
	}

	@Override
	public boolean isSecure() {
		return false;
	}

	@Override
	public Class<String> getType() {
		return String.class;
	}

	@Override
	public String toString() {
		return "HTTP";
	}

	/**
	 * Builds a html response that can be sent
	 * @param code response code that was determined
	 * @param type request type that was sent by the client
	 * @return the html response
	 */
	private Packet buildPacket(String code, String type) {
		String document = "";
		if (type.equals(GET)) {
			document = htmlDocument;
		} else if (type.equals(HEAD) || type.equals(DELETE)) {
			document = "";
		} else if (type.equals(TRACE)) {
			document = request;
		} else {
			document = errorHtmlPrefix + " " + code + errorHtmlSuffix;
		}

		return new Packet(httpVersion + " " + code + headerPrefix + document.length() + headerSuffix + document);
	}
	
	/**
	 * Get the current time in html header format.
	 * @return the formatted server time.
	 */
	private static String getServerTime() {
	    Calendar calendar = Calendar.getInstance();
	    SimpleDateFormat dateFormat = new SimpleDateFormat(
	        "EEE, dd MMM yyyy HH:mm:ss z", Locale.US);
	    dateFormat.setTimeZone(TimeZone.getTimeZone("GMT"));
	    return dateFormat.format(calendar.getTime());
	}

	/** Whole request that was sent by the client */
	private String request	= "";
	//version stuff
	private static String[][][] possibleHttpVersions = {
		{{"Apache/2.0."},{"28","32","35","36","39","40","42","43","44","45","46","47","48","49","50","51","52","53","54","55","58","59","61","63","64","65"}},
		{{"Apache/2.2."},{"0","2","3","4","6","8","9","10","11","12","13","14","15","16","17","18","19","20","21","22","23","24","25"}},
		{{"Apache/2.3."},{"4","5","6","8","10","11","12","14","15","16"}},
		{{"Apache/2.4."},{"1","2","3","4","6"}}
	};
	private static String initServerVersion() {
		SecureRandom rndm = new SecureRandom();
		int majorVersion = rndm.nextInt(possibleHttpVersions.length);
		return possibleHttpVersions[majorVersion][0][0] + possibleHttpVersions[majorVersion][1][rndm.nextInt(possibleHttpVersions[majorVersion][1].length)];
	}
	private String httpVersion	= "HTTP/1.1";
	private static String serverVersion = initServerVersion();
	private static String htmlDocumentContent = HelperUtils.getRandomString(32, false);
	//request codes
	private static final String OPTIONS	= "OPTIONS";
	private static final String GET 	= "GET";
	private static final String HEAD 	= "HEAD";
	private static final String POST	= "POST";
	private static final String PUT		= "PUT";
	private static final String DELETE	= "DELETE";
	private static final String TRACE	= "TRACE";
	private static final String CONNECT	= "CONNECT";
	
	private static final String STATUS_CODE_200	= "200 OK\r\n";
	private static final String STATUS_CODE_400	= "400 Bad Request\r\n";
	private static final String STATUS_CODE_505	= "505 HTTP Version not supported\r\n";
	
	//html header pre and suffix
	private String headerPrefix =				
			"Date: " + getServerTime() + "\r\n" +
			"Server: " + serverVersion + " \r\n" +
			"Vary: Accept-Encoding\r\n" +
			"Content-Length: ";
	private String headerSuffix =
			"\r\n" +	
			"Keep-Alive: timeout=5, max=100\r\n" +
			"Connection: Keep-Alive\r\n" +
			"Content-Type: text/html\r\n" +
			"\r\n";
	//html website
	private String htmlDocument = 
			"<!doctype html>\n" +
			"<html lang=\"en\">\n" +
			"<head>\n" +
			"<meta charset=\"UTF-8\">\n" +
			"<title>" + htmlDocumentContent + "</title>\n" +
			"<body>" + htmlDocumentContent + "</body>\n" +
			"</head>\n" +
			"</html>";
	//html error pre and suffix
	private String errorHtmlPrefix =
			"<!doctype html>\n" +
			"<html lang=\"en\">\n" +
			"<head>\n" +
			"<meta charset=\"UTF-8\">\n" +
			"<title>";
	private String errorHtmlSuffix =
			"</title>\n" +
			"</head>\n" +
			"</html>";

	/**
	 * Sets the html document content for HTTP and HTTPS.
	 * 
	 * @param htmlDocumentContent
	 */
	public static void setHtmlDocumentContent(String htmlDocumentContent) {
		HTTP.htmlDocumentContent = htmlDocumentContent;
	}
}