package chat.server;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.PrintStream;
import java.io.PrintWriter;
import java.io.UnsupportedEncodingException;
import java.net.URLDecoder;
import java.net.URLEncoder;
import java.util.HashSet;
import java.util.Set;

import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.RequestDispatcher;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.log4j.Logger;

import chat.server.call.JSONObject;


public class AppDispatcher implements Filter {

	private static Logger logger;
	private static AppDispatcher instance;
	
	private static String contextPath;
	private static int contextLength;
	private static Set<String> resourceSet;

	
	static {
		logger = Logger.getLogger(AppDispatcher.class);
	}

	public AppDispatcher() {
		instance = this;
		initResourceList(); 
	}

	public synchronized static AppDispatcher getInstance() {
		if (instance == null) {
			instance = new AppDispatcher();
		}

		return instance;
	}

	public void init(FilterConfig filterConfig) throws ServletException {
		ServletContext servletContext = filterConfig.getServletContext();

		contextPath = servletContext.getContextPath();
		contextLength = contextPath.length();
	}

	public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain) throws IOException, ServletException {
		HttpServletRequest request = (HttpServletRequest) req;
		HttpServletResponse response = (HttpServletResponse) res;
		
		request.setCharacterEncoding("utf-8");

		try {
			String uri = request.getRequestURI();
			
			logger.debug("filter request URI:" + uri); 
			
			uri = uri.substring(contextLength);
			
			int pos_root = uri.lastIndexOf("/root/");
			uri = pos_root >= 0 ? uri.substring(pos_root + 5) : uri;
			
			try {
				uri = URLDecoder.decode(uri, "UTF-8");
			} catch (Exception e) {
				e.printStackTrace();
			}
			
			//1.
			String suffix = getSuffix(uri);
			
			if (resourceSet.contains(suffix)) {
				RequestDispatcher dispatcher = request.getRequestDispatcher(uri);
				dispatcher.forward(request, response);
				return;
			}
			
			//2.
//			RequestParams dataPool = new RequestParams(request);
//			HttpResultPool resultPool = new HttpResultPool(response);
			
//			console.receive(uri, dataPool, resultPool);
//			writeResultPool(response, resultPool);
			return;
		}
		catch (Exception e) {
			String error = printStackToString(e);
			logger.error("dispatch error:" + e.getMessage());
			logger.error(error);
			writeError(request, response, error);
		}
	}
	
	private void writeError(HttpServletRequest request, HttpServletResponse response, String error) throws IOException {
		PrintWriter writer = response.getWriter();
		
		JSONObject json = new JSONObject();
		json.beginObject();
		json.addValue("success", false);
		json.addValue("errorcode", "ServerError");
		json.addValue("errorMessage", encode(error));
		json.endObject();
		writer.print(json.toString());
			
		writer.flush();	
	}

	public void destroy() {

	}

	private String printStackToString(Exception e) {
		ByteArrayOutputStream outStream = new ByteArrayOutputStream();
		PrintStream printStream = new PrintStream(outStream);
		e.printStackTrace(printStream);

		return outStream.toString();
	}
	
	private String encode(String value) throws UnsupportedEncodingException {
		return URLEncoder.encode(value, "UTF-8");
	}
	
	private void initResourceList() {
		resourceSet = new HashSet<String>();
		resourceSet.add(".html");
		resourceSet.add(".css");
		resourceSet.add(".js");
		resourceSet.add(".png");
		resourceSet.add(".jpg");
		resourceSet.add(".bmp");
		resourceSet.add(".icon");
	}
	
	private String getSuffix(String uri) {
		String result = null;
		
		int pos = uri.lastIndexOf(".");
		
		if (pos <= 0) {
			return result;
		}
		
		result = uri.substring(pos);
		result = result.toLowerCase();
		
		return result;
	}

}