package org.ariadne_eu.utils.registry.auth;

import java.io.IOException;
import java.io.PrintWriter;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.HashSet;
import java.util.Set;

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

import org.ariadne.config.PropertiesManager;
import org.ariadne_eu.utils.config.RepositoryConstants;
import org.expressme.openid.Association;
import org.expressme.openid.Authentication;
import org.expressme.openid.Endpoint;
import org.expressme.openid.OpenIdException;
import org.expressme.openid.OpenIdManager;

/**
 * Sample servlet using JOpenID.
 * 
 * @author Michael Liao (askxuefeng@gmail.com)
 */
public class OpenIdServlet extends HttpServlet {

    static final long ONE_HOUR = 3600000L;
    static final long TWO_HOUR = ONE_HOUR * 2L;
    static final String ATTR_MAC = "openid_mac";
    static final String ATTR_ALIAS = "openid_alias";

    private OpenIdManager manager;

    @Override
    public void init() throws ServletException {
        super.init();
        manager = new OpenIdManager();
        manager.setRealm(PropertiesManager.getInstance().getProperty(RepositoryConstants.getInstance().REG_URL));
        manager.setReturnTo(PropertiesManager.getInstance().getProperty(RepositoryConstants.getInstance().REG_URL)+PropertiesManager.getInstance().getProperty(RepositoryConstants.getInstance().REG_LOGIN));
    }

    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
    	
    	
        String op = request.getParameter("op");
        if (op==null) {
        	System.out.println("***op=null"+(String)request.getSession().getAttribute("contextURL")+"-"+request.getRequestURI());
            // check sign on result from Google or Yahoo:
            checkNonce(request.getParameter("openid.response_nonce"));
            // get authentication:
            byte[] mac_key = (byte[]) request.getSession().getAttribute(ATTR_MAC);
            String alias = (String) request.getSession().getAttribute(ATTR_ALIAS);
            Authentication authentication = manager.getAuthentication(request, mac_key, alias);
            response.setContentType("text/html; charset=UTF-8");
            //showAuthentication(response.getWriter(), authentication);
            request.getSession().setAttribute("openid", "true");
            request.getSession().setAttribute("login", "true");
            request.getSession().setAttribute("username", authentication.getEmail());
           // request.getRequestDispatcher((String)request.getSession().getAttribute("contextURL")).forward(request, response);
            response.sendRedirect((String)request.getSession().getAttribute("contextURL"));
            return;
        }
        if (op.equals("Google") || op.equals("Yahoo")) {
        	System.out.println("op=Google"+(String)request.getSession().getAttribute("contextURL")+"-"+request.getRequestURI());
            // redirect to Google or Yahoo sign on page:
            Endpoint endpoint = manager.lookupEndpoint(op);
            Association association = manager.lookupAssociation(endpoint);
            request.getSession().setAttribute(ATTR_MAC, association.getRawMacKey());
            request.getSession().setAttribute(ATTR_ALIAS, endpoint.getAlias());
            //request.getSession().setAttribute("contextURL", (String)request.getParameter("contextURL"));
            String url = manager.getAuthenticationUrl(endpoint, association);
            response.sendRedirect(url);
        }
        else {
            throw new ServletException("Unsupported OP: " + op);
        }
    }

    void showAuthentication(PrintWriter pw, Authentication auth) {
        pw.print("<html><head><meta http-equiv=\"Content-Type\" content=\"text/html; charset=utf-8\" /><title>Test JOpenID</title></head><body><h1>You have successfully signed on!</h1>");
        pw.print("<p>Identity: " + auth.getIdentity() + "</p>");
        pw.print("<p>Email: " + auth.getEmail() + "</p>");
        pw.print("<p>Full name: " + auth.getFullname() + "</p>");
        pw.print("<p>First name: " + auth.getFirstname() + "</p>");
        pw.print("<p>Last name: " + auth.getLastname() + "</p>");
        pw.print("<p>Gender: " + auth.getGender() + "</p>");
        pw.print("<p>Language: " + auth.getLanguage() + "</p>");
        pw.print("</body></html>");
        pw.flush();
    }

    void checkNonce(String nonce) {
        // check response_nonce to prevent replay-attack:
        if (nonce==null || nonce.length()<20)
            throw new OpenIdException("Verify failed.");
        // make sure the time of server is correct:
        long nonceTime = getNonceTime(nonce);
        long diff = Math.abs(System.currentTimeMillis() - nonceTime);
        if (diff > ONE_HOUR)
            throw new OpenIdException("Bad nonce time.");
        if (isNonceExist(nonce))
            throw new OpenIdException("Verify nonce failed.");
        storeNonce(nonce, nonceTime + TWO_HOUR);
    }

    // simulate a database that store all nonce:
    private Set<String> nonceDb = new HashSet<String>();

    // check if nonce is exist in database:
    boolean isNonceExist(String nonce) {
        return nonceDb.contains(nonce);
    }

    // store nonce in database:
    void storeNonce(String nonce, long expires) {
        nonceDb.add(nonce);
    }

    long getNonceTime(String nonce) {
        try {
            return new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ssZ")
                    .parse(nonce.substring(0, 19) + "+0000")
                    .getTime();
        }
        catch(ParseException e) {
            throw new OpenIdException("Bad nonce time.");
        }
    }
}