/*
 * Juick
 * Copyright (C) 2008-2013, Ugnich Anton
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as
 * published by the Free Software Foundation, either version 3 of the
 * License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
package com.juick.www;

import com.juick.server.UserQueries;
import org.json.JSONObject;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.dao.EmptyResultDataAccessException;
import org.springframework.jdbc.core.JdbcTemplate;

import javax.servlet.ServletException;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.net.URLEncoder;
import java.util.UUID;

/**
 *
 * @author Ugnich Anton
 */
public class FacebookLogin {

    private static final Logger logger = LoggerFactory.getLogger(FacebookLogin.class);

    private final String FACEBOOK_APPID;
    private final String FACEBOOK_SECRET;
    private final String FACEBOOK_REDIRECT = "http://juick.com/_fblogin";

    public FacebookLogin(String ApplicationID, String secret) {
        this.FACEBOOK_APPID = ApplicationID;
        this.FACEBOOK_SECRET = secret;
    }

    protected void doGet(JdbcTemplate sql, HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        String fbstate;

        String code = request.getParameter("code");
        if (code == null || code.equals("")) {
            fbstate = UUID.randomUUID().toString();

            Cookie c = new Cookie("fbstate", fbstate);
            response.addCookie(c);

            response.setStatus(HttpServletResponse.SC_MOVED_TEMPORARILY);
            response.setHeader("Location", "https://www.facebook.com/dialog/oauth?scope=publish_stream&client_id=" + FACEBOOK_APPID + "&redirect_uri=" + URLEncoder.encode(FACEBOOK_REDIRECT, "utf-8") + "&state=" + fbstate);
            return;
        }

        fbstate = Utils.getCookie(request, "fbstate");
        if (fbstate == null || fbstate.isEmpty() || !fbstate.equals(request.getParameter("state"))) {
            response.setStatus(HttpServletResponse.SC_BAD_REQUEST);
            return;
        } else {
            Cookie c = new Cookie("fbstate", "-");
            c.setMaxAge(0);
            response.addCookie(c);
        }

        String token = Utils.fetchURL("https://graph.facebook.com/oauth/access_token?client_id=" + FACEBOOK_APPID + "&redirect_uri=" + URLEncoder.encode(FACEBOOK_REDIRECT, "utf-8") + "&client_secret=" + FACEBOOK_SECRET + "&code=" + URLEncoder.encode(code, "utf-8"));
        if (token == null || token.isEmpty() || !token.startsWith("access_token=")) {
            logger.error("FACEBOOK TOKEN ERROR: " + token);
            response.setStatus(HttpServletResponse.SC_INTERNAL_SERVER_ERROR);
            return;
        }
        token = token.substring(13); // access_token=...
        int tokenamp = token.indexOf('&'); // &expires=
        if (tokenamp > 0) {
            token = token.substring(0, tokenamp);
        }

        String graph = Utils.fetchURL("https://graph.facebook.com/me?access_token=" + token);
        if (graph == null || graph.isEmpty()) {
            logger.error("FACEBOOK GRAPH ERROR");
            response.setStatus(HttpServletResponse.SC_INTERNAL_SERVER_ERROR);
            return;
        }

        try {
            JSONObject json = new JSONObject(graph);
            String fbIDStr = json.getString("id");
            String fbName = json.getString("name");
            String fbLink = json.getString("link");
            boolean fbVerified = json.getBoolean("verified");

            long fbID = 0;
            if (fbIDStr != null && !fbIDStr.isEmpty()) {
                fbID = Long.parseLong(fbIDStr);
            }

            if (fbID == 0 || fbName == null || fbLink == null || fbName.isEmpty() || fbLink.isEmpty()) {
                throw new Exception();
            }

            int uid = getUIDbyFBID(sql, fbID);
            if (uid > 0) {
                if (!updateDB(sql, fbID, token, fbName, fbLink)) {
                    throw new Exception();
                }
                Cookie c = new Cookie("hash", UserQueries.getHashByUID(sql, uid));
                c.setMaxAge(50 * 24 * 60 * 60);
                response.addCookie(c);
                response.setStatus(HttpServletResponse.SC_MOVED_TEMPORARILY);
                response.setHeader("Location", "/");
            } else if (fbVerified) {
                String loginhash = UUID.randomUUID().toString();
                if (!insertDB(sql, fbID, loginhash, token, fbName, fbLink)) {
                    throw new Exception();
                }
                response.setStatus(HttpServletResponse.SC_MOVED_TEMPORARILY);
                response.setHeader("Location", "/signup?type=fb&hash=" + loginhash);
            } else {
                throw new Exception();
            }
        } catch (Exception e) {
            logger.error("fb error", e);
            response.setStatus(HttpServletResponse.SC_INTERNAL_SERVER_ERROR);
            return;
        }
    }

    private int getUIDbyFBID(JdbcTemplate sql, long fbID) {
        try {
            return sql.queryForObject("SELECT user_id FROM facebook WHERE fb_id=? AND user_id IS NOT NULL",
                    Integer.class, fbID);
        } catch (EmptyResultDataAccessException e) {
            return 0;
        }
    }

    private boolean insertDB(JdbcTemplate sql, long fbID, String loginhash, String token, String fbName, String fbLink) {
        return sql.update("INSERT INTO facebook(fb_id,loginhash,access_token,fb_name,fb_link) VALUES (?,?,?,?,?)",
                fbID, loginhash, token, fbName, fbLink) > 0;
    }

    private boolean updateDB(JdbcTemplate sql, long fbID, String token, String fbName, String fbLink) {
        return sql.update("UPDATE facebook SET access_token=?,fb_name=?,fb_link=? WHERE fb_id=?",
                token, fbName, fbLink, fbID) > 0;
    }
}