/*
 * 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.fasterxml.jackson.annotation.JsonInclude;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.juick.server.UserQueries;
import com.juick.www.vk.Token;
import com.juick.www.vk.UsersResponse;
import org.apache.commons.lang3.CharEncoding;
import org.apache.commons.lang3.StringUtils;
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 VKontakteLogin {
    private static final Logger logger = LoggerFactory.getLogger(VKontakteLogin.class);
    private static final String VK_APPID = "3544101";
    private static final String VK_SECRET = "z2afNI8jA5lIpZ2jsTm1";
    private static final String VK_REDIRECT = "http://juick.com/_vklogin";

    public VKontakteLogin() {
        mapper = new ObjectMapper();
        mapper.setSerializationInclusion(JsonInclude.Include.NON_EMPTY);
        mapper.setSerializationInclusion(JsonInclude.Include.NON_NULL);
        mapper.setSerializationInclusion(JsonInclude.Include.NON_DEFAULT);
    }

    private final ObjectMapper mapper;

    protected void doGet(JdbcTemplate sql, HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        String code = request.getParameter("code");
        if (StringUtils.isBlank(code)) {
            response.setStatus(HttpServletResponse.SC_MOVED_TEMPORARILY);
            response.setHeader("Location", "https://oauth.vk.com/authorize?client_id=" + VK_APPID + "&redirect_uri=" + URLEncoder.encode(VK_REDIRECT, CharEncoding.UTF_8) + "&scope=friends,wall,offline&response_type=code");
            return;
        }


        String tokenjson = Utils.fetchURL("https://oauth.vk.com/access_token?client_id=" + VK_APPID + "&redirect_uri=" + URLEncoder.encode(VK_REDIRECT, CharEncoding.UTF_8) + "&client_secret=" + VK_SECRET + "&code=" + URLEncoder.encode(code, CharEncoding.UTF_8));
        if (tokenjson == null || tokenjson.isEmpty()) {
            logger.error("VK TOKEN EMPTY");
            response.setStatus(HttpServletResponse.SC_INTERNAL_SERVER_ERROR);
            return;
        }
        String token = null;
        long vkID = 0;
        Token json = mapper.readValue(tokenjson, Token.class);
        token = json.getAccessToken();
        vkID = json.getUserId();
        if (token == null || vkID == 0) {
            logger.error("VK TOKEN EMPTY: {}", tokenjson);
            response.setStatus(HttpServletResponse.SC_INTERNAL_SERVER_ERROR);
            return;
        }

        String graph = Utils.fetchURL("https://api.vk.com/method/users.get?uids=" + vkID + "&fields=screen_name&access_token=" + token);
        if (graph == null || graph.isEmpty()) {
            logger.error("VK GRAPH ERROR");
            response.setStatus(HttpServletResponse.SC_INTERNAL_SERVER_ERROR);
            return;
        }

        try {
            com.juick.www.vk.User jsonUser = mapper.readValue(graph, UsersResponse.class).getUsers().get(0);
            String vkName = jsonUser.getFirstName() + " " + jsonUser.getLastName();
            String vkLink = jsonUser.getScreenName();

            if (vkName == null || vkLink == null || vkName.isEmpty() || vkName.length() == 1 || vkLink.isEmpty()) {
                throw new Exception();
            }

            int uid = getUIDbyVKID(sql, vkID);
            if (uid > 0) {
                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 {
                String loginhash = UUID.randomUUID().toString();
                if (!insertDB(sql, vkID, loginhash, token, vkName, vkLink)) {
                    throw new Exception();
                }
                response.setStatus(HttpServletResponse.SC_MOVED_TEMPORARILY);
                response.setHeader("Location", "/signup?type=vk&hash=" + loginhash);
            }
        } catch (Exception e) {
            logger.error("JSON ERROR", e);
            response.setStatus(HttpServletResponse.SC_INTERNAL_SERVER_ERROR);
        }
    }

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

    private boolean insertDB(JdbcTemplate sql, long vkID, String loginhash, String token, String vkName, String vkLink) {
        return sql.update("INSERT INTO vk(vk_id,loginhash,access_token,vk_name,vk_link) VALUES (?,?,?,?,?)",
                vkID, loginhash, token, vkName, vkLink) > 0;
    }
}