/*
 * 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.http.www;

import com.juick.server.UserQueries;
import java.io.IOException;
import java.net.URLEncoder;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.UUID;
import javax.servlet.ServletException;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.json.JSONException;
import org.json.JSONObject;

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

    private static final String VK_APPID = "3544101";
    private static final String VK_SECRET = "z2afNI8jA5lIpZ2jsTm1";
    private static final String VK_REDIRECT = "http://juick.com/_vklogin";

    protected void doGet(Connection sql, HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        String code = request.getParameter("code");
        if (code == null || code.equals("")) {
            response.setStatus(HttpServletResponse.SC_MOVED_TEMPORARILY);
            response.setHeader("Location", "https://oauth.vk.com/authorize?client_id=" + VK_APPID + "&redirect_uri=" + URLEncoder.encode(VK_REDIRECT, "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, "utf-8") + "&client_secret=" + VK_SECRET + "&code=" + URLEncoder.encode(code, "utf-8"));
        if (tokenjson == null || tokenjson.isEmpty()) {
            System.err.println("VK TOKEN EMPTY");
            response.setStatus(HttpServletResponse.SC_INTERNAL_SERVER_ERROR);
            return;
        }
        String token = null;
        long vkID = 0;
        try {
            JSONObject json = new JSONObject(tokenjson);
            token = json.getString("access_token");
            vkID = json.getLong("user_id");
        } catch (JSONException e) {
            System.err.println("VK TOKEN EXCEPTION: " + e);
            response.setStatus(HttpServletResponse.SC_INTERNAL_SERVER_ERROR);
            return;
        }
        if (token == null || vkID == 0) {
            System.err.println("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()) {
            System.err.println("VK GRAPH ERROR");
            response.setStatus(HttpServletResponse.SC_INTERNAL_SERVER_ERROR);
            return;
        }

        try {
            JSONObject json = new JSONObject(graph).getJSONArray("response").getJSONObject(0);
            String vkName = json.getString("first_name") + " " + json.getString("last_name");
            String vkLink = json.getString("screen_name");

            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) {
            System.err.println("JSON ERROR: " + e);
            response.setStatus(HttpServletResponse.SC_INTERNAL_SERVER_ERROR);
            return;
        }
    }

    private int getUIDbyVKID(Connection sql, long vkID) {
        int uid = 0;
        PreparedStatement stmt = null;
        ResultSet rs = null;
        try {
            stmt = sql.prepareStatement("SELECT user_id FROM vk WHERE vk_id=? AND user_id IS NOT NULL");
            stmt.setLong(1, vkID);
            rs = stmt.executeQuery();
            if (rs.first()) {
                uid = rs.getInt(1);
            }
        } catch (SQLException e) {
            System.err.println(e);
        } finally {
            Utils.finishSQL(rs, stmt);
        }
        return uid;
    }

    private boolean insertDB(Connection sql, long vkID, String loginhash, String token, String vkName, String vkLink) {
        boolean ret = false;
        PreparedStatement stmt = null;
        try {
            stmt = sql.prepareStatement("INSERT INTO vk(vk_id,loginhash,access_token,vk_name,vk_link) VALUES (?,?,?,?,?)");
            stmt.setLong(1, vkID);
            stmt.setString(2, loginhash);
            stmt.setString(3, token);
            stmt.setString(4, vkName);
            stmt.setString(5, vkLink);
            stmt.executeUpdate();
            ret = true;
        } catch (SQLException e) {
            System.err.println(e);
        } finally {
            Utils.finishSQL(null, stmt);
        }
        return ret;
    }
}