public class Core extends JavaPlugin implements Listener {

    public static Connection connection;
    public static Core instance;

    public void onEnable(){
        instance = this;
        getServer().getPluginManager().registerEvents(this, this);
    }

    public void onDisable(){
        try {
            if (connection != null && connection.isClosed())
                connection.close();
        }catch (SQLException e){
            e.printStackTrace();
        }
    }

    public synchronized static void openConnection(){
        try {
            connection = DriverManager.getConnection("jdbc:mysql://sql6.freesqldatabase.com:3306/sql6142980", "sql6142980", "YXH5m6ikp8");

        }catch (Exception e){
            e.printStackTrace();
        }
    }
    public synchronized static void closeConnection(){
        try {
            connection.close();
        }catch (Exception e){
            e.printStackTrace();
        }
    }

    public synchronized static boolean playerDataContainsPlayer(Player player){
        try {
            PreparedStatement sql = connection.prepareStatement("SELECT * FROM `player_data` WHERE player=?;");
            sql.setString(1, player.getName());
            ResultSet resultSet = sql.executeQuery();
            boolean containsPlayer = resultSet.next();

            sql.close();
            resultSet.close();

            return containsPlayer;

        }catch (Exception e){
            e.printStackTrace();
            return false;
        }


    }

    @EventHandler
    public void onPlayerLogin(PlayerLoginEvent event){
        openConnection();
        try {
            int previousLogins = 0;
            if(playerDataContainsPlayer(event.getPlayer())){
                PreparedStatement sql = connection.prepareStatement("SELECT logins FROM `player_data` WHERE player=?;");
                sql.setString(1, event.getPlayer().getName());

                ResultSet result = sql.executeQuery();
                result.next();

                previousLogins = result.getInt("logins");

                PreparedStatement loginsUpdate = connection.prepareStatement("UPDATE `player_data` SET logins=? WHERE player=?;");
                loginsUpdate.setInt(1, previousLogins + 1);
                loginsUpdate.setString(2, event.getPlayer().getName());
                loginsUpdate.executeUpdate();
                loginsUpdate.close();
                sql.close();
                result.close();
            }else{
                PreparedStatement newPlayer = connection.prepareStatement("INSERT INTO `player_data` values(?,0,0,0,1);");
                newPlayer.setString(1, event.getPlayer().getName());
                newPlayer.execute();
                newPlayer.close();

                PreparedStatement newCoins = connection.prepareStatement("INSERT INTO `player_data` values(?,0,0,0,0);");
                newCoins.setString(1, event.getPlayer().getName());
                newCoins.setInt(2, 0);
                newCoins.execute();
                newCoins.close();
            }
        }catch (Exception e){
            e.printStackTrace();
        }finally {
            closeConnection();
        }
    }

}