<?php
class Database
{
    /* Singleton ***********************************/
    private static $instance;

    public static function init($name, $server, $user, $password)
    {
        self::$instance = new Database($name, $server, $user, $password);
    }

    public static function get()
    {
        if(!self::$instance->is_open()) self::$instance->open();
        return self::$instance;
    }

    /* Instance ***********************************/
    private $name, $server, $user, $password = '';
    private $connection = NULL;

    public function Database($name, $server, $user, $password)
    {
        $this->name = $name;
        $this->server = $server;
        $this->user = $user;
        $this->password = $password;
    }

    public function is_open()
    {
        return ($this->connection != NULL);
    }

    public function open()
    {
        $this->connection = mysql_connect($this->server, $this->user, $this->password) or $this->dump_error('none');
        mysql_select_db($this->name, $this->connection) or die('Database "' . $this->name . '" does not exist! Contact system administrator.');
    }

    public function close()
    {
        if($this->connection != NULL)
        {
            mysql_close($this->connection);
            $this->connection = NULL;
        }
    }

    public function row($query)
    {
        $result = mysql_query($query, $this->connection) or $this->dump_error($query);
        if(mysql_num_rows($result) > 0)
        {
            return mysql_fetch_assoc($result);
        }
        else
        {
            return NULL;
        }
    }

    public function rows($query)
    {
        $result = mysql_query($query, $this->connection) or $this->dump_error($query);
        $rows = array();
        if(mysql_num_rows($result) > 0)
        {
            while($row = mysql_fetch_assoc($result))
            {
                $rows[] = $row;
            }
        }
        return $rows;
    }

    public function execute($query)
    {
        return mysql_query($query, $this->connection) or $this->dump_error($query);
    }

    public function last_inserted_id()
    {
        return mysql_insert_id($this->connection);
    }

    private function dump_error($query)
    {
        ?>

        <div id="error">
            <h3>Database error!</h3>
            <p><strong>Query:</strong> <em><?=$query?></em></p>
            <p><strong>Message:</strong> <em><?=mysql_error()?></em></p>
        </div>

        <?php
    }
}
?>