date_1.php

<?php
class Date {
    protected $CI;
    private $db_default_timezone;

    public function __construct()
    {
        $this->CI =& get_instance();
        $this->_getDefaultTimestamp();
    }

    /**
     * Converte data vinda da base de dados em timestamp
     *
     * @param $date data no formato Y-m-d H:i:s
     * @return int Timestamp
     */
    public function dateDbToTimestamp($date){
        $date = new DateTime($date, new DateTimeZone($this->db_default_timezone));
        return $date->getTimestamp();
    }

    /**
     * Converte timestamp para Base de Dados
     *
     * @param $timestamp
     * @return string data no formato Y-m-d H:i:s
     */
    public function timestampToDateDb($timestamp){
        $date = new DateTime(date('Y-m-d H:i:s',$timestamp),
                new DateTimeZone($this->db_default_timezone));

        return $date->format('Y-m-d H:i:s');
    }

    /**
     * Coloca na variavel privada $db_default_timezone o Timezone da base de dados
     */
    private function _getDefaultTimestamp(){
        $this->CI->config->load('gfitness');
        $this->db_default_timezone = $this->CI->config->item('db_default_timezone');
    }
}