<?PHP
/**
 * patTemplate modfifier Dateformat
 *
 * $Id$
 *
 * @package     patTemplate
 * @package     Modifiers
 * @author      gERD Schaufelberger <gerd@php-tools.net>
 */

/**
 * patTemplate modfifier Dateformat
 *
 * Formats dates and times according to a format string and locale settings.
 * This modifier is derived from the original one extended with capability 
 * to calculate offsets according to timezone.
 *
 * Possible attributes are:
 * - format (string)
 * - unix (bool) if not empty, return unix timestamp
 * - dateinterval (string) see https://www.php.net/manual/en/dateinterval.construct.php also accepts "-" prefix
 * - adjustoffset (string, default "auto")
 *    auto: add offset according to timezone
 *    any number: add seconds
 *
 * See locale settings in "locale.xml"
 *
 * See the PHP documentation for strftime() for
 * more information.
 *
 * @package     patTemplate
 * @package     Modifiers
 * @author      gERD Schaufelberger <gerd@php-tools.net>
 */
class patTemplate_Modifier_Dateformat extends patTemplate_Modifier
{
    /**
     * configured timezone
     * @var DateTimeZone
     */
    static private $timezone;
    
    /**
     * start timezone object 
     */
    static public function staticConstruct()
    {
        $conf   =   WBClass::create('WBConfig');
        $conf->load('locale');
        self::$timezone =   new DateTimeZone($conf->get('locale/timezone', 'UTC'));
    }
    
    /**
     * modify the value
     * 
     * Format date time. The input value may either be a unix timestamp or ISO 
     * date as used in MySQL. All input values are supposed to be UTC.
     * 
     * In case the input value contains hours and minutes (not just the date), 
     * local time offset will be added. See local settings in etc/locale.xml
     *
     * @access	public
     * @param	string		value
     * @return	string		modified value
     */
	public function modify($value, $params = array())
	{
        $adjustTimeOffset  =   false;
        
        // convert unix timestamp to ISO date
	    if (preg_match('/^[0-9]+$/', $value)) {
            $value              =   gmdate('Y-m-d H:i:s', $value);
            $adjustTimeOffset   =   true;
	    }
        if (preg_match('/\d\d:\d\d/', $value, $match)) {
            $adjustTimeOffset   =   true;
        }

        $params =   array_merge(array(
                    'adjustoffset'  =>  'auto',
                    'dateinterval'  =>  '',
                    'unix'          =>  '',
                    'format'        =>  ''


            ), $params);

        // init timezone
        if (empty(self::$timezone)) {
            self::staticConstruct();
        }
        try{
            $date   =   new DateTime($value);
        }
        catch (Exception $e) {
            return $value;
        }

        // date interval
        if (!empty($params['dateinterval'])) {
            if ('-' == $params['dateinterval'][0]) {
                $di =   new DateInterval(substr($params['dateinterval'], 1));
                $date->sub($di);
            }
            else {
                $di =   new DateInterval($params['dateinterval']);
                $date->add($di);
            }
        }

        $ts     =   intval($date->format('U'));
        
        // return unix timestamp
        if ('yes' == $params['unix']) {
            return $ts;
        }

        if ($adjustTimeOffset) {
            $offset =   $params['adjustoffset'];
            if ('auto' == $offset) {
                $offset =   self::$timezone->getOffset($date);
            }
            else if (is_numeric($offset)) {
                $offset =   intval($offset);
            }
            else {
                $offset =   0;
            }
            $ts +=  $offset;
        } 
        
        // in case there is no format string, return in unix timestamp format
        if (empty($params['format'])) {
            return $ts;
        }

        // apply format
        return strftime($params['format'], $ts);
	}
}