define_tag(
	'grid',
	-namespace='calendar_',
	-opt='id', -type='string',
	-opt='startdate', -type='date', -copy,
	-opt='numweeks', -type='integer',
	-opt='firstday', -type='string', -copy,
	-opt='dayformat', -type='string', -copy,
	-opt='daylink', -type='string', -copy,
	-opt='showweekends', -type='boolean',
	-opt='showheader', -type='boolean',
	-opt='target', -type='string',
	-opt='events', -type='array', -copy,
	-priority='replace',
	-description='Generates a calendar grid.'
);		
	// sort the events array if one was provided
	local_defined('events') ? #events->sort;

	// create an iterator for the events array
	local_defined('events') ? local('eventcursor') = #events->iterator;
	
	// if there's no start date provided, set it to today
	!local_defined('startdate') ? local('startdate' = date);
	
	// retain the current month
	local('currentmonth') = #startdate->month;
	
	// override whatever time is specified in #startdate with 
	// a value that will remain safe from DST issues.
	#startdate->set( -hour=14, -minute=0, -second=0);
	
	// if numweeks is not defined, go to end of current month
	if(!local_defined('numweeks'));
		local('startweek') = integer(#startdate->format('%W'));

		// 'week of year' apparently starts on Monday, so if startdate is a Sunday, add one
		integer(#startdate->format('%w')) == 1 ? #startweek += 1;			

		// find the last day of the current month
		local('endofmonth') = date(#startdate->format('%Y') + '-' + #startdate->format('%m') + '-' + lp_date_monthlastday(#startdate)  + ' 14:00:00');

		// get the week number
		local('endweek') = integer(#endofmonth->format('%W'));
		
		// 'week of year' apparently starts on Monday, so if endofmonth is a Sunday, add one
		integer(#endofmonth->format('%w')) == 1 ? #endweek += 1;			
		
		// subtract the difference and add one to get the correct number of weeks
		local('numweeks') = #endweek - #startweek + 1;		
	/if;
	
	// make sure dayformat is valid
	!local_defined('dayformat') ? local('dayformat' = '%A');
	(: '%w', '%A', '%a') !>> #dayformat ? #dayformat = '%A';
	
	// default to showing weekends
	!local_defined('showweekends') ? local('showweekends' = true);

	// default to showing a header
	!local_defined('showheader') ? local('showheader' = true);

	// make sure firstday value is valid
	!local_defined('firstday') ? local('firstday' = 'Sunday');
	(: 'Sunday', 'Monday') !>> #firstday ? #firstday = 'Sunday';
	!#showweekends ? #firstday = 'Monday';
	local('firstDayNum') = (#firstday == 'Sunday' ? 1 | 2);
			
	// start generating output
	local('out' = '
	<table class="calendar"' + (local_defined('id') ? ' id="' + #id + '"') + '>
		<thead>\
	');
	
	// top label header
	#showheader ? #out += '
			<tr>
				<th colspan="' + (#showweekends ? 7 | 5) + '">' + #startdate->format('%B %Y') + '</th>
			</tr>\
	';
	
	#out += '
			<tr>\
	';

	// find the first day of the week
	#startdate = date_firstdayofweek(
		-date=#startdate, 
		-starton=#firstdayNum
	);

	// day of week headers
	local('hdrDate' = #startdate);
	
	// only loop 5 days if we aren't showing weekends
	loop((#showweekends ? 7 | 5));
		#out += '
				<th>' + #hdrDate->format(#dayformat) + '</th>\
		';

		// add a day
		#hdrDate->add( -day=1);
	/loop;

	#out += '
			</tr>
		</thead>
		<tbody>\
	';

	// weeks
	local(
		'thisDay' = #startdate,
		'thisDayNum' = integer,
		'thisDateNumber' = integer,
		'thisDayLink' = string,
		'classes' = array,
		'daysEvents' = string
	);

	
	// loop 7 days, even if we're not showing weekends
	loop(#numweeks * 7);
		#thisDayNum = integer(#thisDay->format('%w'));
	
		// if we aren't showing weekends, skip them
		if(!#showweekends && (: 1, 7) >> #thisDayNum);
			// still need to add a day
			#thisDay->add( -day=1);			
			loop_continue;
		/if;
	
		// start a new row at the beginning of each week
		if(#thisDayNum == #firstdayNum);
			// close the previous row unless this is the first one
			loop_count > 1 ? #out += '
			</tr>\
			';

			#out += '
			<tr>\
			';
		/if;
					
		// determine which classes to apply
		#classes = array;
		#thisDay->month == #currentmonth ? #classes->insert('currentMonth');
		#thisDay->format('%D') == date->format('%D') ? #classes->insert('today');
		local_defined('events') ? #events->find(match_regexp(#thisDay->format('%Q') + '( [0-9]{1,2}:[0-9]{1,2}:[0-9]{1,2})?'))->size ? #classes->insert('hasEvents');
		
		// create link from individual days
		#thisDateNumber = #thisDay->format('%d');
		#thisDayLink = #thisDateNumber;
		local_defined('daylink') ? #thisDayLink = '<a href="' + string_replace(#daylink, -find='%d', -replace=#thisDay->format('%Q')) + '"' + (local_defined('target') ? ' target="' + #target + '"') + '>' + #thisDateNumber + '</a>';
		
		// add the day
		#out += '
				<td' + (#classes->size ? ' class="' + #classes->join(' ') + '"') + '>
					<div>' + #thisDayLink + '</div>\
		';
		
		// add the day's events
		if(local_defined('events'));
			while( !#eventcursor->atend && date(#eventcursor->value->first) < date(#thisDay->format('%D'))->add( -day=1)& );
				date(#eventcursor->value->first) >= date(#thisDay->format('%D')) ? #out += '
					<a href="' + #eventcursor->value->second->find('link') + '"' + (local_defined('target') ? ' target="' + #target + '"') + '>' + #eventcursor->value->second->find('title') + '</a>\
				';
				
				null(#eventcursor->forward);
			/while;		
		/if;
							
		#out += '
				</td>\	
		';

		// add a day
		#thisDay->add( -day=1);
	/loop;
	
	// close out last row
	#out += '
			</tr>
		</tbody>
	</table>\
	';

	// return the result
	return(@#out);
/define_tag;