<?php

// Class: Calendar
//
// Display calendars with optional events.
class Calendar {

	// Section: Introduction

	// Topic: Legal
	//
	// Copyright (C) 2007 Stephane Lavergne <http://www.imars.com/>
	//
	// This program is free software: you can redistribute it and/or modify it
	// under the terms of the GNU General Public License as published by the
	// Free Software Foundation, either version 3 of the License, or (at your
	// option) any later version.
	//
	// This program is distributed in the hope that it will be useful, but
	// *WITHOUT ANY WARRANTY*; without even the implied warranty of
	// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General
	// Public License for more details.
	//
	// You should have received a copy of the GNU General Public License along
	// with this program. If not, see <http://www.gnu.org/licenses/>.

	// Topic: TODO
	// 
	// Implement <XHTML()>'s year mode.

	// Topic: Description
	//
	// This class specifically addresses the issue of displaying calendars of
	// various kinds, possibly with events involved. It is *not* an events
	// manager.
	//
	// Example:
	//
	// > require_once 'Calendar.inc';
	// > $cal = new Calendar();
	// > echo $cal->XHTML();
	//
	// TODO:
	//
	// There is still no linking nor pop-up possibilities. Year view is not yet
	// implemented.
	//

	// My private properties.
	var $weekstart;
	var $monthstart;
	var $events;
	var $days;
	var $ds;
	var $months;

	// Group: Methods

	// Constructor: Calendar
	//
	// Instantiate the class. Note that this class is designed to be reusable
	// as many times as needed: once events are loaded with <AddEvent()>,
	// multiple calendars of any kind can be generated with that same
	// instance. This could be useful, for example, to load a single list of
	// events to display a current month in <XHTML()>'s 'full' mode along with
	// the previous and next months in its 'compact' mode.
	//
	// Parameters:
	//  $weekstart  - Which day (0-6) to start weeks at. (Optional.)
	//  $monthstart - Which month (1-12) to start year at. (Optional.)
	//
	function Calendar($weekstart = 0, $monthstart = 1) {
		$this->weekstart = $weekstart;
		$this->monthstart = $monthstart;
		$this->SetDays('Sunday','Monday','Tuesday','Wednesday','Thursday','Friday','Saturday');
		$this->SetMonths('January','February','March','April','May','June','July','August','September','October','November','December');
		$this->events = array();
	}

	// Method: SetDays
	//
	// Specify non-English day names. Single letter short versions will be
	// derived from this as well.
	//
	// Parameters:
	//  $sun - String to identify Sunday.
	//  $mon - String to identify Monday.
	//  $tue - String to identify Tuesday.
	//  $wed - String to identify Wednesday.
	//  $thu - String to identify Thursday.
	//  $fri - String to identify Friday.
	//  $sat - String to identify Saturday.
	//
	// Returns:
	//
	// Always returns true.
	//
	function SetDays($sun, $mon, $tue, $wed, $thu, $fri, $sat) {
		$this->days = array($sun, $mon, $tue, $wed, $thu, $fri, $sat);
		$this->ds = array();
		foreach ($this->days as $day) {
			array_push($this->ds, substr($day,0,1));
		};
		return(true);
	}

	// Method: SetMonths
	//
	// Specify non-English month names.
	//
	// Parameters:
	//  $m1  - String to identify month 1  (January).
	//  $m2  - String to identify month 2  (February).
	//  $m3  - String to identify month 3  (March).
	//  $m4  - String to identify month 4  (April).
	//  $m5  - String to identify month 5  (May).
	//  $m6  - String to identify month 6  (June).
	//  $m7  - String to identify month 7  (July).
	//  $m8  - String to identify month 8  (August).
	//  $m9  - String to identify month 9  (September).
	//  $m10 - String to identify month 10 (October).
	//  $m11 - String to identify month 11 (November).
	//  $m12 - String to identify month 12 (December).
	//
	// Returns:
	//
	// Always returns true.
	//
	function SetMonths($m1, $m2, $m3, $m4, $m5, $m6, $m7, $m8, $m9, $m10, $m11, $m12) {
		$this->months = array($m1, $m2, $m3, $m4, $m5, $m6, $m7, $m8, $m9, $m10, $m11, $m12);
		return(true);
	}

	// Method: AddEvent
	//
	// Add an event to the in-memory calendar, for a specific date. Optional
	// start and stop times may be specified as well as a long description.
	//
	// Internally, events are sorted as they are added, so that displaying can
	// be quick and repeatable. For each day, timeless events are added in
	// the order in which they were added. Next, events with start times are
	// sorted in chronological order. If two events start at the same time,
	// they are sorted in the order in which they were added.
	//
	// Parameters:
	//  $year      - Event's year (4-digit format).
	//  $month     - Event's month in the year (1-12).
	//  $day       - Event's day of the month (1-31).
	//  $class     - CSS class to highlight the day with. (Used in display methods.)
	//  $title     - Short description of the event.
	//  $starttime - Start time in "hh:mm" format. (Optional.)
	//  $stoptime  - Stop time in "hh:mm" format. (Optional, even when $starttime is defined.)
	//  $body      - Long description of the event. (Optional.)
	//
	// Returns:
	//
	// Always returns true.
	//
	function AddEvent($year, $month, $day, $class, $title, $starttime = null, $stoptime = null, $body = null) {
		if (!is_array($this->events[$year])) $this->events[$year] = array();
		if (!is_array($this->events[$year][$month])) $this->events[$year][$month] = array();
		if (!is_array($this->events[$year][$month][$day])) $this->events[$year][$month][$day] = array();
		$idx = 0;
		foreach ($this->events[$year][$month][$day] as $key => $event) {
			if ($event['start'] == null) $idx = $key;
			elseif ($event['start'] <= $starttime) $idx = $key;
		};
		array_splice($this->events[$year][$month][$day], $idx+1, 0, array(array(
			'start' => $starttime,
			'stop' => $stoptime,
			'class' => $class,
			'title' => $title,
			'body' => $body,
		)));
		return(true);
	}

	// Method: XHTML
	//
	// Display a calendar in XHTML 1.1 Strict. Each mode returns a different
	// kind of calendar. In each case, it is up to the caller to use some CSS
	// to achieve the desired display characteristics.
	//
	// Compact mode:
	//
	// A table of class 'calendar_compact' is generated. First, a row of
	// headers lists the first letters of each day of the week. Next, as many
	// rows of cells as necessary are generated to contain actual days. Each
	// day cell which is within the current month gets attributed a class, one
	// of:
	//
	//  weekday  - By default, days 1-5 receive this class.
	//  weekend  - By default, days 0 and 6 receive this class.
	//  today    - By default, the current day gets this class.
	//
	// If there are events for a day, the class of the day's first event (see
	// <AddEvent()> for sort order) is used instead of one of the above.
	//
	// Full mode:
	//
	// A table of class 'calendar_full' is generated. First, a row of headers
	// lists the full names of each day of the week. Next, as many rows of
	// cells as necessary are generated to contain actual days. Like compact
	// mode, each day cell can be of class 'weekday', 'weekend', or 'today'. 
	// However, cells are not directly affected by events, as they contain a
	// list of the day's events in this mode.
	//
	// For each event, in order (see <AddEvent()> for sort order), a div of
	// class 'event' is created. Inside, first a span containing a small space
	// is displayed, member of the event's class. This is intended for
	// color-coding. Next, the event's short title is displayed.
	//
	// Year mode:
	//
	// NOT YET IMPLEMENTED. This will essentially call itself 12 times in
	// compact mode, starting with <$monthstart>. I believe 12 tables in a row
	// would wrap according to their containing block, but some testing should
	// confirm this.
	//
	// Parameters:
	//  $mode - One of: compact, full, year. (Optional.)
	//  $year - 4-digit year. (Optional.)
	//  $month - Month (1-12). (Optional.)
	//
	// Returns:
	//
	// The generated XHTML code ready to output.
	//
	function XHTML($mode = 'compact', $year = null, $month = null) {
		$out = '';
		if ($year == null) {
			$d = getdate();
			$year = $d['year'];
			$month = $d['mon'];
		};
		$today = getdate();

		switch ($mode) {

			// Compact, highlighted month view.
			case 'compact':
				$length = $this->mlength($month, $year);
				$startday = $this->mstart($month, $year);

				$out .= "<table class=\"calendar_compact\">\n";

				$out .= "\t<tr>";
				for ($i=0; $i < 7; $i++) $out .= "<th>". $this->ds[($this->weekstart + $i) % 7] ."</th>";
				$out .= "</tr>\n";

				$current = 1;
				while ($current < $length) {
					$out .= "\t<tr>\n";
					for ($i=0; $i < 7; $i++ ) {
						$wday = ($this->weekstart + $i) % 7;
						if ((($current == 1) && ($wday != $startday))  ||  ($current > $length)) {
							$out .= "\t\t<td>&nbsp;</td>\n";
						} else {
							$class = 'weekday';
							if (is_array($this->events[$year][$month][$current])) {
								// Class for the day is that of first event found.
								$class = $this->events[$year][$month][$current][0]['class'];
							} elseif ($i == 0  ||  $i == 6) $class = 'weekend';
							if ($year == $today['year']  &&  $month == $today['mon']  &&  $current == $today['mday']) $class = 'today';
							$out .= "\t\t<td class=\"$class\">$current</td>\n";
							$current++;
						};
					};
					$out .= "\t</tr>\n";
				};

				$out .= "</table>\n";
			break;

			// Full size month view.
			case 'full':
				$length = $this->mlength($month, $year);
				$startday = $this->mstart($month, $year);

				$out .= "<table class=\"calendar_full\">\n";

				$out .= "\t<tr>";
				for ($i=0; $i < 7; $i++) $out .= "<th>". $this->days[($this->weekstart + $i) % 7] ."</th>";
				$out .= "</tr>\n";

				$current = 1;
				while ($current < $length) {
					$out .= "\t<tr>\n";
					for ($i=0; $i < 7; $i++ ) {
						$wday = ($this->weekstart + $i) % 7;
						if ((($current == 1) && ($wday != $startday))  ||  ($current > $length)) {
							$out .= "\t\t<td>&nbsp;</td>\n";
						} else {
							$class = 'weekday';
							$events = false;
							if (is_array($this->events[$year][$month][$current])) {
								// Class for the day is that of first event found.
								$class = $this->events[$year][$month][$current][0]['class'];
								$events = true;
							} elseif ($i == 0  ||  $i == 6) $class = 'weekend';
							if ($year == $today['year']  &&  $month == $today['mon']  &&  $current == $today['mday']) $class = 'today';
							$out .= "\t\t<td class=\"$class\"><div class=\"number\">$current</div>\n";
							if ($events) foreach ($this->events[$year][$month][$current] as $event) {
								$out .= "\t\t\t<div class=\"event\"><span class=\"{$event['class']}\">&nbsp;</span>{$event['title']}</div>\n";
							};
							$out .= "\t\t</td>\n";
							$current++;
						};
					};
					$out .= "\t</tr>\n";
				};

				$out .= "</table>\n";
			break;

			// Compact, highlighted year view.
			case 'year':
			break;

			default:
				$out .= "Calendar::XHTML() ERROR: Unknown mode $mode.";
		};

		return($out);
	}

	function mlength($month, $year) {
		$result = 30;
		switch ($month) {
			case 1:
			case 3:
			case 5:
			case 7:
			case 8:
			case 10:
			case 12:
				$result = 31;
			break;

			case 4:
			case 6:
			case 9:
			case 11:
				$result = 30;
			break;

			case 2:
				// Those darn leap years.
				// CAUTION: I don't check the 4000 rule here. Seriously, this is 2006...
				if     ($year % 400  == 0) $result = 29;
				elseif ($year % 100  == 0) $result = 28;
				elseif ($year %   4  == 0) $result = 29;
				else $result = 28;
			break;

			default:
				echo "Calendar::mlength(): Unknown month $month.";
		};
		return($result);
	}

	function mstart($month, $year) {
		$d = getdate(mktime(0, 0, 0, $month, 1, $year));
		return($d['wday']);
	}

}

?>