<?php
/*
 * getCalendarArray
 * Coprying (C) 2011 Pavel Shub
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or any later version.
 */

/**
 * getCalendarArray generates an array that is a multiple of 7 and can
 * visually represent the current month including the last days of the last
 * month and start days of the next month in a grid display. Each cell of the returned array contains
 * an associative array with the following indecies:
 *  day - day of the month (1-31)
 *  month - month of year (1-12)
 *  year - e.g. 2012
 *  specified - boolean set to true if this is today's date
 *
 * @param Mixed $date - string date that can be passed to a php DateTime constructor or a DateTime object
 * @param Int $dao_adj - integer 0-6 which indicates which day of the week the calendar should start on
 * 						 0 - Sunday, 1 - Monday .... 6 - Saturday
 * @throws Exception if day of week adjustment isn't 0-6 then an exception is thrown.
 * @return single dimensional array of associative arrays representing a day of the calendar year
 */
function getCalendarArray($date = null, $dao_adj = 0){
	if($dao_adj > 6 || $dao_adj < 0){
		throw new Exception("Invalid starting day of the week parameter");
	}
	if ($date instanceof DateTime) {
		$d = $date;
	}
	else {
		$d = new DateTime($date);
	}
	$dm = array(31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31); // all days of the month
	$vals = explode(" ", $d->format('w j L n Y'));
	// 0 - day of the week
	// 1 - day of the month
	// 2 - leap year
	// 3 - month of year
	// 4 - year
	$dm[1] += $vals[2]; // leap year adjustment for February
	$day_of_week = ($vals[0] + $dao_adj*6) % 7;
	$first_day = ($day_of_week + ($vals[1]-1)*6) % 7; // 0 - 7

	$previous_month = (($vals[3] + 10) % 12)+1; // 1 - 12
	$last_month_days = $dm[$previous_month-1]; // 28 -31
	$next_month = ($vals[3] % 12)+1; // 1 - 12

	$calendar = array();
	// calcuate days of the previous month
	for($i = 0; $i < $first_day; $i++){
		$calendar[] = array('day' => $last_month_days - ($first_day - $i - 1),
				'month' => $previous_month,
				'year' => (int)($previous_month != 12 ? $vals[4] : $vals[4]-1),
				'specified' => false);
	}

	// calculate days of the current month
	for($i = 0; $i < $dm[$vals[3]-1]; $i++) {
		$calendar[] = array('day'=>$i+1,
		'month'=>(int)$vals[3],
		'year' => (int)($vals[4]),
		'specified' => $vals[1] == $i+1 ? true : false);
	}

	// calculate days of the future month
	$length = count($calendar);
	if (($length  % 7) > 0) {
		for ($i = 1; $i < ((7-($length  % 7))+1); $i++){
			$calendar[] = array('day'=>$i,
			'month' => $next_month,
			'year' => (int)($next_month != 1 ? $vals[4]: $vals[4]+1),
			'specified' => false);
		}
	}
	return $calendar;
}