<?php
/**
ADOdb Date Library, part of the ADOdb abstraction library
Download: http://php.weblogs.com/adodb_date_time_library

PHP native date functions use integer timestamps for computations.
Because of this, dates are restricted to the years 1901-2038 on Unix 
and 1970-2038 on Windows due to integer overflow for dates beyond 
those years. This library overcomes these limitations by replacing the 
native function's signed integers (normally 32-bits) with PHP floating 
point numbers (normally 64-bits).

Dates from 100 A.D. to 3000 A.D. and later
have been tested. The minimum is 100 A.D. as <100 will invoke the
2 => 4 digit year conversion. The maximum is billions of years in the 
future, but this is a theoretical limit as the computation of that year 
would take too long with the current implementation of adodb_mktime().

This library replaces native functions as follows:

<pre>	
	getdate()  with  adodb_getdate()
	date()     with  adodb_date() 
	gmdate()   with  adodb_gmdate()
	mktime()   with  adodb_mktime()
	gmmktime() with  adodb_gmmktime()45
</pre>
	
The parameters are identical, except that adodb_date() accepts a subset
of date()'s field formats. Mktime() will convert from local time to GMT, 
and date() will convert from GMT to local time, but daylight savings is 
not handled currently.

This library is independant of the rest of ADOdb, and can be used
as standalone code.

PERFORMANCE

For high speed, this library uses the native date functions where
possible, and only switches to PHP code when the dates fall outside 
the 32-bit signed integer range.

GREGORIAN CORRECTION

Pope Gregory shortened October of A.D. 1582 by ten days. Thursday, 
October 4, 1582 (Julian) was followed immediately by Friday, October 15, 
1582 (Gregorian). 

Since 0.06, we handle this correctly, so:

adodb_mktime(0,0,0,10,15,1582) - adodb_mktime(0,0,0,10,4,1582) 
	== 24 * 3600 (1 day)

=============================================================================

COPYRIGHT

(c) 2003 John Lim and released under BSD-style license except for code by jackbbs,
which includes adodb_mktime, adodb_get_gmt_different, adodb_is_leap_year
and originally found at http://www.php.net/manual/en/function.mktime.php

=============================================================================

BUG REPORTS

These should be posted to the ADOdb forums at

	http://phplens.com/lens/lensforum/topics.php?id=4

=============================================================================

FUNCTION DESCRIPTIONS


FUNCTION adodb_getdate($date=false)

Returns an array containing date information, as getdate(), but supports
dates greater than 1901 to 2038.


FUNCTION adodb_date($fmt, $timestamp = false)

Convert a timestamp to a formatted local date. If $timestamp is not defined, the
current timestamp is used. Unlike the function date(), it supports dates
outside the 1901 to 2038 range.

The format fields that adodb_date supports:

<pre>
a - "am" or "pm" 
A - "AM" or "PM" 
d - day of the month, 2 digits with leading zeros; i.e. "01" to "31" 
D - day of the week, textual, 3 letters; e.g. "Fri" 
F - month, textual, long; e.g. "January" 
g - hour, 12-hour format without leading zeros; i.e. "1" to "12" 
G - hour, 24-hour format without leading zeros; i.e. "0" to "23" 
h - hour, 12-hour format; i.e. "01" to "12" 
H - hour, 24-hour format; i.e. "00" to "23" 
i - minutes; i.e. "00" to "59" 
j - day of the month without leading zeros; i.e. "1" to "31" 
l (lowercase 'L') - day of the week, textual, long; e.g. "Friday"  
L - boolean for whether it is a leap year; i.e. "0" or "1" 
m - month; i.e. "01" to "12" 
M - month, textual, 3 letters; e.g. "Jan" 
n - month without leading zeros; i.e. "1" to "12" 
O - Difference to Greenwich time in hours; e.g. "+0200" 
r - RFC 822 formatted date; e.g. "Thu, 21 Dec 2000 16:01:07 +0200" 
s - seconds; i.e. "00" to "59" 
S - English ordinal suffix for the day of the month, 2 characters; 
   			i.e. "st", "nd", "rd" or "th" 
t - number of days in the given month; i.e. "28" to "31"
T - Timezone setting of this machine; e.g. "EST" or "MDT" 
U - seconds since the Unix Epoch (January 1 1970 00:00:00 GMT)  
w - day of the week, numeric, i.e. "0" (Sunday) to "6" (Saturday) 
Y - year, 4 digits; e.g. "1999" 
y - year, 2 digits; e.g. "99" 
z - day of the year; i.e. "0" to "365" 
Z - timezone offset in seconds (i.e. "-43200" to "43200"). 
   			The offset for timezones west of UTC is always negative, 
			and for those east of UTC is always positive. 
</pre>

Unsupported:
<pre>
B - Swatch Internet time 
I (capital i) - "1" if Daylight Savings Time, "0" otherwise.
W - ISO-8601 week number of year, weeks starting on Monday 

</pre>


FUNCTION adodb_gmdate($fmt, $timestamp = false)

Convert a timestamp to a formatted GMT date. If $timestamp is not defined, the
current timestamp is used. Unlike the function date(), it supports dates
outside the 1901 to 2038 range.


FUNCTION adodb_mktime($hr, $min, $sec, $month, $day, $year)

Converts a local date to a unix timestamp.  Unlike the function mktime(), it supports
dates outside the 1901 to 2038 range. Differs from mktime() in that all parameters
are currently compulsory.

FUNCTION adodb_gmmktime($hr, $min, $sec, $month, $day, $year)

Converts a gmt date to a unix timestamp.  Unlike the function gmmktime(), it supports
dates outside the 1901 to 2038 range. Differs from gmmktime() in that all parameters
are currently compulsory.

=============================================================================

NOTES

Useful url for generating test timestamps:
	http://www.4webhelp.net/us/timestamp.php

Possible future optimizations include 

a. Using an algorithm similar to Plauger's in "The Standard C Library" 
(page 428, xttotm.c _Ttotm() function). Plauger's algorithm will not 
work outside 32-bit signed range, so i decided not to implement it.

b. Iterate over a block of years (say 12) when searching for the 
correct year.

c. Implement daylight savings, which looks awfully complicated, see
	http://webexhibits.org/daylightsaving/


CHANGELOG
- 3 March 2003 0.08
Added support for 'S' adodb_date() format char. Added constant ADODB_ALLOW_NEGATIVE_TS
if you want PHP to handle negative timestamps between 1901 to 1969.

- 27 Feb 2003 0.07
All negative numbers handled by adodb now because of RH 7.3+ problems.
See http://bugs.php.net/bug.php?id=20048&edit=2

- 4 Feb 2003 0.06
Fixed a typo, 1852 changed to 1582! This means that pre-1852 dates
are now correctly handled.

- 29 Jan 2003 0.05

Leap year checking differs under Julian calendar (pre 1582). Also
leap year code optimized by checking for most common case first.

We also handle month overflow correctly in mktime (eg month set to 13).

Day overflow for less than one month's days is supported.

- 28 Jan 2003 0.04

Gregorian correction handled. In PHP5, we might throw an error if 
mktime uses invalid dates around 5-14 Oct 1582. Released with ADOdb 3.10.
Added limbo 5-14 Oct 1582 check, when we set to 15 Oct 1582.

- 27 Jan 2003 0.03

Fixed some more month problems due to gmt issues. Added constant ADODB_DATE_VERSION.
Fixed calculation of days since start of year for <1970. 

- 27 Jan 2003 0.02

Changed _adodb_getdate() to inline leap year checking for better performance.
Fixed problem with time-zones west of GMT +0000.

- 24 Jan 2003 0.01

First implementation.
*/


/* Initialization */

/*
	Version Number
*/
define('ADODB_DATE_VERSION',0.08);

/*
	We check for Windows as only +ve ints are accepted as dates on Windows.
	
	Apparently this problem happens also with Linux, RH 7.3 and later!
	
	glibc-2.2.5-34 and greater has been changed to return -1 for dates <
	1970.  This used to work.  The problem exists with RedHat 7.3 and 8.0
	echo (mktime(0, 0, 0, 1, 1, 1960));  // prints -1
	
	References:
	 http://bugs.php.net/bug.php?id=20048&edit=2
	 http://lists.debian.org/debian-glibc/2002/debian-glibc-200205/msg00010.html
*/

if (!defined('ADODB_ALLOW_NEGATIVE_TS')) define('ADODB_NO_NEGATIVE_TS',1);

function adodb_date_test_date($y1,$m)
{
	//print " $y1/$m ";
	$t = adodb_mktime(0,0,0,$m,13,$y1);
	if ("$y1-$m-13 00:00:00" != adodb_date('Y-n-d H:i:s',$t)) {
		print "<b>$y1 error</b><br>";
		return false;
	}
	return true;
}
/**
	 Test Suite
*/
function adodb_date_test()
{
	
	error_reporting(E_ALL);
	print "<h4>Testing adodb_date and adodb_mktime. version=".ADODB_DATE_VERSION. "</h4>";
	set_time_limit(0);
	$fail = false;
	
	// This flag disables calling of PHP native functions, so we can properly test the code
	if (!defined('ADODB_TEST_DATES')) define('ADODB_TEST_DATES',1);
	
	print "<p>Testing gregorian <=> julian conversion<p>";
	$t = adodb_mktime(0,0,0,10,11,1492);
	//http://www.holidayorigins.com/html/columbus_day.html - Friday check
	if (!(adodb_date('D Y-m-d',$t) == 'Fri 1492-10-11')) print 'Error in Columbus landing<br>';
	
	$t = adodb_mktime(0,0,0,2,29,1500);
	if (!(adodb_date('Y-m-d',$t) == '1500-02-29')) print 'Error in julian leap years<br>';
	
	$t = adodb_mktime(0,0,0,2,29,1700);
	if (!(adodb_date('Y-m-d',$t) == '1700-03-01')) print 'Error in gregorian leap years<br>';
	
	print  adodb_mktime(0,0,0,10,4,1582).' ';
	print adodb_mktime(0,0,0,10,15,1582);
	$diff = (adodb_mktime(0,0,0,10,15,1582) - adodb_mktime(0,0,0,10,4,1582));
	if ($diff != 3600*24) print " <b>Error in gregorian correction = ".($diff/3600/24)." days </b><br>";
		
	print " 15 Oct 1582, Fri=".(adodb_dow(1582,10,15) == 5 ? 'Fri' : '<b>Error</b>')."<br>";
	print " 4 Oct 1582, Thu=".(adodb_dow(1582,10,4) == 4 ? 'Thu' : '<b>Error</b>')."<br>";
	
	print "<p>Testing overflow<p>";
	
	$t = adodb_mktime(0,0,0,3,33,1965);
	if (!(adodb_date('Y-m-d',$t) == '1965-04-02')) print 'Error in day overflow 1 <br>';
	$t = adodb_mktime(0,0,0,4,33,1971);
	if (!(adodb_date('Y-m-d',$t) == '1971-05-03')) print 'Error in day overflow 2 <br>';
	$t = adodb_mktime(0,0,0,1,60,1965);
	if (!(adodb_date('Y-m-d',$t) == '1965-03-01')) print 'Error in day overflow 3 '.adodb_date('Y-m-d',$t).' <br>';
	$t = adodb_mktime(0,0,0,12,32,1965);
	if (!(adodb_date('Y-m-d',$t) == '1966-01-01')) print 'Error in day overflow 4 '.adodb_date('Y-m-d',$t).' <br>';
	$t = adodb_mktime(0,0,0,12,63,1965);
	if (!(adodb_date('Y-m-d',$t) == '1966-02-01')) print 'Error in day overflow 5 '.adodb_date('Y-m-d',$t).' <br>';
	$t = adodb_mktime(0,0,0,13,3,1965);
	if (!(adodb_date('Y-m-d',$t) == '1966-01-03')) print 'Error in mth overflow 1 <br>';
	
	print "Testing 2-digit => 4-digit year conversion<p>";
	if (adodb_year_digit_check(00) != 2000) print "Err 2-digit 2000<br>";
	if (adodb_year_digit_check(10) != 2010) print "Err 2-digit 2010<br>";
	if (adodb_year_digit_check(20) != 2020) print "Err 2-digit 2020<br>";
	if (adodb_year_digit_check(30) != 2030) print "Err 2-digit 2030<br>";
	if (adodb_year_digit_check(40) != 1940) print "Err 2-digit 1940<br>";
	if (adodb_year_digit_check(50) != 1950) print "Err 2-digit 1950<br>";
	if (adodb_year_digit_check(90) != 1990) print "Err 2-digit 1990<br>";
	
	// Test string formating
	print "<p>Testing date formating</p>";
	$fmt = '\d\a\t\e T Y-m-d H:i:s a A d D F g G h H i j l L m M n O \R\F\C822 r s t U w y Y z Z 2003';
	$s1 = date($fmt,0);
	$s2 = adodb_date($fmt,0);
	if ($s1 != $s2) {
		print " date() 0 failed<br>$s1<br>$s2<br>";
	}
	flush();
	for ($i=100; --$i > 0; ) {

		$ts = 3600.0*((rand()%60000)+(rand()%60000))+(rand()%60000);
		$s1 = date($fmt,$ts);
		$s2 = adodb_date($fmt,$ts);
		//print "$s1 <br>$s2 <p>";
		$pos = strcmp($s1,$s2);

		if (($s1) != ($s2)) {
			for ($j=0,$k=strlen($s1); $j < $k; $j++) {
				if ($s1[$j] != $s2[$j]) {
					print substr($s1,$j).' ';
					break;
				}
			}
			print "<b>Error date(): $ts<br><pre> 
&nbsp; \"$s1\" (date len=".strlen($s1).")
&nbsp; \"$s2\" (adodb_date len=".strlen($s2).")</b></pre><br>";
			$fail = true;
		}
		
		$a1 = getdate($ts);
		$a2 = adodb_getdate($ts);
		$rez = array_diff($a1,$a2);
		if (sizeof($rez)>0) {
			print "<b>Error getdate() $ts</b><br>";
				print_r($a1);
			print "<br>";
				print_r($a2);
			print "<p>";
			$fail = true;
		}
	}
	
	// Test generation of dates outside 1901-2038
	print "<p>Testing random dates between 100 and 4000</p>";
	adodb_date_test_date(100,1);
	for ($i=100; --$i >= 0;) {
		$y1 = 100+rand(0,1970-100);
		$m = rand(1,12);
		adodb_date_test_date($y1,$m);
		
		$y1 = 3000-rand(0,3000-1970);
		adodb_date_test_date($y1,$m);
	}
	print '<p>';
	$start = 1960+rand(0,10);
	$yrs = 12;
	$i = 365.25*86400*($start-1970);
	$offset = 36000+rand(10000,60000);
	$max = 365*$yrs*86400;
	$lastyear = 0;
	
	// we generate a timestamp, convert it to a date, and convert it back to a timestamp
	// and check if the roundtrip broke the original timestamp value.
	print "Testing $start to ".($start+$yrs).", or $max seconds, offset=$offset: ";
	
	for ($max += $i; $i < $max; $i += $offset) {
		$ret = adodb_date('m,d,Y,H,i,s',$i);
		$arr = explode(',',$ret);
		if ($lastyear != $arr[2]) {
			$lastyear = $arr[2];
			print " $lastyear ";
			flush();
		}
		$newi = adodb_mktime($arr[3],$arr[4],$arr[5],$arr[0],$arr[1],$arr[2]);
		if ($i != $newi) {
			print "Error at $i, adodb_mktime returned $newi ($ret)";
			$fail = true;
			break;
		}
	}
	
	if (!$fail) print "<p>Passed !</p>";
	else print "<p><b>Failed</b> :-(</p>";
}

/**
	Returns day of week, 0 = Sunday,... 6=Saturday. 
	Algorithm from PEAR::Date_Calc
*/
function adodb_dow($year, $month, $day)
{
/*
Pope Gregory removed 10 days - October 5 to October 14 - from the year 1582 and 
proclaimed that from that time onwards 3 days would be dropped from the calendar 
every 400 years.

Thursday, October 4, 1582 (Julian) was followed immediately by Friday, October 15, 1582 (Gregorian). 
*/
	if ($year <= 1582) {
		if ($year < 1582 || 
			($year == 1582 && ($month < 10 || ($month == 10 && $day < 15)))) $greg_correction = 3;
		 else
			$greg_correction = 0;
	} else
		$greg_correction = 0;
	
	if($month > 2)
	    $month -= 2;
	else {
	    $month += 10;
	    $year--;
	}
	
	$day =  ( floor((13 * $month - 1) / 5) +
	        $day + ($year % 100) +
	        floor(($year % 100) / 4) +
	        floor(($year / 100) / 4) - 2 *
	        floor($year / 100) + 77);
	
	return (($day - 7 * floor($day / 7))) + $greg_correction;
}


/**
 Checks for leap year, returns true if it is. No 2-digit year check. Also 
 handles julian calendar correctly.
*/
function _adodb_is_leap_year($year) 
{
	if ($year % 4 != 0) return false;