gitweb.js: Extract and improve datetime handling

Move formatDateISOLocal(epoch, timezone) function (and also helper
timezoneOffset(timezoneInfo) function it requires) from common-lib.js to
datetime.js

Add new functions:
* localTimezoneOffset - to get browser timezone offset in seconds
* localTimezoneInfo   - to get browser timezone in '(+|-)HHMM' format
* formatTimezoneInfo - turn offset in hours and minutes into '(+|-)HHMM'
* parseRFC2822Date - to parse RFC-2822 dates that gitweb uses into epoch
* formatDateRFC2882 - like formatDateISOLocal, only RFC-2822 format

All those functions are meant to be used in future commit
'gitweb: javascript ability to adjust time based on timezone'

An alternative would be to use e.g. Datejs (http://www.datejs.com)
library, or JavaScript framework that has date formatting (perhaps as
a plugin).

While at it escape '-' in character class inside tzRe regexp, as
recommended by JSLint (http://www.jslint.com).

Signed-off-by: Jakub Narebski <jnareb@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

2 files changed, 161 insertions, 51 deletions

diff --git a/gitweb/static/js/lib/common-lib.js b/gitweb/static/js/lib/common-lib.js
index c45454ead2..d6b0c0d46a 100644
--- a/gitweb/static/js/lib/common-lib.js
+++ b/gitweb/static/js/lib/common-lib.js
@@ -89,57 +89,6 @@ function createRequestObject() {
 
 
 /* ............................................................ */
-/* time and data */
-
-/**
- * used to extract hours and minutes from timezone info, e.g '-0900'
- * @constant
- */
-var tzRe = /^([+-])([0-9][0-9])([0-9][0-9])$/;
-
-/**
- * convert numeric timezone +/-ZZZZ to offset from UTC in seconds
- *
- * @param {String} timezoneInfo: numeric timezone '(+|-)HHMM'
- * @returns {Number} offset from UTC in seconds for timezone
- *
- * @globals tzRe
- */
-function timezoneOffset(timezoneInfo) {
-	var match = tzRe.exec(timezoneInfo);
-	var tz_sign = (match[1] === '-' ? -1 : +1);
-	var tz_hour = parseInt(match[2],10);
-	var tz_min  = parseInt(match[3],10);
-
-	return tz_sign*(((tz_hour*60) + tz_min)*60);
-}
-
-/**
- * return date in local time formatted in iso-8601 like format
- * 'yyyy-mm-dd HH:MM:SS +/-ZZZZ' e.g. '2005-08-07 21:49:46 +0200'
- *
- * @param {Number} epoch: seconds since '00:00:00 1970-01-01 UTC'
- * @param {String} timezoneInfo: numeric timezone '(+|-)HHMM'
- * @returns {String} date in local time in iso-8601 like format
- */
-function formatDateISOLocal(epoch, timezoneInfo) {
-	// date corrected by timezone
-	var localDate = new Date(1000 * (epoch +
-		timezoneOffset(timezoneInfo)));
-	var localDateStr = // e.g. '2005-08-07'
-		localDate.getUTCFullYear()                 + '-' +
-		padLeft(localDate.getUTCMonth()+1, 2, '0') + '-' +
-		padLeft(localDate.getUTCDate(),    2, '0');
-	var localTimeStr = // e.g. '21:49:46'
-		padLeft(localDate.getUTCHours(),   2, '0') + ':' +
-		padLeft(localDate.getUTCMinutes(), 2, '0') + ':' +
-		padLeft(localDate.getUTCSeconds(), 2, '0');
-
-	return localDateStr + ' ' + localTimeStr + ' ' + timezoneInfo;
-}
-
-
-/* ............................................................ */
 /* unquoting/unescaping filenames */
 
 /**#@+
diff --git a/gitweb/static/js/lib/datetime.js b/gitweb/static/js/lib/datetime.js
new file mode 100644
index 0000000000..b3dcedb141
--- /dev/null
+++ b/gitweb/static/js/lib/datetime.js
@@ -0,0 +1,161 @@
+// Copyright (C) 2007, Fredrik Kuivinen <frekui@gmail.com>
+//               2007, Petr Baudis <pasky@suse.cz>
+//          2008-2011, Jakub Narebski <jnareb@gmail.com>
+
+/**
+ * @fileOverview Datetime manipulation: parsing and formatting
+ * @license GPLv2 or later
+ */
+
+
+/* ............................................................ */
+/* parsing and retrieving datetime related information */
+
+/**
+ * used to extract hours and minutes from timezone info, e.g '-0900'
+ * @constant
+ */
+var tzRe = /^([+\-])([0-9][0-9])([0-9][0-9])$/;
+
+/**
+ * convert numeric timezone +/-ZZZZ to offset from UTC in seconds
+ *
+ * @param {String} timezoneInfo: numeric timezone '(+|-)HHMM'
+ * @returns {Number} offset from UTC in seconds for timezone
+ *
+ * @globals tzRe
+ */
+function timezoneOffset(timezoneInfo) {
+	var match = tzRe.exec(timezoneInfo);
+	var tz_sign = (match[1] === '-' ? -1 : +1);
+	var tz_hour = parseInt(match[2],10);
+	var tz_min  = parseInt(match[3],10);
+
+	return tz_sign*(((tz_hour*60) + tz_min)*60);
+}
+
+/**
+ * return local (browser) timezone as offset from UTC in seconds
+ *
+ * @returns {Number} offset from UTC in seconds for local timezone
+ */
+function localTimezoneOffset() {
+	// getTimezoneOffset returns the time-zone offset from UTC,
+	// in _minutes_, for the current locale
+	return ((new Date()).getTimezoneOffset() * -60);
+}
+
+/**
+ * return local (browser) timezone as numeric timezone '(+|-)HHMM'
+ *
+ * @returns {String} locat timezone as -/+ZZZZ
+ */
+function localTimezoneInfo() {
+	var tzOffsetMinutes = (new Date()).getTimezoneOffset() * -1;
+
+	return formatTimezoneInfo(0, tzOffsetMinutes);
+}
+
+
+/**
+ * Parse RFC-2822 date into a Unix timestamp (into epoch)
+ *
+ * @param {String} date: date in RFC-2822 format, e.g. 'Thu, 21 Dec 2000 16:01:07 +0200'
+ * @returns {Number} epoch i.e. seconds since '00:00:00 1970-01-01 UTC'
+ */
+function parseRFC2822Date(date) {
+	// Date.parse accepts the IETF standard (RFC 1123 Section 5.2.14 and elsewhere)
+	// date syntax, which is defined in RFC 2822 (obsoletes RFC 822)
+	// and returns number of _milli_seconds since January 1, 1970, 00:00:00 UTC
+	return Date.parse(date) / 1000;
+}
+
+
+/* ............................................................ */
+/* formatting date */
+
+/**
+ * format timezone offset as numerical timezone '(+|-)HHMM' or '(+|-)HH:MM'
+ *
+ * @param {Number} hours:    offset in hours, e.g. 2 for '+0200'
+ * @param {Number} [minutes] offset in minutes, e.g. 30 for '-4030';
+ *                           it is split into hours if not 0 <= minutes < 60,
+ *                           for example 1200 would give '+0100';
+ *                           defaults to 0
+ * @param {String} [sep] separator between hours and minutes part,
+ *                       default is '', might be ':' for W3CDTF (rfc-3339)
+ * @returns {String} timezone in '(+|-)HHMM' or '(+|-)HH:MM' format
+ */
+function formatTimezoneInfo(hours, minutes, sep) {
+	minutes = minutes || 0; // to be able to use formatTimezoneInfo(hh)
+	sep = sep || ''; // default format is +/-ZZZZ
+
+	if (minutes < 0 || minutes > 59) {
+		hours = minutes > 0 ? Math.floor(minutes / 60) : Math.ceil(minutes / 60);
+		minutes = Math.abs(minutes - 60*hours); // sign of minutes is sign of hours
+		// NOTE: this works correctly because there is no UTC-00:30 timezone
+	}
+
+	var tzSign = hours >= 0 ? '+' : '-';
+	if (hours < 0) {
+		hours = -hours; // sign is stored in tzSign
+	}
+
+	return tzSign + padLeft(hours, 2, '0') + sep + padLeft(minutes, 2, '0');
+}
+
+/**
+ * return date in local time formatted in iso-8601 like format
+ * 'yyyy-mm-dd HH:MM:SS +/-ZZZZ' e.g. '2005-08-07 21:49:46 +0200'
+ *
+ * @param {Number} epoch: seconds since '00:00:00 1970-01-01 UTC'
+ * @param {String} timezoneInfo: numeric timezone '(+|-)HHMM'
+ * @returns {String} date in local time in iso-8601 like format
+ */
+function formatDateISOLocal(epoch, timezoneInfo) {
+	// date corrected by timezone
+	var localDate = new Date(1000 * (epoch +
+		timezoneOffset(timezoneInfo)));
+	var localDateStr = // e.g. '2005-08-07'
+		localDate.getUTCFullYear()                 + '-' +
+		padLeft(localDate.getUTCMonth()+1, 2, '0') + '-' +
+		padLeft(localDate.getUTCDate(),    2, '0');
+	var localTimeStr = // e.g. '21:49:46'
+		padLeft(localDate.getUTCHours(),   2, '0') + ':' +
+		padLeft(localDate.getUTCMinutes(), 2, '0') + ':' +
+		padLeft(localDate.getUTCSeconds(), 2, '0');
+
+	return localDateStr + ' ' + localTimeStr + ' ' + timezoneInfo;
+}
+
+/**
+ * return date in local time formatted in rfc-2822 format
+ * e.g. 'Thu, 21 Dec 2000 16:01:07 +0200'
+ *
+ * @param {Number} epoch: seconds since '00:00:00 1970-01-01 UTC'
+ * @param {String} timezoneInfo: numeric timezone '(+|-)HHMM'
+ * @param {Boolean} [padDay] e.g. 'Sun, 07 Aug' if true, 'Sun, 7 Aug' otherwise
+ * @returns {String} date in local time in rfc-2822 format
+ */
+function formatDateRFC2882(epoch, timezoneInfo, padDay) {
+	// A short textual representation of a month, three letters
+	var months = ["Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"];
+	// A textual representation of a day, three letters
+	var days = ["Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"];
+	// date corrected by timezone
+	var localDate = new Date(1000 * (epoch +
+		timezoneOffset(timezoneInfo)));
+	var localDateStr = // e.g. 'Sun, 7 Aug 2005' or 'Sun, 07 Aug 2005'
+		days[localDate.getUTCDay()] + ', ' +
+		(padDay ? padLeft(localDate.getUTCDate(),2,'0') : localDate.getUTCDate()) + ' ' +
+		months[localDate.getUTCMonth()] + ' ' +
+		localDate.getUTCFullYear();
+	var localTimeStr = // e.g. '21:49:46'
+		padLeft(localDate.getUTCHours(),   2, '0') + ':' +
+		padLeft(localDate.getUTCMinutes(), 2, '0') + ':' +
+		padLeft(localDate.getUTCSeconds(), 2, '0');
+
+	return localDateStr + ' ' + localTimeStr + ' ' + timezoneInfo;
+}
+
+/* end of datetime.js */