fixing event dialog to use use timezone-corrected times when displaying start/end times. adding some code to try to guess what your system timezone is

calendar/base/content/calendar-item-editing.js

@@ -36,12 +36,10 @@
  * ***** END LICENSE BLOCK ***** */
 
 
-/* this needs to be a pref/system thing/something.. wtf! */
-var TIMEZONE = "/mozilla.org/20050126_1/America/Los_Angeles"
-
 /* all params are optional */
 function createEventWithDialog(calendar, startDate, endDate, summary)
 {
+    const kDefaultTimezone = calendarDefaultTimezone();
     var event = createEvent();
 
     if (!startDate) {
@@ -49,9 +47,13 @@ function createEventWithDialog(calendar, startDate, endDate, summary)
         startDate.second = 0;
         startDate.normalize();
     } else if (startDate.isDate) {
+        startDate = startDate.clone();
+        startDate.isDate = false;
+
+        event.startDate.isDate = false;
         /* set the hour/minute of startDate to "right now"
            if the day is the same */
-        var now = jsDateToDateTime(new Date()).getInTimezone(TIMEZONE).clone();
+        var now = jsDateToDateTime(new Date()).getInTimezone(kDefaultTimezone).clone();
         var nowDate = now.clone();
         nowDate.isDate = true;
         nowDate.normalize();
@@ -61,12 +63,12 @@ function createEventWithDialog(calendar, startDate, endDate, summary)
                normalize and change startDate to be now. */
             now.second = 0;
             now.normalize();
-
             startDate = now;
         }
     }
 
     event.startDate = startDate.clone();
+    event.startDate.isDate = false;
 
     if (!endDate) {
         endDate = startDate.clone();

calendar/resources/content/calendarUtils.js

@@ -1,3 +1,4 @@
+/* -*- Mode: javascript; tab-width: 20; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
 /* ***** BEGIN LICENSE BLOCK *****
  * Version: MPL 1.1/GPL 2.0/LGPL 2.1
  *
@@ -133,10 +134,35 @@ function calendarDefaultTimezone() {
         try {
             gDefaultTimezone = prefobj.getCharPref("timezone.local");
         } catch (e) {
-            gDefaultTimezone = null;
+            gDefaultTimezone = guessSystemTimezone();
+            dump("gDefaultTimezone: " + gDefaultTimezone);
         }
     }
-
+    
     return gDefaultTimezone;
 }
 
+// XXX this should probably live somewhere else
+
+// XXX this table needs a _lot_ more stuff in it.
+const tzTable = {
+    "GMT-0700 Pacific Daylight Time" : "/mozilla.org/20050126_1/America/Los_Angeles",
+    "GMT-0800 Pacific Standard Time" : "/mozilla.org/20050126_1/America/Los_Angeles"
+};
+
+// returns a ICS timezone string
+function guessSystemTimezone()
+{
+    var m = (new Date()).toString().match(/[^(]* ([^ ]*) \(([^)]+)\)/);
+    var offset = m[1];
+    var timezone = m[2];
+
+    dump("Guessing system timezone:\n");
+    dump("offset  : " + offset + "\ntimezone: " + timezone + "\n");
+
+    try {
+        return tzTable[offset + " " + timezone];
+    } catch(ex) {
+        return null;
+    }
+}

calendar/resources/content/eventDialog.js

@@ -96,6 +96,8 @@ const DEFAULT_ALARM_LENGTH = 15; //default number of time units, an alarm goes o
 */
 function loadCalendarEventDialog()
 {
+    const kDefaultTimezone = calendarDefaultTimezone();
+
     // Get arguments, see description at top of file
     var args = window.arguments[0];
 
@@ -120,12 +122,16 @@ function loadCalendarEventDialog()
     // fill in fields from the event
     switch(componentType) {
     case "event":
-        var startDate = event.startDate.jsDate;
+        var startDate = event.startDate.getInTimezone(kDefaultTimezone).jsDate;
         setElementValue("start-datetime", startDate);
+        dump(startDate + "\n");
 
         // only events have end dates. todos have due dates
-        var endDate   = event.endDate.jsDate;
+        var endDate   = event.endDate.getInTimezone(kDefaultTimezone).jsDate;
         var displayEndDate = new Date(endDate);
+
+        dump(displayEndDate + "\n");
+
         /*
         if (event.isAllDay) {
             //displayEndDate == icalEndDate - 1, in the case of allday events
@@ -424,13 +430,13 @@ function loadCalendarEventDialog()
     var calendarField = document.getElementById('server-field');
     var calendars = getCalendarManager().getCalendars({});
     for (i in calendars) {
-        var menuitem = calendarField.appendItem(calendars[i].name,
-                                                calendars[i].uri);
-        menuitem.calendar = calendars[i];
-        // compare cal.uri because there may be multiple instances of
-        // calICalendar or uri for the same spec, and those instances are
-        // not ==.
         try {
+            var menuitem = calendarField.appendItem(calendars[i].name,
+                                                    calendars[i].uri);
+            menuitem.calendar = calendars[i];
+            // compare cal.uri because there may be multiple instances of
+            // calICalendar or uri for the same spec, and those instances are
+            // not ==.
             if (eventCalendar && eventCalendar.uri.equals(calendars[i].uri))
                 calendarField.selectedIndex = i;
         } catch(ex) {