Revert "Revert "Merge branch 'master' of https://github.com/mono/mono""

[mono.git] / mcs / class / System.Core / System / TimeZoneInfo.cs

diff --git a/mcs/class/System.Core/System/TimeZoneInfo.cs b/mcs/class/System.Core/System/TimeZoneInfo.cs
index 4dbaf3eeb885d75e757cb47be56a5e99575c5459..bdcda5654690c0ce670dcd414a2c6c0c3892069b 100644 (file)
--- a/mcs/class/System.Core/System/TimeZoneInfo.cs
+++ b/mcs/class/System.Core/System/TimeZoneInfo.cs
@@ -227,36 +227,38 @@ namespace System
 
                public static DateTime ConvertTime (DateTime dateTime, TimeZoneInfo destinationTimeZone)
                {
-                       return ConvertTime (dateTime, TimeZoneInfo.Local, destinationTimeZone);
+                       return ConvertTime (dateTime, dateTime.Kind == DateTimeKind.Utc ? TimeZoneInfo.Utc : TimeZoneInfo.Local, destinationTimeZone);
                }
 
                public static DateTime ConvertTime (DateTime dateTime, TimeZoneInfo sourceTimeZone, TimeZoneInfo destinationTimeZone)
                {
+                       if (sourceTimeZone == null)
+                               throw new ArgumentNullException ("sourceTimeZone");
+
+                       if (destinationTimeZone == null)
+                               throw new ArgumentNullException ("destinationTimeZone");
+                       
                        if (dateTime.Kind == DateTimeKind.Local && sourceTimeZone != TimeZoneInfo.Local)
                                throw new ArgumentException ("Kind property of dateTime is Local but the sourceTimeZone does not equal TimeZoneInfo.Local");
 
                        if (dateTime.Kind == DateTimeKind.Utc && sourceTimeZone != TimeZoneInfo.Utc)
                                throw new ArgumentException ("Kind property of dateTime is Utc but the sourceTimeZone does not equal TimeZoneInfo.Utc");
-
+                       
                        if (sourceTimeZone.IsInvalidTime (dateTime))
                                throw new ArgumentException ("dateTime parameter is an invalid time");
 
-                       if (sourceTimeZone == null)
-                               throw new ArgumentNullException ("sourceTimeZone");
-
-                       if (destinationTimeZone == null)
-                               throw new ArgumentNullException ("destinationTimeZone");
-
                        if (dateTime.Kind == DateTimeKind.Local && sourceTimeZone == TimeZoneInfo.Local && destinationTimeZone == TimeZoneInfo.Local)
                                return dateTime;
 
                        DateTime utc = ConvertTimeToUtc (dateTime);
 
-                       if (destinationTimeZone == TimeZoneInfo.Utc)
-                               return utc;
-
-                       return ConvertTimeFromUtc (utc, destinationTimeZone);   
-
+                       if (destinationTimeZone != TimeZoneInfo.Utc) {
+                               utc = ConvertTimeFromUtc (utc, destinationTimeZone);
+                               if (dateTime.Kind == DateTimeKind.Unspecified)
+                                       return DateTime.SpecifyKind (utc, DateTimeKind.Unspecified);
+                       }
+                       
+                       return utc;
                }
 
                public static DateTimeOffset ConvertTime(DateTimeOffset dateTimeOffset, TimeZoneInfo destinationTimeZone) 
@@ -311,7 +313,6 @@ namespace System
 
 
                        AdjustmentRule rule = GetApplicableRule (dateTime);
-               
                        if (rule != null && IsDaylightSavingTime (DateTime.SpecifyKind (dateTime, DateTimeKind.Utc)))
                                return DateTime.SpecifyKind (dateTime + BaseUtcOffset + rule.DaylightDelta , DateTimeKind.Unspecified);
                        else
@@ -754,6 +755,18 @@ namespace System
                        throw new NotImplementedException ();
                }
 
+               bool IsInDSTForYear (AdjustmentRule rule, DateTime dateTime, int year)
+               {
+                       DateTime DST_start = TransitionPoint (rule.DaylightTransitionStart, year);
+                       DateTime DST_end = TransitionPoint (rule.DaylightTransitionEnd, year + ((rule.DaylightTransitionStart.Month < rule.DaylightTransitionEnd.Month) ? 0 : 1));
+                       if (dateTime.Kind == DateTimeKind.Utc) {
+                               DST_start -= BaseUtcOffset;
+                               DST_end -= (BaseUtcOffset + rule.DaylightDelta);
+                       }
+
+                       return (dateTime >= DST_start && dateTime < DST_end);
+               }
+               
                public bool IsDaylightSavingTime (DateTime dateTime)
                {
                        if (dateTime.Kind == DateTimeKind.Local && IsInvalidTime (dateTime))
@@ -761,29 +774,28 @@ namespace System
 
                        if (this == TimeZoneInfo.Utc)
                                return false;
-
+                       
                        if (!SupportsDaylightSavingTime)
                                return false;
+                       
                        //FIXME: do not rely on DateTime implementation !
                        if ((dateTime.Kind == DateTimeKind.Local || dateTime.Kind == DateTimeKind.Unspecified) && this == TimeZoneInfo.Local)
                                return dateTime.IsDaylightSavingTime ();
-
+                       
                        //FIXME: do not rely on DateTime implementation !
                        if (dateTime.Kind == DateTimeKind.Local && this != TimeZoneInfo.Utc)
                                return IsDaylightSavingTime (DateTime.SpecifyKind (dateTime.ToUniversalTime (), DateTimeKind.Utc));
-                               
+                       
                        AdjustmentRule rule = GetApplicableRule (dateTime.Date);
                        if (rule == null)
                                return false;
 
-                       DateTime DST_start = TransitionPoint (rule.DaylightTransitionStart, dateTime.Year);
-                       DateTime DST_end = TransitionPoint (rule.DaylightTransitionEnd, dateTime.Year + ((rule.DaylightTransitionStart.Month < rule.DaylightTransitionEnd.Month) ? 0 : 1));
-                       if (dateTime.Kind == DateTimeKind.Utc) {
-                               DST_start -= BaseUtcOffset;
-                               DST_end -= (BaseUtcOffset + rule.DaylightDelta);
-                       }
+                       // Check whether we're in the dateTime year's DST period
+                       if (IsInDSTForYear (rule, dateTime, dateTime.Year))
+                               return true;
 
-                       return (dateTime >= DST_start && dateTime < DST_end);
+                       // We might be in the dateTime previous year's DST period
+                       return IsInDSTForYear (rule, dateTime, dateTime.Year - 1);
                }
 
                public bool IsDaylightSavingTime (DateTimeOffset dateTimeOffset)