Ticket #5617: handle_dst_changes_for_large_deltas.txt

Index: activesupport/test/core_ext/time_ext_test.rb
===================================================================
--- activesupport/test/core_ext/time_ext_test.rb        (revision 4560)
+++ activesupport/test/core_ext/time_ext_test.rb        (working copy)
@@ -22,6 +22,30 @@
     assert_equal Time.local(2005,11,28), Time.local(2005,12,04,0,0,0).beginning_of_week #sunday    
   end
   
+  def test_daylight_savings_time_crossings_forward_start
+    # st: April 2nd 7:27pm
+    assert_equal Time.local(2005,4,3,19,27,0), Time.local(2005,4,2,19,27,0).since(86400), 'st+1.day=>dt'
+    assert_equal Time.local(2005,4,4,19,27,0), Time.local(2005,4,3,19,27,0).since(86400), 'dt+1.day=>dt'
+  end
+  
+  def test_daylight_savings_time_crossings_forward_end
+    # dt: October 30th 12:45am
+    assert_equal Time.local(2005,10,31,1,45,0), Time.local(2005,10,30,1,45,0).since(86400), 'dt+1.day=>st'
+    assert_equal Time.local(2005,11, 1,1,45,0), Time.local(2005,10,31,1,45,0).since(86400), 'st+1.day=>st'
+  end
+  
+  def test_daylight_savings_time_crossings_backward_start
+    # dt: April 3rd 4:18am
+    assert_equal Time.local(2005,4,2,4,18,0), Time.local(2005,4,3,4,18,0).ago(86400), 'dt-1.day=>st'
+    assert_equal Time.local(2005,4,1,4,18,0), Time.local(2005,4,2,4,18,0).ago(86400), 'st-1.day=>st'
+  end
+  
+  def test_daylight_savings_time_crossings_backward_end
+    # st: October 30th 4:03am
+    assert_equal Time.local(2005,10,29,4,3), Time.local(2005,10,30,4,3,0).ago(86400), 'st-1.day=>dt'
+    assert_equal Time.local(2005,10,28,4,3), Time.local(2005,10,29,4,3,0).ago(86400), 'dt-1.day=>dt'
+  end
+
   def test_beginning_of_day
     assert_equal Time.local(2005,2,4,0,0,0), Time.local(2005,2,4,10,10,10).beginning_of_day
   end
Index: activesupport/lib/active_support/core_ext/time/calculations.rb
===================================================================
--- activesupport/lib/active_support/core_ext/time/calculations.rb      (revision 4560)
+++ activesupport/lib/active_support/core_ext/time/calculations.rb      (working copy)
@@ -25,7 +25,11 @@
 
         # Seconds since midnight: Time.now.seconds_since_midnight
         def seconds_since_midnight
-          self.hour.hours + self.min.minutes + self.sec + (self.usec/1.0e+6)
+          initial_dst = self.dst? ? 1 : 0
+          final_dst   = self.change(:hour => 0).dst? ? 1 : 0
+
+          dst_adj =  (initial_dst != final_dst) ? (final_dst - initial_dst).hours : 0
+          self.hour.hours + self.min.minutes + self.sec + (self.usec/1.0e+6) - dst_adj
         end
             
         # Returns a new Time where one or more of the elements have been changed according to the +options+ parameter. The time options
@@ -56,13 +60,16 @@
         # Returns a new Time representing the time a number of seconds ago, this is basically a wrapper around the Numeric extension
         # Do not use this method in combination with x.months, use months_ago instead!
         def ago(seconds)
-          seconds.until(self)
+          self.since(-seconds)
         end
 
         # Returns a new Time representing the time a number of seconds since the instance time, this is basically a wrapper around 
         #the Numeric extension. Do not use this method in combination with x.months, use months_since instead!
         def since(seconds)
-          seconds.since(self)
+          initial_dst = self.dst? ? 1 : 0
+          f = seconds.since(self)
+          final_dst   = f.dst? ? 1 : 0
+          (seconds.abs >= 86400 && initial_dst != final_dst) ? f + (initial_dst - final_dst).hours : f
         end
         alias :in :since