DateTime calculations analogous to the Date and Time extensions. Closes #7693.

git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@6303 5ecf4fe2-1ee6-0310-87b1-e25e094e27de

4 files changed, 316 insertions, 2 deletions

diff --git a/activesupport/CHANGELOG b/activesupport/CHANGELOG
index 7a5a2f5586..020806ffe6 100644
--- a/activesupport/CHANGELOG
+++ b/activesupport/CHANGELOG
@@ -1,5 +1,7 @@
 *SVN*
 
+* DateTime calculations analogous to the Date and Time extensions.  #7693 [Geoff Buesing]
+
 * Give DateTime correct .to_s implementations, lets it play nice with ActiveRecord quoting. [gbuesing]
 
 * Add File.atomic_write,  allows you to write large files in an atomic manner, preventing users from seeing half written files.  [Koz]
diff --git a/activesupport/lib/active_support/core_ext/date_time.rb b/activesupport/lib/active_support/core_ext/date_time.rb
index 535d94abb7..c99d1283fd 100644
--- a/activesupport/lib/active_support/core_ext/date_time.rb
+++ b/activesupport/lib/active_support/core_ext/date_time.rb
@@ -1,6 +1,8 @@
 require 'date'
 require "#{File.dirname(__FILE__)}/time/behavior"
+require "#{File.dirname(__FILE__)}/date_time/calculations"
 require "#{File.dirname(__FILE__)}/date_time/conversions"
 
 DateTime.send(:include, ActiveSupport::CoreExtensions::Time::Behavior)
-DateTime.send(:include, ActiveSupport::CoreExtensions::DateTime::Conversions)
\ No newline at end of file
+DateTime.send(:include, ActiveSupport::CoreExtensions::DateTime::Calculations)
+DateTime.send(:include, ActiveSupport::CoreExtensions::DateTime::Conversions)
diff --git a/activesupport/lib/active_support/core_ext/date_time/calculations.rb b/activesupport/lib/active_support/core_ext/date_time/calculations.rb
new file mode 100644
index 0000000000..dd30dd07bc
--- /dev/null
+++ b/activesupport/lib/active_support/core_ext/date_time/calculations.rb
@@ -0,0 +1,173 @@
+require 'rational'
+
+module ActiveSupport #:nodoc:
+  module CoreExtensions #:nodoc:
+    module DateTime #:nodoc:
+      # Enables the use of time calculations within DateTime itself
+      module Calculations
+
+        # Seconds since midnight: DateTime.now.seconds_since_midnight
+        def seconds_since_midnight
+          self.sec + (self.min * 60) + (self.hour * 3600)
+        end
+
+        # Returns a new DateTime where one or more of the elements have been changed according to the +options+ parameter. The time options
+        # (hour, minute, sec) reset cascadingly, so if only the hour is passed, then minute and sec is set to 0. If the hour and
+        # minute is passed, then sec is set to 0.
+        def change(options)
+          ::DateTime.civil(
+            options[:year]  || self.year,
+            options[:month] || self.month,
+            options[:mday]  || self.mday,
+            options[:hour]  || self.hour,
+            options[:min]   || (options[:hour] ? 0 : self.min),
+            options[:sec]   || ((options[:hour] || options[:min]) ? 0 : self.sec),
+            options[:offset]  || self.offset,
+            options[:start]  || self.start
+          )
+        end
+
+        # Uses Date to provide precise Time calculations for years, months, and days.  The +options+ parameter takes a hash with
+        # any of these keys: :months, :days, :years.
+        def advance(options)
+          d = ::Date.new(year + (options.delete(:years) || 0), month, day)
+          d = d >> options.delete(:months) if options[:months]
+          d = d +  options.delete(:days)   if options[:days]
+          change(options.merge(:year => d.year, :month => d.month, :mday => d.day))
+        end
+
+        # Returns a new DateTime representing the time a number of seconds ago
+        # Do not use this method in combination with x.months, use months_ago instead!
+        def ago(seconds)
+          self.since(-seconds)
+        end
+
+        # Returns a new DateTime representing the time a number of seconds since the instance time
+        # Do not use this method in combination with x.months, use months_since instead!
+        def since(seconds)
+          self + Rational(seconds, 86400)
+        end
+        alias :in :since
+
+        # Returns a new DateTime representing the time a number of specified months ago
+         def months_ago(months)
+           months_since(-months)
+         end
+
+         def months_since(months)
+           year, month, mday = self.year, self.month, self.mday
+
+           month += months
+
+           # in case months is negative
+           while month < 1
+             month += 12
+             year -= 1
+           end
+
+           # in case months is positive
+           while month > 12
+             month -= 12
+             year += 1
+           end
+
+           max = ::Time.days_in_month(month, year)
+           mday = max if mday > max
+
+           change(:year => year, :month => month, :mday => mday)
+         end
+
+         # Returns a new DateTime representing the time a number of specified years ago
+         def years_ago(years)
+           change(:year => self.year - years)
+         end
+
+         def years_since(years)
+           change(:year => self.year + years)
+         end
+
+         # Short-hand for years_ago(1)
+         def last_year
+           years_ago(1)
+         end
+
+         # Short-hand for years_since(1)
+         def next_year
+           years_since(1)
+         end
+
+         # Short-hand for months_ago(1)
+         def last_month
+           months_ago(1)
+         end
+
+         # Short-hand for months_since(1)
+         def next_month
+           months_since(1)
+         end
+
+         # Returns a new DateTime representing the "start" of this week (Monday, 0:00)
+         def beginning_of_week
+           days_to_monday = self.wday!=0 ? self.wday-1 : 6
+           (self - days_to_monday).midnight
+         end
+         alias :monday :beginning_of_week
+         alias :at_beginning_of_week :beginning_of_week
+
+         # Returns a new DateTime representing the start of the given day in next week (default is Monday).
+         def next_week(day = :monday)
+           days_into_week = { :monday => 0, :tuesday => 1, :wednesday => 2, :thursday => 3, :friday => 4, :saturday => 5, :sunday => 6}
+           ((self + 7).beginning_of_week + days_into_week[day]).change(:hour => 0)
+         end
+
+         # Returns a new DateTime representing the start of the day (0:00)
+         def beginning_of_day
+           change(:hour => 0)
+         end
+         alias :midnight :beginning_of_day
+         alias :at_midnight :beginning_of_day
+         alias :at_beginning_of_day :beginning_of_day
+
+         # Returns a new DateTime representing the end of the day (23:59:59)
+         def end_of_day
+           change(:hour => 23, :min => 59, :sec => 59)
+         end
+
+         # Returns a new DateTime representing the start of the month (1st of the month, 0:00)
+         def beginning_of_month
+           change(:mday => 1,:hour => 0, :min => 0, :sec => 0)
+         end
+         alias :at_beginning_of_month :beginning_of_month
+
+         # Returns a new DateTime representing the end of the month (last day of the month, 0:00)
+         def end_of_month
+           last_day = ::Time.days_in_month( self.month, self.year )
+           change(:mday => last_day,:hour => 0, :min => 0, :sec => 0)
+         end
+         alias :at_end_of_month :end_of_month
+
+         # Returns  a new DateTime representing the start of the quarter (1st of january, april, july, october, 0:00)
+         def beginning_of_quarter
+           beginning_of_month.change(:month => [10, 7, 4, 1].detect { |m| m <= self.month })
+         end
+         alias :at_beginning_of_quarter :beginning_of_quarter
+
+         # Returns  a new DateTime representing the start of the year (1st of january, 0:00)
+         def beginning_of_year
+           change(:month => 1,:mday => 1,:hour => 0, :min => 0, :sec => 0)
+         end
+         alias :at_beginning_of_year :beginning_of_year
+
+         # Convenience method which returns a new DateTime representing the time 1 day ago
+         def yesterday
+           self - 1
+         end
+
+         # Convenience method which returns a new DateTime representing the time 1 day since the instance time
+         def tomorrow
+           self + 1
+         end
+      end
+    end
+  end
+end
diff --git a/activesupport/test/core_ext/date_time_ext_test.rb b/activesupport/test/core_ext/date_time_ext_test.rb
index 94da9de64c..a0c52e3dac 100644
--- a/activesupport/test/core_ext/date_time_ext_test.rb
+++ b/activesupport/test/core_ext/date_time_ext_test.rb
@@ -12,4 +12,141 @@ class DateTimeExtCalculationsTest < Test::Unit::TestCase
   def test_to_date
     assert_equal Date.new(2005, 2, 21), DateTime.new(2005, 2, 21).to_date
   end
-end
\ No newline at end of file
+
+  def test_seconds_since_midnight
+    assert_equal 1,DateTime.civil(2005,1,1,0,0,1).seconds_since_midnight
+    assert_equal 60,DateTime.civil(2005,1,1,0,1,0).seconds_since_midnight
+    assert_equal 3660,DateTime.civil(2005,1,1,1,1,0).seconds_since_midnight
+    assert_equal 86399,DateTime.civil(2005,1,1,23,59,59).seconds_since_midnight
+  end
+
+  def test_begining_of_week
+    assert_equal DateTime.civil(2005,1,31), DateTime.civil(2005,2,4,10,10,10).beginning_of_week
+    assert_equal DateTime.civil(2005,11,28), DateTime.civil(2005,11,28,0,0,0).beginning_of_week #monday
+    assert_equal DateTime.civil(2005,11,28), DateTime.civil(2005,11,29,0,0,0).beginning_of_week #tuesday
+    assert_equal DateTime.civil(2005,11,28), DateTime.civil(2005,11,30,0,0,0).beginning_of_week #wednesday
+    assert_equal DateTime.civil(2005,11,28), DateTime.civil(2005,12,01,0,0,0).beginning_of_week #thursday
+    assert_equal DateTime.civil(2005,11,28), DateTime.civil(2005,12,02,0,0,0).beginning_of_week #friday
+    assert_equal DateTime.civil(2005,11,28), DateTime.civil(2005,12,03,0,0,0).beginning_of_week #saturday
+    assert_equal DateTime.civil(2005,11,28), DateTime.civil(2005,12,04,0,0,0).beginning_of_week #sunday
+  end
+
+  def test_beginning_of_day
+    assert_equal DateTime.civil(2005,2,4,0,0,0), DateTime.civil(2005,2,4,10,10,10).beginning_of_day
+  end
+
+  def test_beginning_of_month
+    assert_equal DateTime.civil(2005,2,1,0,0,0), DateTime.civil(2005,2,22,10,10,10).beginning_of_month
+  end
+
+  def test_beginning_of_quarter
+    assert_equal DateTime.civil(2005,1,1,0,0,0), DateTime.civil(2005,2,15,10,10,10).beginning_of_quarter
+    assert_equal DateTime.civil(2005,1,1,0,0,0), DateTime.civil(2005,1,1,0,0,0).beginning_of_quarter
+    assert_equal DateTime.civil(2005,10,1,0,0,0), DateTime.civil(2005,12,31,10,10,10).beginning_of_quarter
+    assert_equal DateTime.civil(2005,4,1,0,0,0), DateTime.civil(2005,6,30,23,59,59).beginning_of_quarter
+  end
+
+  def test_end_of_month
+    assert_equal DateTime.civil(2005,3,31,0,0,0), DateTime.civil(2005,3,20,10,10,10).end_of_month
+    assert_equal DateTime.civil(2005,2,28,0,0,0), DateTime.civil(2005,2,20,10,10,10).end_of_month
+    assert_equal DateTime.civil(2005,4,30,0,0,0), DateTime.civil(2005,4,20,10,10,10).end_of_month
+
+  end
+
+  def test_beginning_of_year
+    assert_equal DateTime.civil(2005,1,1,0,0,0), DateTime.civil(2005,2,22,10,10,10).beginning_of_year
+  end
+
+  def test_months_ago
+    assert_equal DateTime.civil(2005,5,5,10),  DateTime.civil(2005,6,5,10,0,0).months_ago(1)
+    assert_equal DateTime.civil(2004,11,5,10), DateTime.civil(2005,6,5,10,0,0).months_ago(7)
+    assert_equal DateTime.civil(2004,12,5,10), DateTime.civil(2005,6,5,10,0,0).months_ago(6)
+    assert_equal DateTime.civil(2004,6,5,10),  DateTime.civil(2005,6,5,10,0,0).months_ago(12)
+    assert_equal DateTime.civil(2003,6,5,10),  DateTime.civil(2005,6,5,10,0,0).months_ago(24)
+  end
+
+  def test_months_since
+    assert_equal DateTime.civil(2005,7,5,10),  DateTime.civil(2005,6,5,10,0,0).months_since(1)
+    assert_equal DateTime.civil(2006,1,5,10),  DateTime.civil(2005,12,5,10,0,0).months_since(1)
+    assert_equal DateTime.civil(2005,12,5,10), DateTime.civil(2005,6,5,10,0,0).months_since(6)
+    assert_equal DateTime.civil(2006,6,5,10),  DateTime.civil(2005,12,5,10,0,0).months_since(6)
+    assert_equal DateTime.civil(2006,1,5,10),  DateTime.civil(2005,6,5,10,0,0).months_since(7)
+    assert_equal DateTime.civil(2006,6,5,10),  DateTime.civil(2005,6,5,10,0,0).months_since(12)
+    assert_equal DateTime.civil(2007,6,5,10),  DateTime.civil(2005,6,5,10,0,0).months_since(24)
+  end
+
+  def test_years_ago
+    assert_equal DateTime.civil(2004,6,5,10),  DateTime.civil(2005,6,5,10,0,0).years_ago(1)
+    assert_equal DateTime.civil(1998,6,5,10), DateTime.civil(2005,6,5,10,0,0).years_ago(7)
+  end
+
+  def test_years_since
+    assert_equal DateTime.civil(2006,6,5,10),  DateTime.civil(2005,6,5,10,0,0).years_since(1)
+    assert_equal DateTime.civil(2012,6,5,10),  DateTime.civil(2005,6,5,10,0,0).years_since(7)
+    assert_equal DateTime.civil(2182,6,5,10),  DateTime.civil(2005,6,5,10,0,0).years_since(177)
+  end
+
+  def test_last_year
+    assert_equal DateTime.civil(2004,6,5,10),  DateTime.civil(2005,6,5,10,0,0).last_year
+  end
+
+
+  def test_ago
+    assert_equal DateTime.civil(2005,2,22,10,10,9),  DateTime.civil(2005,2,22,10,10,10).ago(1)
+    assert_equal DateTime.civil(2005,2,22,9,10,10),  DateTime.civil(2005,2,22,10,10,10).ago(3600)
+    assert_equal DateTime.civil(2005,2,20,10,10,10), DateTime.civil(2005,2,22,10,10,10).ago(86400*2)
+    assert_equal DateTime.civil(2005,2,20,9,9,45),   DateTime.civil(2005,2,22,10,10,10).ago(86400*2 + 3600 + 25)
+  end
+
+  def test_since
+    assert_equal DateTime.civil(2005,2,22,10,10,11), DateTime.civil(2005,2,22,10,10,10).since(1)
+    assert_equal DateTime.civil(2005,2,22,11,10,10), DateTime.civil(2005,2,22,10,10,10).since(3600)
+    assert_equal DateTime.civil(2005,2,24,10,10,10), DateTime.civil(2005,2,22,10,10,10).since(86400*2)
+    assert_equal DateTime.civil(2005,2,24,11,10,35), DateTime.civil(2005,2,22,10,10,10).since(86400*2 + 3600 + 25)
+  end
+
+  def test_yesterday
+    assert_equal DateTime.civil(2005,2,21,10,10,10), DateTime.civil(2005,2,22,10,10,10).yesterday
+    assert_equal DateTime.civil(2005,2,28,10,10,10), DateTime.civil(2005,3,2,10,10,10).yesterday.yesterday
+  end
+
+  def test_tomorrow
+    assert_equal DateTime.civil(2005,2,23,10,10,10), DateTime.civil(2005,2,22,10,10,10).tomorrow
+    assert_equal DateTime.civil(2005,3,2,10,10,10),  DateTime.civil(2005,2,28,10,10,10).tomorrow.tomorrow
+  end
+
+  def test_change
+    assert_equal DateTime.civil(2006,2,22,15,15,10), DateTime.civil(2005,2,22,15,15,10).change(:year => 2006)
+    assert_equal DateTime.civil(2005,6,22,15,15,10), DateTime.civil(2005,2,22,15,15,10).change(:month => 6)
+    assert_equal DateTime.civil(2012,9,22,15,15,10), DateTime.civil(2005,2,22,15,15,10).change(:year => 2012, :month => 9)
+    assert_equal DateTime.civil(2005,2,22,16),       DateTime.civil(2005,2,22,15,15,10).change(:hour => 16)
+    assert_equal DateTime.civil(2005,2,22,16,45),    DateTime.civil(2005,2,22,15,15,10).change(:hour => 16, :min => 45)
+    assert_equal DateTime.civil(2005,2,22,15,45),    DateTime.civil(2005,2,22,15,15,10).change(:min => 45)
+  end
+
+  def test_plus
+    assert_equal DateTime.civil(2006,2,28,15,15,10), DateTime.civil(2005,2,28,15,15,10).advance(:years => 1)
+    assert_equal DateTime.civil(2005,6,28,15,15,10), DateTime.civil(2005,2,28,15,15,10).advance(:months => 4)
+    assert_equal DateTime.civil(2012,9,28,15,15,10), DateTime.civil(2005,2,28,15,15,10).advance(:years => 7, :months => 7)
+    assert_equal DateTime.civil(2013,10,3,15,15,10), DateTime.civil(2005,2,28,15,15,10).advance(:years => 7, :months => 19, :days => 5)
+  end
+
+  def test_next_week
+    assert_equal DateTime.civil(2005,2,28), DateTime.civil(2005,2,22,15,15,10).next_week
+    assert_equal DateTime.civil(2005,3,4), DateTime.civil(2005,2,22,15,15,10).next_week(:friday)
+    assert_equal DateTime.civil(2006,10,30), DateTime.civil(2006,10,23,0,0,0).next_week
+    assert_equal DateTime.civil(2006,11,1), DateTime.civil(2006,10,23,0,0,0).next_week(:wednesday)
+  end
+
+  def test_next_month_on_31st
+    assert_equal DateTime.civil(2005, 9, 30), DateTime.civil(2005, 8, 31).next_month
+  end
+
+  def test_last_month_on_31st
+    assert_equal DateTime.civil(2004, 2, 29), DateTime.civil(2004, 3, 31).last_month
+  end
+
+  def test_xmlschema_is_available
+    assert_nothing_raised { DateTime.now.xmlschema }
+  end
+end