module ActiveSupport #:nodoc:
  module CoreExtensions #:nodoc:
    module Time #:nodoc:
      # Converting times to formatted strings, dates, and datetimes.
      module Conversions
        DATE_FORMATS = {
          :db           => "%Y-%m-%d %H:%M:%S",
          :number       => "%Y%m%d%H%M%S",
          :time         => "%H:%M",
          :short        => "%d %b %H:%M",
          :long         => "%B %d, %Y %H:%M",
          :long_ordinal => lambda { |time| time.strftime("%B #{time.day.ordinalize}, %Y %H:%M") },
          :rfc822       => "%a, %d %b %Y %H:%M:%S %z"
        }

        def self.included(base) #:nodoc:
          base.class_eval do
            alias_method :to_default_s, :to_s
            alias_method :to_s, :to_formatted_s
          end
        end

        # Converts to a formatted string. See DATE_FORMATS for builtin formats.
        #
        # This method is aliased to <tt>to_s</tt>.
        #
        #   time = Time.now                     # => Thu Jan 18 06:10:17 CST 2007
        #
        #   time.to_formatted_s(:time)          # => "06:10:17"
        #   time.to_s(:time)                    # => "06:10:17"
        #
        #   time.to_formatted_s(:db)            # => "2007-01-18 06:10:17"
        #   time.to_formatted_s(:short)         # => "18 Jan 06:10"
        #   time.to_formatted_s(:long)          # => "January 18, 2007 06:10"
        #   time.to_formatted_s(:long_ordinal)  # => "January 18th, 2007 06:10"
        #   time.to_formatted_s(:rfc822)        # => "Thu, 18 Jan 2007 06:10:17 -0600"
        #
        # == Adding your own time formats to +to_formatted_s+
        # You can add your own formats to the Time::DATE_FORMATS hash.
        # Use the format name as the hash key and either a strftime string
        # or Proc instance that takes a time argument as the value.
        #
        #   # config/initializers/time_formats.rb
        #   Time::DATE_FORMATS[:month_and_year] = "%B %Y"
        #   Time::DATE_FORMATS[:short_ordinal] = lambda { |time| time.strftime("%B #{time.day.ordinalize}") }
        def to_formatted_s(format = :default)
          return to_default_s unless formatter = DATE_FORMATS[format]
          formatter.respond_to?(:call) ? formatter.call(self).to_s : strftime(formatter)
        end
        
        # Returns the UTC offset as an +HH:MM formatted string.
        #
        #   Time.local(2000).formatted_offset         # => "-06:00"
        #   Time.local(2000).formatted_offset(false)  # => "-0600"
        def formatted_offset(colon = true, alternate_utc_string = nil)
          utc? && alternate_utc_string || utc_offset.to_utc_offset_s(colon)
        end

        # Converts a Time object to a Date, dropping hour, minute, and second precision.
        #
        #   my_time = Time.now  # => Mon Nov 12 22:59:51 -0500 2007
        #   my_time.to_date     # => Mon, 12 Nov 2007
        #
        #   your_time = Time.parse("1/13/2009 1:13:03 P.M.")  # => Tue Jan 13 13:13:03 -0500 2009
        #   your_time.to_date                                 # => Tue, 13 Jan 2009
        def to_date
          ::Date.new(year, month, day)
        end

        # A method to keep Time, Date and DateTime instances interchangeable on conversions.
        # In this case, it simply returns +self+.
        def to_time
          self
        end

        # Converts a Time instance to a Ruby DateTime instance, preserving UTC offset.
        #
        #   my_time = Time.now    # => Mon Nov 12 23:04:21 -0500 2007
        #   my_time.to_datetime   # => Mon, 12 Nov 2007 23:04:21 -0500
        #
        #   your_time = Time.parse("1/13/2009 1:13:03 P.M.")  # => Tue Jan 13 13:13:03 -0500 2009
        #   your_time.to_datetime                             # => Tue, 13 Jan 2009 13:13:03 -0500
        def to_datetime
          ::DateTime.civil(year, month, day, hour, min, sec, Rational(utc_offset, 86400))
        end
      end
    end
  end
end
