module RichUnits
  require 'richunits/weekdays'
  require 'richunits/duration'

  # TODO: Extra Add in_* methods, like in_days, in_hours, etc. ?

  # = Times
  #
  # Plain-English convenience methods for dealing with dates and times.
  #
  # Thanks to Richard Kilmer for the orignal work version this work is based upon.
  #
  module Times

    NEVER = ::Time.mktime(2038)
    ZERO  = ::Time.mktime(1972)

    # = Time Extensions
    #
    module Time

      # Like change but does not reset earlier times.
      #
      # NOTE: It would be better, probably if this were called "change".
      #       and that #change were called "reset".
      #
      def set(options)
        opts={}; options.each_pair{ |k,v| opts[k] = v.to_i }
        self.class.send( self.utc? ? :utc : :local,
          opts[:year]  || self.year,
          opts[:month] || self.month,
          opts[:day]   || self.day,
          opts[:hour]  || self.hour,
          opts[:min]   || self.min,
          opts[:sec]   || self.sec,
          opts[:usec]  || self.usec
        )
      end

      # Returns a new Time where one or more of the elements
      # have been changed according to the +options+ parameter.
      # The time options (hour, minute, sec, usec) reset
      # cascadingly, so if only the hour is passed, then
      # minute, sec, and usec is set to 0. If the hour and
      # minute is passed, then sec and usec is set to 0.
      #
      #  t = Time.now            #=> Sat Dec 01 14:10:15 -0500 2007
      #  t.change(:hour => 11)   #=> Sat Dec 01 11:00:00 -0500 2007
      #
      def change(options)
        opts=options; #{}; options.each_pair{ |k,v| opts[k] = v.to_i }
        self.class.send(
          self.utc? ? :utc : :local,
          opts[:year]  || self.year,
          opts[:month] || self.month,
          opts[:day]   || self.day,
          opts[:hour]  || self.hour,
          opts[:min]   || (opts[:hour] ? 0 : self.min),
          opts[:sec]   || ((opts[:hour] || opts[:min]) ? 0 : self.sec),
          opts[:usec]  || ((opts[:hour] || opts[:min] || opts[:sec]) ? 0 : self.usec)
        )
      end

      # Returns a new Time representing the time
      # a number of time-units ago.
      #
      def ago(number, units=:seconds)
        time =(
          case units.to_s.downcase.to_sym
          when :years
            set(:year => (year - number))
          when :months
            #years = ((month - number) / 12).to_i
            y = ((month - number) / 12).to_i
            m = ((month - number - 1) % 12) + 1
            set(:year => (year - y), :month => m)
          when :weeks
            self - (number * 604800)
          when :days
            self - (number * 86400)
          when :hours
            self - (number * 3600)
          when :minutes
            self - (number * 60)
          when :seconds, nil
            self - number
          else
            raise ArgumentError, "unrecognized time units -- #{units}"
          end
        )
        dst_adjustment(time)
      end

      #
      # Returns a new Time representing the time
      # a number of time-units hence.

      def hence(number, units=:seconds)
        time =(
          case units.to_s.downcase.to_sym
          when :years
            set( :year=>(year + number) )
          when :months
            y = ((month + number) / 12).to_i
            m = ((month + number - 1) % 12) + 1
            set(:year => (year + y), :month => m)
          when :weeks
            self + (number * 604800)
          when :days
            self + (number * 86400)
          when :hours
            self + (number * 3600)
          when :minutes
            self + (number * 60)
          when :seconds
            self + number
          else
            raise ArgumentError, "unrecognized time units -- #{units}"
          end
        )
        dst_adjustment(time)
      end

      alias_method :in, :hence

      # This is a Railism.
      alias_method :since, :hence

      # This is a Railism.
      alias_method :from_now, :hence

      # Adjust DST
      #
      # TODO: Can't seem to get this to pass ActiveSupport tests.
      #       Even though it is essentially identical to the
      #       ActiveSupport code (see Time#since in time/calculations.rb).
      #       It handels all but 4 tests.
      def dst_adjustment(time)
        self_dst = self.dst? ? 1 : 0
        time_dst = time.dst? ? 1 : 0
        seconds  = (self - time).abs
        if (seconds >= 86400 && self_dst != time_dst)
          time + ((self_dst - time_dst) * 60 * 60)
        else
          time
        end
      end

      # 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)
      end

      # Returns a new Time 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)
      #  # This is basically a wrapper around the Numeric extension.
      #  #seconds.until(self)
      #  self - seconds
      #end

      # Returns a new Time representing the time
      # a number of minutes ago.

      def minutes_ago(minutes)
        self - (minutes * 60)
      end

      # Returns a new Time representing the time
      # a number of hours ago.

      def hours_ago(hours)
        self - (hours * 3600)
      end

      # Returns a new Time representing the time
      # a number of days ago.

      def days_ago(days)
        self - (days * 86400)
      end

      # Returns a new Time representing the time
      # a number of weeks ago.

      def weeks_ago(weeks)
        self - (weeks * 604800)
      end

      # Returns a new Time representing the time
      # a number of months ago.

      def months_ago(months)
        years = (month - months / 12).to_i
        set(:year=>(year - years), :month=>(month - months) % 12)
      end

      # Returns a new Time representing the time a number of specified
      # months ago.
      #def months_ago(months)
      #  if months >= self.month
      #    change(:year => self.year - 1, :month => 12).months_ago(months - self.month)
      #  else
      #    change(:year => self.year, :month => self.month - months)
      #  end
      #end

      # Returns a new Time representing the time
      # a number of years ago.

      def years_ago(years)
        set(:year=>(year - years))
      end

      # Returns a new Time representing the time a number of specified
      # years ago.
      #def years_ago(years)
      #  change(:year => self.year - years)
      #end

      # Returns a new Time representing the time
      # a number of minutes hence.

      def minutes_hence(minutes)
        self + (minutes * 60)
      end

      # Returns a new Time representing the time
      # a number of hours hence.

      def hours_hence(hours)
        self + (hours * 3600)
      end

      # Returns a new Time representing the time
      # a number of days hence.

      def days_hence(days)
        self + (days * 86400)
      end

      # Returns a new Time representing the time
      # a number of weeks hence.

      def weeks_hence(weeks)
        self + (weeks * 604800)
      end

      # Returns a new Time representing the time
      # a number of months hence.

      def months_hence(months)
        years = (month + months / 12).to_i
        set(:year=>(year + years), :month=>(month + months) % 12)
      end

      #def months_hence(months)
      #  if months + self.month > 12
      #    change(:year => self.year + 1, :month => 1).months_since(months - (self.month == 1 ? 12 : (self.month + 1)))
      #  else
      #    change(:year => self.year, :month => self.month + months)
      #  end
      #end

      # Returns a new Time representing the time
      # a number of years hence.

      def years_hence(years)
        set(:year=>(year + years))
      end

      # Returns a new Time 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!
      alias_method :since, :hence

      alias_method :minutes_since, :minutes_hence
      alias_method :days_since, :days_hence
      alias_method :weeks_since, :weeks_hence
      alias_method :months_since, :months_hence
      alias_method :years_since, :years_hence

      #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 Time representing the "start" of this week (Monday, 0:00)
      def beginning_of_week
        (self - self.wday.days).midnight + 1.day
      end
      alias :monday :beginning_of_week
      alias :at_beginning_of_week :beginning_of_week

      # Returns a new Time 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 }
        since(1.week).beginning_of_week.since(days_into_week[day].day).change(:hour => 0)
      end

      # Set time to end of day
      #def end_of_day
      #  return Time.mktime(year, month, day, 23, 59, 59, 999)
      #end

      # Returns a new Time representing the start of the day (0:00)
      def beginning_of_day
        self - self.seconds_since_midnight
      end
      alias :midnight :beginning_of_day
      alias :at_midnight :beginning_of_day
      alias :at_beginning_of_day :beginning_of_day
      alias :start_of_day :beginning_of_day

      # Returns a new Time representing the start of the month
      # (1st of the month, 0:00)
      def beginning_of_month
        #self - ((self.mday-1).days + self.seconds_since_midnight)
        change(:day => 1,:hour => 0, :min => 0, :sec => 0, :usec => 0)
      end
      alias_method :at_beginning_of_month, :beginning_of_month

      # Returns  a new Time representing the start of the year (1st of january, 0:00)
      def beginning_of_year
        change(:month => 1,:day => 1,:hour => 0, :min => 0, :sec => 0, :usec => 0)
      end
      alias :at_beginning_of_year :beginning_of_year

      # Convenience method which returns a new Time representing
      # the time 1 day ago
      def yesterday
        self.ago(1.day)
      end

      # Convenience method which returns a new Time representing
      # the time 1 day since the instance time
      def tomorrow
        self.since(1.day)
      end

      # Returns a new time at start of day
      def start_of_day
        return Time.mktime(year, month, day, 0, 0, 0, 0)
      end
      alias_method :to_start_of_day, :start_of_day

      # Returns a new time at end of day
      def end_of_day
        Time.mktime(year, month, day, 23, 59, 59, 999)
      end
      alias_method :to_end_of_day, :end_of_day

      # Returns true only if day of time is included in the
      # range (stime..etime). Only year days are checked.
      def in_day_range?(stime=ZERO, etime=NEVER)
        if (etime <= stime)
          warn "invalid end time (#{etime} < #{stime})" if $DEBUG
          etime = NEVER
        end

        stime = stime.to_start_of_day
        etime = etime.to_end_of_day

        return (stime..etime).include?(time)
      end

    end#module Time

    # = Time Metaclass Extensions
    #
    module TimeClass

      # This method calculates the days extrema given two time objects.
      #   start time is the given time1 at 00:00:00
      #   end time is the given time2 at 23:59:59:999
      #
      # Input:
      # - the two times (if only time1 is provided then you get an extrema
      #   of exactly one day extrema.
      #
      # Output:
      # - the time range. you can get the start/end times using
      #   range methods.
      #
      #  CREDIT George Moschovitis

      def days_extrema(time1, time2=nil)
        time2 = time1 if (not time2.valid? Time)
        time2 = NEVER if (time2 <= time1)
        start_time = time1.start_of_day #start_of_day(time1)
        end_time   = time2.end_of_day #end_of_day(time2)
        return (start_time..end_time)
      end

    end

    # = Numeric Times
    #
    module Numeric

      # Calculates time _before_ a given time. Default time is now.
      # Reads best with arguments: 10.days.before( Time.now - 1.day )
      def before(time = ::Time.now)
        time - self
      end
      alias_method :until, :before   # Reads best with argument: 10.minutes.until(time)
      alias_method :ago, :before     # Reads best without arguments: 10.minutes.ago

      # Calculates time _after_ a given time. Default time is now.
      # Reads best with argument: 10.minutes.after(time)
      def after(time = ::Time.now)
        time + self
      end
      alias_method :since, :after    # Reads best with argument: 10.minutes.since(time)
      alias_method :hence, :after    # Reads best with argument: 10.minutes.since(time)
      alias_method :from_now, :after # Reads best without arguments: 10.minutes.from_now
      alias_method :later, :after    # Reads best without arguments: 10.minutes.later

    end#module Numeric

  end#module Times

end#module RichUnits

class Numeric #:nodoc:
  include RichUnits::Times::Numeric
end

class Time #:nodoc:
  extend  RichUnits::Times::TimeClass
  include RichUnits::Times::Time

  NEVER = Time.mktime(2038)
  ZERO  = Time.mktime(1972)
end