class Time
  
  # Helper method for backwards compatibility with ActiveSupport.
  def days_into_week
    defined?(DAYS_INTO_WEEK) ? DAYS_INTO_WEEK : { :monday => 0, :tuesday => 1, :wednesday => 2, :thursday => 3, :friday => 4, :saturday => 5, :sunday => 6 }
  end
  
  # Helper method for backwards compatibility with ActiveSupport.
  def common_year_days_in_month
    defined?(COMMON_YEAR_DAYS_IN_MONTH) ? COMMON_YEAR_DAYS_IN_MONTH : [nil, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31]
  end
  
  # Returns a new Time representing the start of the unit specified (second by default).
  def floor(unit = :sec)
    self.send("beginning_of_#{unit}")
  end
  alias :beginning_of :floor
  alias :at_beginning_of :floor
  
  # Returns a new Time representing the start of the next unit specified (second by default).
  def ceil(unit = :sec)
    self.send("next_#{unit}").send("beginning_of_#{unit}")
  end
  alias :beginning_of_next :ceil
  alias :at_beginning_of_next :ceil
  
  # Returns a new Time representing the start of the current or next unit specified (second by default) depending which is closest
  def round(unit = :sec)
    next_unit = self.ceil(unit)
    this_unit = self.floor(unit)
    (self - this_unit) < (next_unit - self) ? this_unit : next_unit
  end
  alias :beginning_of_closest :round
  
  # Returns a new Time representing the previoius unit specified (defaults to second).
  def prev(unit = :sec)
    send("prev_#{unit}")
  end
  
  # Returns a new Time representing the next unit specified (defaults to second).
  def next(unit = :sec)
    send("next_#{unit}")
  end
  
  # Short-hand for seconds_ago(1).
  def prev_second
    seconds_ago(1)
  end
  alias :prev_sec :prev_second
  
  # Short-hand for seconds_since(1).
  def next_second
    seconds_since(1)
  end
  alias :next_sec :next_second
  
  # Short-hand for minutes_ago(1).
  def prev_minute
    minutes_ago(1)
  end
  alias :prev_min :prev_minute
  
  # Short-hand for minutes_since(1).
  def next_minute
    minutes_since(1)
  end
  alias :next_min :next_minute
  
  # Short-hand for hours_ago(1).
  def prev_hour
    hours_ago(1)
  end
  
  # Short-hand for hours_since(1).
  def next_hour
    hours_since(1)
  end
  
  # Short-hand for days_ago(1).
  def prev_day
    days_ago(1)
  end
  
  # Short-hand for days_since(1).
  def next_day
    days_since(1)
  end
  
  # Returns a new Time representing the start of the given day in the previous week (default is Monday).
  def prev_week(day = :monday)
    weeks_ago(1).beginning_of_week.since(days_into_week[day].day).change(:hour => 0)
  end
  
  # Short-hand for quarters_since(1).beginning_of_quarter.
  def next_quarter
    quarters_since(1).beginning_of_quarter
  end
  
  # Short-hand for quarters_ago(1).beginning_of_quarter.
  def prev_quarter
    quarters_ago(1).beginning_of_quarter
  end
  
  # Aliases to keep available method names to a standard pattern.
  alias :secs_ago :ago
  alias :seconds_ago :ago
  alias :secs_since :since
  alias :seconds_since :since
  
  # Returns a new Time representing the time a number of specified minutes ago.
  def minutes_ago(minutes)
    ago(minutes.minutes)
  end
  alias :mins_ago :minutes_ago
  
  # Returns a new Time representing the time a number of specified minutes in the future.
  def minutes_since(minutes)
    since(minutes.minutes)
  end
  alias :mins_since :minutes_since
  
  # Returns a new Time representing the time a number of specified hours ago.
  def hours_ago(hours)
    ago(hours.hours)
  end
  
  # Returns a new Time representing the time a number of specified hours in the future.
  def hours_since(hours)
    since(hours.hours)
  end
  
  # Returns a new Time representing the time a number of specified days ago.
  def days_ago(days)
    ago(days.days)
  end
  
  # Returns a new Time representing the time a number of specified days in the future.
  def days_since(days)
    since(days.days)
  end
  
  # Returns a new Time representing the time a number of specified weeks ago.
  def weeks_ago(weeks)
    ago(weeks.weeks)
  end
  
  # Returns a new Time representing the time a number of specified weeks in the future.
  def weeks_since(weeks)
    since(weeks.weeks)
  end
  
  # Returns a new Time representing the time a number of specified quarters (3 months) ago.
  def quarters_ago(quarters)
    ago((quarters * 3).months)
  end
  
  # Returns a new Time representing the time a number of specified quarters (3 months) in the future.
  def quarters_since(quarters)
    since((quarters * 3).months)
  end
  
  # Returns a new Time representing the end of the unit specified (defaults to second).
  def end_of(unit = :sec)
    send("end_of_#{unit}")
  end
  
  # Returns a new Time representing the start of the second, XX:XX:XX.000000 (.000000000 in ruby1.9).
  def beginning_of_second
    change(:usec => 0)
  end
  alias :beginning_of_sec :beginning_of_second
  alias :at_beginning_of_sec :beginning_of_second
  alias :at_beginning_of_second :beginning_of_second
  
  # Returns a new Time representing the end of the hour, XX:XX:XX.999999 (.999999999 in ruby1.9).
  def end_of_second
    change(:usec => 999999.999)
  end
  alias :end_of_sec :end_of_second
  
  # Returns a new Time representing the start of the minute (XX:XX:00).
  def beginning_of_minute
    change(:sec => 0, :usec => 0)
  end
  alias :beginning_of_min :beginning_of_minute
  alias :at_beginning_of_min :beginning_of_minute
  alias :at_beginning_of_minute :beginning_of_minute
  
  # Returns a new Time representing the end of the hour, XX:XX:59.999999 (.999999999 in ruby1.9).
  def end_of_minute
    change(:sec => 59, :usec => 999999.999)
  end
  alias :end_of_min :end_of_minute
  
  # Returns a new Time representing the start of the hour (XX:00:00).
  def beginning_of_hour
    change(:min => 0, :sec => 0, :usec => 0)
  end
  alias :at_beginning_of_hour :beginning_of_hour
  
  # Returns a new Time representing the end of the hour, XX:59:59.999999 (.999999999 in ruby1.9).
  def end_of_hour
    change(:min => 59, :sec => 59, :usec => 999999.999)
  end
  
end