time_or_datetime.rb

require 'date'
require 'rational' unless defined?(Rational)
require 'time'

module TZInfo
  # Used by TZInfo internally to represent either a Time, DateTime or
  # an Integer timestamp (seconds since 1970-01-01 00:00:00).
  class TimeOrDateTime
    include Comparable

    # Constructs a new TimeOrDateTime. timeOrDateTime can be a Time, DateTime
    # or Integer. If using a Time or DateTime, any time zone information
    # is ignored.
    def initialize(timeOrDateTime, ignore_offset = true)
      @time = nil
      @datetime = nil
      @timestamp = nil

      if timeOrDateTime.is_a?(Time)
        @time = timeOrDateTime

        # Avoid using the slower Rational class unless necessary.
        nsec = @time.nsec
        usec = nsec % 1000 == 0 ? nsec / 1000 : Rational(nsec, 1000)

        @time = Time.utc(@time.year, @time.mon, @time.mday, @time.hour, @time.min, @time.sec, usec) unless @time.utc? || !ignore_offset
        @orig = @time
      elsif timeOrDateTime.is_a?(DateTime)
        @datetime = timeOrDateTime
        @datetime = @datetime.new_offset(0) unless @datetime.offset == 0 || !ignore_offset
        @orig = @datetime
      else
        @timestamp = timeOrDateTime.to_i
        @orig = @timestamp
      end
    end

    # Returns the time as a Time.
    #
    # When converting from a DateTime, the result is truncated to microsecond
    # precision.
    def to_time
      # Thread-safety: It is possible that the value of @time may be
      # calculated multiple times in concurrently executing threads. It is not
      # worth the overhead of locking to ensure that @time is only
      # calculated once.

      unless @time
        if @timestamp
          @time = Time.at(@timestamp).utc
        else
          @time = Time.utc(year, mon, mday, hour, min, sec, usec)
        end
      end

      @time
    end

    # Returns the time as a DateTime.
    #
    # When converting from a Time, the result is truncated to microsecond
    # precision.
    def to_datetime
      # Thread-safety: It is possible that the value of @datetime may be
      # calculated multiple times in concurrently executing threads. It is not
      # worth the overhead of locking to ensure that @datetime is only
      # calculated once.

      unless @datetime
        # Avoid using Rational unless necessary.
        u = usec
        s = u == 0 ? sec : Rational(sec * 1000000 + u, 1000000)
        @datetime = DateTime.new(year, mon, mday, hour, min, s)
      end

      @datetime
    end

    # Returns the time as an integer timestamp.
    def to_i
      # Thread-safety: It is possible that the value of @timestamp may be
      # calculated multiple times in concurrently executing threads. It is not
      # worth the overhead of locking to ensure that @timestamp is only
      # calculated once.

      unless @timestamp
        @timestamp = to_time.to_i
      end

      @timestamp
    end

    # Returns the time as the original time passed to new.
    def to_orig
      @orig
    end

    # Returns a string representation of the TimeOrDateTime.
    def to_s
      if @orig.is_a?(Time)
        "Time: #{@orig.to_s}"
      elsif @orig.is_a?(DateTime)
        "DateTime: #{@orig.to_s}"
      else
        "Timestamp: #{@orig.to_s}"
      end
    end

    # Returns internal object state as a programmer-readable string.
    def inspect
      "#<#{self.class}: #{@orig.inspect}>"
    end

    # Returns the year.
    def year
      if @time
        @time.year
      elsif @datetime
        @datetime.year
      else
        to_time.year
      end
    end

    # Returns the month of the year (1..12).
    def mon
      if @time
        @time.mon
      elsif @datetime
        @datetime.mon
      else
        to_time.mon
      end
    end
    alias :month :mon

    # Returns the day of the month (1..n).
    def mday
      if @time
        @time.mday
      elsif @datetime
        @datetime.mday
      else
        to_time.mday
      end
    end
    alias :day :mday

    # Returns the hour of the day (0..23).
    def hour
      if @time
        @time.hour
      elsif @datetime
        @datetime.hour
      else
        to_time.hour
      end
    end

    # Returns the minute of the hour (0..59).
    def min
      if @time
        @time.min
      elsif @datetime
        @datetime.min
      else
        to_time.min
      end
    end

    # Returns the second of the minute (0..60). (60 for a leap second).
    def sec
      if @time
        @time.sec
      elsif @datetime
        @datetime.sec
      else
        to_time.sec
      end
    end

    # Returns the number of microseconds for the time.
    def usec
      if @time
        @time.usec
      elsif @datetime
        # Ruby 1.8 has sec_fraction (of which the documentation says
        # 'I do NOT recommend you to use this method'). sec_fraction no longer
        # exists in Ruby 1.9.

        # Calculate the sec_fraction from the day_fraction.
        ((@datetime.day_fraction - OffsetRationals.rational_for_offset(@datetime.hour * 3600 + @datetime.min * 60 + @datetime.sec)) * 86400000000).to_i
      else
        0
      end
    end

    # Compares this TimeOrDateTime with another Time, DateTime, timestamp
    # (Integer) or TimeOrDateTime. Returns -1, 0 or +1 depending
    # whether the receiver is less than, equal to, or greater than
    # timeOrDateTime.
    #
    # Returns nil if the passed in timeOrDateTime is not comparable with
    # TimeOrDateTime instances.
    #
    # Comparisons involving a DateTime will be performed using DateTime#<=>.
    # Comparisons that don't involve a DateTime, but include a Time will be
    # performed with Time#<=>. Otherwise comparisons will be performed with
    # Integer#<=>.
    def <=>(timeOrDateTime)
      return nil unless timeOrDateTime.is_a?(TimeOrDateTime) ||
                        timeOrDateTime.is_a?(Time) ||
                        timeOrDateTime.is_a?(DateTime) ||
                        timeOrDateTime.respond_to?(:to_i)

      unless timeOrDateTime.is_a?(TimeOrDateTime)
        timeOrDateTime = TimeOrDateTime.wrap(timeOrDateTime)
      end

      orig = timeOrDateTime.to_orig

      if @orig.is_a?(DateTime) || orig.is_a?(DateTime)
        # If either is a DateTime, assume it is there for a reason
        # (i.e. for its larger range of acceptable values on 32-bit systems).
        to_datetime <=> timeOrDateTime.to_datetime
      elsif @orig.is_a?(Time) || orig.is_a?(Time)
        to_time <=> timeOrDateTime.to_time
      else
        to_i <=> timeOrDateTime.to_i
      end
    end

    # Adds a number of seconds to the TimeOrDateTime. Returns a new
    # TimeOrDateTime, preserving what the original constructed type was.
    # If the original type is a Time and the resulting calculation goes out of
    # range for Times, then an exception will be raised by the Time class.
    def +(seconds)
      if seconds == 0
        self
      else
        if @orig.is_a?(DateTime)
          TimeOrDateTime.new(@orig + OffsetRationals.rational_for_offset(seconds))
        else
          # + defined for Time and Integer
          TimeOrDateTime.new(@orig + seconds)
        end
      end
    end

    # Subtracts a number of seconds from the TimeOrDateTime. Returns a new
    # TimeOrDateTime, preserving what the original constructed type was.
    # If the original type is a Time and the resulting calculation goes out of
    # range for Times, then an exception will be raised by the Time class.
    def -(seconds)
      self + (-seconds)
    end

    # Sets offset from UTC for the TimeOrDateTime. Returns a new TimeOrDateTime,
    # preserving original class. Does NOT changes values of hour-min-second,
    # so, (18:00 UTC).offset(3600) will became (18:00 +01:00).
    # Considers original value's UTC offset wisely.
    def offset(seconds)
      return self if seconds == 0

      if @orig.is_a?(DateTime)
        off = OffsetRationals.rational_for_offset(seconds)
        TimeOrDateTime.new(@orig.new_offset(off), false)
      elsif @orig.is_a?(Time)
        offset_str = '%+03i:%02i' % [seconds / 3600, seconds / 60 % 60]

        time = @time + seconds
        nsec_part = Rational(time.nsec, 1_000_000_000)
        time = Time.new(time.year, time.mon, time.mday, time.hour, time.min, time.sec + nsec_part, offset_str)
        TimeOrDateTime.new(time, false)
      else
        # Integer: fallback to "just shift timestamp"
        TimeOrDateTime.new(@orig + seconds)
      end
    end

    # Returns true if todt represents the same time and was originally
    # constructed with the same type (DateTime, Time or timestamp) as this
    # TimeOrDateTime.
    def eql?(todt)
      todt.kind_of?(TimeOrDateTime) && to_orig.eql?(todt.to_orig)
    end

    # Returns a hash of this TimeOrDateTime.
    def hash
      @orig.hash
    end

    # If no block is given, returns a TimeOrDateTime wrapping the given
    # timeOrDateTime. If a block is specified, a TimeOrDateTime is constructed
    # and passed to the block. The result of the block must be a TimeOrDateTime.
    #
    # The result of the block will be converted to the type of the originally
    # passed in timeOrDateTime and then returned as the result of wrap.
    #
    # timeOrDateTime can be a Time, DateTime, timestamp (Integer) or
    # TimeOrDateTime. If a TimeOrDateTime is passed in, no new TimeOrDateTime
    # will be constructed and the value passed to wrap will be used when
    # calling the block.
    def self.wrap(timeOrDateTime)
      t = timeOrDateTime.is_a?(TimeOrDateTime) ? timeOrDateTime : TimeOrDateTime.new(timeOrDateTime)

      if block_given?
        t = yield t

        if timeOrDateTime.is_a?(TimeOrDateTime)
          t
        elsif timeOrDateTime.is_a?(Time)
          t.to_time
        elsif timeOrDateTime.is_a?(DateTime)
          t.to_datetime
        else
          t.to_i
        end
      else
        t
      end
    end
  end
end