ioquatix/time-zone

# Copyright, 2018, by Samuel G. D. Williams. <http://www.codeotaku.com>
# 
# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:
# 
# The above copyright notice and this permission notice shall be included in
# all copies or substantial portions of the Software.
# 
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
# THE SOFTWARE.

require_relative '../zone'

require 'date'

class Time
    module Zone
        class Timestamp
            include Comparable
            
            def self.load(string)
                self.parse(string)
            end
            
            def self.dump(time)
                time.strftime
            end
            
            def self.now(zone)
                self.from(Zone.now(zone), zone)
            end
            
            def self.from(time, zone)
                self.new(time.year, time.month, time.day, time.hour, time.minute, time.second, zone)
            end
            
            def self.parse(*args)
                self.from(*Zone.parse(*args))
            end
            
            def initialize(year, month, day, hour, minute, second, zone = "UTC")
                @year = year
                @month = month
                @day = day
                @hour = hour
                @minute = minute
                @second = second
                @zone = zone
                
                @time = nil
            end
            
            attr :year
            attr :month
            attr :day
            attr :hour
            attr :minute
            attr :second
            attr :zone
            
            def convert(zone)
                self.class.from(Time::Zone.convert(to_time, zone), zone)
            end
            
            # Generate a new time with the specified changes.
            # @param months [Numeric] add this many months
            # @param seconds [Numeric] add this many seconds
            # @param zone [String] forcefully change the timezone without doing any conversion.
            def with_offset(months = 0, seconds = 0, zone = @zone)
                current = self
                
                if months != 0
                    current = current.to_datetime >> months
                end
                
                if seconds != 0
                    # https://bugs.ruby-lang.org/issues/14879
                    current = Time::Zone.convert(current.to_time + seconds, @zone)
                end
                
                self.class.from(current, zone)
            end
            
            # Add duration in various units.
            def offset_by(years: 0, months: 0, weeks: 0, days: 0, hours: 0, minutes: 0, seconds: 0)
                with_offset(
                    years * 12 + months,
                    (((weeks * 7 + days) * 24 + hours) * 60 + minutes) * 60 + seconds
                )
            end
            
            # Add duration in seconds.
            def + duration
                with_offset(0, duration)
            end
            
            # Return difference in seconds.
            def - other
                if other.is_a? Numeric
                    # We are subtracting a duration:
                    with_offset(0, -other)
                else
                    to_time - other.to_time
                end
            end
            
            def to_time
                @time ||= Time::Zone.new(@year, @month, @day, @hour, @minute, @second, @zone).freeze
            end
            
            def to_date
                to_time.to_date
            end
            
            def to_datetime
                to_time.to_datetime
            end
            
            def iso8601
                to_time.iso8601
            end
            
            def <=> other
                to_time <=> other.to_time
            end
            
            DEFAULT_FORMAT = '%Y-%m-%d %H:%M:%S %Z'.freeze
            
            def to_s(format = relative_format)
                to_time.strftime(format.gsub('%Z', @zone))
            end
            
            def strftime(format = DEFAULT_FORMAT)
                to_s(format)
            end
            
            def relative_format(now = Timestamp.now(@zone))
                if self.year != now.year
                    "%-l:%M%P, %B %-d, %Y, %Z"
                elsif self.month != now.month or self.day != now.day
                    "%-l:%M%P, %B %-d, %Z"
                else
                    "%-l:%M%P, %Z"
                end
            end
            
            alias to_str strftime
        end
    end
end