Literal abstract dates

lib/literal/day.rb

@@ -0,0 +1,292 @@
+# frozen_string_literal: true
+
+class Literal::Day < Literal::Data
+	DAY_NAMES = ["Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday", "Sunday"].freeze
+	SHORT_DAY_NAMES = ["Mon", "Tue", "Wed", "Thu", "Fri", "Sat", "Sun"].freeze
+
+	prop :year, Integer
+	prop :month, _Integer(1..12)
+	prop :day, _Integer(1..31)
+
+	#: (year: Integer, month: Integer, day: Integer) -> Integer
+	def self.zellers_congruence(year:, month:, day:)
+		year, month, day = adjusted_date_for_zeller(year:, month:, day:)
+
+		q = day
+		m = month
+		k = year % 100
+		j = year / 100
+
+		(q + ((13 * (m + 1)) / 5) + k + (k / 4) + (j / 4) - (2 * j)) % 7
+	end
+
+	#: (year: Integer, month: Integer, day: Integer) -> [Integer, Integer, Integer]
+	private_class_method def self.adjusted_date_for_zeller(year:, month:, day:)
+		if month < 3
+			month += 12
+			year -= 1
+		end
+
+		[year, month, day].freeze
+	end
+
+	#: () -> void
+	private def after_initialize
+		unless @day <= Literal::Month.number_of_days_in(year: @year, month: @month)
+			raise ArgumentError
+		end
+
+		freeze
+	end
+
+	#: () -> String
+	def name
+		DAY_NAMES[day_of_week_index]
+	end
+
+	#: () -> String
+	def short_name
+		SHORT_DAY_NAMES[day_of_week_index]
+	end
+
+	#: () -> Integer
+	def day_of_year
+		day_of_year = @day
+
+		month = 1
+		while month < @month
+			day_of_year += Literal::Month.number_of_days_in(year: @year, month:)
+			month += 1
+		end
+
+		day_of_year
+	end
+
+	#: () -> Integer
+	def day_of_month
+		@day
+	end
+
+	# Return the day of week from 1 to 7, starting on Monday.
+	#: () -> Integer
+	def day_of_week
+		day_of_week_index + 1
+	end
+
+	#: () -> Literal::Day
+	def next_day
+		days_in_month = Literal::Month.number_of_days_in(year: @year, month: @month)
+
+		if @day < days_in_month
+			Literal::Day.new(year: @year, month: @month, day: @day + 1)
+		elsif @month < 12
+			Literal::Day.new(year: @year, month: @month + 1, day: 1)
+		else
+			Literal::Day.new(year: @year + 1, month: 1, day: 1)
+		end
+	end
+
+	alias_method :succ, :next_day
+
+	#: () -> Literal::Day
+	def prev_day
+		if @day > 1
+			Literal::Day.new(year: @year, month: @month, day: @day - 1)
+		elsif @month > 1
+			Literal::Day.new(year: @year, month: @month - 1, day: Literal::Month.number_of_days_in(year: @year, month: @month - 1))
+		else
+			Literal::Day.new(year: @year - 1, month: 12, day: Literal::Month.number_of_days_in(year: @year - 1, month: 12))
+		end
+	end
+
+	#: () -> bool
+	def monday?
+		0 == day_of_week_index
+	end
+
+	#: () -> bool
+	def tuesday?
+		1 == day_of_week_index
+	end
+
+	#: () -> bool
+	def wednesday?
+		2 == day_of_week_index
+	end
+
+	#: () -> bool
+	def thursday?
+		3 == day_of_week_index
+	end
+
+	#: () -> bool
+	def friday?
+		4 == day_of_week_index
+	end
+
+	#: () -> bool
+	def saturday?
+		5 == day_of_week_index
+	end
+
+	#: () -> bool
+	def sunday?
+		6 == day_of_week_index
+	end
+
+	#: () -> Literal::Month
+	def month
+		Literal::Month.new(year: @year, month: @month)
+	end
+
+	#: () -> Literal::Year
+	def year
+		Literal::Year.new(year: @year)
+	end
+
+	#: () -> bool
+	def weekend?
+		day_of_week_index > 4
+	end
+
+	#: () -> bool
+	def weekday?
+		day_of_week_index < 5
+	end
+
+	def -(other)
+		case other
+		when Literal::Duration
+			self + (-other)
+		end
+	end
+
+	#: () -> Literal::Day
+	def next_monday
+		next_day_of_week(0)
+	end
+
+	#: () -> Literal::Day
+	def next_tuesday
+		next_day_of_week(1)
+	end
+
+	#: () -> Literal::Day
+	def next_wednesday
+		next_day_of_week(2)
+	end
+
+	#: () -> Literal::Day
+	def next_thursday
+		next_day_of_week(3)
+	end
+
+	#: () -> Literal::Day
+	def next_friday
+		next_day_of_week(4)
+	end
+
+	#: () -> Literal::Day
+	def next_saturday
+		next_day_of_week(5)
+	end
+
+	#: () -> Literal::Day
+	def next_sunday
+		next_day_of_week(6)
+	end
+
+	#: () -> Literal::Day
+	def prev_monday
+		prev_day_of_week(0)
+	end
+
+	#: () -> Literal::Day
+	def prev_tuesday
+		prev_day_of_week(1)
+	end
+
+	#: () -> Literal::Day
+	def prev_wednesday
+		prev_day_of_week(2)
+	end
+
+	#: () -> Literal::Day
+	def prev_thursday
+		prev_day_of_week(3)
+	end
+
+	#: () -> Literal::Day
+	def prev_friday
+		prev_day_of_week(4)
+	end
+
+	#: () -> Literal::Day
+	def prev_saturday
+		prev_day_of_week(5)
+	end
+
+	#: () -> Literal::Day
+	def prev_sunday
+		prev_day_of_week(6)
+	end
+
+	#: () { (Literal::Time) -> void } -> void
+	def each_hour
+		hour = 0
+		while hour < 24
+			yield Literal::Time.new(year: @year, month: @month, day: @day, hour: i)
+			hour += 1
+		end
+	end
+
+	#: () { (Literal::Time) -> void } -> void
+	def each_minute
+		hour = 0
+		while hour < 24
+			minute = 0
+			while minute < 60
+				yield Literal::Time.new(year: @year, month: @month, day: @day, hour:, minute:)
+				minute += 1
+			end
+			hour += 1
+		end
+	end
+
+	#: () { (Literal::Time) -> void } -> void
+	def each_second
+		hour = 0
+		while hour < 24
+			minute = 0
+			while minute < 60
+				second = 0
+				while second < 60
+					yield Literal::Time.new(year: @year, month: @month, day: @day, hour:, minute:, second:)
+					second += 1
+				end
+				minute += 1
+			end
+			hour += 1
+		end
+	end
+
+	# Return the day of the week as an integer from 0 to 6 but where the 0th is Monday.
+	#: () -> Integer
+	private def day_of_week_index
+		(self.class.zellers_congruence(year: @year, month: @month, day: @day) + 5) % 7
+	end
+
+	#: (Integer) -> Literal::Day
+	private def next_day_of_week(target_day_index)
+		days_until_target = (target_day_index + 7 - day_of_week_index) % 7
+		days_until_target = 7 if days_until_target == 0
+		self + Literal::Duration.new(days: days_until_target)
+	end
+
+	#: (Integer) -> Literal::Day
+	private def prev_day_of_week(target_day_index)
+		days_until_target = (day_of_week_index - target_day_index) % 7
+		days_until_target = 7 if days_until_target == 0
+		self - Literal::Duration.new(days: days_until_target)
+	end
+end