Calendarプログラムの作成

02.calendar/calendar.rb

@@ -0,0 +1,44 @@
+#!/usr/bin/env ruby
+require "date"
+require "optparse"
+
+def create_calendar
+  opt = OptionParser.new
+  target_year = Date.today.year
+  target_month = Date.today.mon
+  option = {}
+
+  opt.on('-y Integer') do |y| 
+    target_year = y
+  end
+
+  opt.on('-m Integer') do |m| 
+    target_month = m
+  end
+  opt.parse!(ARGV)
+
+  first_date = Date.new(target_year.to_i, target_month.to_i, 1)
+  last_date = Date.new(target_year.to_i, target_month.to_i, -1)
+  day_of_week = first_date.wday
+
+  days = []
+  day_of_week.times do
+    days.push("  ")
+  end
+
+  1.upto(last_date.day) do |d|
+    is_single_digit_date = d < 10
+    if is_single_digit_date
+      days.push(" #{d}")
+    else
+      days.push(d)
+    end
+  end
+
+  week = days.each_slice(7).to_a
+  puts first_date.strftime("%B %Y").center(20)
+  puts ("日 月 火 水 木 金 土")
+  week.each{ |day| puts day.join(" ") }
+end
+
+create_calendar