new tasks

Task/Calendar/Ruby/calendar.rb

@@ -0,0 +1,70 @@
+require 'date'
+
+# Creates a calendar of _year_. Returns this calendar as a multi-line
+# string fit to _columns_.
+def cal(year, columns)
+
+  # Start at January 1.
+  #
+  # Date::ENGLAND marks the switch from Julian calendar to Gregorian
+  # calendar at 1752 September 14. This removes September 3 to 13 from
+  # year 1752. (By fortune, it keeps January 1.)
+  #
+  date = Date.new(year, 1, 1, Date::ENGLAND)
+
+  # Collect calendars of all 12 months.
+  months = (1..12).collect do |month|
+    rows = [Date::MONTHNAMES[month].center(20), "Su Mo Tu We Th Fr Sa"]
+
+    # Make array of 42 days, starting with Sunday.
+    days = []
+    date.wday.times { days.push "  " }
+    while date.month == month
+      days.push("%2d" % date.mday)
+      date += 1
+    end
+    (42 - days.length).times { days.push "  " }
+
+    days.each_slice(7) { |week| rows.push(week.join " ") }
+    next rows
+  end
+
+  # Calculate months per row (mpr).
+  #  1. Divide columns by 22 columns per month, rounded down. (Pretend
+  #     to have 2 extra columns; last month uses only 20 columns.)
+  #  2. Decrease mpr if 12 months would fit in the same months per
+  #     column (mpc). For example, if we can fit 5 mpr and 3 mpc, then
+  #     we use 4 mpr and 3 mpc.
+  mpr = (columns + 2).div 22
+  mpr = 12.div((12 + mpr - 1).div mpr)
+
+  # Use 20 columns per month + 2 spaces between months.
+  width = mpr * 22 - 2
+
+  # Join months into calendar.
+  rows = ["[Snoopy]".center(width), "#{year}".center(width)]
+  months.each_slice(mpr) do |slice|
+    slice[0].each_index do |i|
+      rows.push(slice.map {|a| a[i]}.join "  ")
+    end
+  end
+  return rows.join("\n")
+end
+
+
+ARGV.length == 1 or abort "usage: #{$0} year"
+
+# Guess width of terminal.
+#  1. Obey environment variable COLUMNS.
+#  2. Try to require 'io/console' from Ruby 1.9.3.
+#  3. Try to run `tput co`.
+#  4. Assume 80 columns.
+columns = begin Integer(ENV["COLUMNS"] || "")
+          rescue
+            begin require 'io/console'; IO.console.winsize[1]
+            rescue LoadError
+              begin Integer(`tput co`)
+              rescue
+                80; end; end; end
+
+puts cal(Integer(ARGV[0]), columns)