meetup: add code to write new descriptions

This helps understand the logic used to write the new descriptions.

Author: petertseng

exercises/meetup/newdesc.rb

@@ -0,0 +1,69 @@
+require 'json'
+
+j = JSON.parse(File.read(File.join(__dir__, 'canonical-data.json')))
+
+def ord(n)
+  case n
+  when 1; '1st'
+  when 2; '2nd'
+  when 3; '3rd'
+  when 21; '21st'
+  when 22; '22nd'
+  when 23; '23rd'
+  when 31; '31st'
+  else "#{n}th"
+  end
+end
+
+def mod_desc_for_range(c, week, first, last)
+  raise "bad #{c['input']['week']} != #{week}" if c['input']['week'] != week
+
+  if c['expected'].end_with?('-%02d' % first)
+    c['description'] = "when #{week} #{c['input']['dayofweek']} is the #{ord(first)}, the first day of the #{week} week"
+  elsif c['expected'].end_with?('-%02d' % last)
+    c['description'] = "when #{week} #{c['input']['dayofweek']} is the #{ord(last)}, the last day of the #{week} week"
+  else
+    c['description'] = "when #{week} #{c['input']['dayofweek']} is some day in the middle of the #{week} week"
+  end
+end
+
+j['cases'].each { |c|
+  case c['input']['week']
+  when 'teenth'; mod_desc_for_range(c, 'teenth', 13, 19)
+  when 'first'; mod_desc_for_range(c, 'first', 1, 7)
+  when 'second'; mod_desc_for_range(c, 'second', 8, 14)
+  when 'third'; mod_desc_for_range(c, 'third', 15, 21)
+  when 'fourth'; mod_desc_for_range(c, 'fourth', 22, 28)
+  when 'last'
+    month = Integer(c['expected'].split(?-, 3)[1], 10)
+    day = Integer(c['expected'].split(?-, 3)[2], 10)
+    dow = c['input']['dayofweek']
+    if month == 2 && day == 29
+      c['description'] = "when last #{dow} in February in a leap year is the 29th"
+    elsif month == 2 && day == 22
+      c['description'] = "when last #{dow} in February in a non-leap year is not the 29th"
+    elsif month == 12 && day == 31
+      c['description'] = "last #{dow} in December that also happens to be the last day of the year"
+    else
+      c['description'] = "last #{dow} in a month with #{day > 28 ? 'five' : 'four'} #{dow}s"
+    end
+  else
+    $stderr.puts("no new description for #{c['description']}")
+  end
+}
+
+seen = {}
+# dedup by notating some cases with "another"
+j['cases'].each { |c|
+  desc = c['description']
+  if seen[desc]
+    new_desc = desc.include?('some day') ? desc.sub('some day', 'another day') : desc.sub('a month with', 'another month with')
+    raise "couldn't fix #{desc}" if new_desc == desc
+    raise "tried to fix #{desc} but even #{new_desc} was already seen" if seen[new_desc]
+    seen[new_desc] = true
+    c['description'] = new_desc
+  end
+  seen[desc] = true
+}
+
+puts JSON.pretty_generate(j)