#!/usr/bin/ruby

NOW = Time.now

TIOCGWINSZ = 0x5413
s = ''.ljust(8)
TERMW = $stdin.ioctl(TIOCGWINSZ, s) >= 0 ? s.unpack('SS')[1] : 80

MW = 7*3 + 2

def invert(s)
 "\e[7m#{s}\e[27m"
end

# BWAHAHAHAHA
def showmonth(m, y, nr=1)
 obuf = ' ' * nr * MW
 w = MW-4
 off = 1
 lines = []
 invertme = []
 while m < 1
    m += 12
    y -= 1
 end
 nr.times {
  t = Time.mktime(y, m, 1, 12)	# 12:00 to avoid DST issues
  l = lines[0] ||= obuf.dup
  l[off, w] = t.strftime('%B %Y').center(w)
  l = lines[1] ||= obuf.dup
  l[off, w] = 'Mo Tu We Th Fr Sa Su'
  loff = 2
  while t.month == m
   l = lines[loff] ||= obuf.dup
   wd = (t.wday-1) % 7
   l[off+3*wd, 2] = '%2s' % t.day
   invertme << [loff, off+3*wd, 2] if t.year == NOW.year and t.month == NOW.month and t.day == NOW.day
   loff += 1 if wd == 6
   t += 24*3600
  end
  off += MW
  m += 1
  if m > 12
    m = 1
    y += 1
  end
 }
 invertme.each { |lo, o, l| lines[lo][o, l] = invert(lines[lo][o, l]) }
 puts lines, ''
end

if ARGV.length == 2
 m, y = ARGV.map { |i| i.to_i }.sort
 showmonth(m, y)
elsif ARGV.length == 1
 m = ARGV[0].to_i
 if m > 12 or m < 1
  showmonth(1, m, 3)
  showmonth(4, m, 3)
  showmonth(7, m, 3)
  showmonth(10, m, 3)
 else
  showmonth(m, NOW.year)
 end
else
 nr = TERMW / MW
 nr = 1 if nr < 1
 nr = 4 if nr > 4
 showmonth(NOW.month - (nr > 2 ? 1 : 0), NOW.year, nr)
end