#!/usr/bin/ruby

require 'io/console'

# Map arrow keys to VI keys, and Ctrl+C to 'q'
key_map = {
   'D' => 'h',
   'C' => 'l',
   'A' => 'k',
   'B' => 'j',
   "\3" => 'q'
}

# Map key values to themselves
key_map.values().each{|x| key_map[x] = x }

# Spawn thread to read keys, since getch will block
last_key = 'j'
input_thread = Thread.new{
   while last_key != 'q'
      key = STDIN.getch()
      last_key = key_map[key] || last_key
   end
}

# Show banner text and hide cursor
print "Type 'q' to quit\n\n\e[?25l"
frame = 0
while last_key != 'q'
   text = "\e[1A\e[1G"
   if last_key == 'h'
      text += "Left "
   elsif last_key == 'l'
      text += "Right"
   elsif last_key == 'k'
      text += "Up   "
   else
      text += "Down "
   end
   text += "\e[1B\e[5DFrame %2d" % frame
   print text
   frame = -~frame % 30

   sleep 1. / 30
end

# Show cursor again and reset colors
print "\e[?25h\e[0m\n"

input_thread.join