require 'io/console'
height, width = $stdout.winsize

# No cursor, input 1 char at a time
print "\e[?25l"; at_exit { print "\e[?25h" }
$stdin.raw!;     at_exit { $stdin.cooked! }

# Load or create the new canvas
if ARGV[0]
  canvas = File.read(ARGV[0]).lines.map { |line| line.chomp.chars.map(&:to_i) }
else
  canvas = Array.new(height-1) { Array.new width-1, 0 }
end

# To save it once done (doing it this way so we have access to the canvas local var)
define_method :save do
  filename = ARGV[0]||'image'
  File.write filename, canvas.map(&:join).join("\n")
  print "\r\nSaved in #{filename.inspect}"
end

# Promt whether to save, upon exit
at_exit do
  print "\e[1;1HSAVE? "
  save if $stdin.getc == 'y'
end

# Edit the canvas
x = y = 0
loop do
  # Draw each square the colour specified
  image = canvas.map { |ns| ns.map { |n| "\e[4#{n}m " }.join }.join("\e[0m\r\n")
  print "\e[2;1H#{image}\e[#{y+2};#{x+1}H\e[4#{canvas[y][x]}m#{canvas[y][x]}"

  # Depending on what they press, we'll either quit, save, move, or colour the canvas
  char = $stdin.getc
  case char
  when "\x03", "q" then break
  when 's'         then save
  when 'h'         then x -= 1
  when 'j'         then y += 1
  when 'k'         then y -= 1
  when 'l'         then x += 1
  when /\d/        then canvas[y][x] = char.to_i
  end
end