reasonable_typos.rb

KEYBOARD = [
  '1234567890-='.chars,
  'qwertyuiop[]'.chars,
  'asdfghjkl;\''.chars,
  'zxcvbnm,./'.chars,
]

def reasonable_typos(distance: 3)
  typo_map = Hash.new do |h, initial_key|
    h[initial_key] = {}
  end

  KEYBOARD.each_with_index do |row, x|
    row.each_with_index do |key, y|
      distance.times do |initial_offset|
        offset = initial_offset + 1

        [
          [x + offset, y], # Right
          [x - offset, y], # Left
          [x, y + offset], # Up
          [x, y - offset], # Down

          [x + offset, y + offset], # Up Right
          [x + offset, y - offset], # Down Right
          [x - offset, y + offset], # Up Left
          [x + offset, y - offset], # Down Left
        ].each do |x2, y2|
          next if x2.negative? || y2.negative?

          new_key = KEYBOARD.dig(x2, y2)

          next if new_key.nil?
          next if typo_map[key].key?(new_key)
          
          typo_map[key][new_key] = offset
        end
      end
    end
  end

  typo_map
end