cyang-el · December 3, 2024 13:15 · Dec 3, 2024 · Dec 3, 2024
diff --git a/2048.rb b/2048.rb
@@ -0,0 +1,260 @@
+# frozen_string_literal: true
+
+require 'io/console'
+
+SIZE = 5
+
+def run
+  $stdin.echo = false
+  board = init_board
+  render!(board)
+  loop do
+    render!(update(board))
+  end
+ensure
+  $stdin.echo = true
+end
+
+def init_board
+  board = []
+  4.times { board << [nil, nil, nil, nil] } # 4 x 4 game
+  srand(Time.now.to_i)
+  rand(0..3)
+  pos1 = rand(0..3)
+  pos2 = (pos1 + 2) % 4
+  board[pos1][pos1] = 2
+  board[pos2][pos2] = 2
+  board
+end
+
+def update(board)
+  key_in = $stdin.getch
+  # ^ blocking
+  exit if key_in.eql?('q')
+  return board unless %w[h j k l].include? key_in
+
+  update_board(key_in, board)
+end
+
+def update_board(key_in, board)
+  handler = {
+    'j' => method(:down!),
+    'k' => method(:up!),
+    'h' => method(:left!),
+    'l' => method(:right!)
+  }[key_in]
+  raise RuntimeError if handler.nil?
+
+  handler.call(board)
+
+  if win?(board)
+    raise 'congrats, you win!!!!!'
+  elsif fail?(board)
+    raise 'oh no, you lost :('
+  else
+    add_2!(board)
+  end
+
+  board
+end
+
+def up!(board)
+  move_along_x!(board, true)
+end
+
+def down!(board)
+  move_along_x!(board, false)
+end
+
+def right!(board)
+  move_along_y!(board, false)
+end
+
+def left!(board)
+  move_along_y!(board, true)
+end
+
+def win?(board)
+  board.any? { |row| row.any? { |n| n.eql? 2048 } }
+end
+
+def fail?(board)
+  board.all? { |row| row.all? { |n| !n.nil? } }
+end
+
+def add_2!(board)
+  nil_coords = []
+  board.each_with_index do |row, y|
+    row.each_with_index do |val, x|
+      nil_coords << [x, y] if val.nil?
+    end
+  end
+  ty, tx = nil_coords.sample
+  board[ty][tx] = 2
+end
+
+def column_at(board, x)
+  0.upto(3).each.map { |y| board[y][x] }.filter { |v| !v.nil? }
+end
+
+def collect(line)
+  0.upto(line.length - 1).each do |i|
+    if line[i].eql?(line[i + 1])
+      line[i] = line[i] + line[i + 1]
+      line[i + 1] = 0
+    end
+  end
+  line.filter(&:positive?)
+end
+
+def fold_column_at(board, x, is_up)
+  column = is_up ? column_at(board, x) : column_at(board, x).reverse
+  column = collect(column)
+  is_up ? column : column.reverse
+end
+
+def move_along_x!(board, is_up)
+  # move
+  0.upto(3).each do |x|
+    column = fold_column_at(board, x, is_up)
+    if is_up
+      column.fill(nil, column.length...4)
+    else
+      column = Array.new(4 - column.length) + column
+    end
+    0.upto(3).each { |y| board[y][x] = column[y] }
+  end
+end
+
+def fold_row_at(board, y, is_left)
+  row = board[y].filter { |v| !v.nil? }
+  row = is_left ? row : row.reverse
+  row = collect(row)
+  is_left ? row : row.reverse
+end
+
+def move_along_y!(board, is_left)
+  0.upto(3).each do |y|
+    row = fold_row_at(board, y, is_left)
+    if is_left
+      row.fill(nil, row.length...4)
+    else
+      row = Array.new(4 - row.length) + row
+    end
+    board[y] = row
+  end
+end
+
+def map_bg_color(val)
+  case val
+  when nil
+    "\e[42m" # Green
+  when 2
+    "\e[105m" # Bright Magenta
+  when 4
+    "\e[96m"  # Bright Cyan
+  when 8
+    "\e[43m"  # Yellow
+  when 16
+    "\e[104m" # Bright Blue
+  when 32
+    "\e[45m"  # Magenta
+  when 64
+    "\e[46m"  # Cyan
+  when 128
+    "\e[101m" # Bright Red
+  when 256
+    "\e[102m" # Bright Green
+  when 512
+    "\e[103m" # Bright Yellow
+  when 1024
+    "\e[44m"  # Blue
+  when 2048
+    "\e[41m"  # Red
+  else
+    raise ArgumentError, 'only nil or 2048 nums can be colored'
+  end
+end
+
+def color_txt(txt, bg_color)
+  raise ArgumentError if txt.nil?
+
+  reset = "\e[0m"
+  "#{bg_color}#{txt}#{reset}"
+end
+
+def pos_block(pos, size = SIZE)
+  pos_start = pos * size
+  pos_end = pos_start + size - 1
+  [pos_start, pos_end]
+end
+
+def pos_val_in_row(val, xhead, xtail)
+  txt_len = val.to_s.length
+  center = (xhead + xtail) / 2
+  center - txt_len / 2
+end
+
+def center_row(ytop, ybottom)
+  (ytop + ybottom) / 2
+end
+
+def place_block!(pos_x, pos_y, val, color, canvas)
+  ytop, ybottom = pos_block(pos_y)
+  xhead, xtail = pos_block(pos_x)
+
+  val = val.nil? ? ' ' : val
+
+  (ytop..ybottom).each do |y|
+    (xhead..xtail).each do |x|
+      canvas[y][x] = color_txt(' ', color)
+    end
+  end
+  place_txt!(val, xhead, xtail,
+             ytop, ybottom, color, canvas)
+end
+
+def place_txt!(val, xhead, xtail,
+               ytop, ybottom, color, canvas)
+  return if val.nil?
+
+  xtxt = pos_val_in_row val, xhead, xtail
+  ytxt = center_row ytop, ybottom
+  (0...val.to_s.length).each do |idx|
+    canvas[ytxt][xtxt + idx] = color_txt(val.to_s[idx], color)
+  end
+end
+
+def place_board!(board, canvas)
+  board.each_with_index do |row, y|
+    row.each_with_index do |val, x|
+      color = map_bg_color(val)
+      place_block! x, y, val, color, canvas
+    end
+  end
+end
+
+def a_clean_canvas(size = SIZE)
+  # 4 x 4 game
+  len = size * 4
+  Array.new(len) { Array.new(len, nil) }
+end
+
+def print_canvas!(canvas)
+  canvas.each { |row| puts row.join }
+end
+
+def render_board(board)
+  canvas = a_clean_canvas
+  place_board! board, canvas
+  print_canvas! canvas
+end
+
+def render!(board)
+  print "\033[2J" # clear screen
+  print "\033[H" # cursor to the top left
+  render_board board
+  print "\n"
+end
+
+run if __FILE__ == $PROGRAM_NAME