#!/usr/bin/env ruby

require 'io/console'
#   STDIN.getch

W = 100
H = 25
WI = W - 2
HI = H - 2

class Screen
  def initialize(w, h, *args)
    @w, @h = w - 2, h - 2
    self.clear()
  end

  def clear()
    # @screen = [['='] * @w] * @h # DO NOT: copies by reference
    @screen = Array.new(@h) {[' '] * @w}
  end

  def set(x, y, val='0')
    @screen[y][x] = val
  end

  def unset(x, y)
    @screen[y][x] = ' '
  end

  def print()
    tmp = ['+' + '-' * @w + '+']
    for row in @screen do
      tmp << '|' + row.join('') + '|'
    end
    tmp << ['+' + '-' * @w + '+']
    puts tmp.join("\n")
  end
end

# Infinite loop using function objects as arguments
def inf_loop(fps, xzoom, f)
  s = Screen.new(W, H)
  for x in 1...WI do
    y = f.call(x/xzoom.to_f)
    s.set(x, y)
    s.print()
    #s.unset(x, y)
    sleep(1.0/fps)
  end
end

def cos(x)
  return HI/2 + (Math.cos(x) * (HI/2)).to_int
end

# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
# BLOCKS
# {|| code} works only in combination with yield.

# Infinite loop using blocks an yield
def inf_loop_y(fps, xzoom)
  s = Screen.new(W, H)
  # zoom 2x
  for x in 1...WI do
    y = yield x/xzoom.to_f
    s.set(x, y)
    s.print()
    sleep(1.0/fps)
  end
end

# SIN (lambda)
#inf_loop_y(15, 10) { |x| HI/2 + (Math.sin(x) * (HI/2)).to_int}

# Thunder (lambda)
inf_loop_y(15, 1) do |x|
  # last computed value is automatically returned.
  # do not use return (will return calling function)
  (x%HI).to_int
end