require 'ffi-ncurses'

module Helpers
  # Run a code block every interval seconds
  def every(interval, &code)
    Thread.new do
      loop do
        sleep interval
        code.call
      end
    end
  end

  # Run a code block now and then every interval seconds thereafter
  def now_and_every(interval, &code)
    code.call
    every(interval, &code)
  end

  # Use ncurses to print text to the screen
  def cprint(text, options = {})
    options = { x: 0, y: 0 }.merge(options)
    FFI::NCurses.move(options[:y], options[:x])
    FFI::NCurses.attron FFI::NCurses.COLOR_PAIR(1)
    FFI::NCurses.addstr(text)
  end
end

module MyProgram
  class Window
    include FFI::NCurses

    attr_reader :screen

    def initialize
      # Various screen setup
      @screen = initscr
      @in_screen = true
      curs_set 0
      noecho
      raw
      cbreak
      keypad @screen, 1
      timeout 0

      # Clear the screen
      clear
      refresh

      # Ensure curses clears the screen up nicely when the app ends
      at_exit { endwin if @in_screen }
    end

    def close
      @in_screen = false
      endwin
    end

    def maxx
      @screen.getmaxx(@screen)
    end

    def maxy
      @screen.getmaxy(@screen)
    end

  end
end

window = MyProgram::Window.new

include FFI::NCurses
include Helpers

@angle = 0

# Twice per second, print a random number onto the screen
now_and_every(1.0 / 60) do
  clear
  s = "-" * window.maxx
  s[((s.length / 2) + Math.sin(@angle / 57.296) * (s.length / 2)).to_i] = "_"
  cprint s, x: 0, y: 10

  s = "-" * window.maxx
  s[((s.length / 2) + Math.cos(@angle / 57.296) * (s.length / 2)).to_i] = "_"
  cprint s, x: 0, y: 12
  refresh
end

every(1.0 / 120) do
  @angle = (@angle + 1) % 360
end

# Sit around waiting for input
loop do
  case k = getch
    when 27, 'q'.ord
      exit
  end
end