# File: snake7.py
#
# A simple program that uses the graphics module
# and the curses module to draw a "snake" on
# the graphics window that is controlled by 
# the arrow keys on the keyboard
#
# In this version, the program checks if the
# snake intersects itself. If so, when the
# tail reaches the point of intersection,
# we don't erase the box at the intersection.


from graphics import * 
import time
import curses



def main():

   def drawBox(x, y, color):
      box = Rectangle(Point(x,y), Point(x+20,y+20))
      box.setFill(color)
      box.setWidth(0)
      box.draw(win)

   # start curses 
   # don't print to screen
   # don't wait for 'enter' to be pressed
   # map special keys to curses constants
   # don't wait for keypress

   stdscr = curses.initscr()
   curses.noecho()
   curses.cbreak()
   stdscr.keypad(1)
   stdscr.nodelay(True)

   # make a window for drawing stuff
   win = GraphWin("Hello", 500, 500)

   # draw initial configuration
   pos = [ (0,240) ]
   drawBox(0,240,"orange")

   # snake is how long?
   snakeLen = 20

   # initial direction is right
   x_inc = 20
   y_inc = 0

   done = False
   while not done:

      # get current position
      (x,y) = pos[-1]

      # get a character
      c = stdscr.getch()

      if c == curses.KEY_LEFT :
         x_inc = -20
         y_inc = 0
      elif c == curses.KEY_RIGHT :
         x_inc = 20
         y_inc = 0
      elif c == curses.KEY_UP :
         x_inc = 0
         y_inc = -20
      elif c == curses.KEY_DOWN :
         x_inc = 0
         y_inc = 20
      elif c == ord('q'):
         done = True

      # erase oldest location
      if len(pos) >= snakeLen:
         (oldest_x, oldest_y) = pos.pop(0)

         # check if oldest point, is in buffer elsewhere
         selfIntersect = False
         for (p,q) in pos:
            if oldest_x == p and oldest_y == q:
               selfIntersect = True

         # if self-intersect, do not erase
         if not selfIntersect:
            drawBox(oldest_x,oldest_y,"white")


      # draw new box
      new_x = (x + x_inc) % 500
      new_y = (y + y_inc) % 500
      drawBox(new_x, new_y,"orange")

      # store new position
      pos.append((new_x, new_y))

      time.sleep(.1)

   # end of while not done


   # wait before closing window
   time.sleep(2)

   # make the window go away
   win.close()

   # restore things to normal
   stdscr.nodelay(False)
   stdscr.keypad(0)
   curses.nocbreak()
   curses.echo()
   curses.endwin()

# end of main()

main()