from tkinter import * 
import random        

w = 740
h = 540  
a = 20  
T = 100
IN_GAME  = True    
PAUSE    = False
 
def quicker():
  global T  
  if T>40:
      T-=20
def slower():
    global T  
    T+=20

def create_block():                  
  global BLOCK
  x = a * random.randint(1,(w-a)/a) 
  y = a * random.randint(1,(h-a)/a)  
  BLOCK = c.create_oval(x, y, x+a, y+a, fill="red")

class Segment(object):      
  def __init__(self, x, y):  
    self.instance = c.create_rectangle(x,y,x+a,y+a,fill="white")

class Snake(object):
  def __init__(self, segments):
    self.segments = segments
    self.mapping = {"Down":(0,1), "Right":(1,0), "Up":(0,-1), "Left":(-1,0)}
    self.vector = self.mapping["Right"]
  def move(self):  # метод руху в поточному напрямку
    for index in range(len(self.segments)-1): 
      segment = self.segments[index].instance  
      x1, y1, x2, y2 = c.coords(self.segments[index+1].instance)
      c.coords(segment, x1, y1, x2, y2)                          
    x1, y1, x2, y2 = c.coords(self.segments[-2].instance)
    c.coords(self.segments[-1].instance,
      x1+self.vector[0]*a, y1+self.vector[1]*a,
      x2+self.vector[0]*a, y2+self.vector[1]*a)
  def add_segment(self):  # додавання сегмента
    last = c.coords(self.segments[0].instance) 
    x = last[0]
    y = last[1]
    self.segments.insert(0, Segment(x, y))
  def change_direction(self, event):
    if event.keysym in self.mapping:
      self.vector = self.mapping[event.keysym]

def new():
  global b1,b2,b3,b4,c,root, IN_GAME  
  del b1,b2,b3,b4,c
  IN_GAME  = True
  root.destroy()
  start()    

def start():
  global b1,b2,b3,b4,c,root, IN_GAME    
  root = Tk()               
  root.title("Гра «Змійка»") 
  c = Canvas(root, width=w, height=h, bg="#005500") 
  c.grid(row=0, column=0, columnspan=4)
  c.focus_set()
  b1 = Button (root, text='Нова гра',   width=14, height=1, bg='white', fg='black', font='ubuntu 15')
  b2 = Button (root, text='Пришвидшити',width=14, height=1, bg='white', fg='black', font='ubuntu 15')
  b3 = Button (root, text='Сповільнити',width=14, height=1, bg='white', fg='black', font='ubuntu 15')
  b4 = Button (root, text='||  /  ► ',  width=14, height=1, bg='white', fg='black', font='ubuntu 15')
  b1.grid(row=1,  column=0)
  b2.grid(row=1,  column=1)
  b3.grid(row=1,  column=2)
  b4.grid(row=1,  column=3)
  s = Snake([Segment(a,a), Segment(a*2,a), Segment(a*3,a)])
  create_block()
 
  def main():      # основну функція керування перебігом гри
    global IN_GAME, BLOCK
    if IN_GAME:
      s.move()                                      
      head_coords = c.coords(s.segments[-1].instance) 
      x1, y1, x2, y2 = head_coords
      if x2 > w or x1 < 0 or y1 < 0 or y2 > h: 
        IN_GAME = False                      
      elif head_coords == c.coords(BLOCK):     
        s.add_segment()
        c.delete(BLOCK)                      
        create_block()
      else:
        for index in range(len(s.segments)-1): 
          if head_coords == c.coords(s.segments[index].instance): 
            IN_GAME = False                    
      if not PAUSE:
        root.after(T, main)
    else:                                     
      c.create_text(w/2, h/2, text="Гру завершено з довжиною змійки "+str(len(s.segments)), font="Ubuntu 28", fill="yellow")
 
  def set():
    global PAUSE  
    PAUSE = not PAUSE
    if not PAUSE:  main()

  c.bind("<KeyPress>", s.change_direction)
  b1.bind('<Button-1>', lambda event: new())
  b2.bind('<Button-1>', lambda event: quicker())
  b3.bind('<Button-1>', lambda event: slower())
  b4.bind('<Button-1>', lambda event: set())
  main()
  root.mainloop()

start()