# Python 2.7.7 Code
# Pygame 1.9.1 (for Python 2.7.7)
# Jonathan Frech 16th of June, 2015
#         edited 17th of June, 2015

# importing needed modules
import pygame, sys, time, math, os, random

""" CLASSES """
# dummy class for global variables
class dummy():
	pass

# snake class (controls the whole game)
class snake():
	# init
	def __init__(self, _pos, _dir = [1, 0]):
		self.pos = _pos
		self.dir = _dir
		self.color = [0, 150, 0]
		
		self.parts = []
		self.partcolor = [0, 255, 0]
		self.length = 3
		
		self.apples = []
		self.applecolor = [255, 0, 0]
		self.appleticks = 0
		self.maxapples = 3
		
		self.speed = 10
		self.canChangeDir = True
		
		self.setCaption()
	
	# update screen caption
	def setCaption(self):
		if main.GAMEOVER:
			pygame.display.set_caption(main.CAPTION + " (gameover, " + str(self.length) + " points)")
		else:
			pygame.display.set_caption(main.CAPTION + " (" + str(self.length) + " points)")
	
	# change direction
	def setdir(self, _dir):
		if self.canChangeDir:
			if self.dir[0] != 0:
				# cannot change in x
				if _dir[1] != 0:
					# can change
					self.dir = _dir
					self.canChangeDir = False
			
			elif self.dir[1] != 0:
				# cannot change in y
				if _dir[0] != 0:
					# can change
					self.dir = _dir
					self.canChangeDir = False
	
	# tick
	def tick(self):
		# interpret keys
		if pygame.K_UP in main.KEYSDOWN:
			self.setdir([0, -1])
		if pygame.K_DOWN in main.KEYSDOWN:
			self.setdir([0, 1])
		
		if pygame.K_LEFT in main.KEYSDOWN:
			self.setdir([-1, 0])
		if pygame.K_RIGHT in main.KEYSDOWN:
			self.setdir([1, 0])
		
		# apples
		if len(self.apples) < self.maxapples:
			self.appleticks += 1
			
			# spawn in a new apple
			if self.appleticks >= 60:
				self.appleticks = 0
				
				# random position for the new apple
				p = [random.randint(0, main.WIDTH - 1), random.randint(0, main.HEIGHT - 1)]
				
				# apples must not appear inside the snake
				add = True
				for _ in self.parts:
					if p[0] == _[0] and p[1] == _[1]:
						add = False
				if self.pos[0] == p[0] and self.pos[1] == p[1]:
					add = False
				
				if add:
					self.apples.append(p)
		
		# move
		if main.TICKS % self.speed == 0:
			# check for any apples
			for _ in self.apples:
				if _[0] == self.pos[0] and _[1] == self.pos[1]:
					# apple collected!
					self.apples.remove(_)
					self.length += 1
					self.setCaption()
			
			# check if snake can move
			move = True
			for _ in self.parts:
				if self.pos[0] == _[0]:
					if self.pos[1] + self.dir[1] == _[1]:
						move = False
				if self.pos[1] == _[1]:
					if self.pos[0] + self.dir[0] == _[0]:
						move = False
			
			# check screen borders
			if self.pos[0] + self.dir[0] < 0 or self.pos[0] + self.dir[0] >= main.WIDTH:
				move = False
			
			if self.pos[1] + self.dir[1] < 0 or self.pos[1] + self.dir[1] >= main.HEIGHT:
				move = False
			
			# move or set gameover to true
			if move:
				# create part
				self.parts.append(self.pos[:])
				
				self.pos[0] += self.dir[0]
				self.pos[1] += self.dir[1]
				self.canChangeDir = True
			
			else:
				main.GAMEOVER = True
				self.setCaption()
			
			# remove excess parts
			while len(self.parts) > self.length:
				self.parts.pop(0)
			
	# render
	def render(self, _surface):
		# render parts
		for _ in self.parts:
			_surface.set_at(_, self.partcolor)
		
		# render snake head
		_surface.set_at(self.pos, self.color)
		
		# render apples
		for _ in self.apples:
			_surface.set_at(_, self.applecolor)

""" FUNCTIONS """
# gets the mouse position
def getMousePos():
	p = pygame.mouse.get_pos()
	return [p[0], p[1]]

# validates color integer
# extra feature: _min and _max implementation
def colorValid(_color, _min = 0, _max = 255):
	newColor = math.fabs(_color)
	n = _max - _min
	if newColor > n:
		if int(newColor / n) % 2 == 0:
			newColor = newColor % n
		else:
			newColor = n - (newColor % n)
	
	return int(newColor) + _min

# gets the position on a circle
# circle center                           : '_pos'
# circle radius                           : '_radius'
# angle from center to point on the circle: '_angle'
def getCirclePos(_pos, _radius, _angle):
	return [
				_pos[0] + _radius * math.cos(math.radians(_angle)),
				_pos[1] + _radius * math.sin(math.radians(_angle))
			]

# returns an integer version of given positon
def intpos(_pos):
	return [int(_pos[0]), int(_pos[1])]

# basic vector functions
def vecConvert(p1, p2):
	return [p2[0] - p1[0], p2[1] - p1[1]]
def vecLen(vec):
	return math.sqrt( (vec[0]**2) + (vec[1]**2) )
def vecMultiply(vec, n):
	return [vec[0] * n, vec[1] * n]
def vecGetPoint(vec, point):
	return [point[0] + vec[0], point[1] + vec[1]]
def vecAdd(vec1, vec2):
	return [vec1[0] + vec2[0], vec1[1] + vec2[1]]

# calculates distance between given positions
def posDistance(p1, p2):
	return math.sqrt( (p2[0] - p1[0])**2 + (p2[1] - p1[1])**2 )

# quits the program
def quit():
	sys.exit()

""" TICK; RENDER """
# tick function
def tick():
	# handle events
	for event in pygame.event.get():
		# quit
		if event.type == pygame.QUIT:
			quit()
		
		# keyup
		if event.type == pygame.KEYUP:
			# handle 'main.KEYSDOWN'
			if event.key in main.KEYSDOWN:
				main.KEYSDOWN.remove(event.key)
		
		# keydown
		if event.type == pygame.KEYDOWN:
			# handle 'main.KEYSDOWN'
			if event.key not in main.KEYSDOWN:
				main.KEYSDOWN.append(event.key)
			
			# reset
			if event.key == pygame.K_r:
				reset()
			
			# pause
			if event.key == pygame.K_ESCAPE:
				if main.PAUSED:
					main.PAUSED = False
				else:
					main.PAUSED = True
	
	# tick snake
	if not main.PAUSED and not main.GAMEOVER:
		main.SNAKE.tick()

# render function
def render():
	# render gameover screen
	if main.GAMEOVER:
		if main.GAMEOVERVISTICKS < main.WIDTH * 2:
			pygame.draw.line(main.SURF, [0, 0, 0], [0, main.GAMEOVERVISTICKS], [main.GAMEOVERVISTICKS, 0])
			main.GAMEOVERVISTICKS += 1
	else:
		# fill
		main.SURF.fill(main.COLOR)
		
		# snake
		main.SNAKE.render(main.SURF)
		
		# pause
		if main.PAUSED:
			for _ in range(0, main.WIDTH * 2, 4):
				pygame.draw.line(main.SURF, [255, 255, 255], [0, _], [_, 0])
	
	# blit and flip
	main.SCREEN.blit(pygame.transform.scale(main.SURF, main.SCALEDSIZE), [0, 0])
	pygame.display.flip()

""" RESET; INIT """
# resets game
def reset():
	main.PAUSED = False
	main.GAMEOVER = False
	main.GAMEOVERVISTICKS = 0
	main.SNAKE = snake([0, 0])

# initialize program
def init():
	main.PIXELSIZE = [20, 20]
	
	main.WIDTH, main.HEIGHT = 1080 / main.PIXELSIZE[0], 720 / main.PIXELSIZE[1]
	main.SIZE = [main.WIDTH, main.HEIGHT]
	main.SURF = pygame.Surface(main.SIZE)
	
	main.SCALEDSIZE = [main.WIDTH * main.PIXELSIZE[0], main.HEIGHT * main.PIXELSIZE[1]]
	main.SCREEN = pygame.display.set_mode(main.SCALEDSIZE)
	
	main.CAPTION = "Jake"
	main.COLOR = [50, 50, 50]
	main.TICKS = 0
	main.KEYSDOWN = []
	
	# functions
	reset()

""" RUN """
# run function (uses tick() and render())
def run():
	ticksPerSecond = 60
	lastTime = time.time() * 1000000000
	nsPerTick =  1000000000.0 / float(ticksPerSecond)
	
	ticks = 0
	frames = 0
	
	lastTimer = time.time() * 1000
	delta = 0.0
	
	while True:
		now = time.time() * 1000000000
		delta += float(now - lastTime) / float(nsPerTick)
		lastTime = now
		shouldRender = False
				
		while delta >= 1:
			ticks += 1
			main.TICKS += 1
			tick()
			delta -= 1
			shouldRender = True
		
		if shouldRender:
			frames += 1
			render()
		
		if time.time() * 1000 - lastTimer >= 1000:
			lastTimer += 1000
			
			# debug
			# print("Frames: " + str(frames) + ", ticks: " + str(ticks))
			
			frames = 0
			ticks = 0

# main variable
main = dummy()
init()

# start program
run()