import pygame
import collections

def start_loop():
	global g_timer, g_elapsed
	g_elapsed = 0
	g_elapsed_sec = 0.0
	g_timer = pygame.time.get_ticks()
	reset_fps_count()
	
def next_frame(skipping=False):
	global g_timer, g_elapsed, g_elapsed_sec

	newticks = pygame.time.get_ticks()
	#if skipping:
	#	# reset g_timer to it's value from the previous frame
	#	g_timer -= g_elapsed
	g_elapsed = newticks - g_timer
	g_timer = newticks
	g_elapsed_sec = float(g_elapsed) / 1000.0

	if g_elapsed != 0:
		update_fps_count(g_elapsed)
	
	
def reset_fps_count():
	global g_framelist, update_fps_count
	g_framelist = collections.deque()
	update_fps_count = update_fps_count_empty
	
def update_fps_count_empty(elapsed):
	global g_framelist, update_fps_count
	g_framelist.append(elapsed)
	if len(g_framelist) >= 25:
		update_fps_count = update_fps_count_full
	
def update_fps_count_full(elapsed):
	global g_framelist
	g_framelist.popleft()
	g_framelist.append(elapsed)
	
def update_fps_count(elapsed):
	"this is replaced with either the _empty or _full variant, depending on the situation"
	pass
	
def elapsed():
	"""
	get the amount of time in milliseconds passed since the last frame was displayed
	"""
	return g_elapsed
	
def elapsed_sec():
	"""
	get the amount of time in seconds passed since the last frame was displayed
	"""
	return g_elapsed_sec

def num_frames(delay, offset=0):
	"""
	if you want something to occur every "delay" milliseconds,
	this will return the number of times you should make it happen
	in this particular frame (can be 0)
	"""
	global g_elapsed, g_timer
	return int((g_timer - offset) / delay) - int((g_timer - g_elapsed - offset) / delay)

def loop_frames(delay, offset=0):
	return range(num_frames(delay, offset))

def get_timer():
	return g_timer

def average(d):
	#spf = (float(sum(g_framelist)) / (len(g_framelist) * 1000.0))
	if len(d) == 0:
		return 0.0

	smooth = 0.85
	#v2 = float(d[-1])
	#for i in xrange(len(d) - 2, 0, -1):
	#	pass
		
	v2 = float(d[0])
	for i in range(1, len(d)):
		v1 = float(d[i])
		v2 = (smooth * v2) + ((1.0 - smooth) * v1)
	
	return v2
	
	
def get_fps():
	global g_framelist
	#return ",".join([str(x) for x in sorted(g_framelist)])
	if len(g_framelist) == 0.0:
		return 0.0
	spf = average(g_framelist) / 1000.0
	if spf == 0.0:
		return 0.0
	#print "%s < %s" % (1.0 / spf, g_framelist)
	return 1.0 / spf