Trip on the Funny Boat Code

import math
import pygame
from pygame.locals import *

MIN_LENGTH = 35
MAX_LENGTH = 300

FLOOR_POS = 400
CEILING_POS = 200

screen = pygame.display.set_mode((640, 480))

head = pygame.image.load("frog_head.png")
head_open = pygame.image.load("frog_head_open.png")
legs = pygame.image.load("frog_legs.png")

locked_angle = 0
locked_mouse_pos = (0,0)

tongue_activated = False
tongue_length = 0
tongue_extending = False
tongue_retreating = False
tongue_locked = False
tongue_pos = (0,0)

done = False

mouse_pos = (0,0)

frog_pos = [320,240]
frog_dir = [0,0]
frog_standing = False

while not done:
    for e in pygame.event.get():
        if e.type == QUIT:
            done = True
        elif e.type == KEYDOWN:
            if e.key == K_ESCAPE:
                done = True
        elif e.type == MOUSEBUTTONDOWN:
            if e.button == 1:
                if not tongue_activated:
                    tongue_activated = True
                    tongue_extending = True
                    tongue_retreating = False
            elif e.button == 3 and not tongue_activated:
                if frog_standing:
                    frog_dir[1] = -10
        elif e.type == MOUSEBUTTONUP:
            if e.button == 1:
                if tongue_activated:
                    tongue_extending = False
                    tongue_retreating = True
                    tongue_locked = False

    if frog_standing:
        keys = pygame.key.get_pressed()
        if keys[K_LEFT] and not keys[K_RIGHT]:
            frog_dir[0] = -5
        elif keys[K_RIGHT] and not keys[K_LEFT]:
            frog_dir[0] = 5
        else:
            #if not tongue_locked:
            frog_dir[0] = 0
            #pass
    elif tongue_locked:
        keys = pygame.key.get_pressed()
        if keys[K_LEFT]:
            frog_dir[0] -= 0.1
        if keys[K_RIGHT]:
            frog_dir[0] += 0.1
    if tongue_locked:
        if keys[K_UP]:
            if tongue_length > MIN_LENGTH:
                tongue_length -= 4
        if keys[K_DOWN]:
            if tongue_length < MAX_LENGTH:
                tongue_length += 4

    screen.fill((0,0,0))

    mouse_pos = pygame.mouse.get_pos()
    rel_mouse_pos = (mouse_pos[0]-frog_pos[0], mouse_pos[1]-frog_pos[1])

    frog_dir[1] += 1

    if frog_pos[1] + frog_dir[1] > FLOOR_POS:
        frog_dir[1] = 0
        frog_pos[1] = FLOOR_POS
        frog_standing = True
    else:
        frog_standing = False

    frog_pos[0] += frog_dir[0]
    frog_pos[1] += frog_dir[1]

    if rel_mouse_pos[1] == 0:
        if rel_mouse_pos[0] < 0:
            angle = -math.pi/2
        else:
            angle = math.pi/2
    else:
        angle = math.atan(float(rel_mouse_pos[0])/float(rel_mouse_pos[1]))

    if rel_mouse_pos[1] >= 0:
        angle += math.pi

    angle += math.pi*13/48

    if tongue_activated:
        if tongue_extending:
            if tongue_length < MAX_LENGTH:
                tongue_length += 32
            else:
                tongue_extending = False
        if tongue_retreating:
            if tongue_length >= 64:
                tongue_length -= 64
            else:
                tongue_activated = False
            locked_angle = angle
            locked_mouse_pos = rel_mouse_pos
        rel_mouse_pos = locked_mouse_pos
        angle = locked_angle


        if not tongue_locked:
            len = math.sqrt(math.pow(rel_mouse_pos[0],2) + math.pow(rel_mouse_pos[1],2))
            tongue_pos = [frog_pos[0] + int(rel_mouse_pos[0]*tongue_length/len),
                        frog_pos[1] + int(rel_mouse_pos[1]*tongue_length/len)]

        if tongue_pos[1] < CEILING_POS:
            tongue_pos[1] = CEILING_POS
            tongue_extending = False
            tongue_locked = True
            #tongue_length -= 20

    if tongue_activated and tongue_locked:
        diff = [tongue_pos[0]-(frog_pos[0]+frog_dir[0]), tongue_pos[1]-(frog_pos[1]+frog_dir[1])]
        len = math.sqrt(math.pow(diff[0],2) + math.pow(diff[1],2))
        if len < tongue_length:
            #tongue_length = len
            pass
        if tongue_length < len:
            frog_dir[0] += diff[0]/len*(len-tongue_length)
            frog_dir[1] += diff[1]/len*(len-tongue_length)

        diff = [tongue_pos[0]-frog_pos[0], tongue_pos[1]-frog_pos[1]]
        angle = math.atan(float(diff[0])/diff[1])
        if diff[1] >= 0:
            angle += math.pi

        angle += math.pi*13/48

            

    if tongue_activated:
        head_rotated = pygame.transform.rotate(head_open, 180.0/math.pi*angle)
    else:
        head_rotated = pygame.transform.rotate(head, 180.0/math.pi*angle)
        locked_angle = angle
        locked_mouse_pos = rel_mouse_pos


    if tongue_activated:
        pygame.draw.line(screen, (200,10,5), (frog_pos[0],frog_pos[1]), tongue_pos, 2)
        pygame.draw.circle(screen, (210,15,10), (int(tongue_pos[0]),int(tongue_pos[1])), 3)
    rect = head_rotated.get_rect()
    rect.center = (frog_pos[0],frog_pos[1])

    screen.blit(head_rotated, rect)

    rect = legs.get_rect()
    rect.center = (frog_pos[0],frog_pos[1])
    screen.blit(legs, rect)

    pygame.draw.line(screen, (255,255,255), (320,0), (320, 100))
    pygame.draw.line(screen, (255,255,255), (320,380), (320, 480))
    pygame.draw.line(screen, (255,255,255), (0,240), (100, 240))
    pygame.draw.line(screen, (255,255,255), (540,240), (640, 240))

    pygame.display.flip()