"""
See: http://www.pymunk.org/en/latest/examples.html
Pymunk constraints demo. Showcase of all the constraints included in Pymunk.
Adapted from the Chipmunk Joints demo:
https://github.com/slembcke/Chipmunk2D/blob/master/demo/Joints.c
"""

import inspect
import math

import pygame
import pygame.color
from pygame.locals import *

import pymunk
from pymunk.vec2d import Vec2d
import pymunk.pygame_util
pymunk.pygame_util.positive_y_is_up = False

pygame.init()
screen = pygame.display.set_mode((1200, 600))
clock = pygame.time.Clock()
font = pygame.font.Font(None, 24)


help_txt = font.render(
    "Pymunk constraints demo. Use mouse to drag/drop. Hover to see descr.", 
    1, pygame.color.THECOLORS["darkgray"])

space = pymunk.Space()
space.gravity = (0.0, 900.0)
draw_options = pymunk.pygame_util.DrawOptions(screen)

# containers
box_size = 200
w = screen.get_width()
h = screen.get_height()
for i in range(6):
    sw = pymunk.Segment(space.static_body, 
        (0, i*box_size), (w, i* box_size), 1)
    sw.friction = 1
    sw.elasticity = 1
    sh = pymunk.Segment(space.static_body, 
        (i*box_size, 0), (i*box_size, h-box_size), 1)
    sh.friction = 1
    sh.elasticity = 1
    space.add(sw, sh)

def add_ball(space, pos, box_offset):
    body = pymunk.Body()
    body.position = Vec2d(pos) + box_offset
    shape = pymunk.Circle(body, 20)
    shape.mass = 1
    shape.friction = 0.7
    space.add(body, shape)
    return body

def add_bar(space, pos, box_offset):
    body = pymunk.Body()
    body.position = Vec2d(pos) + box_offset
    shape = pymunk.Segment(body, (0,40), (0,-40), 6)
    shape.mass = 2
    shape.friction = 0.7
    space.add(body, shape)
    return body

def add_lever(space, pos, box_offset):
    body = pymunk.Body()
    body.position = pos + Vec2d(box_offset) + (0,-20)
    shape = pymunk.Segment(body, (0,20), (0,-20), 5)
    shape.mass = 1
    shape.friction = 0.7
    space.add(body, shape)
    return body 

txts = {}

box_offset = 0,0
b1 = add_ball(space, (50,60), box_offset)
b2 = add_ball(space, (150,60), box_offset)
c = pymunk.PinJoint(b1, b2, (20, 0), (-20, 0))
txts[box_offset] = inspect.getdoc(c)
space.add(c)

box_offset = box_size, 0
b1 = add_ball(space, (50,60), box_offset)
b2 = add_ball(space, (150,60), box_offset)
c = pymunk.SlideJoint(b1, b2, (20,0), (-20, 0),40,80)
txts[box_offset] = inspect.getdoc(c)
space.add(c)

box_offset = box_size*2, 0
b1 = add_ball(space, (50,60), box_offset)
b2 = add_ball(space, (150,60), box_offset)
c = pymunk.PivotJoint(b1, b2, Vec2d(box_offset) + (100,60))
txts[box_offset] = inspect.getdoc(c)
space.add(c)

box_offset = box_size*3, 0
b1 = add_ball(space, (50,60), box_offset)
b2 = add_ball(space, (150,60), box_offset)
c = pymunk.GrooveJoint(b1, b2, (50,50), (50,-50), (-50,0))
txts[box_offset] = inspect.getdoc(c)
space.add(c)

box_offset = box_size*4, 0
b1 = add_ball(space, (50,60), box_offset)
b2 = add_ball(space, (150,60), box_offset)
c = pymunk.DampedSpring(b1, b2, (30,0), (-30,0), 20, 5, 0.3)
txts[box_offset] = inspect.getdoc(c)
space.add(c)

box_offset = box_size*5, 0
b1 = add_bar(space, (50,80), box_offset)
b2 = add_bar(space, (150,80), box_offset)
# Add some joints to hold the circles in place.
space.add(pymunk.PivotJoint(b1, space.static_body, (50,80)+Vec2d(box_offset)))
space.add(pymunk.PivotJoint(b2, space.static_body, (150,80)+Vec2d(box_offset)))
c = pymunk.DampedRotarySpring(b1, b2, 0, 3000, 60)
txts[box_offset] = inspect.getdoc(c)
space.add(c)

box_offset = 0, box_size
b1 = add_lever(space, (50,100), box_offset)
b2 = add_lever(space, (150,100), box_offset)
# Add some joints to hold the circles in place.
space.add(pymunk.PivotJoint(b1, space.static_body, (50,100)+Vec2d(box_offset)))
space.add(pymunk.PivotJoint(b2, space.static_body, (150,100)+Vec2d(box_offset)))
# Hold their rotation within 90 degrees of each other.
c = pymunk.RotaryLimitJoint(b1, b2, math.pi/2, math.pi/2)
txts[box_offset] = inspect.getdoc(c)
space.add(c)

box_offset = box_size, box_size
b1 = add_lever(space, (50,100), box_offset)
b2 = add_lever(space, (150,100), box_offset)
# Add some pin joints to hold the circles in place.
space.add(pymunk.PivotJoint(b1, space.static_body, (50,100)+Vec2d(box_offset)))
space.add(pymunk.PivotJoint(b2, space.static_body, (150,100)+Vec2d(box_offset)))
# Ratchet every 90 degrees
c = pymunk.RatchetJoint(b1, b2, 0, math.pi/2)
txts[box_offset] = inspect.getdoc(c)
space.add(c)

box_offset = box_size*2, box_size
b1 = add_bar(space, (50,100), box_offset)
b2 = add_bar(space, (150,100), box_offset)
# Add some pin joints to hold the circles in place.
space.add(pymunk.PivotJoint(b1, space.static_body, (50,100)+Vec2d(box_offset)))
space.add(pymunk.PivotJoint(b2, space.static_body, (150,100)+Vec2d(box_offset)))
# Force one to sping 2x as fast as the other
c = pymunk.GearJoint(b1, b2, 0, 2)
txts[box_offset] = inspect.getdoc(c)
space.add(c)

box_offset = box_size*3, box_size
b1 = add_bar(space, (50,100), box_offset)
b2 = add_bar(space, (150,100), box_offset)
# Add some pin joints to hold the circles in place.
space.add(pymunk.PivotJoint(b1, space.static_body, (50,100)+Vec2d(box_offset)))
space.add(pymunk.PivotJoint(b2, space.static_body, (150,100)+Vec2d(box_offset)))
# Make them spin at 1/2 revolution per second in relation to each other.
c = pymunk.SimpleMotor(b1, b2, math.pi)
txts[box_offset] = inspect.getdoc(c)
space.add(c)

# TODO add one or two advanced constraints examples, such as a car or rope

mouse_joint = None
mouse_body = pymunk.Body(body_type=pymunk.Body.KINEMATIC)

# Build rendered help texts
box_texts = {}
for k in txts:
    l = 0
    box_texts[k] = []
    # Only take the first 5 lines.
    for line in txts[k].splitlines()[:5]:
        txt = font.render(line, 1, pygame.color.THECOLORS["black"])
        box_texts[k].append(txt)

while True:
    for event in pygame.event.get():
        if event.type == QUIT:
            exit()
        elif event.type == KEYDOWN and event.key == K_ESCAPE:
            exit()
        elif event.type == MOUSEBUTTONDOWN:
            if mouse_joint != None:
                space.remove(mouse_joint)
                mouse_joint = None

            p = Vec2d(event.pos)
            hit = space.point_query_nearest(p, 5, pymunk.ShapeFilter())
            if hit != None and hit.shape.body.body_type == pymunk.Body.DYNAMIC:
                shape = hit.shape
                # Use the closest point on the surface if the click is outside 
                # of the shape.
                if hit.distance > 0:
                    nearest = hit.point 
                else:
                    nearest = p
                mouse_joint = pymunk.PivotJoint(mouse_body, shape.body, 
                    (0,0), shape.body.world_to_local(nearest))
                mouse_joint.max_force = 50000
                mouse_joint.error_bias = (1-0.15) ** 60
                space.add(mouse_joint)
                
        elif event.type == MOUSEBUTTONUP:
            if mouse_joint != None:
                space.remove(mouse_joint)
                mouse_joint = None

    screen.fill(pygame.color.THECOLORS["white"])

    screen.blit(help_txt, (5, screen.get_height() - 20))
    
    mouse_pos = pygame.mouse.get_pos()

    # Display help message
    x = mouse_pos[0] / box_size * box_size
    y = mouse_pos[1] / box_size * box_size
    if (x,y) in box_texts:    
        txts = box_texts[(x,y)]
        i = 0
        for txt in txts:
            pos = (5,box_size * 2 + 10 + i*20)
            screen.blit(txt, pos)        
            i += 1

    mouse_body.position = mouse_pos

    space.step(1./60)
    
    space.debug_draw(draw_options)
    pygame.display.flip()

    clock.tick(60)
    pygame.display.set_caption("fps: " + str(clock.get_fps()))
