import pygame

class Bridge:
    def __init__(self, game):
        self.game = game
        self.screen = game.screen
        self.world = game.world
        self.joints = []
        self.cost = 0
        self.stress = 0
        self.capacity = 1
        self.first_train = None
        self.train_off_screen = False

    def create_world(self):
        self.world.set_color((100,150,50))
        rect = pygame.Rect((-400,800), (750, -250))
        rect.normalize()
        pygame.draw.rect(self.screen, (100,180,255), rect, 3)
        self.world.add.rect(rect.center, rect.width / 2, rect.height / 2,
            dynamic=False)
        rect = pygame.Rect((1200,800), (-350, -250))
        rect.normalize()
        pygame.draw.rect(self.screen, (100,180,255), rect, 3)
        self.world.add.rect(rect.center, rect.width / 2, rect.height / 2,
            dynamic=False)
        self.world.reset_color()

    def add_cost(self, value):
        self.cost = self.cost + value
        print "cost now", value

    def joint_added(self, joint):
        print "joint added!"
        self.joints.append(joint)
        self.add_cost(100)
        self.capacity += 500

    def box_added(self):
        self.add_cost(10)

    def for_each_frame(self):
        self.stress = 0
        for joint in self.joints:
            force = joint.GetReactionForce().Length()
            self.stress += force

            if force > 500:
                print "destroy joint!"
                self.world.world.DestroyJoint(joint)
                self.joints.remove(joint)
                self.capacity -= 500
            else:
                vec = joint.GetAnchor1()
                coord = int(self.world.meter_to_screen(vec.x)),int(780 - self.world.meter_to_screen(vec.y))
                pygame.draw.circle(self.screen, (int(force/2),255-int(force/2),0), coord, 4)

        pos = self.first_train.GetPosition()
        if pos.y < 0:
            print "TRAIN FELL OFF!"
            self.train_off_screen = True

    def create_train(self, worldpoint = (-100,490), train = (100, 50), wheelrad = 20, cars = 3):
        points = []
        self.train_off_screen = False
        for i in range(0,cars):
            startpoint = (worldpoint[0]-(train[0]+7)*i, worldpoint[1])
            points.append(startpoint)
            rect = pygame.Rect(startpoint, train)
            rect.normalize()
            pygame.draw.rect(self.screen, (200, 50, 100), rect, 3)
            rect = self.world.add.rect(rect.center, rect.width / 2, rect.height / 2,
                dynamic = True, density=10.0, restitution=0.16, friction=0.5)
            if i == 0:
                self.first_train = rect
                
            self.world.set_color((0,0,0))
            rearwheel = (startpoint[0]+wheelrad,startpoint[1]+train[1]-wheelrad/2)
            pygame.draw.circle(self.screen, (0,0,0), rearwheel, wheelrad, 3)
            self.world.add.ball(rearwheel,wheelrad, dynamic=True, density=10.0, 
                restitution=0.16, friction=0.5)
    
            frontwheel = (startpoint[0]+train[0]-wheelrad,startpoint[1]+train[1]-wheelrad/2)
            pygame.draw.circle(self.screen, (0,0,0), frontwheel, wheelrad, 3)
            self.world.add.ball(frontwheel,wheelrad, dynamic=True, density=10.0, 
                restitution=0.16, friction=0.5)
            self.world.reset_color()
            
            rearaxle = self.world.get_bodies_at_pos(rearwheel)
            frontaxle = self.world.get_bodies_at_pos(frontwheel)
            if len(rearaxle) == 2:
                self.world.add.jointMotor(rearaxle[0],rearaxle[1],rearwheel)
            if len(frontaxle) == 2:
                self.world.add.jointMotor(frontaxle[0],frontaxle[1],frontwheel)
            
        for i in range(1,len(points)):
            backlink = (points[i][0]+train[0]-1,points[i][1]+train[1]-1)
            frontlink = (points[i-1][0]+1,points[i-1][1]+train[1]-1)
            btrain = self.world.get_bodies_at_pos(backlink)
            ftrain = self.world.get_bodies_at_pos(frontlink)
            if len(ftrain) and len(btrain):
                self.world.add.distanceJoint(btrain[0], ftrain[0], backlink, frontlink)