import math
import sys
from kivy.graphics import Color,Line,Rectangle

from point import Point,l_infinity
from tools import isint_nonzero,sgn,in_interval

class Square():
    # size
    size=50

    def __init__(self,x,y,**kwargs):
        self.pos=Point(x,y)
        self.color=kwargs.get("color",(0,0,1))
        self.selected=False

    # set position
    def setpos(self,x,y):
        self.pos.x=x
        self.pos.y=y

    def draw(self,**kwargs):
        # set color
        if not self.selected:
            Color(*self.color)
        else:
            (r,g,b)=self.color
            # darken selected
            Color(r/2,g/2,b/2)

        Rectangle(pos=((self.pos.x-0.5)*self.size,(self.pos.y-0.5)*self.size),size=(self.size,self.size))

    # check whether a square at pos interacts with square
    def check_interaction(self,pos):
        return l_infinity(pos-self.pos)>=1

    # check whether a square at position pos is touching self
    def check_touch(self,pos):
        # allow for error
        if in_interval(l_infinity(pos-solf.pos),1-1e-11,1+1e-11):
                return True
        return False

    # find position along a line that comes in contact with the line going through pos in direction v
    def move_on_line_to_stick(self,pos,v):
        # compute intersections with four lines making up square
        intersections=[\
        Point(self.pos.x+1/2,pos.y+v.y/v.x*(self.pos.x+1/2-pos.x)),\
        Point(self.pos.x-1/2,pos.y+v.y/v.x*(self.pos.x-1/2-pos.x)),\
        Point(pos.x+v.x/v.y*(self.pos.y+1/2-pos.y),self.pos.y+1/2),\
        Point(pos.x+v.x/v.y*(self.pos.y-1/2-pos.y),self.pos.y-1/2)\
        ]

        # compute closest one, on square
        closest=None
        dist=math.inf
        for i in range(0,4):
            # check that it is on square
            if abs(intersections[i].x-self.pos.x)<=1/2+1e-11 and abs(intersections[i].y-self.pos.y)<=1/2+1e-11:
                if (intersections[i]-pos)**2<dist:
                    closest=intersections[i]
                    dist=(intersections[i]-pos)**2

        if closest==None:
            print("error: cannot move particle at (",pos.x,",",pos.y,") to the boundary of (",self.pos.x,",",self.pos.y,")",file=sys.stderr)
            exit(-1)

        return closest

    # move along edge of square
    def move_along(self,newpos,pos):
        rel=pos-self.pos
        # check if the particle is stuck in the x direction
        if isint_nonzero(rel.x):
            # check y direction
            if isint_nonzero(rel.y):
                # in corner
                if sgn(newpos.y-pos.y)==-sgn(rel.y):
                    # stuck in x direction
                    return self.move_stuck_x(newpos,pos)
                elif sgn(newpos.x-pos.x)==-sgn(rel.x):
                    # stuck in y direction
                    return self.move_stuck_y(newpos,pos)
                # stuck in both directions
                return pos
            else:
                # stuck in x direction
                return self.move_stuck_x(newpos,pos)
        elif isint_nonzero(rel.y):
            # stuck in y direction
            return self.move_stuck_y(newpos,pos)
        # this should never happen
        else:
            print("error: stuck particle has non-integer relative position: (",rel.x,",",rel.y,")",file=sys.stderr)
            exit(-1)
    # move when stuck in the x direction
    def move_stuck_x(self,newpos,pos):
        # only move in y direction
        candidate=Point(pos.x,newpos.y)
        # do not move past corners
        rel=pos.y-self.pos.y
        newrel=newpos.y-self.pos.y
        if newpos.y>pos.y:
            if rel<math.ceil(rel)-1e-11 and newrel>math.ceil(rel)+1e-11 and math.ceil(rel)!=0:
                # stick to corner
                candidate.y=math.ceil(rel)+self.pos.y
        else:
            if rel>math.floor(rel)+1e-11 and newrel<math.floor(rel)-1e-11 and math.floor(rel)!=0:
                # stick to corner
                candidate.y=math.floor(rel)+self.pos.y
        return candidate
    # move when stuck in the y direction
    def move_stuck_y(self,newpos,pos):
        # onlx move in x direction
        candidate=Point(pos.x,newpos.x)
        # do not move past corners
        rel=pos.x-self.pos.x
        newrel=newpos.x-self.pos.x
        if newpos.x>pos.x:
            if rel<math.ceil(rel)-1e-11 and newrel>math.ceil(rel)+1e-11 and math.ceil(rel)!=0:
                # stick to corner
                candidate.x=math.ceil(rel)+self.pos.x
        else:
            if rel>math.floor(rel)+1e-11 and newrel<math.floor(rel)-1e-11 and math.floor(rel)!=0:
                # stick to corner
                candidate.x=math.floor(rel)+self.pos.x
        return candidate