import numpy as np
import itertools as it

from scene import Scene
from graphs import *

from mobject import *
from animation import *
from region import *
from constants import *
from helpers import *


BIG_N_PASCAL_ROWS = 11
N_PASCAL_ROWS = 7
class PascalsTriangleScene(Scene):
    args_list = [
        (N_PASCAL_ROWS,),
        (BIG_N_PASCAL_ROWS,),
    ]
    @staticmethod
    def args_to_string(*args):
        return str(args[0])

    def __init__(self, nrows, *args, **kwargs):
        Scene.__init__(self, *args, **kwargs)
        self.nrows            = nrows
        self.diagram_height   = 2*SPACE_HEIGHT - 1
        self.diagram_width    = 1.5*SPACE_WIDTH
        self.cell_height      = self.diagram_height / nrows
        self.cell_width       = self.diagram_width / nrows
        self.portion_to_fill  = 0.7
        self.bottom_left      = np.array(
            (-self.cell_width * nrows / 2.0, -self.cell_height * nrows / 2.0, 0)
        )
        num_to_num_mob   = {} 
        self.coords_to_mobs   = {}
        self.coords = [(n, k) for n in range(nrows) for k in range(n+1)]    
        for n, k in self.coords:
            num = choose(n, k)              
            center = self.coords_to_center(n, k)
            if num not in num_to_num_mob:
                num_to_num_mob[num] = tex_mobject(str(num))
            num_mob = deepcopy(num_to_num_mob[num])  
            scale_factor = min(
                1,
                self.portion_to_fill * self.cell_height / num_mob.get_height(),
                self.portion_to_fill * self.cell_width / num_mob.get_width(),
            )
            num_mob.center().scale(scale_factor).shift(center)
            if n not in self.coords_to_mobs:
                self.coords_to_mobs[n] = {}
            self.coords_to_mobs[n][k] = num_mob
        self.add(*[self.coords_to_mobs[n][k] for n, k in self.coords])

    def coords_to_center(self, n, k):
        return self.bottom_left + (
                self.cell_width * (k+self.nrows/2.0 - n/2.0), 
                self.cell_height * (self.nrows - n), 
                0
            )

    def generate_n_choose_k_mobs(self):
        self.coords_to_n_choose_k = {}
        for n, k in self.coords:
            nck_mob = tex_mobject(r"{%d \choose %d}"%(n, k)) 
            scale_factor = min(
                1,
                self.portion_to_fill * self.cell_height / nck_mob.get_height(),
                self.portion_to_fill * self.cell_width / nck_mob.get_width(),
            )
            center = self.coords_to_mobs[n][k].get_center()
            nck_mob.center().scale(scale_factor).shift(center)
            if n not in self.coords_to_n_choose_k:
                self.coords_to_n_choose_k[n] = {}
            self.coords_to_n_choose_k[n][k] = nck_mob

    def generate_sea_of_zeros(self):
        zero = tex_mobject("0")
        self.sea_of_zeros = []
        for n in range(self.nrows):
            for a in range((self.nrows - n)/2 + 1):
                for k in (n + a + 1, -a -1):
                    self.coords.append((n, k))
                    mob = deepcopy(zero)
                    mob.shift(self.coords_to_center(n, k))
                    self.coords_to_mobs[n][k] = mob
                    self.add(mob)