import math
import matplotlib.pyplot as plt
from .Generaldistribution import Distribution

class Binomial(Distribution):

    def __init__(self, prob=.5, size=20):
        self.n = size
        self.p = prob
        Distribution.__init__(self, self.calculate_mean(), self.calculate_stdev())
        
    
    def calculate_mean(self):
        self.mean = self.p * self.n
        return self.mean


    def calculate_stdev(self):
        self.stdev = math.sqrt(self.n * self.p * (1 - self.p))
        return self.stdev

        
    def replace_stats_with_data(self):
        self.n = len(self.data)
        self.p = 1.0 * sum(self.data) / len(self.data)
        self.mean = self.calculate_mean()
        self.stdev = self.calculate_stdev()   


    def plot_bar(self):
        plt.bar(x = ['0', '1'], height = [(1 - self.p) * self.n, self.p * self.n])
        plt.title('Bar Chart of Data')
        plt.xlabel('outcome')
        plt.ylabel('count')

        
    def pdf(self, k):
        a = math.factorial(self.n) / (math.factorial(k) * (math.factorial(self.n - k)))
        b = (self.p ** k) * (1 - self.p) ** (self.n - k)
        return a * b
        

    def plot_bar_pdf(self):
        x = []
        y = []

        for i in range(self.n + 1):
            x.append(i)
            y.append(self.pdf(i))

        plt.bar(x, y)
        plt.title('Distribution of Outcomes')
        plt.ylabel('Probability')
        plt.xlabel('Outcome')
        plt.show()

        return x, y
        
    def __add__(self, other):

        try:
            assert self.p == other.p, 'p values are not equal'
        except AssertionError as error:
            raise
        
        result = Binomial()
        result.n = self.n + other.n
        result.p = self.p
        result.calculate_mean()
        result.calculate_stdev()
        
        return result
        
        
    def __repr__(self):
        return "mean {}, standard deviation {}, p {}, n {}".\
        format(self.mean, self.stdev, self.p, self.n)