from collections import deque

import random

class ReplayBuffer(object):

    def __init__(self, buffer_size):

        self.buffer_size = buffer_size

        self.num_experiences = 0

        self.buffer = deque()

    def get_batch(self, batch_size):

        # Randomly sample batch_size examples

        return random.sample(self.buffer, batch_size)

    def size(self):

        return self.buffer_size

    def add(self,transition):

        if self.num_experiences < self.buffer_size:

            self.buffer.append(transition)

            self.num_experiences += 1

        else:

            self.buffer.popleft()

            self.buffer.append(transition)

    def count(self):

        # if buffer is full, return buffer size

        # otherwise, return experience counter

        return self.num_experiences

    def erase(self):

        self.buffer = deque()

        self.num_experiences = 0