# -*- coding: utf-8 -*-
#Author: Lart Pang (https://github.com/lartpang) 

from collections import deque


class AvgMeter(object):
    __slots__ = ["value", "sum", "count"]

    def __init__(self):
        self.value = 0
        self.sum = 0
        self.count = 0

    def reset(self):
        self.value = 0
        self.sum = 0
        self.count = 0

    def update(self, value, num=1):
        self.value = value
        self.sum += value * num
        self.count += num

    @property
    def avg(self):
        return self.sum / self.count

    def __repr__(self) -> str:
        return f"{self.avg:.5f}"


class HistoryBuffer:
    """The class tracks a series of values and provides access to the smoothed
    value over a window or the global average / sum of the sequence.

    Args:
        window_size (int): The maximal number of values that can
            be stored in the buffer. Defaults to 20.

    Example::

        >>> his_buf = HistoryBuffer()
        >>> his_buf.update(0.1)
        >>> his_buf.update(0.2)
        >>> his_buf.avg
        0.15
    """

    def __init__(self, window_size: int = 20) -> None:
        self._history = deque(maxlen=window_size)
        self._count: int = 0
        self._sum: float = 0
        self.reset()

    def reset(self):
        self._history.clear()
        self._count = 0
        self._sum = 0

    def update(self, value: float, num: int = 1) -> None:
        """Add a new scalar value. If the length of queue exceeds ``window_size``,
        the oldest element will be removed from the queue.
        """
        self._history.append(value)
        self._count += num
        self._sum += value * num

    @property
    def latest(self) -> float:
        """The latest value of the queue."""
        return self._history[-1]

    @property
    def avg(self) -> float:
        """The average over the window."""
        if len(self._history) == 0:
            return 0
        else:
            return sum(self._history) / len(self._history)

    @property
    def global_avg(self) -> float:
        """The global average of the queue."""
        if self._count == 0:
            return 0
        else:
            return self._sum / self._count

    @property
    def global_sum(self) -> float:
        """The global sum of the queue."""
        return self._sum