#  Copyright (c) 2016 The WebRTC project authors. All Rights Reserved.
#
#  Use of this source code is governed by a BSD-style license
#  that can be found in the LICENSE file in the root of the source
#  tree. An additional intellectual property rights grant can be found
#  in the file PATENTS.  All contributing project authors may
#  be found in the AUTHORS file in the root of the source tree.
"""Utility functions for calculating statistics.
"""

from __future__ import division
import collections
import sys


def CountReordered(sequence_numbers):
    """Returns number of reordered indices.

  A reordered index is an index `i` for which sequence_numbers[i] >=
  sequence_numbers[i + 1]
  """
    return sum(1 for (s1, s2) in zip(sequence_numbers, sequence_numbers[1:])
               if s1 >= s2)


def SsrcNormalizedSizeTable(data_points):
    """Counts proportion of data for every SSRC.

  Args:
     data_points: list of pb_parse.DataPoint

  Returns:
     A dictionary mapping from every SSRC in the data points. The
     value of an SSRC `s` is the proportion of sizes of packets with
     SSRC `s` to the total size of all packets.

  """
    mapping = collections.defaultdict(int)
    for point in data_points:
        mapping[point.ssrc] += point.size
    return NormalizeCounter(mapping)


def NormalizeCounter(counter):
    """Returns a normalized version of the dictionary `counter`.

  Does not modify `counter`.

  Returns:
    A new dictionary, in which every value in `counter`
    has been divided by the total to sum up to 1.
  """
    total = sum(counter.values())
    return {key: counter[key] / total for key in counter}


def Unwrap(data, mod):
    """Returns `data` unwrapped modulo `mod`. Does not modify data.

  Adds integer multiples of mod to all elements of data except the
  first, such that all pairs of consecutive elements (a, b) satisfy
  -mod / 2 <= b - a < mod / 2.

  E.g. Unwrap([0, 1, 2, 0, 1, 2, 7, 8], 3) -> [0, 1, 2, 3,
  4, 5, 4, 5]
  """
    lst = data[:]
    for i in range(1, len(data)):
        lst[i] = lst[i - 1] + (lst[i] - lst[i - 1] + mod // 2) % mod - (mod //
                                                                        2)
    return lst


def SsrcDirections(data_points):
    ssrc_is_incoming = {}
    for point in data_points:
        ssrc_is_incoming[point.ssrc] = point.incoming
    return ssrc_is_incoming


# Python 2/3-compatible input function
if sys.version_info[0] <= 2:
    get_input = raw_input  # pylint: disable=invalid-name
else:
    get_input = input  # pylint: disable=invalid-name