import typing

import scipy.io.wavfile


def trim_where(
    # https://docs.python.org/3.8/library/collections.abc.html#collections-abstract-base-classes
    sequence: typing.Sequence,
    condition: typing.Sequence[bool],
) -> typing.Sequence:
    start = 0
    for item_condition in condition:
        if item_condition:
            start += 1
        else:
            break
    stop = len(sequence)
    assert stop == len(condition)
    for item_condition in condition[::-1]:
        if item_condition:
            stop -= 1
        else:
            break
    return sequence[start:stop]


def wavfile_read_mono(path):
    # https://docs.scipy.org/doc/scipy/reference/generated/scipy.io.wavfile.read.html
    rate, data = scipy.io.wavfile.read(path)
    data_first_channel = data[:, 0]
    for channel_index in range(1, data.shape[1]):
        assert (data_first_channel == data[:, channel_index]).all()
    return rate, data_first_channel