# -*- coding: utf-8 -*-


def get_signature_bytes(path):
    """
    Reads file from disk and returns the first 256 bytes
    of data representing the magic number header signature.

    :param path str
    :rtype bytearray
    """
    with open(path, 'rb') as f:
        return bytearray(f.read(256))


def signature(array):
    """
    Returns the first 256 bytes of the given bytearray
    as part of the file header signature.

    :param array bytearray
    :rtype bytearray
    """
    length = len(array)
    index = 256 if length > 256 else length
    return array[:index]


def get_bytes(obj):
    """
    Infers the input type and reads the first 256 bytes,
    returning a sliced bytearray.

    :param obj obj
    :rtype bytearray
    """
    kind = type(obj)

    if kind == bytearray:
        return signature(obj)

    if kind == str:
        return get_signature_bytes(obj)

    if kind is bytes:
        return signature(bytearray(obj))

    raise TypeError('Unsupported type as file input: %s' % kind)