# Copyright (c) 2016 Egor Tensin <Egor.Tensin@gmail.com>
# This file is part of the "Sorting algorithms" project.
# For details, see https://github.com/egor-tensin/sorting-algorithms.
# Distributed under the MIT License.

from array import array
from enum import Enum
from random import seed, sample


seed()


class InputKind(Enum):
    BEST, AVERAGE, WORST = 'best', 'average', 'worst'

    def __str__(self):
        return self.value


def _gen_input_from(xs):
    return array('l', xs)


def gen_input_for_sorting(n, case=InputKind.AVERAGE):
    if n < 0:
        raise ValueError('input length cannot be less than zero')
    if case is InputKind.BEST:
        return _gen_input_from(range(n))
    if case is InputKind.AVERAGE:
        return _gen_input_from(sample(range(n), n))
    if case is InputKind.WORST:
        return _gen_input_from(range(n - 1, -1, -1))
    raise NotImplementedError('invalid input kind: ' + str(case))