import os
import re
import pandas

import validators


RE_NATURAL_SORT = re.compile('([0-9]+)')
convert = lambda text: int(text) if text.isdigit() else text.lower()
natural_sort = lambda item: [convert(c) for c in RE_NATURAL_SORT.split(item)]


def read_data_file(data_file, usecols):
    with open(data_file.path, 'r', encoding='UTF-8') as file_handle:
        return pandas.read_csv(
            file_handle, sep='\t', decimal=data_file.separator, header=0,
            index_col=False, skiprows=data_file.skip, usecols=usecols)


def write_excel_file(path, data_frame):
    data_frame.to_excel(path)