# -*- encoding: utf-8 -*-

import os

class Disk(object):
    """
    Class for disk operations.
    """
    @staticmethod
    def free_disk_space(path):
        """
        Calculate free disk space for given path.

        Returned available_bytes or None when path not exists or writable.
        """
        if Disk.path_writeble(path):
            stats = os.statvfs(path)

            available_bytes = (stats.f_bavail * stats.f_frsize)
            return available_bytes
        else:
            return None


    @staticmethod
    def path_writeble(path):
        """
        Check if a given path is writable for user.
        """
        if os.path.exists(path):
            return os.access(path, os.W_OK)
        elif os.access(os.path.dirname(path), os.W_OK) and \
                os.access(path, os.W_OK):
            return True
        else:
            return False

    @staticmethod
    def sizeof_fmt(num, suffix="B"):
        """
        Convert number of bytes into human readable format.
        Source: https://web.archive.org/web/20111010015624/http://blogmag.net/blog/read/38/Print_human_readable_file_size
        """
        for unit in ["", "Ki", "Mi", "Gi", "Ti", "Pi", "Ei", "Zi"]:
            if abs(num) < 1024.0:
                return "%3.1f %s%s" % (num, unit, suffix)
            num /= 1024.0

        return "%.1f %s%s" % (num, "Yi", suffix)