import os
from shutil import disk_usage
import time

BS = 1024**2

def set_utilization(du, utilization_percent=0.6, baloon_filename='baloon'):
    fs = os.path.realpath(du)
    du = disk_usage(fs)
    print(f'total: {int(du.total/ 2**30)}GB, used: {int(du.used/ 2**30)}GB, free: {int(du.free/ 2**30)}GB')
    to_be_wasted = int((du.total * utilization_percent) - du.used)
    print(f'to_be_wasted: {int(to_be_wasted/ 2**30)}GB')
    if to_be_wasted < 0:
        to_be_trimmed = abs(to_be_wasted)
        baloon_size = os.path.getsize(os.path.join(fs, baloon_filename))
        if  baloon_size> to_be_trimmed:
            os.truncate(os.path.join(fs, baloon_filename), baloon_size - to_be_trimmed)
        else: print(f'can\'t trim {baloon_size} > {to_be_trimmed}')
    elif to_be_wasted > 0:
        with open(os.path.join(fs, baloon_filename) , 'ab') as f:
            last = 0
            while to_be_wasted > 0:
                if time.time() - last > 1:
                    print('\r', end='')
                    print(f'left {int(to_be_wasted/ 2**30)}GB                    ', end='')
                    last = time.time()                          
                write_size = min(to_be_wasted, BS)
                f.write(b'x' * write_size)
                to_be_wasted -= write_size
            print('Done               ')
                

set_utilization('.')