import hashlib
from django.core.files.storage import FileSystemStorage
import os

def md5sum(file):
    """Calculate the md5 checksum of a file-like object without reading its
    whole content in memory.

    >>> from StringIO import StringIO
    >>> md5sum(StringIO('file content to hash'))
    '784406af91dd5a54fbb9c84c2236595a'
    """
    m = hashlib.md5()
    while 1:
        d = file.read(8096)
        if not d:
            break
        m.update(d)
    return m.hexdigest()

class PoolStorage(FileSystemStorage):
    """
    Saves file in file pool ;)
    """                                                              
    def _save(self, name, content):
        oname = name.split('/')
        key = md5sum(content)
        name = os.path.join(oname[0], key[0:2], oname[1])
        return super(PoolStorage, self)._save(name, content)