# encoding: utf-8
#
# Copyright 2009-2017 Greg Neagle.
#
# Licensed under the Apache License, Version 2.0 (the 'License');
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#      https://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an 'AS IS' BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
"""
munkihash.py

Created by Greg Neagle on 2016-12-14.


Munki's hash functions
"""

import hashlib
import os

def gethash(filename, hash_function):
    """
    Calculates the hashvalue of the given file with the given hash_function.

    Args:
      filename: The file name to calculate the hash value of.
      hash_function: The hash function object to use, which was instanciated
          before calling this function, e.g. hashlib.md5().

    Returns:
      The hashvalue of the given file as hex string.
    """
    if not os.path.isfile(filename):
        return 'NOT A FILE'

    fileref = open(filename, 'rb')
    while 1:
        chunk = fileref.read(2**16)
        if not chunk:
            break
        hash_function.update(chunk)
    fileref.close()
    return hash_function.hexdigest()


def getmd5hash(filename):
    """
    Returns hex of MD5 checksum of a file
    """
    hash_function = hashlib.md5()
    return gethash(filename, hash_function)


def getsha256hash(filename):
    """
    Returns the SHA-256 hash value of a file as a hex string.
    """
    hash_function = hashlib.sha256()
    return gethash(filename, hash_function)


if __name__ == '__main__':
    print 'This is a library of support tools for the Munki Suite.'
