#!/usr/bin/env python
# vim: set fileencoding=utf-8 :

###############################################################################
#                                                                             #
# Copyright (c) 2016 Idiap Research Institute, http://www.idiap.ch/           #
# Contact: beat.support@idiap.ch                                              #
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# This file is part of the beat.backend.python module of the BEAT platform.   #
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# and Idiap. For further information contact tto@idiap.ch                     #
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# in the file LICENSE.AGPL included in the packaging of this file.            #
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# WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY  #
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# You should have received a copy of the GNU Affero Public License along      #
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"""Various functions for hashing platform contributions and others"""


import hashlib
import simplejson
import collections
import copy
import six


def _sha256(s):
  """A python2/3 replacement for :py:func:`haslib.sha256`"""

  try:
    if isinstance(s, str): s = six.u(s)
    return hashlib.sha256(s.encode('utf8')).hexdigest()
  except:
    return hashlib.sha256(s).hexdigest()



def _stringify(dictionary):
  names = sorted(dictionary.keys())

  converted_dictionary = '{'
  for name in names:
    converted_dictionary += '"%s":%s,' % (name, str(dictionary[name]))

  if len(converted_dictionary) > 1:
    converted_dictionary = converted_dictionary[:-1]

  converted_dictionary += '}'

  return converted_dictionary



def hash(dictionary_or_string):
  if isinstance(dictionary_or_string, dict):
    return _sha256(_stringify(dictionary_or_string))
  else:
    return _sha256(dictionary_or_string)



def hashJSON(contents, description):
  """Hashes the pre-loaded JSON object using :py:func:`hashlib.sha256`

  Excludes description changes
  """

  if description in contents:
    contents = copy.deepcopy(contents) #temporary copy
    del contents[description]
  contents = simplejson.dumps(contents, sort_keys=True)
  return hashlib.sha256(contents).hexdigest()



def hashJSONFile(path, description):
  """Hashes the JSON file contents using :py:func:`hashlib.sha256`

  Excludes description changes
  """

  try:
    with open(path, 'rb') as f:
      return hashJSON(simplejson.load(f,
        object_pairs_hook=collections.OrderedDict), description) #preserve order
  except simplejson.JSONDecodeError:
    # falls back to normal file content hashing
    return hashFileContents(path)



def hashFileContents(path):
  """Hashes the file contents using :py:func:`hashlib.sha256`."""

  with open(path, 'rb') as f:
    return hashlib.sha256(f.read()).hexdigest()