import collections
import json

from hashlib import sha256


def canonicalize(json_obj):
  """This function canonicalizes a Python object that will be serialized as JSON.

  Args:
    json_obj (object): the Python object that will later be serialized as JSON.

  Returns:
    object: json_obj now sorted to its canonical form.

  """
  if isinstance(json_obj, collections.MutableMapping):
    sorted_obj = sorted({key: canonicalize(val) for key, val in json_obj.items()}.items())
    return collections.OrderedDict(sorted_obj)
  elif isinstance(json_obj, (list, tuple)):
    return [canonicalize(val) for val in json_obj]
  return json_obj


def canonical_kid(jwk):
  """This function returns the SHA256 hash of a canonical JWK.

  Args:
    jwk (object): the JWK for which a kid will be generated.

  Returns:
    string: the unique kid for the given JWK.

  """
  return sha256(json.dumps(canonicalize(jwk), separators=(',', ':'))).hexdigest()