import django.contrib.auth.hashers
from django.utils.crypto import pbkdf2


class PBKDF2PasswordHasher(django.contrib.auth.hashers.PBKDF2PasswordHasher):
    """
    A subclass of PBKDF2PasswordHasher for discourse.
    """
    algorithm = "pbkdf2_sha256_dis"
    iterations = 64000

    def encode(self, password, salt, iterations=None):
        assert password is not None
        assert salt and '$' not in salt
        iterations = iterations or self.iterations
        hash = pbkdf2(password, salt, iterations, digest=self.digest)
        hash = ''.join(map(lambda s: ('0' + hex(s)[2:])[-2:], hash))
        return "%s$%d$%s$%s" % (self.algorithm, iterations, salt, hash)