# Source code for M2Crypto.DH

    """M2Crypto wrapper for OpenSSL DH API.

    Copyright (c) 1999-2003 Ng Pheng Siong. All rights reserved."""

    from M2Crypto import BIO, m2, types as C
    from M2Crypto.util import genparam_callback
    from typing import Callable, Optional, Union  # noqa

    class DHError(Exception):
        pass

    m2.dh_init(DHError)

    class DH(object):
        """Object interface to the Diffie-Hellman key exchange protocol."""

        def __init__(self, dh: C.DH, _pyfree: int = 0) -> None:
            assert m2.dh_type_check(dh)
            self.dh = dh
            self._pyfree = _pyfree

        @staticmethod
        def m2_dh_free(dh: C.DH) -> None:
            m2.dh_free(dh)

        def __del__(self) -> None:
            if getattr(self, "_pyfree", 0):
                self.m2_dh_free(self.dh)

        def __len__(self) -> int:
            assert m2.dh_type_check(self.dh), "'dh' type error"
            return int(m2.dh_size(self.dh))

        def __getattr__(self, name: str) -> bytes:
            if name in ("p", "g", "pub", "priv"):
                method = getattr(m2, "dh_get_%s" % (name,))
                assert m2.dh_type_check(self.dh), "'dh' type error"
                return method(self.dh)
            else:
                raise AttributeError

        def __setattr__(self, name: str, value: bytes) -> None:
            if name in ("p", "g"):
                raise DHError("set (p, g) via set_params()")
            elif name in ("pub", "priv"):
                raise DHError("generate (pub, priv) via gen_key()")
            else:
                self.__dict__[name] = value

        def _ptr(self):
            return self.dh

        def check_params(self) -> int:
            assert m2.dh_type_check(self.dh), "'dh' type error"
            return m2.dh_check(self.dh)

        def gen_key(self) -> None:
            assert m2.dh_type_check(self.dh), "'dh' type error"
            m2.dh_generate_key(self.dh)

        def compute_key(self, pubkey: bytes) -> bytes:
            assert m2.dh_type_check(self.dh), "'dh' type error"
            return m2.dh_compute_key(self.dh, pubkey)

        def print_params(self, bio: BIO.BIO) -> int:
            assert m2.dh_type_check(self.dh), "'dh' type error"
            return m2.dhparams_print(bio._ptr(), self.dh)

    def gen_params(
        plen: int,
        g: int,
        callback: Callable = genparam_callback,
    ) -> DH:
        dh_parms = m2.dh_generate_parameters(plen, g, callback)
        dh_obj = DH(dh_parms, 1)
        return dh_obj

    def load_params(file: Union[str, bytes]) -> DH:
        with BIO.openfile(file) as bio:
            return load_params_bio(bio)

    def load_params_bio(bio: BIO.BIO) -> DH:
        dh_ptr = m2.dh_read_parameters(bio._ptr())
        if dh_ptr is None:
            raise DHError("Failed to load DH parameters.")
        return DH(dh_ptr, 1)

    def set_params(p: bytes, g: bytes) -> DH:
        dh = m2.dh_new()
        m2.dh_set_pg(dh, p, g)
        return DH(dh, 1)

    # def free_params(cptr):
    #    m2.dh_free(cptr)

    DH_GENERATOR_2 = m2.DH_GENERATOR_2
    DH_GENERATOR_5 = m2.DH_GENERATOR_5