# This file is dual licensed under the terms of the Apache License, Version
# 2.0, and the BSD License. See the LICENSE file in the root of this repository
# for complete details.

import typing

from cryptography import exceptions
from cryptography.hazmat.primitives import serialization
from cryptography.hazmat.primitives.asymmetric.ed25519 import (
    Ed25519PrivateKey,
    Ed25519PublicKey,
    _ED25519_KEY_SIZE,
    _ED25519_SIG_SIZE,
)

if typing.TYPE_CHECKING:
    from cryptography.hazmat.backends.openssl.backend import Backend


class _Ed25519PublicKey(Ed25519PublicKey):
    def __init__(self, backend: "Backend", evp_pkey):
        self._backend = backend
        self._evp_pkey = evp_pkey

    def public_bytes(
        self,
        encoding: serialization.Encoding,
        format: serialization.PublicFormat,
    ) -> bytes:
        if (
            encoding is serialization.Encoding.Raw
            or format is serialization.PublicFormat.Raw
        ):
            if (
                encoding is not serialization.Encoding.Raw
                or format is not serialization.PublicFormat.Raw
            ):
                raise ValueError(
                    "When using Raw both encoding and format must be Raw"
                )

            return self._raw_public_bytes()

        return self._backend._public_key_bytes(
            encoding, format, self, self._evp_pkey, None
        )

    def _raw_public_bytes(self) -> bytes:
        buf = self._backend._ffi.new("unsigned char []", _ED25519_KEY_SIZE)
        buflen = self._backend._ffi.new("size_t *", _ED25519_KEY_SIZE)
        res = self._backend._lib.EVP_PKEY_get_raw_public_key(
            self._evp_pkey, buf, buflen
        )
        self._backend.openssl_assert(res == 1)
        self._backend.openssl_assert(buflen[0] == _ED25519_KEY_SIZE)
        return self._backend._ffi.buffer(buf, _ED25519_KEY_SIZE)[:]

    def verify(self, signature: bytes, data: bytes) -> None:
        evp_md_ctx = self._backend._lib.EVP_MD_CTX_new()
        self._backend.openssl_assert(evp_md_ctx != self._backend._ffi.NULL)
        evp_md_ctx = self._backend._ffi.gc(
            evp_md_ctx, self._backend._lib.EVP_MD_CTX_free
        )
        res = self._backend._lib.EVP_DigestVerifyInit(
            evp_md_ctx,
            self._backend._ffi.NULL,
            self._backend._ffi.NULL,
            self._backend._ffi.NULL,
            self._evp_pkey,
        )
        self._backend.openssl_assert(res == 1)
        res = self._backend._lib.EVP_DigestVerify(
            evp_md_ctx, signature, len(signature), data, len(data)
        )
        if res != 1:
            self._backend._consume_errors()
            raise exceptions.InvalidSignature


class _Ed25519PrivateKey(Ed25519PrivateKey):
    def __init__(self, backend: "Backend", evp_pkey):
        self._backend = backend
        self._evp_pkey = evp_pkey

    def public_key(self) -> Ed25519PublicKey:
        buf = self._backend._ffi.new("unsigned char []", _ED25519_KEY_SIZE)
        buflen = self._backend._ffi.new("size_t *", _ED25519_KEY_SIZE)
        res = self._backend._lib.EVP_PKEY_get_raw_public_key(
            self._evp_pkey, buf, buflen
        )
        self._backend.openssl_assert(res == 1)
        self._backend.openssl_assert(buflen[0] == _ED25519_KEY_SIZE)
        public_bytes = self._backend._ffi.buffer(buf)[:]
        return self._backend.ed25519_load_public_bytes(public_bytes)

    def sign(self, data: bytes) -> bytes:
        evp_md_ctx = self._backend._lib.EVP_MD_CTX_new()
        self._backend.openssl_assert(evp_md_ctx != self._backend._ffi.NULL)
        evp_md_ctx = self._backend._ffi.gc(
            evp_md_ctx, self._backend._lib.EVP_MD_CTX_free
        )
        res = self._backend._lib.EVP_DigestSignInit(
            evp_md_ctx,
            self._backend._ffi.NULL,
            self._backend._ffi.NULL,
            self._backend._ffi.NULL,
            self._evp_pkey,
        )
        self._backend.openssl_assert(res == 1)
        buf = self._backend._ffi.new("unsigned char[]", _ED25519_SIG_SIZE)
        buflen = self._backend._ffi.new("size_t *", len(buf))
        res = self._backend._lib.EVP_DigestSign(
            evp_md_ctx, buf, buflen, data, len(data)
        )
        self._backend.openssl_assert(res == 1)
        self._backend.openssl_assert(buflen[0] == _ED25519_SIG_SIZE)
        return self._backend._ffi.buffer(buf, buflen[0])[:]

    def private_bytes(
        self,
        encoding: serialization.Encoding,
        format: serialization.PrivateFormat,
        encryption_algorithm: serialization.KeySerializationEncryption,
    ) -> bytes:
        if (
            encoding is serialization.Encoding.Raw
            or format is serialization.PublicFormat.Raw
        ):
            if (
                format is not serialization.PrivateFormat.Raw
                or encoding is not serialization.Encoding.Raw
                or not isinstance(
                    encryption_algorithm, serialization.NoEncryption
                )
            ):
                raise ValueError(
                    "When using Raw both encoding and format must be Raw "
                    "and encryption_algorithm must be NoEncryption()"
                )

            return self._raw_private_bytes()

        return self._backend._private_key_bytes(
            encoding, format, encryption_algorithm, self, self._evp_pkey, None
        )

    def _raw_private_bytes(self) -> bytes:
        buf = self._backend._ffi.new("unsigned char []", _ED25519_KEY_SIZE)
        buflen = self._backend._ffi.new("size_t *", _ED25519_KEY_SIZE)
        res = self._backend._lib.EVP_PKEY_get_raw_private_key(
            self._evp_pkey, buf, buflen
        )
        self._backend.openssl_assert(res == 1)
        self._backend.openssl_assert(buflen[0] == _ED25519_KEY_SIZE)
        return self._backend._ffi.buffer(buf, _ED25519_KEY_SIZE)[:]