from __future__ import absolute_import

"""M2Crypto wrapper for OpenSSL BIO API.

Copyright (c) 1999-2004 Ng Pheng Siong. All rights reserved."""

import logging
import io  # noqa

from M2Crypto import m2, six, util
if util.py27plus:
    from typing import AnyStr, Callable, Iterable, Optional, Union  # noqa

log = logging.getLogger('BIO')


class BIOError(Exception):
    pass

m2.bio_init(BIOError)


class BIO(object):

    """Abstract object interface to the BIO API."""

    m2_bio_free = m2.bio_free

    def __init__(self, bio=None, _pyfree=0, _close_cb=None):
        # type: (Optional[BIO], int, Optional[Callable]) -> None
        self.bio = bio
        self._pyfree = _pyfree
        self._close_cb = _close_cb
        self.closed = 0
        self.write_closed = 0

    def __del__(self):
        if self._pyfree:
            self.m2_bio_free(self.bio)

    def _ptr(self):
        return self.bio

    # Deprecated.
    bio_ptr = _ptr

    def fileno(self):
        # type: () -> int
        return m2.bio_get_fd(self.bio)

    def readable(self):
        # type: () -> bool
        return not self.closed

    def read(self, size=None):
        # type: (int) -> Union[bytes, bytearray]
        if not self.readable():
            raise IOError('cannot read')
        if size is None:
            buf = bytearray()
            while 1:
                data = m2.bio_read(self.bio, 4096)
                if not data:
                    break
                buf += data
            return buf
        elif size == 0:
            return b''
        elif size < 0:
            raise ValueError('read count is negative')
        else:
            return bytes(m2.bio_read(self.bio, size))

    def readline(self, size=4096):
        # type: (int) -> bytes
        if not self.readable():
            raise IOError('cannot read')
        buf = m2.bio_gets(self.bio, size)
        return buf

    def readlines(self, sizehint='ignored'):
        # type: (Union[AnyStr, int]) -> Iterable[bytes]
        if not self.readable():
            raise IOError('cannot read')
        lines = []
        while 1:
            buf = m2.bio_gets(self.bio, 4096)
            if buf is None:
                break
            lines.append(buf)
        return lines

    def writeable(self):
        # type: () -> bool
        return (not self.closed) and (not self.write_closed)

    def write(self, data):
        # type: (AnyStr) -> int
        """

        :return: either data written, or [0, -1] for nothing written,
                 -2 not implemented
        """
        if not self.writeable():
            raise IOError('cannot write')
        if isinstance(data, six.text_type):
            data = data.encode('utf8')
        return m2.bio_write(self.bio, data)

    def write_close(self):
        # type: () -> None
        self.write_closed = 1

    def flush(self):
        # type: () -> None
        """

        :return: 1 for success, and 0 or -1 for failure
        """
        m2.bio_flush(self.bio)

    def reset(self):
        # type: () -> int
        """
        Sets the bio to its initial state
        :return: 1 for success, and 0 or -1 for failure
        """
        return m2.bio_reset(self.bio)

    def close(self):
        # type: () -> None
        self.closed = 1
        if self._close_cb:
            self._close_cb()

    def should_retry(self):
        # type: () -> int
        """
        Can the call be attempted again, or was there an error
        ie do_handshake

        """
        return m2.bio_should_retry(self.bio)

    def should_read(self):
        # type: () -> int
        """
        Returns whether the cause of the condition is the bio
        should read more data
        """
        return m2.bio_should_read(self.bio)

    def should_write(self):
        # type: () -> int
        """
        Returns whether the cause of the condition is the bio
        should write more data
        """
        return m2.bio_should_write(self.bio)

    def tell(self):
        """
        Return the current offset.
        """
        return m2.bio_tell(self.bio)

    def seek(self, off):
        """
        Seek to the specified absolute offset.
        """
        return m2.bio_seek(self.bio, off)

    def __enter__(self):
        return self

    def __exit__(self, *args):
        # type: (*Any) -> int
        self.close()


class MemoryBuffer(BIO):
    """
    Object interface to BIO_s_mem.

    Empirical testing suggests that this class performs less well than
    cStringIO, because cStringIO is implemented in C, whereas this class
    is implemented in Python. Thus, the recommended practice is to use
    cStringIO for regular work and convert said cStringIO object to
    a MemoryBuffer object only when necessary.
    """

    def __init__(self, data=None):
        # type: (Optional[bytes]) -> None
        if data is not None and not isinstance(data, bytes):
            raise TypeError(
                "data must be bytes or None, not %s" % (type(data).__name__, ))
        BIO.__init__(self)
        self.bio = m2.bio_new(m2.bio_s_mem())
        self._pyfree = 1
        if data is not None:
            m2.bio_write(self.bio, data)

    def __len__(self):
        # type: () -> int
        return m2.bio_ctrl_pending(self.bio)

    def read(self, size=0):
        # type: (int) -> bytes
        if not self.readable():
            raise IOError('cannot read')
        if size:
            return m2.bio_read(self.bio, size)
        else:
            return m2.bio_read(self.bio, m2.bio_ctrl_pending(self.bio))

    # Backwards-compatibility.
    getvalue = read_all = read

    def write_close(self):
        # type: () -> None
        self.write_closed = 1
        m2.bio_set_mem_eof_return(self.bio, 0)

    close = write_close


class File(BIO):

    """
    Object interface to BIO_s_pyfd

    This class interfaces Python to OpenSSL functions that expect BIO \*. For
    general file manipulation in Python, use Python's builtin file object.
    """

    def __init__(self, pyfile, close_pyfile=1):
        # type: (io.BytesIO, int) -> None
        BIO.__init__(self, _pyfree=1)
        self.pyfile = pyfile
        self.close_pyfile = close_pyfile
        # Be wary of https://github.com/openssl/openssl/pull/1925
        # BIO_new_fd is NEVER to be used before OpenSSL 1.1.1
        if hasattr(m2, "bio_new_pyfd"):
            self.bio = m2.bio_new_pyfd(pyfile.fileno(), m2.bio_noclose)
        else:
            self.bio = m2.bio_new_pyfile(pyfile, m2.bio_noclose)

    def close(self):
        # type: () -> None
        self.closed = 1
        if self.close_pyfile:
            self.pyfile.close()

    def reset(self):
        # type: () -> int
        """
        Sets the bio to its initial state
        :return: 0 for success, and -1 for failure
        """
        return super(File, self).reset()


def openfile(filename, mode='rb'):
    # type: (AnyStr, AnyStr) -> File
    return File(open(filename, mode))


class IOBuffer(BIO):

    """
    Object interface to BIO_f_buffer.

    Its principal function is to be BIO_push()'ed on top of a BIO_f_ssl, so
    that makefile() of said underlying SSL socket works.
    """

    m2_bio_pop = m2.bio_pop
    m2_bio_free = m2.bio_free

    def __init__(self, under_bio, mode='rwb', _pyfree=1):
        # type: (BIO, str, int) -> None
        BIO.__init__(self, _pyfree=_pyfree)
        self.io = m2.bio_new(m2.bio_f_buffer())
        self.bio = m2.bio_push(self.io, under_bio._ptr())
        # This reference keeps the underlying BIO alive while we're not closed.
        self._under_bio = under_bio
        if 'w' in mode:
            self.write_closed = 0
        else:
            self.write_closed = 1

    def __del__(self):
        # type: () -> None
        if getattr(self, '_pyfree', 0):
            self.m2_bio_pop(self.bio)
        self.m2_bio_free(self.io)

    def close(self):
        # type: () -> None
        BIO.close(self)


class CipherStream(BIO):

    """
    Object interface to BIO_f_cipher.
    """

    SALT_LEN = m2.PKCS5_SALT_LEN

    m2_bio_pop = m2.bio_pop
    m2_bio_free = m2.bio_free

    def __init__(self, obio):
        # type: (BIO) -> None
        BIO.__init__(self, _pyfree=1)
        self.obio = obio
        self.bio = m2.bio_new(m2.bio_f_cipher())
        self.closed = 0

    def __del__(self):
        # type: () -> None
        if not getattr(self, 'closed', 1):
            self.close()

    def close(self):
        # type: () -> None
        self.m2_bio_pop(self.bio)
        self.m2_bio_free(self.bio)
        self.closed = 1

    def write_close(self):
        # type: () -> None
        self.obio.write_close()

    def set_cipher(self, algo, key, iv, op):
        # type: (str, AnyStr, AnyStr, int) -> None
        cipher = getattr(m2, algo, None)
        if cipher is None:
            raise ValueError('unknown cipher', algo)
        else:
            if not isinstance(key, bytes):
                key = key.encode('utf8')
            if not isinstance(iv, bytes):
                iv = iv.encode('utf8')
        m2.bio_set_cipher(self.bio, cipher(), key, iv, int(op))
        m2.bio_push(self.bio, self.obio._ptr())


class SSLBio(BIO):
    """
    Object interface to BIO_f_ssl
    """
    def __init__(self, _pyfree=1):
        # type: (int) -> None
        BIO.__init__(self, _pyfree=_pyfree)
        self.bio = m2.bio_new(m2.bio_f_ssl())
        self.closed = 0

    def set_ssl(self, conn, close_flag=m2.bio_noclose):
        # type: (Connection, int) -> None
        """
        Sets the bio to the SSL pointer which is
        contained in the connection object.
        """
        self._pyfree = 0
        m2.bio_set_ssl(self.bio, conn.ssl, close_flag)
        if close_flag == m2.bio_noclose:
            conn.set_ssl_close_flag(m2.bio_close)

    def do_handshake(self):
        # type: () -> int
        """
        Do the handshake.

        Return 1 if the handshake completes
        Return 0 or a negative number if there is a problem
        """
        return m2.bio_do_handshake(self.bio)
