from __future__ import absolute_import

"""M2Crypto wrapper for OpenSSL BIO API.

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

import io
import logging
from typing import Any, Callable, Iterable, Optional, Union  # noqa

from M2Crypto import m2, types as C

log = logging.getLogger('BIO')


class BIOError(ValueError):
    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: Optional[C.BIO] = None,
        _pyfree: int = 0,
        _close_cb: Optional[Callable] = None,
    ) -> 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) -> int:
        return m2.bio_get_fd(self.bio)

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

    def read(
        self, size: Optional[int] = None
    ) -> 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: int = 4096) -> bytes:
        if not self.readable():
            raise IOError('cannot read')
        buf = m2.bio_gets(self.bio, size)
        return '' if buf is None else buf

    def readlines(
        self, sizehint: Union[str, bytes, int] = 'ignored'
    ) -> 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) -> bool:
        return (not self.closed) and (not self.write_closed)

    def write(self, data: Union[str, bytes]) -> int:
        """Write data to BIO.

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

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

    def flush(self) -> None:
        """Flush the buffers.

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

    def reset(self) -> int:
        """Set 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) -> None:
        self.closed = 1
        if self._close_cb:
            self._close_cb()

    def should_retry(self) -> 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) -> int:
        """Should we read more data?"""

        return m2.bio_should_read(self.bio)

    def should_write(self) -> int:
        """Should we 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) -> 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: Optional[bytes] = None) -> None:
        super(MemoryBuffer, self).__init__(self)
        if data is not None and not isinstance(data, bytes):
            raise TypeError(
                "data must be bytes or None, not %s"
                % (type(data).__name__,)
            )
        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) -> int:
        return m2.bio_ctrl_pending(self.bio)

    def read(self, size: int = 0) -> bytes:
        m2.err_clear_error()
        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) -> None:
        super(MemoryBuffer, self).write_close()
        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: Union[io.BytesIO, str, bytes],
        close_pyfile: int = 1,
        mode: Union[str, bytes] = 'rb',
    ) -> None:
        super(File, self).__init__(self, _pyfree=1)

        if isinstance(pyfile, str):
            pyfile = open(pyfile, mode)

        # This is for downward compatibility, but I don't think, that it is
        # good practice to have two handles for the same file. Whats about
        # concurrent write access? Last write, last wins? Especially since Py3
        # has its own buffer management. See:
        #
        #  https://docs.python.org/3.3/c-api/file.html
        #
        pyfile.flush()
        self.fname = pyfile.name
        self.pyfile = 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)

        self.close_pyfile = close_pyfile
        self.closed = False

    def flush(self) -> None:
        super(File, self).flush()
        self.pyfile.flush()

    def close(self) -> None:
        self.flush()
        super(File, self).close()
        if self.close_pyfile:
            self.pyfile.close()

    def reset(self) -> int:
        """Set the bio to its initial state.

        :return: 0 for success, and -1 for failure
        """
        return super(File, self).reset()


def openfile(filename: Union[str, bytes], mode: Union[str, bytes] = 'rb') -> File:
    try:
        f = open(filename, mode)
    except IOError as ex:
        raise BIOError(ex.args)

    return File(f)


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: BIO, mode: str = 'rwb', _pyfree: int = 1) -> None:
        super(IOBuffer, self).__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) -> None:
        if getattr(self, '_pyfree', 0):
            self.m2_bio_pop(self.bio)
        self.m2_bio_free(self.io)

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

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

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

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

    def set_cipher(self, algo: str, key: Union[str, bytes], iv: Union[str, bytes], op: 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')
        try:
            m2.bio_set_cipher(self.bio, cipher(), key, iv, int(op))
        except (OSError, ValueError) as ex:
            raise BIOError("BIOError: {}".format(str(ex)))
        m2.bio_push(self.bio, self.obio._ptr())


class SSLBio(BIO):
    """Object interface to BIO_f_ssl."""

    def __init__(self, _pyfree: int = 1) -> None:
        super(SSLBio, self).__init__(self, _pyfree=_pyfree)
        self.bio = m2.bio_new(m2.bio_f_ssl())
        self.closed = 0

    def set_ssl(self, conn: Any, close_flag: int = m2.bio_noclose) -> None:
        # conn should actually be SSL.Connection, but we cannot import
        # it here without getting into some serious circular dependency
        # business.
        """
        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) -> 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)
