# Copyright (c) 2009-2014 Denis Bilenko and gevent contributors. See LICENSE for details.
from __future__ import absolute_import

# standard functions and classes that this module re-implements in a gevent-aware way:
_implements = [
    'create_connection',
    'socket',
    'SocketType',
    'fromfd',
    'socketpair',
]

__dns__ = [
    'getaddrinfo',
    'gethostbyname',
    'gethostbyname_ex',
    'gethostbyaddr',
    'getnameinfo',
    'getfqdn',
]

_implements += __dns__

# non-standard functions that this module provides:
__extensions__ = [
    'cancel_wait',
    'wait_read',
    'wait_write',
    'wait_readwrite',
]

# standard functions and classes that this module re-imports
__imports__ = [
    'error',
    'gaierror',
    'herror',
    'htonl',
    'htons',
    'ntohl',
    'ntohs',
    'inet_aton',
    'inet_ntoa',
    'inet_pton',
    'inet_ntop',
    'timeout',
    'gethostname',
    'getprotobyname',
    'getservbyname',
    'getservbyport',
    'getdefaulttimeout',
    'setdefaulttimeout',
    # Windows:
    'errorTab',
]

__py3_imports__ = [
    # Python 3
    'AddressFamily',
    'SocketKind',
    'CMSG_LEN',
    'CMSG_SPACE',
    'dup',
    'if_indextoname',
    'if_nameindex',
    'if_nametoindex',
    'sethostname',
]

__imports__.extend(__py3_imports__)

import time
import sys
from gevent._hub_local import get_hub_noargs as get_hub
from gevent._compat import string_types, integer_types, PY3
from gevent._util import copy_globals

is_windows = sys.platform == 'win32'
is_macos = sys.platform == 'darwin'

# pylint:disable=no-name-in-module,unused-import
if is_windows:
    # no such thing as WSAEPERM or error code 10001 according to winsock.h or MSDN
    from errno import WSAEINVAL as EINVAL
    from errno import WSAEWOULDBLOCK as EWOULDBLOCK
    from errno import WSAEINPROGRESS as EINPROGRESS
    from errno import WSAEALREADY as EALREADY
    from errno import WSAEISCONN as EISCONN
    from gevent.win32util import formatError as strerror
    EAGAIN = EWOULDBLOCK
else:
    from errno import EINVAL
    from errno import EWOULDBLOCK
    from errno import EINPROGRESS
    from errno import EALREADY
    from errno import EAGAIN
    from errno import EISCONN
    from os import strerror

try:
    from errno import EBADF
except ImportError:
    EBADF = 9

# macOS can return EPROTOTYPE when writing to a socket that is shutting
# Down. Retrying the write should return the expected EPIPE error.
# Downstream classes (like pywsgi) know how to handle/ignore EPIPE.
# This set is used by socket.send() to decide whether the write should
# be retried. The default is to retry only on EWOULDBLOCK. Here we add
# EPROTOTYPE on macOS to handle this platform-specific race condition.
GSENDAGAIN = (EWOULDBLOCK,)
if is_macos:
    from errno import EPROTOTYPE
    GSENDAGAIN += (EPROTOTYPE,)

import _socket
_realsocket = _socket.socket
import socket as __socket__

_name = _value = None
__imports__ = copy_globals(__socket__, globals(),
                           only_names=__imports__,
                           ignore_missing_names=True)

for _name in __socket__.__all__:
    _value = getattr(__socket__, _name)
    if isinstance(_value, (integer_types, string_types)):
        globals()[_name] = _value
        __imports__.append(_name)

del _name, _value

_timeout_error = timeout # pylint: disable=undefined-variable

from gevent import _hub_primitives
_hub_primitives.set_default_timeout_error(_timeout_error)

wait = _hub_primitives.wait_on_watcher
wait_read = _hub_primitives.wait_read
wait_write = _hub_primitives.wait_write
wait_readwrite = _hub_primitives.wait_readwrite

#: The exception raised by default on a call to :func:`cancel_wait`
class cancel_wait_ex(error): # pylint: disable=undefined-variable
    def __init__(self):
        super(cancel_wait_ex, self).__init__(
            EBADF,
            'File descriptor was closed in another greenlet')


def cancel_wait(watcher, error=cancel_wait_ex):
    """See :meth:`gevent.hub.Hub.cancel_wait`"""
    get_hub().cancel_wait(watcher, error)


def gethostbyname(hostname):
    """
    gethostbyname(host) -> address

    Return the IP address (a string of the form '255.255.255.255') for a host.

    .. seealso:: :doc:`/dns`
    """
    return get_hub().resolver.gethostbyname(hostname)


def gethostbyname_ex(hostname):
    """
    gethostbyname_ex(host) -> (name, aliaslist, addresslist)

    Return the true host name, a list of aliases, and a list of IP addresses,
    for a host.  The host argument is a string giving a host name or IP number.
    Resolve host and port into list of address info entries.

    .. seealso:: :doc:`/dns`
    """
    return get_hub().resolver.gethostbyname_ex(hostname)


def getaddrinfo(host, port, family=0, socktype=0, proto=0, flags=0):
    """
    Resolve host and port into list of address info entries.

    Translate the host/port argument into a sequence of 5-tuples that contain
    all the necessary arguments for creating a socket connected to that service.
    host is a domain name, a string representation of an IPv4/v6 address or
    None. port is a string service name such as 'http', a numeric port number or
    None. By passing None as the value of host and port, you can pass NULL to
    the underlying C API.

    The family, type and proto arguments can be optionally specified in order to
    narrow the list of addresses returned. Passing zero as a value for each of
    these arguments selects the full range of results.

    .. seealso:: :doc:`/dns`
    """
    return get_hub().resolver.getaddrinfo(host, port, family, socktype, proto, flags)

if PY3:
    # The name of the socktype param changed to type in Python 3.
    # See https://github.com/gevent/gevent/issues/960
    # Using inspect here to directly detect the condition is painful because we have to
    # wrap it with a try/except TypeError because not all Python 2
    # versions can get the args of a builtin; we also have to use a with to suppress
    # the deprecation warning.
    d = getaddrinfo.__doc__

    def getaddrinfo(host, port, family=0, type=0, proto=0, flags=0): # pylint:disable=function-redefined
        return get_hub().resolver.getaddrinfo(host, port, family, type, proto, flags)
    getaddrinfo.__doc__ = d
    del d


def gethostbyaddr(ip_address):
    """
    gethostbyaddr(ip_address) -> (name, aliaslist, addresslist)

    Return the true host name, a list of aliases, and a list of IP addresses,
    for a host.  The host argument is a string giving a host name or IP number.

    .. seealso:: :doc:`/dns`
    """
    return get_hub().resolver.gethostbyaddr(ip_address)


def getnameinfo(sockaddr, flags):
    """
    getnameinfo(sockaddr, flags) -> (host, port)

    Get host and port for a sockaddr.

    .. seealso:: :doc:`/dns`
    """
    return get_hub().resolver.getnameinfo(sockaddr, flags)


def getfqdn(name=''):
    """Get fully qualified domain name from name.

    An empty argument is interpreted as meaning the local host.

    First the hostname returned by gethostbyaddr() is checked, then
    possibly existing aliases. In case no FQDN is available, hostname
    from gethostname() is returned.
    """
    # pylint: disable=undefined-variable
    name = name.strip()
    if not name or name == '0.0.0.0':
        name = gethostname()
    try:
        hostname, aliases, _ = gethostbyaddr(name)
    except error:
        pass
    else:
        aliases.insert(0, hostname)
        for name in aliases: # EWW! pylint:disable=redefined-argument-from-local
            if isinstance(name, bytes):
                if b'.' in name:
                    break
            elif '.' in name:
                break
        else:
            name = hostname
    return name

def __send_chunk(socket, data_memory, flags, timeleft, end, timeout=_timeout_error):
    """
    Send the complete contents of ``data_memory`` before returning.
    This is the core loop around :meth:`send`.

    :param timeleft: Either ``None`` if there is no timeout involved,
       or a float indicating the timeout to use.
    :param end: Either ``None`` if there is no timeout involved, or
       a float giving the absolute end time.
    :return: An updated value for ``timeleft`` (or None)
    :raises timeout: If ``timeleft`` was given and elapsed while
       sending this chunk.
    """
    data_sent = 0
    len_data_memory = len(data_memory)
    started_timer = 0
    while data_sent < len_data_memory:
        chunk = data_memory[data_sent:]
        if timeleft is None:
            data_sent += socket.send(chunk, flags)
        elif started_timer and timeleft <= 0:
            # Check before sending to guarantee a check
            # happens even if each chunk successfully sends its data
            # (especially important for SSL sockets since they have large
            # buffers). But only do this if we've actually tried to
            # send something once to avoid spurious timeouts on non-blocking
            # sockets.
            raise timeout('timed out')
        else:
            started_timer = 1
            data_sent += socket.send(chunk, flags, timeout=timeleft)
            timeleft = end - time.time()

    return timeleft

def _sendall(socket, data_memory, flags,
             SOL_SOCKET=__socket__.SOL_SOCKET,  # pylint:disable=no-member
             SO_SNDBUF=__socket__.SO_SNDBUF):  # pylint:disable=no-member
    """
    Send the *data_memory* (which should be a memoryview)
    using the gevent *socket*, performing well on PyPy.
    """

    # On PyPy up through 5.10.0, both PyPy2 and PyPy3, subviews
    # (slices) of a memoryview() object copy the underlying bytes the
    # first time the builtin socket.send() method is called. On a
    # non-blocking socket (that thus calls socket.send() many times)
    # with a large input, this results in many repeated copies of an
    # ever smaller string, depending on the networking buffering. For
    # example, if each send() can process 1MB of a 50MB input, and we
    # naively pass the entire remaining subview each time, we'd copy
    # 49MB, 48MB, 47MB, etc, thus completely killing performance. To
    # workaround this problem, we work in reasonable, fixed-size
    # chunks. This results in a 10x improvement to bench_sendall.py,
    # while having no measurable impact on CPython (since it doesn't
    # copy at all the only extra overhead is a few python function
    # calls, which is negligible for large inputs).

    # On one macOS machine, PyPy3 5.10.1 produced ~ 67.53 MB/s before this change,
    # and ~ 616.01 MB/s after.

    # See https://bitbucket.org/pypy/pypy/issues/2091/non-blocking-socketsend-slow-gevent

    # Too small of a chunk (the socket's buf size is usually too
    # small) results in reduced perf due to *too many* calls to send and too many
    # small copies. With a buffer of 143K (the default on my system), for
    # example, bench_sendall.py yields ~264MB/s, while using 1MB yields
    # ~653MB/s (matching CPython). 1MB is arbitrary and might be better
    # chosen, say, to match a page size?

    len_data_memory = len(data_memory)
    if not len_data_memory:
        # Don't try to send empty data at all, no point, and breaks ssl
        # See issue 719
        return 0


    chunk_size = max(socket.getsockopt(SOL_SOCKET, SO_SNDBUF), 1024 * 1024)

    data_sent = 0
    end = None
    timeleft = None
    if socket.timeout is not None:
        timeleft = socket.timeout
        end = time.time() + timeleft

    while data_sent < len_data_memory:
        chunk_end = min(data_sent + chunk_size, len_data_memory)
        chunk = data_memory[data_sent:chunk_end]

        timeleft = __send_chunk(socket, chunk, flags, timeleft, end)
        data_sent += len(chunk) # Guaranteed it sent the whole thing
