# client.py -- Implementation of the client side git protocols
# Copyright (C) 2008-2013 Jelmer Vernooij <jelmer@jelmer.uk>
#
# Dulwich is dual-licensed under the Apache License, Version 2.0 and the GNU
# General Public License as public by the Free Software Foundation; version 2.0
# or (at your option) any later version. You can redistribute it and/or
# modify it under the terms of either of these two licenses.
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
#
# You should have received a copy of the licenses; if not, see
# <http://www.gnu.org/licenses/> for a copy of the GNU General Public License
# and <http://www.apache.org/licenses/LICENSE-2.0> for a copy of the Apache
# License, Version 2.0.
#

"""Client side support for the Git protocol.

The Dulwich client supports the following capabilities:

 * thin-pack
 * multi_ack_detailed
 * multi_ack
 * side-band-64k
 * ofs-delta
 * quiet
 * report-status
 * delete-refs

Known capabilities that are not supported:

 * shallow
 * no-progress
 * include-tag
"""

from contextlib import closing
from io import BytesIO, BufferedReader
import select
import socket
import subprocess
import sys

try:
    from urllib import quote as urlquote
    from urllib import unquote as urlunquote
except ImportError:
    from urllib.parse import quote as urlquote
    from urllib.parse import unquote as urlunquote

try:
    import urlparse
except ImportError:
    import urllib.parse as urlparse

import dulwich
from dulwich.errors import (
    GitProtocolError,
    NotGitRepository,
    SendPackError,
    UpdateRefsError,
    )
from dulwich.protocol import (
    HangupException,
    _RBUFSIZE,
    agent_string,
    capability_agent,
    extract_capability_names,
    CAPABILITY_AGENT,
    CAPABILITY_DELETE_REFS,
    CAPABILITY_MULTI_ACK,
    CAPABILITY_MULTI_ACK_DETAILED,
    CAPABILITY_OFS_DELTA,
    CAPABILITY_QUIET,
    CAPABILITY_REPORT_STATUS,
    CAPABILITY_SHALLOW,
    CAPABILITY_SYMREF,
    CAPABILITY_SIDE_BAND_64K,
    CAPABILITY_THIN_PACK,
    CAPABILITIES_REF,
    KNOWN_RECEIVE_CAPABILITIES,
    KNOWN_UPLOAD_CAPABILITIES,
    COMMAND_DEEPEN,
    COMMAND_SHALLOW,
    COMMAND_UNSHALLOW,
    COMMAND_DONE,
    COMMAND_HAVE,
    COMMAND_WANT,
    SIDE_BAND_CHANNEL_DATA,
    SIDE_BAND_CHANNEL_PROGRESS,
    SIDE_BAND_CHANNEL_FATAL,
    PktLineParser,
    Protocol,
    ProtocolFile,
    TCP_GIT_PORT,
    ZERO_SHA,
    extract_capabilities,
    parse_capability,
    )
from dulwich.pack import (
    write_pack_data,
    write_pack_objects,
    )
from dulwich.refs import (
    read_info_refs,
    ANNOTATED_TAG_SUFFIX,
    )


class InvalidWants(Exception):
    """Invalid wants."""

    def __init__(self, wants):
        Exception.__init__(
            self,
            "requested wants not in server provided refs: %r" % wants)


def _fileno_can_read(fileno):
    """Check if a file descriptor is readable."""
    return len(select.select([fileno], [], [], 0)[0]) > 0


def _win32_peek_avail(handle):
    """Wrapper around PeekNamedPipe to check how many bytes are available."""
    from ctypes import byref, wintypes, windll
    c_avail = wintypes.DWORD()
    c_message = wintypes.DWORD()
    success = windll.kernel32.PeekNamedPipe(
        handle, None, 0, None, byref(c_avail),
        byref(c_message))
    if not success:
        raise OSError(wintypes.GetLastError())
    return c_avail.value


COMMON_CAPABILITIES = [CAPABILITY_OFS_DELTA, CAPABILITY_SIDE_BAND_64K]
UPLOAD_CAPABILITIES = ([CAPABILITY_THIN_PACK, CAPABILITY_MULTI_ACK,
                        CAPABILITY_MULTI_ACK_DETAILED, CAPABILITY_SHALLOW]
                       + COMMON_CAPABILITIES)
RECEIVE_CAPABILITIES = [CAPABILITY_REPORT_STATUS] + COMMON_CAPABILITIES


class ReportStatusParser(object):
    """Handle status as reported by servers with 'report-status' capability.
    """

    def __init__(self):
        self._done = False
        self._pack_status = None
        self._ref_status_ok = True
        self._ref_statuses = []

    def check(self):
        """Check if there were any errors and, if so, raise exceptions.

        :raise SendPackError: Raised when the server could not unpack
        :raise UpdateRefsError: Raised when refs could not be updated
        """
        if self._pack_status not in (b'unpack ok', None):
            raise SendPackError(self._pack_status)
        if not self._ref_status_ok:
            ref_status = {}
            ok = set()
            for status in self._ref_statuses:
                if b' ' not in status:
                    # malformed response, move on to the next one
                    continue
                status, ref = status.split(b' ', 1)

                if status == b'ng':
                    if b' ' in ref:
                        ref, status = ref.split(b' ', 1)
                else:
                    ok.add(ref)
                ref_status[ref] = status
            # TODO(jelmer): don't assume encoding of refs is ascii.
            raise UpdateRefsError(', '.join([
                refname.decode('ascii') for refname in ref_status
                if refname not in ok]) +
                ' failed to update', ref_status=ref_status)

    def handle_packet(self, pkt):
        """Handle a packet.

        :raise GitProtocolError: Raised when packets are received after a
            flush packet.
        """
        if self._done:
            raise GitProtocolError("received more data after status report")
        if pkt is None:
            self._done = True
            return
        if self._pack_status is None:
            self._pack_status = pkt.strip()
        else:
            ref_status = pkt.strip()
            self._ref_statuses.append(ref_status)
            if not ref_status.startswith(b'ok '):
                self._ref_status_ok = False


def read_pkt_refs(proto):
    server_capabilities = None
    refs = {}
    # Receive refs from server
    for pkt in proto.read_pkt_seq():
        (sha, ref) = pkt.rstrip(b'\n').split(None, 1)
        if sha == b'ERR':
            raise GitProtocolError(ref.decode('utf-8', 'replace'))
        if server_capabilities is None:
            (ref, server_capabilities) = extract_capabilities(ref)
        refs[ref] = sha

    if len(refs) == 0:
        return {}, set([])
    if refs == {CAPABILITIES_REF: ZERO_SHA}:
        refs = {}
    return refs, set(server_capabilities)


class FetchPackResult(object):
    """Result of a fetch-pack operation.

    :var refs: Dictionary with all remote refs
    :var symrefs: Dictionary with remote symrefs
    :var agent: User agent string
    """

    _FORWARDED_ATTRS = [
            'clear', 'copy', 'fromkeys', 'get', 'has_key', 'items',
            'iteritems', 'iterkeys', 'itervalues', 'keys', 'pop', 'popitem',
            'setdefault', 'update', 'values', 'viewitems', 'viewkeys',
            'viewvalues']

    def __init__(self, refs, symrefs, agent, new_shallow=None,
                 new_unshallow=None):
        self.refs = refs
        self.symrefs = symrefs
        self.agent = agent
        self.new_shallow = new_shallow
        self.new_unshallow = new_unshallow

    def _warn_deprecated(self):
        import warnings
        warnings.warn(
            "Use FetchPackResult.refs instead.",
            DeprecationWarning, stacklevel=3)

    def __eq__(self, other):
        if isinstance(other, dict):
            self._warn_deprecated()
            return (self.refs == other)
        return (self.refs == other.refs and
                self.symrefs == other.symrefs and
                self.agent == other.agent)

    def __contains__(self, name):
        self._warn_deprecated()
        return name in self.refs

    def __getitem__(self, name):
        self._warn_deprecated()
        return self.refs[name]

    def __len__(self):
        self._warn_deprecated()
        return len(self.refs)

    def __iter__(self):
        self._warn_deprecated()
        return iter(self.refs)

    def __getattribute__(self, name):
        if name in type(self)._FORWARDED_ATTRS:
            self._warn_deprecated()
            return getattr(self.refs, name)
        return super(FetchPackResult, self).__getattribute__(name)

    def __repr__(self):
        return "%s(%r, %r, %r)" % (
                self.__class__.__name__, self.refs, self.symrefs, self.agent)


def _read_shallow_updates(proto):
    new_shallow = set()
    new_unshallow = set()
    for pkt in proto.read_pkt_seq():
        cmd, sha = pkt.split(b' ', 1)
        if cmd == COMMAND_SHALLOW:
            new_shallow.add(sha.strip())
        elif cmd == COMMAND_UNSHALLOW:
            new_unshallow.add(sha.strip())
        else:
            raise GitProtocolError('unknown command %s' % pkt)
    return (new_shallow, new_unshallow)


# TODO(durin42): this doesn't correctly degrade if the server doesn't
# support some capabilities. This should work properly with servers
# that don't support multi_ack.
class GitClient(object):
    """Git smart server client.

    """

    def __init__(self, thin_packs=True, report_activity=None, quiet=False):
        """Create a new GitClient instance.

        :param thin_packs: Whether or not thin packs should be retrieved
        :param report_activity: Optional callback for reporting transport
            activity.
        """
        self._report_activity = report_activity
        self._report_status_parser = None
        self._fetch_capabilities = set(UPLOAD_CAPABILITIES)
        self._fetch_capabilities.add(capability_agent())
        self._send_capabilities = set(RECEIVE_CAPABILITIES)
        self._send_capabilities.add(capability_agent())
        if quiet:
            self._send_capabilities.add(CAPABILITY_QUIET)
        if not thin_packs:
            self._fetch_capabilities.remove(CAPABILITY_THIN_PACK)

    def get_url(self, path):
        """Retrieves full url to given path.

        :param path: Repository path (as string)
        :return: Url to path (as string)
        """
        raise NotImplementedError(self.get_url)

    @classmethod
    def from_parsedurl(cls, parsedurl, **kwargs):
        """Create an instance of this client from a urlparse.parsed object.

        :param parsedurl: Result of urlparse.urlparse()
        :return: A `GitClient` object
        """
        raise NotImplementedError(cls.from_parsedurl)