# Copyright (C) 2014-2020 RhodeCode GmbH
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU Affero General Public License, version 3
# (only), as published by the Free Software Foundation.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU Affero General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.
#
# This program is dual-licensed. If you wish to learn more about the
# RhodeCode Enterprise Edition, including its added features, Support services,
# and proprietary license terms, please see https://rhodecode.com/licenses/

"""
Various version Control System version lib (vcs) management abstraction layer
for Python. Build with server client architecture.
"""
import io
import atexit
import logging

import rhodecode
from rhodecode.lib.str_utils import safe_bytes
from rhodecode.lib.vcs.conf import settings
from rhodecode.lib.vcs.backends import get_vcs_instance, get_backend
from rhodecode.lib.vcs.exceptions import (
    VCSError, RepositoryError, CommitError, VCSCommunicationError)

__all__ = [
    'get_vcs_instance', 'get_backend',
    'VCSError', 'RepositoryError', 'CommitError', 'VCSCommunicationError'
]

log = logging.getLogger(__name__)

# The pycurl library directly accesses C API functions and is not patched by
# gevent. This will potentially lead to deadlocks due to incompatibility to
# gevent. Therefore we check if gevent is active and import a gevent compatible
# wrapper in that case.
try:
    from gevent import monkey
    if monkey.is_module_patched('__builtin__'):
        import geventcurl as pycurl
        log.debug('Using gevent comapatible pycurl: %s', pycurl)
    else:
        import pycurl
except ImportError:
    import pycurl


def connect_http(server_and_port):
    log.debug('Initialized VCSServer connections to %s.', server_and_port)

    from rhodecode.lib.vcs import connection, client_http
    from rhodecode.lib.middleware.utils import scm_app

    session_factory = client_http.ThreadlocalSessionFactory()

    connection.Git = client_http.RemoteVCSMaker(
        server_and_port, '/git', 'git', session_factory)
    connection.Hg = client_http.RemoteVCSMaker(
        server_and_port, '/hg', 'hg', session_factory)
    connection.Svn = client_http.RemoteVCSMaker(
        server_and_port, '/svn', 'svn', session_factory)
    connection.Service = client_http.ServiceConnection(
        server_and_port, '/_service', session_factory)

    scm_app.HG_REMOTE_WSGI = client_http.VcsHttpProxy(
        server_and_port, '/proxy/hg')
    scm_app.GIT_REMOTE_WSGI = client_http.VcsHttpProxy(
        server_and_port, '/proxy/git')

    @atexit.register
    def free_connection_resources():
        connection.Git = None
        connection.Hg = None
        connection.Svn = None
        connection.Service = None


def connect_vcs(server_and_port, protocol):
    """
    Initializes the connection to the vcs server.

    :param server_and_port: str, e.g. "localhost:9900"
    :param protocol: str or "http"
    """
    if protocol == 'http':
        connect_http(server_and_port)
    else:
        raise Exception('Invalid vcs server protocol "{}"'.format(protocol))


class CurlSession(object):
    """
    Modeled so that it provides a subset of the requests interface.

    This has been created so that it does only provide a minimal API for our
    needs. The parts which it provides are based on the API of the library
    `requests` which allows us to easily benchmark against it.

    Please have a look at the class :class:`requests.Session` when you extend
    it.
    """
    CURL_UA = f'RhodeCode HTTP {rhodecode.__version__}'

    def __init__(self):
        curl = pycurl.Curl()
        # TODO: johbo: I did test with 7.19 of libcurl. This version has
        # trouble with 100 - continue being set in the expect header. This
        # can lead to massive performance drops, switching it off here.

        curl.setopt(curl.TCP_NODELAY, True)
        curl.setopt(curl.PROTOCOLS, curl.PROTO_HTTP)
        curl.setopt(curl.USERAGENT, safe_bytes(self.CURL_UA))
        curl.setopt(curl.SSL_VERIFYPEER, 0)
        curl.setopt(curl.SSL_VERIFYHOST, 0)
        self._curl = curl

    def post(self, url, data, allow_redirects=False, headers=None):
        headers = headers or {}
        # format is ['header_name1: header_value1', 'header_name2: header_value2'])
        headers_list = [b"Expect:"] + [safe_bytes('{}: {}'.format(k, v)) for k, v in headers.items()]
        response_buffer = io.BytesIO()

        curl = self._curl
        curl.setopt(curl.URL, url)
        curl.setopt(curl.POST, True)
        curl.setopt(curl.POSTFIELDS, data)
        curl.setopt(curl.FOLLOWLOCATION, allow_redirects)
        curl.setopt(curl.WRITEDATA, response_buffer)
        curl.setopt(curl.HTTPHEADER, headers_list)
        curl.perform()

        status_code = curl.getinfo(pycurl.HTTP_CODE)
        content_type = curl.getinfo(pycurl.CONTENT_TYPE)
        return CurlResponse(response_buffer, status_code, content_type)


class CurlResponse(object):
    """
    The response of a request, modeled after the requests API.

    This class provides a subset of the response interface known from the
    library `requests`. It is intentionally kept similar, so that we can use
    `requests` as a drop in replacement for benchmarking purposes.
    """

    def __init__(self, response_buffer, status_code, content_type=''):
        self._response_buffer = response_buffer
        self._status_code = status_code
        self._content_type = content_type

    def __repr__(self):
        return f'CurlResponse(code={self._status_code}, content_type={self._content_type})'

    @property
    def content(self):
        try:
            return self._response_buffer.getvalue()
        finally:
            self._response_buffer.close()

    @property
    def status_code(self):
        return self._status_code

    @property
    def content_type(self):
        return self._content_type

    def iter_content(self, chunk_size):
        self._response_buffer.seek(0)
        while 1:
            chunk = self._response_buffer.read(chunk_size)
            if not chunk:
                break
            yield chunk


def _create_http_rpc_session():
    session = CurlSession()
    return session