# -*- coding: utf-8 -*-

# Copyright (C) 2014-2016  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.
"""


VERSION = (0, 5, 0, 'dev')

__version__ = '.'.join((str(each) for each in VERSION[:4]))

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

import atexit
import logging
import subprocess
import time
import urlparse
from cStringIO import StringIO

import Pyro4
from Pyro4.errors import CommunicationError

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)

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 get_version():
    """
    Returns shorter version (digit parts only) as string.
    """
    return '.'.join((str(each) for each in VERSION[:3]))


def connect_pyro4(server_and_port):
    from rhodecode.lib.vcs import connection, client
    from rhodecode.lib.middleware.utils import scm_app

    git_remote = client.RequestScopeProxyFactory(
        settings.pyro_remote(settings.PYRO_GIT, server_and_port))
    hg_remote = client.RequestScopeProxyFactory(
        settings.pyro_remote(settings.PYRO_HG, server_and_port))
    svn_remote = client.RequestScopeProxyFactory(
        settings.pyro_remote(settings.PYRO_SVN, server_and_port))

    connection.Git = client.RepoMaker(proxy_factory=git_remote)
    connection.Hg = client.RepoMaker(proxy_factory=hg_remote)
    connection.Svn = client.RepoMaker(proxy_factory=svn_remote)

    scm_app.GIT_REMOTE_WSGI = Pyro4.Proxy(
        settings.pyro_remote(
            settings.PYRO_GIT_REMOTE_WSGI, server_and_port))
    scm_app.HG_REMOTE_WSGI = Pyro4.Proxy(
        settings.pyro_remote(
            settings.PYRO_HG_REMOTE_WSGI, server_and_port))

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


def connect_http(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.RepoMaker(
        server_and_port, '/git', session_factory)
    connection.Hg = client_http.RepoMaker(
        server_and_port, '/hg', session_factory)
    connection.Svn = client_http.RepoMaker(
        server_and_port, '/svn', 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


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, "pyro4" or "http"
    """
    if protocol == 'pyro4':
        connect_pyro4(server_and_port)
    elif protocol == 'http':
        connect_http(server_and_port)
    else:
        raise Exception('Invalid vcs server protocol "{}"'.format(protocol))


# TODO: johbo: This function should be moved into our test suite, there is
# no reason to support starting the vcsserver in Enterprise itself.
def start_vcs_server(server_and_port, protocol, log_level=None):
    """
    Starts the vcs server in a subprocess.
    """
    log.info('Starting VCSServer as a sub process with %s protocol', protocol)
    if protocol == 'http':
        return _start_http_vcs_server(server_and_port, log_level)
    elif protocol == 'pyro4':
        return _start_pyro4_vcs_server(server_and_port, log_level)
    else:
        raise Exception('Invalid vcs server protocol "{}"'.format(protocol))


def _start_pyro4_vcs_server(server_and_port, log_level=None):
    _try_to_shutdown_running_server(server_and_port, protocol='pyro4')
    host, port = server_and_port.rsplit(":", 1)
    host = host.strip('[]')
    args = [
        'vcsserver', '--port', port, '--host', host, '--locale', 'en_US.UTF-8',
        '--threadpool', '32']
    if log_level:
        args += ['--log-level', log_level]
    proc = subprocess.Popen(args)

    def cleanup_server_process():
        proc.kill()
    atexit.register(cleanup_server_process)

    server = create_vcsserver_proxy(server_and_port, protocol='pyro4')
    _wait_until_vcs_server_is_reachable(server)


def _start_http_vcs_server(server_and_port, log_level=None):
    # TODO: mikhail: shutdown if an http server already runs

    host, port = server_and_port.rsplit(":", 1)
    args = [
        'pserve', 'vcsserver/development_pyramid.ini',
        'http_port=%s' % (port, ), 'http_host=%s' % (host, )]
    proc = subprocess.Popen(args)

    def cleanup_server_process():
        proc.kill()
    atexit.register(cleanup_server_process)

    server = create_vcsserver_proxy(server_and_port, protocol='http')
    _wait_until_vcs_server_is_reachable(server)


def _wait_until_vcs_server_is_reachable(server):
    while xrange(80):  # max 40s of sleep
        try:
            server.ping()
            break
        except (CommunicationError, pycurl.error):
            pass
        time.sleep(0.5)


def _try_to_shutdown_running_server(server_and_port, protocol):
    server = create_vcsserver_proxy(server_and_port, protocol)
    try:
        server.shutdown()
    except (CommunicationError, pycurl.error):
        return

    # TODO: Not sure why this is important, but without it the following start
    # of the server fails.
    server = create_vcsserver_proxy(server_and_port, protocol)
    server.ping()


def create_vcsserver_proxy(server_and_port, protocol):
    if protocol == 'pyro4':
        return _create_vcsserver_proxy_pyro4(server_and_port)
    elif protocol == 'http':
        return _create_vcsserver_proxy_http(server_and_port)
    else:
        raise Exception('Invalid vcs server protocol "{}"'.format(protocol))


def _create_vcsserver_proxy_pyro4(server_and_port):
    server = Pyro4.Proxy(
        settings.pyro_remote(settings.PYRO_VCSSERVER, server_and_port))
    return server


def _create_vcsserver_proxy_http(server_and_port):
    from rhodecode.lib.vcs import client_http

    session = _create_http_rpc_session()
    url = urlparse.urljoin('http://%s' % server_and_port, '/server')
    return client_http.RemoteObject(url, session)


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.
    """

    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.HTTPHEADER, ["Expect:"])
        curl.setopt(curl.TCP_NODELAY, True)
        curl.setopt(curl.PROTOCOLS, curl.PROTO_HTTP)
        self._curl = curl

    def post(self, url, data, allow_redirects=False):
        response_buffer = StringIO()

        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.perform()

        return CurlResponse(response_buffer)


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):
        self._response_buffer = response_buffer

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


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