import itertools

from contextlib import contextmanager
from warnings import warn
from cgi import FieldStorage

import rql

from cubicweb.web.request import CubicWebRequestBase
from cubicweb import repoapi

import cubicweb
import cubicweb.web
from cubicweb.server import session as cwsession

from pyramid import httpexceptions

from pyramid_cubicweb import tools

import logging

log = logging.getLogger(__name__)


class Connection(cwsession.Connection):
    """ A specialised Connection that access the session data through a
    property.

    This behavior makes sure the actual session data is not loaded until
    actually accessed.
    """
    def __init__(self, session, *args, **kw):
        super(Connection, self).__init__(session, *args, **kw)
        self._session = session

    def _get_session_data(self):
        return self._session.data

    def _set_session_data(self, data):
        pass

    _session_data = property(_get_session_data, _set_session_data)


class Session(cwsession.Session):
    """ A Session that access the session data through a property.

    Along with :class:`Connection`, it avoid any load of the pyramid session
    data until it is actually accessed.
    """
    def __init__(self, pyramid_request, user, repo):
        super(Session, self).__init__(user, repo)
        self._pyramid_request = pyramid_request

    def get_data(self):
        if not getattr(self, '_protect_data_access', False):
            self._data_accessed = True
            return self._pyramid_request.session

    def set_data(self, data):
        if getattr(self, '_data_accessed', False):
            self._pyramid_request.session.clear()
            self._pyramid_request.session.update(data)

    data = property(get_data, set_data)

    def new_cnx(self):
        self._protect_data_access = True
        try:
            return Connection(self)
        finally:
            self._protect_data_access = False


def cw_headers(request):
    return itertools.chain(
        *[[(k, item) for item in v]
          for k, v in request.cw_request.headers_out.getAllRawHeaders()])


@contextmanager
def cw_to_pyramid(request):
    """ Context manager to wrap a call to the cubicweb API.

    All CW exceptions will be transformed into their pyramid equivalent.
    When needed, some CW reponse bits may be converted too (mainly headers)"""
    try:
        yield
    except cubicweb.web.Redirect as ex:
        assert 300 <= ex.status < 400
        raise httpexceptions.status_map[ex.status](
            ex.location, headers=cw_headers(request))
    except cubicweb.web.StatusResponse as ex:
        warn('[3.16] StatusResponse is deprecated use req.status_out',
             DeprecationWarning, stacklevel=2)
        request.body = ex.content
        request.status_int = ex.status
    except cubicweb.web.Unauthorized as ex:
        raise httpexceptions.HTTPForbidden(
            request.cw_request._(
                'You\'re not authorized to access this page. '
                'If you think you should, please contact the site '
                'administrator.'),
            headers=cw_headers(request))
    except cubicweb.web.Forbidden:
        raise httpexceptions.HTTPForbidden(
            request.cw_request._(
                'This action is forbidden. '
                'If you think it should be allowed, please contact the site '
                'administrator.'),
            headers=cw_headers(request))
    except (rql.BadRQLQuery, cubicweb.web.RequestError) as ex:
        raise


class CubicWebPyramidRequest(CubicWebRequestBase):
    """ A CubicWeb request that only wraps a pyramid request.

    :param request: A pyramid request

    """
    def __init__(self, request):
        self._request = request

        self.path = request.upath_info

        vreg = request.registry['cubicweb.registry']
        https = request.scheme == 'https'

        post = request.params.mixed()
        headers_in = request.headers

        super(CubicWebPyramidRequest, self).__init__(vreg, https, post,
                                                     headers=headers_in)

        self.content = request.body_file_seekable

    def setup_params(self, params):
        self.form = {}
        for param, val in params.iteritems():
            if param in self.no_script_form_params and val:
                val = self.no_script_form_param(param, val)
            if isinstance(val, FieldStorage) and val.file:
                val = (val.filename, val.file)
            if param == '_cwmsgid':
                self.set_message_id(val)
            elif param == '__message':
                warn('[3.13] __message in request parameter is deprecated '
                     '(may only be given to .build_url). Seeing this message '
                     'usualy means your application hold some <form> where '
                     'you should replace use of __message hidden input by '
                     'form.set_message, so new _cwmsgid mechanism is properly '
                     'used',
                     DeprecationWarning)
                self.set_message(val)
            else:
                self.form[param] = val

    def is_secure(self):
        return self._request.scheme == 'https'

    def relative_path(self, includeparams=True):
        path = self._request.path[1:]
        if includeparams and self._request.query_string:
            return '%s?%s' % (path, self._request.query_string)
        return path

    def instance_uri(self):
        return self._request.application_url

    def get_full_path(self):
        path = self._request.path
        if self._request.query_string:
            return '%s?%s' % (path, self._request.query_string)
        return path

    def http_method(self):
        return self._request.method

    def _set_status_out(self, value):
        self._request.response.status_int = value

    def _get_status_out(self):
        return self._request.response.status_int

    status_out = property(_get_status_out, _set_status_out)

    @property
    def message(self):
        """Returns a '<br>' joined list of the cubicweb current message and the
        default pyramid flash queue messages.
        """
        return u'\n<br>\n'.join(
            self._request.session.pop_flash()
            + self._request.session.pop_flash('cubicweb'))

    def set_message(self, msg):
        self.reset_message()
        self._request.session.flash(msg, 'cubicweb')

    def set_message_id(self, msgid):
        self.reset_message()
        self.set_message(
            self._request.session.pop(msgid, u''))

    def reset_message(self):
        self._request.session.pop_flash('cubicweb')


def render_view(request, vid, **kwargs):
    """ Helper function to render a CubicWeb view.

    :param request: A pyramid request
    :param vid: A CubicWeb view id
    :param **kwargs: Keyword arguments to select and instanciate the view
    :returns: The rendered view content
    """
    vreg = request.registry['cubicweb.registry']
    # XXX The select() function could, know how to handle a pyramid
    # request, and feed it directly to the views that supports it.
    # On the other hand, we could refine the View concept and decide it works
    # with a cnx, and never with a WebRequest

    with cw_to_pyramid(request):
        view = vreg['views'].select(vid, request.cw_request, **kwargs)
        view.set_stream()
        view.render()
        return view._stream.getvalue()


def _cw_cnx(request):
    """ Obtains a cw session from a pyramid request

    The connection will be commited or rolled-back in a request finish
    callback (this is temporary, we should make use of the transaction manager
    in a later version).

    Not meant for direct use, use ``request.cw_cnx`` instead.

    :param request: A pyramid request
    :returns type: :class:`cubicweb.server.session.Connection`
    """
    cnx = repoapi.ClientConnection(request.cw_session)

    def cleanup(request):
        if (request.exception is not None and not isinstance(
            request.exception, (
                httpexceptions.HTTPSuccessful,
                httpexceptions.HTTPRedirection))):
            cnx.rollback()
        elif cnx._cnx.commit_state == 'uncommitable':
            cnx.rollback()
        else:
            cnx.commit()
        cnx.__exit__(None, None, None)

    request.add_finished_callback(cleanup)
    cnx.__enter__()
    return cnx


def repo_connect(request, repo, eid):
    """A lightweight version of
    :meth:`cubicweb.server.repository.Repository.connect` that does not keep
    track of opened sessions, removing the need of closing them"""
    user = tools.cached_build_user(repo, eid)
    session = Session(request, user, repo)
    tools.cnx_attach_entity(session, user)
    # Calling the hooks should be done only once, disabling it completely for
    # now
    #with session.new_cnx() as cnx:
        #repo.hm.call_hooks('session_open', cnx)
        #cnx.commit()
    # repo._sessions[session.sessionid] = session
    return session


def _cw_session(request):
    """Obtains a cw session from a pyramid request

    :param request: A pyramid request
    :returns type: :class:`cubicweb.server.session.Session`

    Not meant for direct use, use ``request.cw_session`` instead.
    """
    repo = request.registry['cubicweb.repository']

    if not request.authenticated_userid:
        session = repo_connect(
            request, repo, eid=request.registry['cubicweb.anonymous_eid'])
    else:
        session = request._cw_cached_session

    return session


def _cw_request(request):
    """ Obtains a CubicWeb request wrapper for the pyramid request.

    :param request: A pyramid request
    :return: A CubicWeb request
    :returns type: :class:`CubicWebPyramidRequest`

    Not meant for direct use, use ``request.cw_request`` instead.

    """
    req = CubicWebPyramidRequest(request)
    req.set_cnx(request.cw_cnx)
    return req


def get_principals(login, request):
    """ Returns the group names of the authenticated user.

    This function is meant to be used as an authentication policy callback.

    It also pre-open the cubicweb session and put it in
    request._cw_cached_session for later usage by :func:`_cw_session`.

    .. note::

        It the default authentication policy is not used, make sure this
        function gets called by the active authentication policy.

    :param login: A cubicweb user eid
    :param request: A pyramid request
    :returns: A list of group names
    """
    repo = request.registry['cubicweb.repository']

    try:
        session = repo_connect(request, repo, eid=login)
        request._cw_cached_session = session
    except:
        log.exception("Failed")
        raise

    return session.user.groups


def includeme(config):
    """ Enables the core features of Pyramid CubicWeb.

    Automatically called by the 'pyramid' command, or via
    ``config.include('pyramid_cubicweb.code')``. In the later case,
    the following registry entries must be defined first:

    'cubicweb.config'
        A cubicweb 'config' instance.

    'cubicweb.repository'
        The correponding cubicweb repository.

    'cubicweb.registry'
        The vreg.
    """
    repo = config.registry['cubicweb.repository']

    with repo.internal_cnx() as cnx:
        login = config.registry['cubicweb.config'].anonymous_user()[0]
        config.registry['cubicweb.anonymous_eid'] = cnx.find(
            'CWUser', login=login).one().eid

    config.add_request_method(
        _cw_session, name='cw_session', property=True, reify=True)
    config.add_request_method(
        _cw_cnx, name='cw_cnx', property=True, reify=True)
    config.add_request_method(
        _cw_request, name='cw_request', property=True, reify=True)

    cwcfg = config.registry['cubicweb.config']
    for cube in cwcfg.cubes():
        pkgname = 'cubes.' + cube
        mod = __import__(pkgname)
        mod = getattr(mod, cube)
        if hasattr(mod, 'includeme'):
            config.include('cubes.' + cube)