# copyright 2003-2011 LOGILAB S.A. (Paris, FRANCE), all rights reserved.

# contact http://www.logilab.fr/ -- mailto:contact@logilab.fr

#

# This file is part of CubicWeb.

#

# CubicWeb is free software: you can redistribute it and/or modify it under the

# terms of the GNU Lesser General Public License as published by the Free

# Software Foundation, either version 2.1 of the License, or (at your option)

# any later version.

#

# CubicWeb 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 Lesser General Public License for more

# details.

#

# You should have received a copy of the GNU Lesser General Public License along

# with CubicWeb.  If not, see <http://www.gnu.org/licenses/>.

"""Associate url's path to view identifier / rql queries.

CubicWeb finds all registered URLPathEvaluators, orders them according

to their ``priority`` attribute and calls their ``evaluate_path()``

method. The first that returns something and doesn't raise a

``PathDontMatch`` exception wins.

Here is the default evaluator chain:

1. :class:`cubicweb.web.views.urlpublishing.RawPathEvaluator` handles

   unique url segments that match exactly one of the registered

   controller's *__regid__*. Urls such as */view?*, */edit?*, */json?*

   fall in that category;

2. :class:`cubicweb.web.views.urlpublishing.EidPathEvaluator` handles

   unique url segments that are eids (e.g. */1234*);

3. :class:`cubicweb.web.views.urlpublishing.URLRewriteEvaluator`

   selects all urlrewriter components, sorts them according to their

   priority, call their ``rewrite()`` method, the first one that

   doesn't raise a ``KeyError`` wins. This is where the

   :mod:`cubicweb.web.views.urlrewrite` and

   :class:`cubicweb.web.views.urlrewrite.SimpleReqRewriter` comes into

   play;

4. :class:`cubicweb.web.views.urlpublishing.RestPathEvaluator` handles

   urls based on entity types and attributes : <etype>((/<attribute

   name>])?/<attribute value>)?  This is why ``cwuser/carlos`` works;

5. :class:`cubicweb.web.views.urlpublishing.ActionPathEvaluator`

   handles any of the previous paths with an additional trailing

   "/<action>" segment, <action> being one of the registered actions'

   __regid__.

.. note::

 Actionpath executes a query whose results is lost

 because of redirecting instead of direct traversal.

"""

__docformat__ = "restructuredtext en"

from rql import TypeResolverException

from cubicweb import RegistryException

from cubicweb.web import NotFound, Redirect, component

class PathDontMatch(Exception):

    """exception used by url evaluators to notify they can't evaluate

    a path

    """

class URLPublisherComponent(component.Component):

    """Associate url path to view identifier / rql queries, by

    applying a chain of urlpathevaluator components.

    An evaluator is a URLPathEvaluator subclass with an .evaluate_path

    method taking the request object and the path to publish as

    argument.  It will either return a publishing method identifier

    and an rql query on success or raise a `PathDontMatch` exception

    on failure. URL evaluators are called according to their

    `priority` attribute, with 0 as the greatest priority and greater

    values as lower priority. The first evaluator returning a result

    or raising something else than `PathDontMatch` will stop the

    handlers chain.

    """

    __regid__ = 'urlpublisher'

    vreg = None # XXX necessary until property for deprecation warning is on appobject

    def __init__(self, vreg, default_method='view'):

        super(URLPublisherComponent, self).__init__()

        self.vreg = vreg

        self.default_method = default_method

        evaluators = []

        for evaluatorcls in vreg['components']['urlpathevaluator']:

            # instantiation needed

            evaluator = evaluatorcls(self)

            evaluators.append(evaluator)

        self.evaluators = sorted(evaluators, key=lambda x: x.priority)

    def process(self, req, path):

        """Given a URL (essentially characterized by a path on the

        server, but additional information may be found in the request

        object), return a publishing method identifier

        (e.g. controller) and an optional result set.

        :type req: `cubicweb.web.request.CubicWebRequestBase`

        :param req: the request object

        :type path: str

        :param path: the path of the resource to publish. If empty, None or "/"

                     "view" is used as the default path.

        :rtype: tuple(str, `cubicweb.rset.ResultSet` or None)

        :return: the publishing method identifier and an optional result set

        :raise NotFound: if no handler is able to decode the given path

        """

        parts = [part for part in path.split('/')

                 if part != ''] or (self.default_method,)

        if req.form.get('rql'):

            if parts[0] in self.vreg['controllers']:

                return parts[0], None

            return 'view', None

        for evaluator in self.evaluators:

            try:

                pmid, rset = evaluator.evaluate_path(req, parts[:])

                break

            except PathDontMatch:

                continue

        else:

            raise NotFound(path)

        if pmid is None:

            pmid = self.default_method

        return pmid, rset

class URLPathEvaluator(component.Component):

    __abstract__ = True

    __regid__ = 'urlpathevaluator'

    vreg = None # XXX necessary until property for deprecation warning is on appobject

    def __init__(self, urlpublisher):

        self.urlpublisher = urlpublisher

        self.vreg = urlpublisher.vreg

class RawPathEvaluator(URLPathEvaluator):

    """handle path of the form::

        <publishing_method>?parameters...

    """

    priority = 0

    def evaluate_path(self, req, parts):

        if len(parts) == 1 and parts[0] in self.vreg['controllers']:

            return parts[0], None

        raise PathDontMatch()

class EidPathEvaluator(URLPathEvaluator):

    """handle path with the form::

        <eid>

    """

    priority = 1

    def evaluate_path(self, req, parts):

        if len(parts) != 1:

            raise PathDontMatch()

        try:

            rset = req.execute('Any X WHERE X eid %(x)s', {'x': int(parts[0])})

        except ValueError:

            raise PathDontMatch()

        if rset.rowcount == 0:

            raise NotFound()

        return None, rset

class RestPathEvaluator(URLPathEvaluator):

    """handle path with the form::

        <etype>[[/<attribute name>]/<attribute value>]*

    """

    priority = 3

    def evaluate_path(self, req, parts):

        if not (0 < len(parts) < 4):

            raise PathDontMatch()

        try:

            etype = self.vreg.case_insensitive_etypes[parts.pop(0).lower()]

        except KeyError:

            raise PathDontMatch()

        cls = self.vreg['etypes'].etype_class(etype)

        if parts:

            if len(parts) == 2:

                attrname = parts.pop(0).lower()

                try:

                    cls.e_schema.subjrels[attrname]

                except KeyError:

                    raise PathDontMatch()

            else:

                attrname = cls.cw_rest_attr_info()[0]

            value = req.url_unquote(parts.pop(0))

            return self.handle_etype_attr(req, cls, attrname, value)

        return self.handle_etype(req, cls)

    def set_vid_for_rset(self, req, cls, rset):# cls is there to ease overriding

        if rset.rowcount == 0:

            raise NotFound()

        # we've to set a default vid here, since vid_from_rset may try to use a

        # table view if fetch_rql include some non final relation

        if rset.rowcount == 1:

            req.form.setdefault('vid', 'primary')

        else: # rset.rowcount >= 1

            if len(rset.column_types(0)) > 1:

                req.form.setdefault('vid', 'list')

            else:

                req.form.setdefault('vid', 'sameetypelist')

    def handle_etype(self, req, cls):

        rset = req.execute(cls.fetch_rql(req.user))

        self.set_vid_for_rset(req, cls, rset)

        return None, rset

    def handle_etype_attr(self, req, cls, attrname, value):

        st = cls.fetch_rqlst(req.user, ordermethod=None)

        st.add_constant_restriction(st.get_variable('X'), attrname,

                                    'x', 'Substitute')

        if attrname == 'eid':

            try:

                rset = req.execute(st.as_string(), {'x': int(value)})

            except (ValueError, TypeResolverException):

                # conflicting eid/type

                raise PathDontMatch()

        else:

            rset = req.execute(st.as_string(), {'x': value})

        self.set_vid_for_rset(req, cls, rset)

        return None, rset

class URLRewriteEvaluator(URLPathEvaluator):

    """tries to find a rewrite rule to apply

    URL rewrite rule definitions are stored in URLRewriter objects

    """

    priority = 2

    def evaluate_path(self, req, parts):

        # uri <=> req._twreq.path or req._twreq.uri

        uri = req.url_unquote('/' + '/'.join(parts))

        evaluators = sorted(self.vreg['urlrewriting'].all_objects(),

                            key=lambda x: x.priority, reverse=True)

        for rewritercls in evaluators:

            rewriter = rewritercls(req)

            try:

                # XXX we might want to chain url rewrites

                return rewriter.rewrite(req, uri)

            except KeyError:

                continue

        raise PathDontMatch()

class ActionPathEvaluator(URLPathEvaluator):

    """handle path with the form::

    <any evaluator path>/<action>

    """

    priority = 4

    def evaluate_path(self, req, parts):

        if len(parts) < 2:

            raise PathDontMatch()

        # remove last part and see if this is something like an actions

        # if so, call

        # XXX bad smell: refactor to simpler code

        try:

            actionsreg = self.vreg['actions']

            requested = parts.pop(-1)

            actions = actionsreg[requested]

        except RegistryException:

            raise PathDontMatch()

        for evaluator in self.urlpublisher.evaluators:

            if evaluator is self or evaluator.priority == 0:

                continue

            try:

                pmid, rset = evaluator.evaluate_path(req, parts[:])

            except PathDontMatch:

                continue

            else:

                try:

                    action = actionsreg._select_best(actions, req, rset=rset)

                    if action is not None:

                        raise Redirect(action.url())

                except RegistryException:

                    pass # continue searching

        raise PathDontMatch()