"""provide class to do Apache rewrite rules'job inside cubicweb (though functionnalities

are much more limited for the moment)

:organization: Logilab

:copyright: 2007-2010 LOGILAB S.A. (Paris, FRANCE), license is LGPL v2.

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

:license: GNU Lesser General Public License, v2.1 - http://www.gnu.org/licenses

"""

__docformat__ = "restructuredtext en"

from re import compile

from cubicweb.web import Redirect

from cubicweb.web.component import Component

class RewriteCond(object):

    def __init__(self, condition, match='host', rules=(), action='rewrite'):

        self.condition = compile(condition)

        assert match in ('host', 'path'), match

        self.match_part = match

        self.rules = []

        for rule, replace in rules:

            rulergx = compile(rule)

            self.rules.append( (rulergx, replace) )

        assert action in ('rewrite', 'redirect', 'stop'), action

        self.process = getattr(self, 'action_%s' % action)

    def match(self, **kwargs):

        self._match = self.condition.match(kwargs[self.match_part])

        return not self._match is None

    def action_rewrite(self, path):

        for rgx, replace in self.rules:

            if not rgx.match(path) is None:

                matchdict = self._match.groupdict() or None

                if not matchdict is None:

                    replace = replace % matchdict

                return rgx.sub(replace, path)

        return path

    def action_redirect(self, path):

        url = self.action_rewrite(path)

        raise Redirect(url)

    def action_stop(self, path):

        return path

class ApacheURLRewrite(Component):

    """inherit from this class with actual rules to activate apache style rewriting

    rules should have the form :

    [('condition pattern 1', [('rule1 pattern', 'replace expression'),

                              ('rule2 pattern', 'replace expression')],

     ('condition pattern 2', [('rule1 pattern', 'replace expression'),

                              ('rule2 pattern', 'replace expression')]

    ]

    for instance the equivalent of the following apache rules:

        RewriteCond %{HTTP_HOST} ^logilab\.fr

        RewriteRule ^/(.*) http://www.logilab.fr/$1 [L,R=301]

        RewriteCond %{HTTP_HOST} ^www\.logilab\.fr

        RewriteRule ^/(.*) http://localhost:8080/$1 [L,P]

        RewriteCond %{HTTP_HOST} ^(.+)\.logilab\.fr

        RewriteRule ^/(data/.*) http://localhost:8080/$1 [L,P]

        RewriteRule ^/(json.*) http://localhost:8080/$1 [L,P]

        RewriteRule ^/(.*) http://localhost:8080/m_%1/$1 [L,P]

    could be written (considering that no "host rewritting" is necessary):

      class MyAppRules(ApacheURLRewrite):

        rules = [

          RewriteCond('logilab\.fr', match='host',

                      rules=[('/(.*)', r'http://www.logilab.fr/\1')],

                      action='redirect'),

          RewriteCond('(www)\.logilab\.fr', match='host', action='stop'),

          RewriteCond('/(data|json)/', match='path', action='stop'),

          RewriteCond('(?P<cat>.*)\.logilab\.fr', match='host',

                      rules=[('/(.*)', r'/m_%(cat)s/\1')]),

        ]

    """

    __abstract__ = True

    __regid__ = 'urlrewriter'

    rules = []

    def get_rules(self, req):

        return self.rules

    def rewrite(self, host, path, req):

        for cond in self.get_rules(req):

            if cond.match(host=host, path=path):

                return cond.process(path)

        return path