"""provide class to do Apache rewrite rules'job inside cubicweb (though functionnalities
are much more limited for the moment)

:organization: Logilab
:copyright: 2007-2008 LOGILAB S.A. (Paris, FRANCE), all rights reserved.
:contact: http://www.logilab.fr/ -- mailto:contact@logilab.fr
"""

__docformat__ = "restructuredtext en"

from re import compile

from cubicweb.web import Redirect
from cubicweb.web.component import SingletonComponent

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(SingletonComponent):
    """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
    id = 'urlrewriter'
    rules = []
        
    def rewrite(self, host, path):
        for cond in self.rules:
            if cond.match(host=host, path=path):
                return cond.process(path)
        return path