"""Rules based url rewriter component, to get configurable RESTful urls

:organization: Logilab

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

"""

import re

from cubicweb.appobject import AppObject

def rgx(pattern, flags=0):

    """this is just a convenient shortcout to add the $ sign"""

    return re.compile(pattern+'$', flags)

class metarewriter(type):

    """auto-extend rules dictionnary"""

    def __new__(mcs, name, bases, classdict):

        # collect baseclass' rules

        rules = []

        ignore_baseclass_rules = classdict.get('ignore_baseclass_rules', False)

        if not ignore_baseclass_rules:

            for base in bases:

                rules[0:0] = getattr(base, 'rules', [])

        rules[0:0] = classdict.get('rules', [])

        inputs = set()

        for data in rules[:]:

            try:

                input, output, groups = data

            except ValueError:

                input, output = data

            if input in inputs:

                rules.remove( (input, output) )

            else:

                inputs.add(input)

        classdict['rules'] = rules

        return super(metarewriter, mcs).__new__(mcs, name, bases, classdict)

class URLRewriter(AppObject):

    """base class for URL rewriters

    url rewriters should have a `rules` dict that maps an input URI

    to something that should be used for rewriting.

    The actual logic that defines how the rules dict is used is implemented

    in the `rewrite` method

    A `priority` attribute might be used to indicate which rewriter

    should be tried first. The higher the priority is, the earlier the

    rewriter will be tried

    """

    __metaclass__ = metarewriter

    __registry__ = 'urlrewriting'

    __abstract__ = True

    id = 'urlrewriting'

    priority = 1

    def rewrite(self, req, uri):

        raise NotImplementedError

class SimpleReqRewriter(URLRewriter):

    """The SimpleReqRewriters uses a `rules` dict that maps

    input URI (regexp or plain string) to a dictionary to update the

    request's form

    If the input uri is a regexp, group substitution is allowed

    """

    id = 'simple'

    rules = [

        ('/schema',  dict(vid='schema')),

        ('/index', dict(vid='index')),

        ('/myprefs', dict(vid='propertiesform')),

        ('/siteconfig', dict(vid='systempropertiesform')),

        ('/manage', dict(vid='manage')),

        ('/notfound', dict(vid='404')),

        ('/error', dict(vid='error')),

        (rgx('/schema/([^/]+?)/?'),  dict(vid='eschema', rql=r'Any X WHERE X is CWEType, X name "\1"')),

        (rgx('/add/([^/]+?)/?'), dict(vid='creation', etype=r'\1')),

        (rgx('/doc/images/(.+?)/?'), dict(vid='wdocimages', fid=r'\1')),

        (rgx('/doc/?'), dict(vid='wdoc', fid=r'main')),

        (rgx('/doc/(.+?)/?'), dict(vid='wdoc', fid=r'\1')),

        (rgx('/changelog/?'), dict(vid='changelog')),

        ]

    def rewrite(self, req, uri):

        """for each `input`, `output `in rules, if `uri` matches `input`,

        req's form is updated with `output`

        """

        for data in self.rules:

            try:

                inputurl, infos, required_groups = data

            except ValueError:

                inputurl, infos = data

                required_groups = None

            if required_groups and not req.user.matching_groups(required_groups):

                continue

            if isinstance(inputurl, basestring):

                if inputurl == uri:

                    req.form.update(infos)

                    break

            elif inputurl.match(uri): # it's a regexp

                # XXX what about i18n ? (vtitle for instance)

                for param, value in infos.items():

                    if isinstance(value, basestring):

                        req.form[param] = inputurl.sub(value, uri)

                    else:

                        req.form[param] = value

                break

        else:

            self.debug("no simple rewrite rule found for %s", uri)

            raise KeyError(uri)

        return None, None

def build_rset(rql, rgxgroups=None, cachekey=None, setuser=False,

               vid=None, vtitle=None, form={}, **kwargs):

    def do_build_rset(inputurl, uri, req, schema):

        if rgxgroups:

            match = inputurl.match(uri)

            for arg, group in rgxgroups:

                kwargs[arg] = match.group(group)

        req.form.update(form)

        if setuser:

            kwargs['u'] = req.user.eid

        if vid:

            req.form['vid'] = vid

        if vtitle:

            req.form['vtitle'] = req._(vtitle) % kwargs

        return None, req.execute(rql, kwargs, cachekey)

    return do_build_rset

def update_form(**kwargs):

    def do_build_rset(inputurl, uri, req, schema):

        match = inputurl.match(uri)

        kwargs.update(match.groupdict())

        req.form.update(kwargs)

        return None, None

    return do_build_rset

def rgx_action(rql=None, args=None, cachekey=None, argsgroups=(), setuser=False,

               form=None, formgroups=(), transforms={}, controller=None):

    def do_build_rset(inputurl, uri, req, schema):

        if rql:

            kwargs = args and args.copy() or {}

            if argsgroups:

                match = inputurl.match(uri)

                for key in argsgroups:

                    value = match.group(key)

                    try:

                        kwargs[key] = transforms[key](value)

                    except KeyError:

                        kwargs[key] = value

            if setuser:

                kwargs['u'] = req.user.eid

            rset = req.execute(rql, kwargs, cachekey)

        else:

            rset = None

        form2 = form and form.copy() or {}

        if formgroups:

            match = inputurl.match(uri)

            for key in formgroups:

                form2[key] = match.group(key)

        if form2:

            req.form.update(form2)

        return controller, rset

    return do_build_rset

class SchemaBasedRewriter(URLRewriter):

    """Here, the rules dict maps regexps or plain strings to

    callbacks that will be called with (input, uri, req, schema)

    """

    id = 'schemabased'

    rules = [

        # rgxp : callback

        (rgx('/search/(.+)'), build_rset(rql=r'Any X WHERE X has_text %(text)s',

                                         rgxgroups=[('text', 1)])),

        ]

    def rewrite(self, req, uri):

        # XXX this could be refacted with SimpleReqRewriter

        for data in self.rules:

            try:

                inputurl, callback, required_groups = data

            except ValueError:

                inputurl, callback = data

                required_groups = None

            if required_groups and not req.user.matching_groups(required_groups):

                continue

            if isinstance(inputurl, basestring):

                if inputurl == uri:

                    return callback(inputurl, uri, req, self.schema)

            elif inputurl.match(uri): # it's a regexp

                return callback(inputurl, uri, req, self.schema)

        else:

            self.debug("no schemabased rewrite rule found for %s", uri)

            raise KeyError(uri)