"""Base class for request/session

:organization: Logilab

:copyright: 2001-2009 LOGILAB S.A. (Paris, FRANCE), license is LGPL v2.

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

:license: Library General Public License version 2 - http://www.gnu.org/licenses

"""

__docformat__ = "restructuredtext en"

from urllib import quote as urlquote, unquote as urlunquote

from datetime import time, datetime, timedelta

from logilab.common.decorators import cached

from cubicweb import Unauthorized, typed_eid

from cubicweb.rset import ResultSet

from cubicweb.utils import ustrftime, strptime, todate, todatetime

ONESECOND = timedelta(0, 1, 0)

CACHE_REGISTRY = {}

class Cache(dict):

    def __init__(self):

        super(Cache, self).__init__()

        _now = datetime.now()

        self.cache_creation_date = _now

        self.latest_cache_lookup = _now

class RequestSessionBase(object):

    """base class containing stuff shared by server session and web request

    request/session is the main resources accessor, mainly through it's vreg

    attribute:

    :vreg:

      the instance's registry

    :vreg.schema:

      the instance's schema

    :vreg.config:

      the instance's configuration

    """

    def __init__(self, vreg):

        self.vreg = vreg

        try:

            encoding = vreg.property_value('ui.encoding')

        except: # no vreg or property not registered

            encoding = 'utf-8'

        self.encoding = encoding

        # cache result of execution for (rql expr / eids),

        # should be emptied on commit/rollback of the server session / web

        # connection

        self.local_perm_cache = {}

        self._ = unicode

    def property_value(self, key):

        """return value of the property with the given key, giving priority to

        user specific value if any, else using site value

        """

        if self.user:

            return self.user.property_value(key)

        return self.vreg.property_value(key)

    def etype_rset(self, etype, size=1):

        """return a fake result set for a particular entity type"""

        rset = ResultSet([('A',)]*size, '%s X' % etype,

                         description=[(etype,)]*size)

        def get_entity(row, col=0, etype=etype, req=self, rset=rset):

            return req.vreg.etype_class(etype)(req, rset, row, col)

        rset.get_entity = get_entity

        return self.decorate_rset(rset)

    def eid_rset(self, eid, etype=None):

        """return a result set for the given eid without doing actual query

        (we have the eid, we can suppose it exists and user has access to the

        entity)

        """

        eid = typed_eid(eid)

        if etype is None:

            etype = self.describe(eid)[0]

        rset = ResultSet([(eid,)], 'Any X WHERE X eid %(x)s', {'x': eid},

                         [(etype,)])

        return self.decorate_rset(rset)

    def empty_rset(self):

        """return a result set for the given eid without doing actual query

        (we have the eid, we can suppose it exists and user has access to the

        entity)

        """

        return self.decorate_rset(ResultSet([], 'Any X WHERE X eid -1'))

    def entity_from_eid(self, eid, etype=None):

        """return an entity instance for the given eid. No query is done"""

        try:

            return self.entity_cache(eid)

        except KeyError:

            rset = self.eid_rset(eid, etype)

            entity = rset.get_entity(0, 0)

            self.set_entity_cache(entity)

            return entity

    def entity_cache(self, eid):

        raise KeyError

    def set_entity_cache(self, entity):

        pass

    # XXX move to CWEntityManager or even better as factory method (unclear

    # where yet...)

    def create_entity(self, etype, *args, **kwargs):

        rql = 'INSERT %s X' % etype

        relations = []

        restrictions = []

        cachekey = []

        for rtype, rvar in args:

            relations.append('X %s %s' % (rtype, rvar))

            restrictions.append('%s eid %%(%s)s' % (rvar, rvar))

            cachekey.append(rvar)

        for attr in kwargs:

            if attr in cachekey:

                continue

            relations.append('X %s %%(%s)s' % (attr, attr))

        if relations:

            rql = '%s: %s' % (rql, ', '.join(relations))

        if restrictions:

            rql = '%s WHERE %s' % (rql, ', '.join(restrictions))

        return self.execute(rql, kwargs, cachekey).get_entity(0, 0)

    def ensure_ro_rql(self, rql):

        """raise an exception if the given rql is not a select query"""

        first = rql.split(' ', 1)[0].lower()

        if first in ('insert', 'set', 'delete'):

            raise Unauthorized(self._('only select queries are authorized'))

    def get_cache(self, cachename):

        """

        NOTE: cachename should be dotted names as in :

        - cubicweb.mycache

        - cubes.blog.mycache

        - etc.

        """

        if cachename in CACHE_REGISTRY:

            cache = CACHE_REGISTRY[cachename]

        else:

            cache = CACHE_REGISTRY[cachename] = Cache()

        _now = datetime.now()

        if _now > cache.latest_cache_lookup + ONESECOND:

            ecache = self.execute(

                'Any C,T WHERE C is CWCache, C name %(name)s, C timestamp T',

                {'name':cachename}).get_entity(0,0)

            cache.latest_cache_lookup = _now

            if not ecache.valid(cache.cache_creation_date):

                cache.clear()

                cache.cache_creation_date = _now

        return cache

    # url generation methods ##################################################

    def build_url(self, *args, **kwargs):

        """return an absolute URL using params dictionary key/values as URL

        parameters. Values are automatically URL quoted, and the

        publishing method to use may be specified or will be guessed.

        """

        # use *args since we don't want first argument to be "anonymous" to

        # avoid potential clash with kwargs

        if args:

            assert len(args) == 1, 'only 0 or 1 non-named-argument expected'

            method = args[0]

        else:

            method = None

        # XXX I (adim) think that if method is passed explicitly, we should

        #     not try to process it and directly call req.build_url()

        if method is None:

            if self.from_controller() == 'view' and not '_restpath' in kwargs:

                method = self.relative_path(includeparams=False) or 'view'

            else:

                method = 'view'

        base_url = kwargs.pop('base_url', None)

        if base_url is None:

            base_url = self.base_url()

        if '_restpath' in kwargs:

            assert method == 'view', method

            path = kwargs.pop('_restpath')

        else:

            path = method

        if not kwargs:

            return u'%s%s' % (base_url, path)

        return u'%s%s?%s' % (base_url, path, self.build_url_params(**kwargs))

    def build_url_params(self, **kwargs):

        """return encoded params to incorporate them in an URL"""

        args = []

        for param, values in kwargs.items():

            if not isinstance(values, (list, tuple)):

                values = (values,)

            for value in values:

                args.append(u'%s=%s' % (param, self.url_quote(value)))

        return '&'.join(args)

    def url_quote(self, value, safe=''):

        """urllib.quote is not unicode safe, use this method to do the

        necessary encoding / decoding. Also it's designed to quote each

        part of a url path and so the '/' character will be encoded as well.

        """

        if isinstance(value, unicode):

            quoted = urlquote(value.encode(self.encoding), safe=safe)

            return unicode(quoted, self.encoding)

        return urlquote(str(value), safe=safe)

    def url_unquote(self, quoted):

        """returns a unicode unquoted string

        decoding is based on `self.encoding` which is the encoding

        used in `url_quote`

        """

        if isinstance(quoted, unicode):

            quoted = quoted.encode(self.encoding)

        try:

            return unicode(urlunquote(quoted), self.encoding)

        except UnicodeDecodeError: # might occurs on manually typed URLs

            return unicode(urlunquote(quoted), 'iso-8859-1')

    # bound user related methods ###############################################

    @cached

    def user_data(self):

        """returns a dictionnary with this user's information"""

        userinfo = {}

        if self.is_internal_session:

            userinfo['login'] = "cubicweb"

            userinfo['name'] = "cubicweb"

            userinfo['email'] = ""

            return userinfo

        user = self.actual_session().user

        userinfo['login'] = user.login

        userinfo['name'] = user.name()

        userinfo['email'] = user.get_email()

        return userinfo

    def is_internal_session(self):

        """overrided on the server-side"""

        return False

    # formating methods #######################################################

    def view(self, __vid, rset=None, __fallback_oid=None, __registry='views',

             **kwargs):

        """shortcut to self.vreg.view method avoiding to pass the request"""

        return self.vreg[__registry].render(__vid, self, __fallback_oid,

                                            rset=rset, **kwargs)

    def format_date(self, date, date_format=None, time=False):

        """return a string for a date time according to instance's

        configuration

        """

        if date:

            if date_format is None:

                if time:

                    date_format = self.property_value('ui.datetime-format')

                else:

                    date_format = self.property_value('ui.date-format')

            return ustrftime(date, date_format)

        return u''

    def format_time(self, time):

        """return a string for a time according to instance's

        configuration

        """

        if time:

            return ustrftime(time, self.property_value('ui.time-format'))

        return u''

    def format_float(self, num):

        """return a string for floating point number according to instance's

        configuration

        """

        if num:

            return self.property_value('ui.float-format') % num

        return u''

    def parse_datetime(self, value, etype='Datetime'):

        """get a datetime or time from a string (according to etype)

        Datetime formatted as Date are accepted

        """

        assert etype in ('Datetime', 'Date', 'Time'), etype

        # XXX raise proper validation error

        if etype == 'Datetime':

            format = self.property_value('ui.datetime-format')

            try:

                return todatetime(strptime(value, format))

            except ValueError:

                pass

        elif etype == 'Time':

            format = self.property_value('ui.time-format')

            try:

                # (adim) I can't find a way to parse a Time with a custom format

                date = strptime(value, format) # this returns a DateTime

                return time(date.hour, date.minute, date.second)

            except ValueError:

                raise ValueError('can\'t parse %r (expected %s)' % (value, format))

        try:

            format = self.property_value('ui.date-format')

            dt = strptime(value, format)

            if etype == 'Datetime':

                return todatetime(dt)

            return todate(dt)

        except ValueError:

            raise ValueError('can\'t parse %r (expected %s)' % (value, format))

    # abstract methods to override according to the web front-end #############

    def base_url(self):

        """return the root url of the instance"""

        raise NotImplementedError

    def decorate_rset(self, rset):

        """add vreg/req (at least) attributes to the given result set """

        raise NotImplementedError

    def describe(self, eid):

        """return a tuple (type, sourceuri, extid) for the entity with id <eid>"""

        raise NotImplementedError