"""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 logilab.common.deprecation import deprecated

from cubicweb import Unauthorized, RegistryException, 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, _cw_unsafe=False, **kwargs):

        """add a new entity of the given type

        Example (in a shell session):

        c = create_entity('Company', name=u'Logilab')

        create_entity('Person', works_for=c, firstname=u'John', lastname=u'Doe')

        """

        if _cw_unsafe:

            execute = self.unsafe_execute

        else:

            execute = self.execute

        rql = 'INSERT %s X' % etype

        relations = []

        restrictions = set()

        cachekey = []

        pending_relations = []

        for attr, value in kwargs.items():

            if isinstance(value, (tuple, list, set, frozenset)):

                if len(value) == 1:

                    value = iter(value).next()

                else:

                    del kwargs[attr]

                    pending_relations.append( (attr, value) )

                    continue

            if hasattr(value, 'eid'): # non final relation

                rvar = attr.upper()

                # XXX safer detection of object relation

                if attr.startswith('reverse_'):

                    relations.append('%s %s X' % (rvar, attr[len('reverse_'):]))

                else:

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

                restriction = '%s eid %%(%s)s' % (rvar, attr)

                if not restriction in restrictions:

                    restrictions.add(restriction)

                cachekey.append(attr)

                kwargs[attr] = value.eid

            else: # attribute

                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))

        created = execute(rql, kwargs, cachekey).get_entity(0, 0)

        for attr, values in pending_relations:

            if attr.startswith('reverse_'):

                restr = 'Y %s X' % attr[len('reverse_'):]

            else:

                restr = 'X %s Y' % attr

            execute('SET %s WHERE X eid %%(x)s, Y eid IN (%s)' % (

                restr, ','.join(str(r.eid) for r in values)),

                         {'x': created.eid}, 'x')

        return created

    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',

             initargs=None, **kwargs):

        """Select object with the given id (`__oid`) then render it.  If the

        object isn't selectable, try to select fallback object if

        `__fallback_oid` is specified.

        If specified `initargs` is expected to be a dictionnary containing

        arguments that should be given to selection (hence to object's __init__

        as well), but not to render(). Other arbitrary keyword arguments will be

        given to selection *and* to render(), and so should be handled by

        object's call or cell_call method..

        """

        if initargs is None:

            initargs = kwargs

        else:

            initargs.update(kwargs)

        try:

            view =  self.vreg[__registry].select(__vid, self, rset=rset, **initargs)

        except RegistryException:

            view =  self.vreg[__registry].select(__fallback_oid, self,

                                                 rset=rset, **initargs)

        return view.render(**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

    @property

    @deprecated('[3.6] use _cw.vreg.config')

    def config(self):

        return self.vreg.config

    @property

    @deprecated('[3.6] use _cw.vreg.schema')

    def schema(self):

        return self.vreg.schema