"""Base class for request/session

"""

__docformat__ = "restructuredtext en"

from warnings import warn

from urlparse import urlsplit, urlunsplit

from urllib import quote as urlquote, unquote as urlunquote

from datetime import time, datetime, timedelta

from cgi import parse_qs, parse_qsl

from logilab.common.decorators import cached

from logilab.common.deprecation import deprecated

from logilab.common.date import ustrftime, strptime, todate, todatetime

from cubicweb import Unauthorized, RegistryException, typed_eid

from cubicweb.rset import ResultSet

ONESECOND = timedelta(0, 1, 0)

CACHE_REGISTRY = {}

def _check_cw_unsafe(kwargs):

    if kwargs.pop('_cw_unsafe', False):

        warn('[3.7] _cw_unsafe argument is deprecated, now unsafe by '

             'default, control it using cw_[read|write]_security.',

             DeprecationWarning, stacklevel=3)

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:

    :attribute vreg: the instance's registry

    :attribute vreg.schema: the instance's schema

    :attribute 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

        rset.req = self

        return 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,)])

        rset.req = self

        return 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)

        """

        rset = ResultSet([], 'Any X WHERE X eid -1')

        rset.req = self

        return rset

    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

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

        """add a new entity of the given type

        Example (in a shell session):

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

        >>> create_entity('Person', firstname=u'John', lastname=u'Doe',

        ...               works_for=c)

        """

        _check_cw_unsafe(kwargs)

        cls = self.vreg['etypes'].etype_class(etype)

        return cls.cw_instantiate(self.execute, **kwargs)

    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):

        """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.iteritems():

            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')

    def url_parse_qsl(self, querystring):

        """return a list of (key, val) found in the url quoted query string"""

        if isinstance(querystring, unicode):

            querystring = querystring.encode(self.encoding)

        for key, val in parse_qsl(querystring):

            try:

                yield unicode(key, self.encoding), unicode(val, self.encoding)

            except UnicodeDecodeError: # might occurs on manually typed URLs

                yield unicode(key, 'iso-8859-1'), unicode(val, 'iso-8859-1')

    def rebuild_url(self, url, **newparams):

        """return the given url with newparams inserted. If any new params

        is already specified in the url, it's overriden by the new value

        newparams may only be mono-valued.

        """

        if isinstance(url, unicode):

            url = url.encode(self.encoding)

        schema, netloc, path, query, fragment = urlsplit(url)

        query = parse_qs(query)

        # sort for testing predictability

        for key, val in sorted(newparams.iteritems()):

            query[key] = (self.url_quote(val),)

        query = '&'.join(u'%s=%s' % (param, value)

                         for param, values in query.items()

                         for value in values)

        return urlunsplit((schema, netloc, path, query, fragment))

    # 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.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 is not None:

            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(self._('can\'t parse %(value)r (expected %(format)s)')

                                 % {'value': value, 'format': 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(self._('can\'t parse %(value)r (expected %(format)s)')

                             % {'value': value, 'format': 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 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