"""Base class for dynamically loaded objects manipulated in the web interface

:organization: Logilab

:copyright: 2001-2009 LOGILAB S.A. (Paris, FRANCE), all rights reserved.

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

"""

__docformat__ = "restructuredtext en"

from datetime import datetime, timedelta

from simplejson import dumps

from logilab.common.decorators import classproperty

from logilab.common.deprecation import obsolete

from rql.nodes import VariableRef, SubQuery

from rql.stmts import Union, Select

from cubicweb import Unauthorized, NoSelectableObject

from cubicweb.vregistry import VObject, AndSelector

from cubicweb.selectors import yes

from cubicweb.utils import UStringIO, ustrftime

ONESECOND = timedelta(0, 1, 0)

class Cache(dict):    

    def __init__(self):

        super(Cache, self).__init__()

        self.cache_creation_date = None

        self.latest_cache_lookup = datetime.now()

CACHE_REGISTRY = {}

class AppRsetObject(VObject):

    """This is the base class for CubicWeb application objects

    which are selected according to a request and result set.

    Classes are kept in the vregistry and instantiation is done at selection

    time.

    At registration time, the following attributes are set on the class:

    :vreg:

      the application's registry

    :schema:

      the application's schema

    :config:

      the application's configuration

    At instantiation time, the following attributes are set on the instance:

    :req:

      current request

    :rset:

      result set on which the object is applied

    """

    __select__ = yes()

    @classmethod

    def registered(cls, vreg):

        super(AppRsetObject, cls).registered(vreg)

        cls.vreg = vreg

        cls.schema = vreg.schema

        cls.config = vreg.config

        cls.register_properties()

        return cls

    @classmethod

    def vreg_initialization_completed(cls):

        pass

    @classmethod

    def selected(cls, *args, **kwargs):

        """by default web app objects are usually instantiated on

        selection according to a request, a result set, and optional

        row and col

        """

        assert len(args) <= 2

        return cls(*args, **kwargs)

    # Eproperties definition:

    # key: id of the property (the actual EProperty key is build using

    #      <registry name>.<obj id>.<property id>

    # value: tuple (property type, vocabfunc, default value, property description)

    #        possible types are those used by `logilab.common.configuration`

    #

    # notice that when it exists multiple objects with the same id (adaptation,

    # overriding) only the first encountered definition is considered, so those

    # objects can't try to have different default values for instance.

    property_defs = {}

    @classmethod

    def register_properties(cls):

        for propid, pdef in cls.property_defs.items():

            pdef = pdef.copy() # may be shared

            pdef['default'] = getattr(cls, propid, pdef['default'])

            pdef['sitewide'] = getattr(cls, 'site_wide', pdef.get('sitewide'))

            cls.vreg.register_property(cls.propkey(propid), **pdef)

    @classmethod

    def propkey(cls, propid):

        return '%s.%s.%s' % (cls.__registry__, cls.id, propid)

    @classproperty

    @obsolete('use __select__ and & or | operators')

    def __selectors__(cls):

        selector = cls.__select__

        if isinstance(selector, AndSelector):

            return tuple(selector.selectors)

        if not isinstance(selector, tuple):

            selector = (selector,)

        return selector

    def __init__(self, req=None, rset=None, row=None, col=None, **extra):

        super(AppRsetObject, self).__init__()

        self.req = req

        self.rset = rset

        self.row = row

        self.col = col

        self.extra_kwargs = extra

    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()

            CACHE_REGISTRY[cachename] = cache

        _now = datetime.now()

        if _now > cache.latest_cache_lookup + ONESECOND:

            ecache = self.req.execute('Any C,T WHERE C is ECache, 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

    def propval(self, propid):

        assert self.req

        return self.req.property_value(self.propkey(propid))

    def limited_rql(self):

        """return a printable rql for the result set associated to the object,

        with limit/offset correctly set according to maximum page size and

        currently displayed page when necessary

        """

        # try to get page boundaries from the navigation component

        # XXX we should probably not have a ref to this component here (eg in

        #     cubicweb.common)

        nav = self.vreg.select_component('navigation', self.req, self.rset)

        if nav:

            start, stop = nav.page_boundaries()

            rql = self._limit_offset_rql(stop - start, start)

        # result set may have be limited manually in which case navigation won't

        # apply

        elif self.rset.limited:

            rql = self._limit_offset_rql(*self.rset.limited)

        # navigation component doesn't apply and rset has not been limited, no

        # need to limit query

        else:

            rql = self.rset.printable_rql()

        return rql

    def _limit_offset_rql(self, limit, offset):

        rqlst = self.rset.syntax_tree()

        if len(rqlst.children) == 1:

            select = rqlst.children[0]

            olimit, ooffset = select.limit, select.offset

            select.limit, select.offset = limit, offset

            rql = rqlst.as_string(kwargs=self.rset.args)

            # restore original limit/offset

            select.limit, select.offset = olimit, ooffset

        else:

            newselect = Select()

            newselect.limit = limit

            newselect.offset = offset

            aliases = [VariableRef(newselect.get_variable(vref.name, i))

                       for i, vref in enumerate(rqlst.selection)]

            newselect.set_with([SubQuery(aliases, rqlst)], check=False)

            newunion = Union()

            newunion.append(newselect)

            rql = rqlst.as_string(kwargs=self.rset.args)

            rqlst.parent = None

        return rql

    def view(self, __vid, rset=None, __fallback_vid=None, **kwargs):

        """shortcut to self.vreg.render method avoiding to pass self.req"""

        try:

            view = self.vreg.select_view(__vid, self.req, rset, **kwargs)

        except NoSelectableObject:

            if __fallback_vid is None:

                raise

            view = self.vreg.select_view(__fallback_vid, self.req, rset, **kwargs)

        return view.dispatch(**kwargs)

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

    controller = 'view'

    def build_url(self, method=None, **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.

        """

        # 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:

            method = self.controller

            if method == 'view' and self.req.from_controller() == 'view' and \

                   not '_restpath' in kwargs:

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

        return self.req.build_url(method, **kwargs)

    # various resources accessors #############################################

    def entity(self, row, col=0):

        """short cut to get an entity instance for a particular row/column

        (col default to 0)

        """

        return self.rset.get_entity(row, col)

    def complete_entity(self, row, col=0, skip_bytes=True):

        """short cut to get an completed entity instance for a particular

        row (all instance's attributes have been fetched)

        """

        entity = self.entity(row, col)

        entity.complete(skip_bytes=skip_bytes)

        return entity

    def user_rql_callback(self, args, msg=None):

        """register a user callback to execute some rql query and return an url

        to call it ready to be inserted in html

        """

        def rqlexec(req, rql, args=None, key=None):

            req.execute(rql, args, key)

        return self.user_callback(rqlexec, args, msg)

    def user_callback(self, cb, args, msg=None, nonify=False):

        """register the given user callback and return an url to call it ready to be

        inserted in html

        """

        self.req.add_js('cubicweb.ajax.js')

        cbname = self.req.register_onetime_callback(cb, *args)

        msg = dumps(msg or '') 

        return "javascript:userCallbackThenReloadPage('%s', %s)" % (

            cbname, msg)

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

    def tal_render(self, template, variables):

        """render a precompiled page template with variables in the given

        dictionary as context

        """

        from cubicweb.common.tal import CubicWebContext

        context = CubicWebContext()

        context.update({'self': self, 'rset': self.rset, '_' : self.req._,

                        'req': self.req, 'user': self.req.user})

        context.update(variables)

        output = UStringIO()

        template.expand(context, output)

        return output.getvalue()

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

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

        configuration

        """

        if date:

            if date_format is None:

                if time:

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

                else:

                    date_format = self.req.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 application's

        configuration

        """

        if time:

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

        return u''

    def format_float(self, num):

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

        configuration

        """

        if num:

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

        return u''

    # security related methods ################################################

    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.req._('only select queries are authorized'))

class AppObject(AppRsetObject):

    """base class for application objects which are not selected

    according to a result set, only by their identifier.

    Those objects may not have req, rset and cursor set.

    """

    @classmethod

    def selected(cls, *args, **kwargs):

        """by default web app objects are usually instantiated on

        selection

        """

        return cls(*args, **kwargs)

    def __init__(self, req=None, rset=None, **kwargs):

        self.req = req

        self.rset = rset

        self.__dict__.update(kwargs)