# copyright 2003-2011 LOGILAB S.A. (Paris, FRANCE), all rights reserved.
# contact http://www.logilab.fr/ -- mailto:contact@logilab.fr
#
# This file is part of CubicWeb.
#
# CubicWeb is free software: you can redistribute it and/or modify it under the
# terms of the GNU Lesser General Public License as published by the Free
# Software Foundation, either version 2.1 of the License, or (at your option)
# any later version.
#
# CubicWeb is distributed in the hope that it will be useful, but WITHOUT
# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
# FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public License for more
# details.
#
# You should have received a copy of the GNU Lesser General Public License along
# with CubicWeb.  If not, see <http://www.gnu.org/licenses/>.
"""Some parsers to detect action to do from text

Currently only a parser to look for state change instruction is provided.
Take care to security when you're using it, think about the user that
will provide the text to analyze...
"""

import re

from cubicweb import UnknownEid
from cubicweb.view import Component


class TextAnalyzer(Component):
    """analyze and extract information from plain text by calling registered
    text parsers
    """
    __regid__ = 'textanalyzer'

    def parse(self, caller, text):
        for parsercls in self._cw.vreg['components'].get('textparser', ()):
            parsercls(self._cw).parse(caller, text)


class TextParser(Component):
    """base class for text parser, responsible to extract some information
    from plain text. When something is done, it usually call the

      .fire_event(something, {event args})

    method on the caller.
    """
    __regid__ = 'textparser'
    __abstract__ = True

    def parse(self, caller, text):
        raise NotImplementedError


class ChangeStateTextParser(TextParser):
    """search some text for change state instruction in the form

         :<transition name>: #?<eid>
    """
    instr_rgx = re.compile(r':(\w+):\s*#?(\d+)', re.U)

    def parse(self, caller, text):
        for trname, eid in self.instr_rgx.findall(text):
            try:
                entity = self._cw.entity_from_eid(int(eid))
            except UnknownEid:
                self.error("can't get entity with eid %s", eid)
                continue
            if not hasattr(entity, 'in_state'):
                self.error('bad change state instruction for eid %s', eid)
                continue
            iworkflowable = entity.cw_adapt_to('IWorkflowable')
            if iworkflowable.current_workflow:
                tr = iworkflowable.current_workflow.transition_by_name(trname)
            else:
                tr = None
            if tr and tr.may_be_fired(entity.eid):
                try:
                    trinfo = iworkflowable.fire_transition(tr)
                    caller.fire_event('state-changed', {'trinfo': trinfo,
                                                        'entity': entity})
                except Exception:
                    self.exception('while changing state of %s', entity)
            else:
                self.error("can't pass transition %s on entity %s",
                           trname, entity)