# copyright 2003-2012 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/>.

"""workflow handling:

* entity types defining workflow (Workflow, State, Transition...)

* workflow history (TrInfo)

* adapter for workflowable entities (IWorkflowableAdapter)

"""

from logilab.common.decorators import cached, clear_cache

from cubicweb.entities import AnyEntity, fetch_config

from cubicweb.entity import EntityAdapter

from cubicweb.predicates import relation_possible

try:

    from cubicweb import server

except ImportError:

    # We need to lookup DEBUG from there,

    # however a pure dbapi client may not have it.

    class server(object): pass

    server.DEBUG = False

class WorkflowException(Exception): pass

class Workflow(AnyEntity):

    __regid__ = 'Workflow'

    @property

    def initial(self):

        """return the initial state for this workflow"""

        return self.initial_state and self.initial_state[0] or None

    def is_default_workflow_of(self, etype):

        """return True if this workflow is the default workflow for the given

        entity type

        """

        return any(et for et in self.reverse_default_workflow

                   if et.name == etype)

    def iter_workflows(self, _done=None):

        """return an iterator on actual workflows, eg this workflow and its

        subworkflows

        """

        # infinite loop safety belt

        if _done is None:

            _done = set()

        yield self

        _done.add(self.eid)

        for tr in self._cw.execute('Any T WHERE T is WorkflowTransition, '

                                   'T transition_of WF, WF eid %(wf)s',

                                   {'wf': self.eid}).entities():

            if tr.subwf.eid in _done:

                continue

            for subwf in tr.subwf.iter_workflows(_done):

                yield subwf

    # state / transitions accessors ############################################

    def state_by_name(self, statename):

        rset = self._cw.execute('Any S, SN WHERE S name SN, S name %(n)s, '

                                'S state_of WF, WF eid %(wf)s',

                                {'n': statename, 'wf': self.eid})

        if rset:

            return rset.get_entity(0, 0)

        return None

    def state_by_eid(self, eid):

        rset = self._cw.execute('Any S, SN WHERE S name SN, S eid %(s)s, '

                                'S state_of WF, WF eid %(wf)s',

                                {'s': eid, 'wf': self.eid})

        if rset:

            return rset.get_entity(0, 0)

        return None

    def transition_by_name(self, trname):

        rset = self._cw.execute('Any T, TN WHERE T name TN, T name %(n)s, '

                                'T transition_of WF, WF eid %(wf)s',

                                {'n': trname, 'wf': self.eid})

        if rset:

            return rset.get_entity(0, 0)

        return None

    def transition_by_eid(self, eid):

        rset = self._cw.execute('Any T, TN WHERE T name TN, T eid %(t)s, '

                                'T transition_of WF, WF eid %(wf)s',

                                {'t': eid, 'wf': self.eid})

        if rset:

            return rset.get_entity(0, 0)

        return None

    # wf construction methods ##################################################

    def add_state(self, name, initial=False, **kwargs):

        """add a state to this workflow"""

        state = self._cw.create_entity('State', name=name, **kwargs)

        self._cw.execute('SET S state_of WF WHERE S eid %(s)s, WF eid %(wf)s',

                         {'s': state.eid, 'wf': self.eid})

        if initial:

            assert not self.initial, "Initial state already defined as %s" % self.initial

            self._cw.execute('SET WF initial_state S '

                             'WHERE S eid %(s)s, WF eid %(wf)s',

                             {'s': state.eid, 'wf': self.eid})

        return state

    def _add_transition(self, trtype, name, fromstates,

                        requiredgroups=(), conditions=(), **kwargs):

        tr = self._cw.create_entity(trtype, name=name, **kwargs)

        self._cw.execute('SET T transition_of WF '

                         'WHERE T eid %(t)s, WF eid %(wf)s',

                         {'t': tr.eid, 'wf': self.eid})

        assert fromstates, fromstates

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

            fromstates = (fromstates,)

        for state in fromstates:

            if hasattr(state, 'eid'):

                state = state.eid

            self._cw.execute('SET S allowed_transition T '

                             'WHERE S eid %(s)s, T eid %(t)s',

                             {'s': state, 't': tr.eid})

        tr.set_permissions(requiredgroups, conditions, reset=False)

        return tr

    def add_transition(self, name, fromstates, tostate=None,

                       requiredgroups=(), conditions=(), **kwargs):

        """add a transition to this workflow from some state(s) to another"""

        tr = self._add_transition('Transition', name, fromstates,

                                  requiredgroups, conditions, **kwargs)

        if tostate is not None:

            if hasattr(tostate, 'eid'):

                tostate = tostate.eid

            self._cw.execute('SET T destination_state S '

                             'WHERE S eid %(s)s, T eid %(t)s',

                             {'t': tr.eid, 's': tostate})

        return tr

    def add_wftransition(self, name, subworkflow, fromstates, exitpoints=(),

                         requiredgroups=(), conditions=(), **kwargs):

        """add a workflow transition to this workflow"""

        tr = self._add_transition('WorkflowTransition', name, fromstates,

                                  requiredgroups, conditions, **kwargs)

        if hasattr(subworkflow, 'eid'):

            subworkflow = subworkflow.eid

        assert self._cw.execute('SET T subworkflow WF WHERE WF eid %(wf)s,T eid %(t)s',

                                {'t': tr.eid, 'wf': subworkflow})

        for fromstate, tostate in exitpoints:

            tr.add_exit_point(fromstate, tostate)

        return tr

    def replace_state(self, todelstate, replacement):

        """migration convenience method"""

        if not hasattr(todelstate, 'eid'):

            todelstate = self.state_by_name(todelstate)

        if not hasattr(replacement, 'eid'):

            replacement = self.state_by_name(replacement)

        args = {'os': todelstate.eid, 'ns': replacement.eid}

        execute = self._cw.execute

        execute('SET X in_state NS WHERE X in_state OS, '

                'NS eid %(ns)s, OS eid %(os)s', args)

        execute('SET X from_state NS WHERE X from_state OS, '

                'OS eid %(os)s, NS eid %(ns)s', args)

        execute('SET X to_state NS WHERE X to_state OS, '

                'OS eid %(os)s, NS eid %(ns)s', args)

        todelstate.cw_delete()

class BaseTransition(AnyEntity):

    """customized class for abstract transition

    provides a specific may_be_fired method to check if the relation may be

    fired by the logged user

    """

    __regid__ = 'BaseTransition'

    fetch_attrs, cw_fetch_order = fetch_config(['name', 'type'])

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

        if self.cw_etype == 'BaseTransition':

            raise WorkflowException('should not be instantiated')

        super(BaseTransition, self).__init__(*args, **kwargs)

    @property

    def workflow(self):

        return self.transition_of[0]

    def has_input_state(self, state):

        if hasattr(state, 'eid'):

            state = state.eid

        return any(s for s in self.reverse_allowed_transition if s.eid == state)

    def may_be_fired(self, eid):

        """return true if the logged user may fire this transition

        `eid` is the eid of the object on which we may fire the transition

        """

        DBG = False

        if server.DEBUG & server.DBG_SEC:

            if 'transition' in server._SECURITY_CAPS:

                DBG = True

        user = self._cw.user

        # check user is at least in one of the required groups if any

        groups = frozenset(g.name for g in self.require_group)

        if groups:

            matches = user.matching_groups(groups)

            if matches:

                if DBG:

                    print('may_be_fired: %r may fire: user matches %s' % (self.name, groups))

                return matches

            if 'owners' in groups and user.owns(eid):

                if DBG:

                    print('may_be_fired: %r may fire: user is owner' % self.name)

                return True

        # check one of the rql expression conditions matches if any

        if self.condition:

            if DBG:

                print('may_be_fired: %r: %s' %

                      (self.name, [(rqlexpr.expression,

                                    rqlexpr.check_expression(self._cw, eid))

                                    for rqlexpr in self.condition]))

            for rqlexpr in self.condition:

                if rqlexpr.check_expression(self._cw, eid):

                    return True

        if self.condition or groups:

            return False

        return True

    def set_permissions(self, requiredgroups=(), conditions=(), reset=True):

        """set or add (if `reset` is False) groups and conditions for this

        transition

        """

        if reset:

            self._cw.execute('DELETE T require_group G WHERE T eid %(x)s',

                             {'x': self.eid})

            self._cw.execute('DELETE T condition R WHERE T eid %(x)s',

                             {'x': self.eid})

        for gname in requiredgroups:

            rset = self._cw.execute('SET T require_group G '

                                    'WHERE T eid %(x)s, G name %(gn)s',

                                    {'x': self.eid, 'gn': gname})

            assert rset, '%s is not a known group' % gname

        if isinstance(conditions, str):

            conditions = (conditions,)

        for expr in conditions:

            if isinstance(expr, str):

                kwargs = {'expr': expr}

            else:

                assert isinstance(expr, dict)

                kwargs = expr

            kwargs['x'] = self.eid

            kwargs.setdefault('mainvars', u'X')

            self._cw.execute('INSERT RQLExpression X: X exprtype "ERQLExpression", '

                             'X expression %(expr)s, X mainvars %(mainvars)s, '

                             'T condition X WHERE T eid %(x)s', kwargs)

        # XXX clear caches?

class Transition(BaseTransition):

    """customized class for Transition entities"""

    __regid__ = 'Transition'

    def dc_long_title(self):

        return '%s (%s)' % (self.name, self._cw._(self.name))

    def destination(self, entity):

        try:

            return self.destination_state[0]

        except IndexError:

            return entity.cw_adapt_to('IWorkflowable').latest_trinfo().previous_state

    def potential_destinations(self):

        try:

            yield self.destination_state[0]

        except IndexError:

            for incomingstate in self.reverse_allowed_transition:

                for tr in incomingstate.reverse_destination_state:

                    for previousstate in tr.reverse_allowed_transition:

                        yield previousstate

class WorkflowTransition(BaseTransition):

    """customized class for WorkflowTransition entities"""

    __regid__ = 'WorkflowTransition'

    @property

    def subwf(self):

        return self.subworkflow[0]

    def destination(self, entity):

        return self.subwf.initial

    def potential_destinations(self):

        yield self.subwf.initial

    def add_exit_point(self, fromstate, tostate):

        if hasattr(fromstate, 'eid'):

            fromstate = fromstate.eid

        if tostate is None:

            self._cw.execute('INSERT SubWorkflowExitPoint X: T subworkflow_exit X, '

                             'X subworkflow_state FS WHERE T eid %(t)s, FS eid %(fs)s',

                             {'t': self.eid, 'fs': fromstate})

        else:

            if hasattr(tostate, 'eid'):

                tostate = tostate.eid

            self._cw.execute('INSERT SubWorkflowExitPoint X: T subworkflow_exit X, '

                             'X subworkflow_state FS, X destination_state TS '

                             'WHERE T eid %(t)s, FS eid %(fs)s, TS eid %(ts)s',

                             {'t': self.eid, 'fs': fromstate, 'ts': tostate})

    def get_exit_point(self, entity, stateeid):

        """if state is an exit point, return its associated destination state"""

        if hasattr(stateeid, 'eid'):

            stateeid = stateeid.eid

        try:

            tostateeid = self.exit_points()[stateeid]

        except KeyError:

            return None

        if tostateeid is None:

            # go back to state from which we've entered the subworkflow

            return entity.cw_adapt_to('IWorkflowable').subworkflow_input_trinfo().previous_state

        return self._cw.entity_from_eid(tostateeid)

    @cached

    def exit_points(self):

        result = {}

        for ep in self.subworkflow_exit:

            result[ep.subwf_state.eid] = ep.destination and ep.destination.eid

        return result

    def cw_clear_all_caches(self):

        super(WorkflowTransition, self).cw_clear_all_caches()

        clear_cache(self, 'exit_points')

class SubWorkflowExitPoint(AnyEntity):

    """customized class for SubWorkflowExitPoint entities"""

    __regid__ = 'SubWorkflowExitPoint'

    @property

    def subwf_state(self):

        return self.subworkflow_state[0]

    @property

    def destination(self):

        return self.destination_state and self.destination_state[0] or None

class State(AnyEntity):

    """customized class for State entities"""

    __regid__ = 'State'

    fetch_attrs, cw_fetch_order = fetch_config(['name'])

    rest_attr = 'eid'

    def dc_long_title(self):

        return '%s (%s)' % (self.name, self._cw._(self.name))