from warnings import warn

from logilab.common.decorators import cached

from logilab.common.deprecation import deprecated

from cubicweb.interfaces import IWorkflowable

from cubicweb.common.mixins import MI_REL_TRIGGERS

class Workflow(AnyEntity):

    id = 'Workflow'

    @property

    def initial(self):

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

        return self.initial_state and self.initial_state[0]

    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.default_workflow_of if et.name == etype)

    def after_deletion_path(self):

        """return (path, parameters) which should be used as redirect

        information when this entity is being deleted

        """

        if self.workflow_of:

            return self.workflow_of[0].rest_path(), {'vid': 'workflow'}

        return super(Workflow, self).after_deletion_path()

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

    def state_by_name(self, statename):

        rset = self.req.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}, 'wf')

        if rset:

            return rset.get_entity(0, 0)

        return None

    def state_by_eid(self, eid):

        rset = self.req.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}, ('wf', 's'))

        if rset:

            return rset.get_entity(0, 0)

        return None

    def transition_by_name(self, trname):

        rset = self.req.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}, 'wf')

        if rset:

            return rset.get_entity(0, 0)

        return None

    def transition_by_eid(self, eid):

        rset = self.req.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}, ('wf', 't'))

        if rset:

            return rset.get_entity(0, 0)

        return None

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

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

        """method to ease workflow definition: add a state for one or more

        entity type(s)

        """

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

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

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

        if initial:

            assert not self.initial

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

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

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

        return state

    def add_transition(self, name, fromstates, tostate,

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

        """method to ease workflow definition: add a transition for one or more

        entity type(s), from one or more state and to a single state

        """

        tr = self.req.create_entity('Transition', name=name, **kwargs)

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

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

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

        for state in fromstates:

            if hasattr(state, 'eid'):

                state = state.eid

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

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

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

        if hasattr(tostate, 'eid'):

            tostate = tostate.eid

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

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

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

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

        return tr

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

    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

            return self.transition_of[0].rest_path(), {}

    def set_transition_permissions(self, requiredgroups=(), conditions=(),

                                   reset=True):

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

        transition

        """

        if reset:

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

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

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

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

        for gname in requiredgroups:

            ### XXX ensure gname validity

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

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

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

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

        if isinstance(conditions, basestring):

            conditions = (conditions,)

        for expr in conditions:

            if isinstance(expr, str):

                expr = unicode(expr)

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

                             'X expression %(expr)s, T condition X '

                             'WHERE T eid %(x)s',

                             {'x': self.eid, 'expr': expr}, 'x')

        # XXX clear caches?

class Transition(BaseTransition):

    """customized class for Transition entities"""

    id = 'Transition'

    def destination(self):

        return self.destination_state[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)

class WorkflowTransition(BaseTransition):

    """customized class for WorkflowTransition entities"""

    id = 'WorkflowTransition'

    @property

    def subwf(self):

        return self.subworkflow[0]

    def destination(self):

        return self.subwf.initial

    """customized class for State entities"""

            return self.state_of[0].rest_path(), {}

        return self.wf_info_for[0]

        return self.from_state[0]

    @property

    def transition(self):

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

class WorkflowableMixIn(object):

    """base mixin providing workflow helper methods for workflowable entities.

    This mixin will be automatically set on class supporting the 'in_state'

    relation (which implies supporting 'wf_info_for' as well)

    """

    __implements__ = (IWorkflowable,)

    @property

    @cached

    def current_workflow(self):

        """return current workflow applied to this entity"""

        if self.custom_workflow:

            return self.custom_workflow[0]

        wfrset = self.req.execute('Any WF WHERE X is ET, X eid %(x)s, WF workflow_of ET',

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

        if len(wfrset) == 1:

            return wfrset.get_entity(0, 0)

        if len(wfrset) > 1:

            for wf in wfrset.entities():

                if wf.is_default_workflow_of(self.id):

                    return wf

            self.warning("can't find default workflow for %s", self.id)

        else:

            self.warning("can't find any workflow for %s", self.id)

        return None

    @property

    def current_state(self):

        """return current state entity"""

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

    @property

    def state(self):

        """return current state name"""

        try:

            return self.in_state[0].name

        except IndexError:

            self.warning('entity %s has no state', self)

            return None

    @property

    def printable_state(self):

        """return current state name translated to context's language"""

        state = self.current_state

        if state:

            return self.req._(state.name)

        return u''

    def latest_trinfo(self):

        """return the latest transition information for this entity"""

        return self.reverse_wf_info_for[-1]

    def possible_transitions(self):

        """generates transition that MAY be fired for the given entity,

        expected to be in this state

        """

        if self.current_state is None or self.current_workflow is None:

            return

        rset = self.req.execute(

            'Any T,N WHERE S allowed_transition T, S eid %(x)s, '

            'T name N, T transition_of WF, WF eid %(wfeid)s',

            {'x': self.current_state.eid,

             'wfeid': self.current_workflow.eid}, 'x')

        for tr in rset.entities():

            if tr.may_be_fired(self.eid):

                yield tr

    def _get_tr_kwargs(self, comment, commentformat):

        kwargs = {}

        if comment is not None:

            kwargs['comment'] = comment

            if commentformat is not None:

                kwargs['comment_format'] = commentformat

        return kwargs

    def fire_transition(self, trname, comment=None, commentformat=None):

        """change the entity's state by firing transition of the given name in

        entity's workflow

        """

        assert self.current_workflow

        tr = self.current_workflow.transition_by_name(trname)

        assert tr is not None, 'not a %s transition: %s' % (self.id, state)

        # XXX try to find matching transition?

        self.req.create_entity('TrInfo', ('by_transition', 'T'),

                               ('wf_info_for', 'E'), T=tr.eid, E=self.eid,

                               **self._get_tr_kwargs(comment, commentformat))

    def change_state(self, statename, comment=None, commentformat=None):

        """change the entity's state to the state of the given name in entity's

        workflow. This method should only by used by manager to fix an entity's

        state when their is no matching transition, otherwise fire_transition

        should be used.

        """

        assert self.current_workflow

        if not isinstance(statename, basestring):

            warn('give a state name')

            state = self.current_workflow.state_by_eid(statename)

            assert state is not None, 'not a %s state: %s' % (self.id, state)

        else:

            state = self.current_workflow.state_by_name(statename)

        # XXX try to find matching transition?

        self.req.create_entity('TrInfo', ('to_state', 'S'),

                               ('wf_info_for', 'E'), S=state.eid, E=self.eid,

                               **self._get_tr_kwargs(comment, commentformat))

    @deprecated('get transition from current workflow and use its may_be_fired method')

    def can_pass_transition(self, trname):

        """return the Transition instance if the current user can fire the

        transition with the given name, else None

        """

        tr = self.current_workflow and self.current_workflow.transition_by_name(trname)

        if tr and tr.may_be_fired(self.eid):

            return tr

    @property

    @deprecated('use printable_state')

    def displayable_state(self):

        return self.req._(self.state)

MI_REL_TRIGGERS[('in_state', 'subject')] = WorkflowableMixIn