"""workflow definition and history related entities

:organization: Logilab
:copyright: 2001-2009 LOGILAB S.A. (Paris, FRANCE), license is LGPL v2.
:contact: http://www.logilab.fr/ -- mailto:contact@logilab.fr
:license: GNU Lesser General Public License, v2.1 - http://www.gnu.org/licenses
"""
__docformat__ = "restructuredtext en"

from warnings import warn

from logilab.common.decorators import cached, clear_cache
from logilab.common.deprecation import deprecated

from cubicweb.entities import AnyEntity, fetch_config
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] 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 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=unicode(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=unicode(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
    """
    id = 'Transition'
    fetch_attrs, fetch_order = fetch_config(['name'])

    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
        """
        user = self.req.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:
                return matches
            if 'owners' in groups and user.owns(eid):
                return True
        # check one of the rql expression conditions matches if any
        if self.condition:
            for rqlexpr in self.condition:
                if rqlexpr.check_expression(self.req, eid):
                    return True
        if self.condition or groups:
            return False
        return True

    def after_deletion_path(self):
        """return (path, parameters) which should be used as redirect
        information when this entity is being deleted
        """
        if self.transition_of:
            return self.transition_of[0].rest_path(), {}
        return super(Transition, self).after_deletion_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


class State(AnyEntity):
    """customized class for State entities"""
    id = 'State'
    fetch_attrs, fetch_order = fetch_config(['name'])
    rest_attr = 'eid'

    def after_deletion_path(self):
        """return (path, parameters) which should be used as redirect
        information when this entity is being deleted
        """
        if self.state_of:
            return self.state_of[0].rest_path(), {}
        return super(State, self).after_deletion_path()


class TrInfo(AnyEntity):
    """customized class for Transition information entities
    """
    id = 'TrInfo'
    fetch_attrs, fetch_order = fetch_config(['creation_date', 'comment'],
                                            pclass=None) # don't want modification_date
    @property
    def for_entity(self):
        return self.wf_info_for[0]

    @property
    def previous_state(self):
        return self.from_state[0]

    @property
    def new_state(self):
        return self.to_state[0]

    @property
    def transition(self):
        return self.by_transition and self.by_transition[0] or None

    def after_deletion_path(self):
        """return (path, parameters) which should be used as redirect
        information when this entity is being deleted
        """
        if self.for_entity:
            return self.for_entity.rest_path(), {}
        return 'view', {}


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
    def current_workflow(self):
        """return current workflow applied to this entity"""
        if self.custom_workflow:
            return self.custom_workflow[0]
        return self.cwetype_workflow()

    @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''

    @property
    def workflow_history(self):
        """return the workflow history for this entity (eg ordered list of
        TrInfo entities)
        """
        return self.reverse_wf_info_for

    def latest_trinfo(self):
        """return the latest transition information for this entity"""
        return self.reverse_wf_info_for[-1]

    @cached
    def cwetype_workflow(self):
        """return the default workflow for entities of this type"""
        # XXX CWEType method
        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

    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))


    def clear_all_caches(self):
        super(WorkflowableMixIn, self).clear_all_caches()
        clear_cache(self, 'cwetype_workflow')

    @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