from apscheduler.triggers.base import BaseTrigger
from apscheduler.util import obj_to_ref, ref_to_obj


class BaseCombiningTrigger(BaseTrigger):
    __slots__ = ('triggers', 'jitter')

    def __init__(self, triggers, jitter=None):
        self.triggers = triggers
        self.jitter = jitter

    def __getstate__(self):
        return {
            'version': 1,
            'triggers': [(obj_to_ref(trigger.__class__), trigger.__getstate__())
                         for trigger in self.triggers],
            'jitter': self.jitter
        }

    def __setstate__(self, state):
        if state.get('version', 1) > 1:
            raise ValueError(
                'Got serialized data for version %s of %s, but only versions up to 1 can be '
                'handled' % (state['version'], self.__class__.__name__))

        self.jitter = state['jitter']
        self.triggers = []
        for clsref, state in state['triggers']:
            cls = ref_to_obj(clsref)
            trigger = cls.__new__(cls)
            trigger.__setstate__(state)
            self.triggers.append(trigger)

    def __repr__(self):
        return '<{}({}{})>'.format(self.__class__.__name__, self.triggers,
                                   ', jitter={}'.format(self.jitter) if self.jitter else '')


class AndTrigger(BaseCombiningTrigger):
    """
    Always returns the earliest next fire time that all the given triggers can agree on.
    The trigger is considered to be finished when any of the given triggers has finished its
    schedule.

    Trigger alias: ``and``

    :param list triggers: triggers to combine
    :param int|None jitter: advance or delay the job execution by ``jitter`` seconds at most.
    """

    __slots__ = ()

    def get_next_fire_time(self, previous_fire_time, now):
        while True:
            fire_times = [trigger.get_next_fire_time(previous_fire_time, now)
                          for trigger in self.triggers]
            if None in fire_times:
                return None
            elif min(fire_times) == max(fire_times):
                return self._apply_jitter(fire_times[0], self.jitter, now)
            else:
                now = max(fire_times)

    def __str__(self):
        return 'and[{}]'.format(', '.join(str(trigger) for trigger in self.triggers))


class OrTrigger(BaseCombiningTrigger):
    """
    Always returns the earliest next fire time produced by any of the given triggers.
    The trigger is considered finished when all the given triggers have finished their schedules.

    Trigger alias: ``or``

    :param list triggers: triggers to combine
    :param int|None jitter: advance or delay the job execution by ``jitter`` seconds at most.

    .. note:: Triggers that depends on the previous fire time, such as the interval trigger, may
        seem to behave strangely since they are always passed the previous fire time produced by
        any of the given triggers.
    """

    __slots__ = ()

    def get_next_fire_time(self, previous_fire_time, now):
        fire_times = [trigger.get_next_fire_time(previous_fire_time, now)
                      for trigger in self.triggers]
        fire_times = [fire_time for fire_time in fire_times if fire_time is not None]
        if fire_times:
            return self._apply_jitter(min(fire_times), self.jitter, now)
        else:
            return None

    def __str__(self):
        return 'or[{}]'.format(', '.join(str(trigger) for trigger in self.triggers))
