from django.core.exceptions import ValidationError


def check_speaker_event_camp_consistency(sender, instance, **kwargs):
    if kwargs['action'] == 'pre_add':
        from program.models import Speaker, Event
        if isinstance(instance, Event):
            # loop over speakers being added to this event
            for pk in kwargs['pk_set']:
                # check if this speaker belongs to a different Camp than the event does
                speaker = Speaker.objects.get(id=pk)
                if speaker.camp != instance.camp:
                    raise ValidationError({'speakers': 'The speaker (%s) belongs to a different camp (%s) than the event does (%s)' % (speaker, speaker.camp, instance.camp)})
        elif isinstance(instance, Speaker):
            # loop over events being added to this speaker
            for pk in kwargs['pk_set']:
                # check if this event belongs to a different Camp than the speaker does
                event = Event.objects.get(id=pk)
                if event.camp != instance.camp:
                    raise ValidationError({'events': 'The event (%s) belongs to a different camp (%s) than the event does (%s)' % (event, event.camp, instance.camp)})


def check_speaker_camp_change(sender, instance, **kwargs):
    if instance.pk:
        for event in instance.events.all():
            if event.camp != instance.camp:
                raise ValidationError({'camp': 'You cannot change the camp a speaker belongs to if the speaker is associated with one or more events.'})