from __future__ import absolute_import

from django.db import transaction
from django.db.models.signals import post_save
from django.db.utils import DatabaseError
from django.dispatch import receiver
from django.utils.translation import ugettext_lazy as _

from south.signals import post_migrate

from common.utils import encapsulate
from navigation.api import register_links, register_model_list_columns
from project_tools.api import register_tool

from .classes import Property, PropertyNamespace
from .links import link_menu_link, link_namespace_details, link_namespace_list
from .models import Installation
    

@receiver(post_migrate, dispatch_uid='trigger_first_time')
def trigger_first_time(sender, **kwargs):
    if kwargs['app'] == 'installation':
        details = Installation.objects.get()
        details.is_first_run = True
        details.save()


@transaction.commit_on_success
def check_first_run():
    try:
        details = Installation.objects.get()
    except DatabaseError:
        # Avoid database errors when the app tables haven't been created yet
        transaction.rollback()        
    else:
        if details.is_first_run:
            details.submit()


register_model_list_columns(PropertyNamespace, [
    {
        'name': _(u'label'),
        'attribute': 'label'
    },
    {
        'name': _(u'items'),
        'attribute': encapsulate(lambda entry: len(entry.get_properties()))
    }    
])

register_model_list_columns(Property, [
    {
        'name': _(u'label'),
        'attribute': 'label'
    },
    {
        'name': _(u'value'),
        'attribute': 'value'
    }    
])

register_links(PropertyNamespace, [link_namespace_details])
register_links(['namespace_list', PropertyNamespace], [link_namespace_list], menu_name='secondary_menu')

register_tool(link_menu_link)

check_first_run()