from django.conf.urls import patterns, include, url
from django.conf import settings
from django.core.exceptions import ImproperlyConfigured
from django.utils.importlib import import_module


from . import models
from . import views


class Admin2(object):
    """
    The base Admin2 object.
    It keeps a registry of all registered Models and collects the urls of their
    related ModelAdmin2 instances.

    It also provides an index view that serves as an entry point to the admin site.
    """
    index_view = views.IndexView

    def __init__(self, name='admin2'):
        self.registry = {}
        self.apps = {}
        self.name = name

    def register(self, model, modeladmin=None, **kwargs):
        """
        Registers the given model with the given admin class.

        If no modeladmin is passed, it will use ModelAdmin2. If keyword
        arguments are given they will be passed to the admin class on
        instantiation.

        If a model is already registered, this will raise ImproperlyConfigured.

        Once a model is registered in self.registry, we also add it to app registries
        in self.apps.
        """
        if model in self.registry:
            raise ImproperlyConfigured('%s is already registered in django-admin2' % model)
        if not modeladmin:
            modeladmin = models.ModelAdmin2
        self.registry[model] = modeladmin(model, **kwargs)

        # Add the model to the apps registry
        app_label = model._meta.app_label
        if app_label in self.apps.keys():
            self.apps[app_label][model] = self.registry[model]
        else:
            self.apps[app_label] = {model: self.registry[model]}

    def deregister(self, model):
        """
        Deregisters the given model.

        If the model is not already registered, this will raise ImproperlyConfigured.

        TODO: Remove the model from the self.app as well
        """
        try:
            del self.registry[model]
        except KeyError:
            raise ImproperlyConfigured

    def autodiscover(self):
        """
        Autodiscovers all admin2.py modules for apps in INSTALLED_APPS by
        trying to import them.
        """
        for app_name in [x for x in settings.INSTALLED_APPS]:
            try:
                import_module("%s.admin2" % app_name)
            except ImportError as e:
                if str(e) == "No module named admin2":
                    continue
                raise e

    def get_index_kwargs(self):
        return {
            'registry': self.registry,
            'apps': self.apps,
        }

    def get_urls(self):
        urlpatterns = patterns('',
            url(r'^$', self.index_view.as_view(**self.get_index_kwargs()), name='dashboard'),
        )
        for model, modeladmin in self.registry.iteritems():
            app_label = model._meta.app_label
            model_name = model._meta.object_name.lower()

            urlpatterns += patterns('',
                url('^{}/{}/'.format(app_label, model_name),
                    include(modeladmin.urls)),
            )
        return urlpatterns

    @property
    def urls(self):
        return self.get_urls(), self.name, self.name