# All this craziness is so that we can allow the classes in nested_admin.formsets
# to be importable directly from this module, e.g.:
#
#     from nested_admin import NestedInlineFormSet
#
# without running afoul of the strict import order required by Django 1.9+.
# This implementation is shamelessly stolen from werkzeug's ``__init__.py``.
#
# Also included is a monkey-patch for django.forms.formsets.all_valid().
import pkg_resources
import sys
from types import ModuleType

import django
import django.forms.formsets
import monkeybiz

try:
    __version__ = pkg_resources.get_distribution('django-nested-admin').version
except pkg_resources.DistributionNotFound:
    __version__ = None

# import mapping to objects in other modules
all_by_module = {
    'nested_admin.formsets': (
        'NestedInlineFormSet', 'NestedBaseGenericInlineFormSet'),
    'nested_admin.nested': (
        'NestedModelAdmin', 'NestedModelAdminMixin', 'NestedInlineAdminFormset',
        'NestedInlineModelAdmin', 'NestedStackedInline', 'NestedTabularInline',
        'NestedInlineModelAdminMixin', 'NestedGenericInlineModelAdmin',
        'NestedGenericStackedInline', 'NestedGenericTabularInline')
}

# modules that should be imported when accessed as attributes of nested_admin
attribute_modules = frozenset(['formsets', 'nested'])

object_origins = {}
for module, items in all_by_module.items():
    for item in items:
        object_origins[item] = module


class module(ModuleType):

    def __dir__(self):
        """Just show what we want to show."""
        result = list(new_module.__all__)
        result.extend(('__file__', '__path__', '__doc__', '__all__',
                       '__docformat__', '__name__', '__path__',
                       '__package__', '__version__'))
        return result

    def __getattr__(self, name):
        if name in object_origins:
            module = __import__(object_origins[name], None, None, [name])
            for extra_name in all_by_module[module.__name__]:
                setattr(self, extra_name, getattr(module, extra_name))
            return getattr(module, name)
        elif name in attribute_modules:
            __import__('nested_admin.' + name)
        return ModuleType.__getattribute__(self, name)


# keep a reference to this module so that it's not garbage collected
old_module = sys.modules[__name__]

# setup the new module and patch it into the dict of loaded modules
new_module = sys.modules[__name__] = module(__name__)
new_module.__dict__.update({
    '__file__':         __file__,
    '__package__':      'nested_admin',
    '__path__':         __path__,
    '__doc__':          __doc__,
    '__version__':      __version__,
    '__all__':          tuple(object_origins) + tuple(attribute_modules),
    '__docformat__':    'restructuredtext en',
})

all_valid_patch_modules = [django.forms.formsets]

# If django.contrib.admin.options has already been imported, we'll need to
# monkeypatch all_valid in that module as well
admin_module = sys.modules.get('django.contrib.admin.options')
if admin_module:
    all_valid_patch_modules.append(admin_module)


@monkeybiz.patch(all_valid_patch_modules)
def all_valid(original_all_valid, formsets):
    """
    Checks validation on formsets, then handles a case where an inline
    has new data but one of its parent forms is blank.

    This causes a bug when one of the parent forms has empty_permitted == True,
    which happens if it is an "extra" form in the formset and its index
    is >= the formset's min_num.
    """
    if not original_all_valid(formsets):
        return False

    for formset in formsets:
        if formset.has_changed() and getattr(formset, 'parent_form', None):
            parent_form = formset.parent_form

            while True:
                if parent_form.empty_permitted:
                    parent_form.empty_permitted = False
                    # Reset the validation errors
                    parent_form._errors = None
                    if not parent_form.instance.pk and not parent_form.has_changed():
                        # Force Django to try to save the instance,
                        # since we need it for the fk to work
                        changed_data = parent_form.fields.keys()
                        if django.VERSION > (1, 9):
                            parent_form.__dict__['changed_data'] = changed_data
                        else:
                            parent_form._changed_data = changed_data
                if not hasattr(parent_form, 'parent_formset'):
                    break
                parent_form.parent_formset._errors = None
                if not hasattr(parent_form.parent_formset, 'parent_form'):
                    break
                parent_form = parent_form.parent_formset.parent_form

    if not original_all_valid(formsets):
        return False

    return True