from django.core import meta

def validate_app(app_label):
    mod = meta.get_app(app_label)
    for klass in mod._MODELS:
        try:
            validate_class(klass)
        except AssertionError, e:
            print e

def validate_class(klass):
    opts = klass._meta
    # Fields.
    for f in opts.fields:
        if isinstance(f, meta.ManyToManyField):
            assert isinstance(f.rel, meta.ManyToMany), "ManyToManyField %s should have 'rel' set to a ManyToMany instance." % f.name
    # Inline related objects.
    for rel_opts, rel_field in opts.get_inline_related_objects():
        assert len([f for f in rel_opts.fields if f.core]) > 0, "At least one field in %s should have core=True, because it's being edited inline by %s." % (rel_opts.object_name, opts.object_name)
    # All related objects.
    related_apps_seen = []
    for rel_opts, rel_field in opts.get_all_related_objects():
        if rel_opts in related_apps_seen:
            assert rel_field.rel.related_name is not None, "Relationship in field %s.%s needs to set 'related_name' because more than one %s object is referenced in %s." % (rel_opts.object_name, rel_field.name, opts.object_name, rel_opts.object_name)
        related_apps_seen.append(rel_opts)
    # Etc.
    if opts.admin is not None:
        assert opts.admin.ordering or opts.ordering, "%s needs to set 'ordering' on either its 'admin' or its model, because it has 'admin' set." % opts.object_name

if __name__ == "__main__":
    import sys
    try:
        validate_app(sys.argv[1])
    except IndexError:
        sys.stderr.write("Usage: %s [appname]\n" % __file__)
        sys.exit(1)