import os
import sys
import unittest
from importlib import import_module
from zipimport import zipimporter

from django.test import SimpleTestCase, modify_settings
from django.test.utils import extend_sys_path
from django.utils.module_loading import (
    autodiscover_modules,
    import_string,
    module_has_submodule,
)


class DefaultLoader(unittest.TestCase):
    def test_loader(self):
        "Normal module existence can be tested"
        test_module = import_module("utils_tests.test_module")
        test_no_submodule = import_module("utils_tests.test_no_submodule")

        # An importable child
        self.assertTrue(module_has_submodule(test_module, "good_module"))
        mod = import_module("utils_tests.test_module.good_module")
        self.assertEqual(mod.content, "Good Module")

        # A child that exists, but will generate an import error if loaded
        self.assertTrue(module_has_submodule(test_module, "bad_module"))
        with self.assertRaises(ImportError):
            import_module("utils_tests.test_module.bad_module")

        # A child that doesn't exist
        self.assertFalse(module_has_submodule(test_module, "no_such_module"))
        with self.assertRaises(ImportError):
            import_module("utils_tests.test_module.no_such_module")

        # A child that doesn't exist, but is the name of a package on the path
        self.assertFalse(module_has_submodule(test_module, "django"))
        with self.assertRaises(ImportError):
            import_module("utils_tests.test_module.django")

        # Don't be confused by caching of import misses
        import types  # NOQA: causes attempted import of utils_tests.types

        self.assertFalse(module_has_submodule(sys.modules["utils_tests"], "types"))

        # A module which doesn't have a __path__ (so no submodules)
        self.assertFalse(module_has_submodule(test_no_submodule, "anything"))
        with self.assertRaises(ImportError):
            import_module("utils_tests.test_no_submodule.anything")

    def test_has_sumbodule_with_dotted_path(self):
        """Nested module existence can be tested."""
        test_module = import_module("utils_tests.test_module")
        # A grandchild that exists.
        self.assertIs(
            module_has_submodule(test_module, "child_module.grandchild_module"), True
        )
        # A grandchild that doesn't exist.
        self.assertIs(
            module_has_submodule(test_module, "child_module.no_such_module"), False
        )
        # A grandchild whose parent doesn't exist.
        self.assertIs(
            module_has_submodule(test_module, "no_such_module.grandchild_module"), False
        )
        # A grandchild whose parent is not a package.
        self.assertIs(
            module_has_submodule(test_module, "good_module.no_such_module"), False
        )


class EggLoader(unittest.TestCase):
    def setUp(self):
        self.egg_dir = "%s/eggs" % os.path.dirname(__file__)

    def tearDown(self):
        sys.path_importer_cache.clear()

        sys.modules.pop("egg_module.sub1.sub2.bad_module", None)
        sys.modules.pop("egg_module.sub1.sub2.good_module", None)
        sys.modules.pop("egg_module.sub1.sub2", None)
        sys.modules.pop("egg_module.sub1", None)
        sys.modules.pop("egg_module.bad_module", None)
        sys.modules.pop("egg_module.good_module", None)
        sys.modules.pop("egg_module", None)

    def test_shallow_loader(self):
        "Module existence can be tested inside eggs"
        egg_name = "%s/test_egg.egg" % self.egg_dir
        with extend_sys_path(egg_name):
            egg_module = import_module("egg_module")

            # An importable child
            self.assertTrue(module_has_submodule(egg_module, "good_module"))
            mod = import_module("egg_module.good_module")
            self.assertEqual(mod.content, "Good Module")

            # A child that exists, but will generate an import error if loaded
            self.assertTrue(module_has_submodule(egg_module, "bad_module"))
            with self.assertRaises(ImportError):
                import_module("egg_module.bad_module")

            # A child that doesn't exist
            self.assertFalse(module_has_submodule(egg_module, "no_such_module"))
            with self.assertRaises(ImportError):
                import_module("egg_module.no_such_module")

    def test_deep_loader(self):
        "Modules deep inside an egg can still be tested for existence"
        egg_name = "%s/test_egg.egg" % self.egg_dir
        with extend_sys_path(egg_name):
            egg_module = import_module("egg_module.sub1.sub2")

            # An importable child
            self.assertTrue(module_has_submodule(egg_module, "good_module"))
            mod = import_module("egg_module.sub1.sub2.good_module")
            self.assertEqual(mod.content, "Deep Good Module")

            # A child that exists, but will generate an import error if loaded
            self.assertTrue(module_has_submodule(egg_module, "bad_module"))
            with self.assertRaises(ImportError):
                import_module("egg_module.sub1.sub2.bad_module")

            # A child that doesn't exist
            self.assertFalse(module_has_submodule(egg_module, "no_such_module"))
            with self.assertRaises(ImportError):
                import_module("egg_module.sub1.sub2.no_such_module")


class ModuleImportTests(SimpleTestCase):
    def test_import_string(self):
        cls = import_string("django.utils.module_loading.import_string")
        self.assertEqual(cls, import_string)

        # Test exceptions raised
        with self.assertRaises(ImportError):
            import_string("no_dots_in_path")
        msg = 'Module "utils_tests" does not define a "unexistent" attribute'
        with self.assertRaisesMessage(ImportError, msg):
            import_string("utils_tests.unexistent")


@modify_settings(INSTALLED_APPS={"append": "utils_tests.test_module"})
class AutodiscoverModulesTestCase(SimpleTestCase):
    def tearDown(self):
        sys.path_importer_cache.clear()

        sys.modules.pop("utils_tests.test_module.another_bad_module", None)
        sys.modules.pop("utils_tests.test_module.another_good_module", None)
        sys.modules.pop("utils_tests.test_module.bad_module", None)
        sys.modules.pop("utils_tests.test_module.good_module", None)
        sys.modules.pop("utils_tests.test_module", None)

    def test_autodiscover_modules_found(self):
        autodiscover_modules("good_module")

    def test_autodiscover_modules_not_found(self):
        autodiscover_modules("missing_module")

    def test_autodiscover_modules_found_but_bad_module(self):
        with self.assertRaisesMessage(
            ImportError, "No module named 'a_package_name_that_does_not_exist'"
        ):
            autodiscover_modules("bad_module")

    def test_autodiscover_modules_several_one_bad_module(self):
        with self.assertRaisesMessage(
            ImportError, "No module named 'a_package_name_that_does_not_exist'"
        ):
            autodiscover_modules("good_module", "bad_module")

    def test_autodiscover_modules_several_found(self):
        autodiscover_modules("good_module", "another_good_module")

    def test_autodiscover_modules_several_found_with_registry(self):
        from .test_module import site

        autodiscover_modules("good_module", "another_good_module", register_to=site)
        self.assertEqual(site._registry, {"lorem": "ipsum"})

    def test_validate_registry_keeps_intact(self):
        from .test_module import site

        with self.assertRaisesMessage(Exception, "Some random exception."):
            autodiscover_modules("another_bad_module", register_to=site)
        self.assertEqual(site._registry, {})

    def test_validate_registry_resets_after_erroneous_module(self):
        from .test_module import site

        with self.assertRaisesMessage(Exception, "Some random exception."):
            autodiscover_modules(
                "another_good_module", "another_bad_module", register_to=site
            )
        self.assertEqual(site._registry, {"lorem": "ipsum"})

    def test_validate_registry_resets_after_missing_module(self):
        from .test_module import site

        autodiscover_modules(
            "does_not_exist", "another_good_module", "does_not_exist2", register_to=site
        )
        self.assertEqual(site._registry, {"lorem": "ipsum"})


class TestFinder:
    def __init__(self, *args, **kwargs):
        self.importer = zipimporter(*args, **kwargs)

    def find_spec(self, path, target=None):
        return self.importer.find_spec(path, target)


class CustomLoader(EggLoader):
    """The Custom Loader test is exactly the same as the EggLoader, but
    it uses a custom defined Loader class. Although the EggLoader combines both
    functions into one class, this isn't required.
    """

    def setUp(self):
        super().setUp()
        sys.path_hooks.insert(0, TestFinder)
        sys.path_importer_cache.clear()

    def tearDown(self):
        super().tearDown()
        sys.path_hooks.pop(0)