# We import importlib *ASAP* in order to test #15386
import importlib
import importlib.util
from importlib._bootstrap_external import _get_sourcefile
import builtins
import marshal
import os
import py_compile
import random
import shutil
import subprocess
import stat
import sys
import threading
import time
import unittest
import unittest.mock as mock
import textwrap
import errno
import contextlib
import glob

import test.support
from test.support import (
    TESTFN, forget, is_jython,
    make_legacy_pyc, rmtree, swap_attr, swap_item, temp_umask,
    unlink, unload, cpython_only, TESTFN_UNENCODABLE,
    temp_dir, DirsOnSysPath)
from test.support import script_helper
from test.test_importlib.util import uncache


skip_if_dont_write_bytecode = unittest.skipIf(
        sys.dont_write_bytecode,
        "test meaningful only when writing bytecode")

def remove_files(name):
    for f in (name + ".py",
              name + ".pyc",
              name + ".pyw",
              name + "$py.class"):
        unlink(f)
    rmtree('__pycache__')


@contextlib.contextmanager
def _ready_to_import(name=None, source=""):
    # sets up a temporary directory and removes it
    # creates the module file
    # temporarily clears the module from sys.modules (if any)
    # reverts or removes the module when cleaning up
    name = name or "spam"
    with temp_dir() as tempdir:
        path = script_helper.make_script(tempdir, name, source)
        old_module = sys.modules.pop(name, None)
        try:
            sys.path.insert(0, tempdir)
            yield name, path
            sys.path.remove(tempdir)
        finally:
            if old_module is not None:
                sys.modules[name] = old_module
            elif name in sys.modules:
                del sys.modules[name]


class ImportTests(unittest.TestCase):

    def setUp(self):
        remove_files(TESTFN)
        importlib.invalidate_caches()

    def tearDown(self):
        unload(TESTFN)

    def test_import_raises_ModuleNotFoundError(self):
        with self.assertRaises(ModuleNotFoundError):
            import something_that_should_not_exist_anywhere

    def test_from_import_missing_module_raises_ModuleNotFoundError(self):
        with self.assertRaises(ModuleNotFoundError):
            from something_that_should_not_exist_anywhere import blah

    def test_from_import_missing_attr_raises_ImportError(self):
        with self.assertRaises(ImportError):
            from importlib import something_that_should_not_exist_anywhere

    def test_from_import_missing_attr_has_name_and_path(self):
        with self.assertRaises(ImportError) as cm:
            from os import i_dont_exist
        self.assertEqual(cm.exception.name, 'os')
        self.assertEqual(cm.exception.path, os.__file__)
        self.assertRegex(str(cm.exception), r"cannot import name 'i_dont_exist' from 'os' \(.*os.py\)")

    @cpython_only
    def test_from_import_missing_attr_has_name_and_so_path(self):
        import _testcapi
        with self.assertRaises(ImportError) as cm:
            from _testcapi import i_dont_exist
        self.assertEqual(cm.exception.name, '_testcapi')
        self.assertEqual(cm.exception.path, _testcapi.__file__)
        self.assertRegex(str(cm.exception), r"cannot import name 'i_dont_exist' from '_testcapi' \(.*\.(so|pyd)\)")

    def test_from_import_missing_attr_has_name(self):
        with self.assertRaises(ImportError) as cm:
            # _warning has no path as it's a built-in module.
            from _warning import i_dont_exist
        self.assertEqual(cm.exception.name, '_warning')
        self.assertIsNone(cm.exception.path)

    def test_from_import_missing_attr_path_is_canonical(self):
        with self.assertRaises(ImportError) as cm:
            from os.path import i_dont_exist
        self.assertIn(cm.exception.name, {'posixpath', 'ntpath'})
        self.assertIsNotNone(cm.exception)

    def test_from_import_star_invalid_type(self):
        import re
        with _ready_to_import() as (name, path):
            with open(path, 'w') as f:
                f.write("__all__ = [b'invalid_type']")
            globals = {}
            with self.assertRaisesRegex(
                TypeError, f"{re.escape(name)}\\.__all__ must be str"
            ):
                exec(f"from {name} import *", globals)
            self.assertNotIn(b"invalid_type", globals)
        with _ready_to_import() as (name, path):
            with open(path, 'w') as f:
                f.write("globals()[b'invalid_type'] = object()")
            globals = {}
            with self.assertRaisesRegex(
                TypeError, f"{re.escape(name)}\\.__dict__ must be str"
            ):
                exec(f"from {name} import *", globals)
            self.assertNotIn(b"invalid_type", globals)

    def test_case_sensitivity(self):
        # Brief digression to test that import is case-sensitive:  if we got
        # this far, we know for sure that "random" exists.
        with self.assertRaises(ImportError):
            import RAnDoM

    def test_double_const(self):
        # Another brief digression to test the accuracy of manifest float
        # constants.
        from test import double_const  # don't blink -- that *was* the test

    def test_import(self):
        def test_with_extension(ext):
            # The extension is normally ".py", perhaps ".pyw".
            source = TESTFN + ext
            if is_jython:
                pyc = TESTFN + "$py.class"
            else:
                pyc = TESTFN + ".pyc"

            with open(source, "w") as f:
                print("# This tests Python's ability to import a",
                      ext, "file.", file=f)
                a = random.randrange(1000)
                b = random.randrange(1000)
                print("a =", a, file=f)
                print("b =", b, file=f)

            if TESTFN in sys.modules:
                del sys.modules[TESTFN]
            importlib.invalidate_caches()
            try:
                try:
                    mod = __import__(TESTFN)
                except ImportError as err:
                    self.fail("import from %s failed: %s" % (ext, err))

                self.assertEqual(mod.a, a,
                    "module loaded (%s) but contents invalid" % mod)
                self.assertEqual(mod.b, b,
                    "module loaded (%s) but contents invalid" % mod)
            finally:
                forget(TESTFN)
                unlink(source)
                unlink(pyc)

        sys.path.insert(0, os.curdir)
        try:
            test_with_extension(".py")
            if sys.platform.startswith("win"):
                for ext in [".PY", ".Py", ".pY", ".pyw", ".PYW", ".pYw"]:
                    test_with_extension(ext)
        finally:
            del sys.path[0]

    def test_module_with_large_stack(self, module='longlist'):
        # Regression test for http://bugs.python.org/issue561858.
        filename = module + '.py'

        # Create a file with a list of 65000 elements.
        with open(filename, 'w') as f:
            f.write('d = [\n')
            for i in range(65000):
                f.write('"",\n')
            f.write(']')

        try:
            # Compile & remove .py file; we only need .pyc.
            # Bytecode must be relocated from the PEP 3147 bytecode-only location.
            py_compile.compile(filename)
        finally:
            unlink(filename)

        # Need to be able to load from current dir.
        sys.path.append('')
        importlib.invalidate_caches()

        namespace = {}
        try:
            make_legacy_pyc(filename)
            # This used to crash.
            exec('import ' + module, None, namespace)
        finally:
            # Cleanup.
            del sys.path[-1]
            unlink(filename + 'c')
            unlink(filename + 'o')

            # Remove references to the module (unload the module)
            namespace.clear()
            try:
                del sys.modules[module]
            except KeyError:
                pass

    def test_failing_import_sticks(self):
        source = TESTFN + ".py"
        with open(source, "w") as f:
            print("a = 1/0", file=f)

        # New in 2.4, we shouldn't be able to import that no matter how often
        # we try.
        sys.path.insert(0, os.curdir)
        importlib.invalidate_caches()
        if TESTFN in sys.modules:
            del sys.modules[TESTFN]
        try:
            for i in [1, 2, 3]:
                self.assertRaises(ZeroDivisionError, __import__, TESTFN)
                self.assertNotIn(TESTFN, sys.modules,
                                 "damaged module in sys.modules on %i try" % i)
        finally:
            del sys.path[0]
            remove_files(TESTFN)

    def test_import_name_binding(self):
        # import x.y.z binds x in the current namespace
        import test as x
        import test.support
        self.assertIs(x, test, x.__name__)
        self.assertTrue(hasattr(test.support, "__file__"))

        # import x.y.z as w binds z as w
        import test.support as y
        self.assertIs(y, test.support, y.__name__)

    def test_issue31286(self):
        # import in a 'finally' block resulted in SystemError
        try:
            x = ...
        finally:
            import test.support.script_helper as x

        # import in a 'while' loop resulted in stack overflow
        i = 0
        while i < 10:
            import test.support.script_helper as x
            i += 1

        # import in a 'for' loop resulted in segmentation fault
        for i in range(2):
            import test.support.script_helper as x

    def test_failing_reload(self):
        # A failing reload should leave the module object in sys.modules.
        source = TESTFN + os.extsep + "py"
        with open(source, "w") as f:
            f.write("a = 1\nb=2\n")

        sys.path.insert(0, os.curdir)
        try:
            mod = __import__(TESTFN)
            self.assertIn(TESTFN, sys.modules)
            self.assertEqual(mod.a, 1, "module has wrong attribute values")
            self.assertEqual(mod.b, 2, "module has wrong attribute values")

            # On WinXP, just replacing the .py file wasn't enough to
            # convince reload() to reparse it.  Maybe the timestamp didn't
            # move enough.  We force it to get reparsed by removing the
            # compiled file too.
            remove_files(TESTFN)

            # Now damage the module.
            with open(source, "w") as f:
                f.write("a = 10\nb=20//0\n")

            self.assertRaises(ZeroDivisionError, importlib.reload, mod)
            # But we still expect the module to be in sys.modules.
            mod = sys.modules.get(TESTFN)
            self.assertIsNotNone(mod, "expected module to be in sys.modules")

            # We should have replaced a w/ 10, but the old b value should
            # stick.
            self.assertEqual(mod.a, 10, "module has wrong attribute values")
            self.assertEqual(mod.b, 2, "module has wrong attribute values")

        finally:
            del sys.path[0]
            remove_files(TESTFN)
            unload(TESTFN)

    @skip_if_dont_write_bytecode
    def test_file_to_source(self):
        # check if __file__ points to the source file where available
        source = TESTFN + ".py"
        with open(source, "w") as f:
            f.write("test = None\n")

        sys.path.insert(0, os.curdir)
        try:
            mod = __import__(TESTFN)
            self.assertTrue(mod.__file__.endswith('.py'))
            os.remove(source)
            del sys.modules[TESTFN]
            make_legacy_pyc(source)
            importlib.invalidate_caches()
            mod = __import__(TESTFN)
            base, ext = os.path.splitext(mod.__file__)
            self.assertEqual(ext, '.pyc')
        finally:
            del sys.path[0]
            remove_files(TESTFN)
            if TESTFN in sys.modules:
                del sys.modules[TESTFN]

    def test_import_by_filename(self):
        path = os.path.abspath(TESTFN)
        encoding = sys.getfilesystemencoding()