import os.path
import sys
import tempfile
import unittest
from contextlib import contextmanager

from django.template import TemplateDoesNotExist
from django.template.engine import Engine
from django.test import SimpleTestCase, override_settings
from django.utils.functional import lazystr

from .utils import TEMPLATE_DIR


class CachedLoaderTests(SimpleTestCase):

    def setUp(self):
        self.engine = Engine(
            dirs=[TEMPLATE_DIR],
            loaders=[
                ('django.template.loaders.cached.Loader', [
                    'django.template.loaders.filesystem.Loader',
                ]),
            ],
        )

    def test_get_template(self):
        template = self.engine.get_template('index.html')
        self.assertEqual(template.origin.name, os.path.join(TEMPLATE_DIR, 'index.html'))
        self.assertEqual(template.origin.template_name, 'index.html')
        self.assertEqual(template.origin.loader, self.engine.template_loaders[0].loaders[0])

        cache = self.engine.template_loaders[0].get_template_cache
        self.assertEqual(cache['index.html'], template)

        # Run a second time from cache
        template = self.engine.get_template('index.html')
        self.assertEqual(template.origin.name, os.path.join(TEMPLATE_DIR, 'index.html'))
        self.assertEqual(template.origin.template_name, 'index.html')
        self.assertEqual(template.origin.loader, self.engine.template_loaders[0].loaders[0])

    def test_get_template_missing_debug_off(self):
        """
        With template debugging disabled, the raw TemplateDoesNotExist class
        should be cached when a template is missing. See ticket #26306 and
        docstrings in the cached loader for details.
        """
        self.engine.debug = False
        with self.assertRaises(TemplateDoesNotExist):
            self.engine.get_template('prod-template-missing.html')
        e = self.engine.template_loaders[0].get_template_cache['prod-template-missing.html']
        self.assertEqual(e, TemplateDoesNotExist)

    def test_get_template_missing_debug_on(self):
        """
        With template debugging enabled, a TemplateDoesNotExist instance
        should be cached when a template is missing.
        """
        self.engine.debug = True
        with self.assertRaises(TemplateDoesNotExist):
            self.engine.get_template('debug-template-missing.html')
        e = self.engine.template_loaders[0].get_template_cache['debug-template-missing.html']
        self.assertIsInstance(e, TemplateDoesNotExist)
        self.assertEqual(e.args[0], 'debug-template-missing.html')

    def test_cached_exception_no_traceback(self):
        """
        When a TemplateDoesNotExist instance is cached, the cached instance
        should not contain the __traceback__, __context__, or __cause__
        attributes that Python sets when raising exceptions.
        """
        self.engine.debug = True
        with self.assertRaises(TemplateDoesNotExist):
            self.engine.get_template('no-traceback-in-cache.html')
        e = self.engine.template_loaders[0].get_template_cache['no-traceback-in-cache.html']

        error_msg = "Cached TemplateDoesNotExist must not have been thrown."
        self.assertIsNone(e.__traceback__, error_msg)
        self.assertIsNone(e.__context__, error_msg)
        self.assertIsNone(e.__cause__, error_msg)

    def test_template_name_leading_dash_caching(self):
        """
        #26536 -- A leading dash in a template name shouldn't be stripped
        from its cache key.
        """
        self.assertEqual(self.engine.template_loaders[0].cache_key('-template.html', []), '-template.html')

    def test_template_name_lazy_string(self):
        """
        #26603 -- A template name specified as a lazy string should be forced
        to text before computing its cache key.
        """
        self.assertEqual(self.engine.template_loaders[0].cache_key(lazystr('template.html'), []), 'template.html')


class FileSystemLoaderTests(SimpleTestCase):

    @classmethod
    def setUpClass(cls):
        cls.engine = Engine(dirs=[TEMPLATE_DIR], loaders=['django.template.loaders.filesystem.Loader'])
        super().setUpClass()

    @contextmanager
    def set_dirs(self, dirs):
        original_dirs = self.engine.dirs
        self.engine.dirs = dirs
        try:
            yield
        finally:
            self.engine.dirs = original_dirs

    @contextmanager
    def source_checker(self, dirs):
        loader = self.engine.template_loaders[0]

        def check_sources(path, expected_sources):
            expected_sources = [os.path.abspath(s) for s in expected_sources]
            self.assertEqual(
                [origin.name for origin in loader.get_template_sources(path)],
                expected_sources,
            )

        with self.set_dirs(dirs):
            yield check_sources

    def test_get_template(self):
        template = self.engine.get_template('index.html')
        self.assertEqual(template.origin.name, os.path.join(TEMPLATE_DIR, 'index.html'))
        self.assertEqual(template.origin.template_name, 'index.html')
        self.assertEqual(template.origin.loader, self.engine.template_loaders[0])
        self.assertEqual(template.origin.loader_name, 'django.template.loaders.filesystem.Loader')

    def test_loaders_dirs(self):
        engine = Engine(loaders=[('django.template.loaders.filesystem.Loader', [TEMPLATE_DIR])])
        template = engine.get_template('index.html')
        self.assertEqual(template.origin.name, os.path.join(TEMPLATE_DIR, 'index.html'))

    def test_loaders_dirs_empty(self):
        """An empty dirs list in loaders overrides top level dirs."""
        engine = Engine(dirs=[TEMPLATE_DIR], loaders=[('django.template.loaders.filesystem.Loader', [])])
        with self.assertRaises(TemplateDoesNotExist):
            engine.get_template('index.html')

    def test_directory_security(self):
        with self.source_checker(['/dir1', '/dir2']) as check_sources:
            check_sources('index.html', ['/dir1/index.html', '/dir2/index.html'])
            check_sources('/etc/passwd', [])
            check_sources('etc/passwd', ['/dir1/etc/passwd', '/dir2/etc/passwd'])
            check_sources('../etc/passwd', [])
            check_sources('../../../etc/passwd', [])
            check_sources('/dir1/index.html', ['/dir1/index.html'])
            check_sources('../dir2/index.html', ['/dir2/index.html'])
            check_sources('/dir1blah', [])
            check_sources('../dir1blah', [])

    def test_unicode_template_name(self):
        with self.source_checker(['/dir1', '/dir2']) as check_sources:
            # UTF-8 bytestrings are permitted.
            check_sources(b'\xc3\x85ngstr\xc3\xb6m', ['/dir1/Ångström', '/dir2/Ångström'])
            # Strings are permitted.
            check_sources('Ångström', ['/dir1/Ångström', '/dir2/Ångström'])

    def test_utf8_bytestring(self):
        """
        Invalid UTF-8 encoding in bytestrings should raise a useful error
        """
        engine = self.engine
        loader = engine.template_loaders[0]
        with self.assertRaises(UnicodeDecodeError):
            list(loader.get_template_sources(b'\xc3\xc3'))

    def test_unicode_dir_name(self):
        with self.source_checker([b'/Stra\xc3\x9fe']) as check_sources:
            check_sources('Ångström', ['/Straße/Ångström'])
            check_sources(b'\xc3\x85ngstr\xc3\xb6m', ['/Straße/Ångström'])

    @unittest.skipUnless(
        os.path.normcase('/TEST') == os.path.normpath('/test'),
        "This test only runs on case-sensitive file systems.",
    )
    def test_case_sensitivity(self):
        with self.source_checker(['/dir1', '/DIR2']) as check_sources:
            check_sources('index.html', ['/dir1/index.html', '/DIR2/index.html'])
            check_sources('/DIR1/index.HTML', ['/DIR1/index.HTML'])

    def test_file_does_not_exist(self):
        with self.assertRaises(TemplateDoesNotExist):
            self.engine.get_template('doesnotexist.html')

    @unittest.skipIf(
        sys.platform == 'win32',
        "Python on Windows doesn't have working os.chmod().",
    )
    def test_permissions_error(self):
        with tempfile.NamedTemporaryFile() as tmpfile:
            tmpdir = os.path.dirname(tmpfile.name)
            tmppath = os.path.join(tmpdir, tmpfile.name)
            os.chmod(tmppath, 0o0222)
            with self.set_dirs([tmpdir]):
                with self.assertRaisesMessage(IOError, 'Permission denied'):
                    self.engine.get_template(tmpfile.name)

    def test_notafile_error(self):
        with self.assertRaises(IOError):
            self.engine.get_template('first')


class AppDirectoriesLoaderTests(SimpleTestCase):

    @classmethod
    def setUpClass(cls):
        cls.engine = Engine(
            loaders=['django.template.loaders.app_directories.Loader'],
        )
        super().setUpClass()

    @override_settings(INSTALLED_APPS=['template_tests'])
    def test_get_template(self):
        template = self.engine.get_template('index.html')
        self.assertEqual(template.origin.name, os.path.join(TEMPLATE_DIR, 'index.html'))
        self.assertEqual(template.origin.template_name, 'index.html')
        self.assertEqual(template.origin.loader, self.engine.template_loaders[0])

    @override_settings(INSTALLED_APPS=[])
    def test_not_installed(self):
        with self.assertRaises(TemplateDoesNotExist):
            self.engine.get_template('index.html')


class LocmemLoaderTests(SimpleTestCase):

    @classmethod
    def setUpClass(cls):
        cls.engine = Engine(
            loaders=[('django.template.loaders.locmem.Loader', {
                'index.html': 'index',
            })],
        )
        super().setUpClass()

    def test_get_template(self):
        template = self.engine.get_template('index.html')
        self.assertEqual(template.origin.name, 'index.html')
        self.assertEqual(template.origin.template_name, 'index.html')
        self.assertEqual(template.origin.loader, self.engine.template_loaders[0])
