import re

from django.forms import CharField, Form, Media
from django.http import HttpRequest, HttpResponse
from django.middleware.csrf import (
    CsrfViewMiddleware, _does_token_match as equivalent_tokens, get_token,
)
from django.template import TemplateDoesNotExist, TemplateSyntaxError
from django.template.backends.dummy import TemplateStrings
from django.test import SimpleTestCase


class TemplateStringsTests(SimpleTestCase):

    engine_class = TemplateStrings
    backend_name = 'dummy'
    options = {}

    @classmethod
    def setUpClass(cls):
        super().setUpClass()
        params = {
            'DIRS': [],
            'APP_DIRS': True,
            'NAME': cls.backend_name,
            'OPTIONS': cls.options,
        }
        cls.engine = cls.engine_class(params)

    def test_from_string(self):
        template = self.engine.from_string("Hello!\n")
        content = template.render()
        self.assertEqual(content, "Hello!\n")

    def test_get_template(self):
        template = self.engine.get_template('template_backends/hello.html')
        content = template.render({'name': 'world'})
        self.assertEqual(content, "Hello world!\n")

    def test_get_template_nonexistent(self):
        with self.assertRaises(TemplateDoesNotExist) as e:
            self.engine.get_template('template_backends/nonexistent.html')
        self.assertEqual(e.exception.backend, self.engine)

    def test_get_template_syntax_error(self):
        # There's no way to trigger a syntax error with the dummy backend.
        # The test still lives here to factor it between other backends.
        if self.backend_name == 'dummy':
            self.skipTest("test doesn't apply to dummy backend")
        with self.assertRaises(TemplateSyntaxError):
            self.engine.get_template('template_backends/syntax_error.html')

    def test_html_escaping(self):
        template = self.engine.get_template('template_backends/hello.html')
        context = {'name': '<script>alert("XSS!");</script>'}
        content = template.render(context)

        self.assertIn('&lt;script&gt;', content)
        self.assertNotIn('<script>', content)

    def test_django_html_escaping(self):
        if self.backend_name == 'dummy':
            self.skipTest("test doesn't apply to dummy backend")

        class TestForm(Form):
            test_field = CharField()

        media = Media(js=['my-script.js'])
        form = TestForm()
        template = self.engine.get_template('template_backends/django_escaping.html')
        content = template.render({'media': media, 'test_form': form})

        expected = '{}\n\n{}\n\n{}'.format(media, form, form['test_field'])

        self.assertHTMLEqual(content, expected)

    def test_csrf_token(self):
        request = HttpRequest()
        CsrfViewMiddleware(lambda req: HttpResponse()).process_view(request, lambda r: None, (), {})

        template = self.engine.get_template('template_backends/csrf.html')
        content = template.render(request=request)

        expected = '<input type="hidden" name="csrfmiddlewaretoken" value="([^"]+)">'
        match = re.match(expected, content) or re.match(expected.replace('"', "'"), content)
        self.assertTrue(match, "hidden csrftoken field not found in output")
        self.assertTrue(equivalent_tokens(match[1], get_token(request)))

    def test_no_directory_traversal(self):
        with self.assertRaises(TemplateDoesNotExist):
            self.engine.get_template('../forbidden/template_backends/hello.html')

    def test_non_ascii_characters(self):
        template = self.engine.get_template('template_backends/hello.html')
        content = template.render({'name': 'Jérôme'})
        self.assertEqual(content, "Hello Jérôme!\n")