import re

from django.forms import CharField, Form, Media
from django.http import HttpRequest, HttpResponse
from django.middleware.csrf import (
    CSRF_TOKEN_LENGTH,
    CsrfViewMiddleware,
    _unmask_cipher_token,
    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 check_tokens_equivalent(self, token1, token2):
        self.assertEqual(len(token1), CSRF_TOKEN_LENGTH)
        self.assertEqual(len(token2), CSRF_TOKEN_LENGTH)
        token1, token2 = map(_unmask_cipher_token, (token1, token2))
        self.assertEqual(token1, token2)

    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.check_tokens_equivalent(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")