Add a view returning the server rules.

Closes #171.

3 files changed, 172 insertions, 3 deletions

diff --git a/api/tests/test_rules.py b/api/tests/test_rules.py
new file mode 100644
index 00000000..6552333c
--- /dev/null
+++ b/api/tests/test_rules.py
@@ -0,0 +1,35 @@
+from django_hosts.resolvers import reverse
+
+from .base import APISubdomainTestCase
+from ..views import RulesView
+
+
+class HealthcheckAPITests(APISubdomainTestCase):
+    def setUp(self):
+        super().setUp()
+        self.client.force_authenticate(user=None)
+
+    def test_can_access_rules_view(self):
+        url = reverse('rules', host='api')
+        response = self.client.get(url)
+
+        self.assertEqual(response.status_code, 200)
+        self.assertIsInstance(response.json(), list)
+
+    def test_link_format_query_param_produces_different_results(self):
+        url = reverse('rules', host='api')
+        markdown_links_response = self.client.get(url + '?link_format=md')
+        html_links_response = self.client.get(url + '?link_format=html')
+        self.assertNotEqual(
+            markdown_links_response.json(),
+            html_links_response.json()
+        )
+
+    def test_format_link_raises_value_error_for_invalid_target(self):
+        with self.assertRaises(ValueError):
+            RulesView._format_link("a", "b", "c")
+
+    def test_get_returns_400_for_wrong_link_format(self):
+        url = reverse('rules', host='api')
+        response = self.client.get(url + '?link_format=unknown')
+        self.assertEqual(response.status_code, 400)
diff --git a/api/urls.py b/api/urls.py
index 7d6a4f7d..66d3fb9e 100644
--- a/api/urls.py
+++ b/api/urls.py
@@ -1,7 +1,7 @@
 from django.urls import include, path
 from rest_framework.routers import DefaultRouter
 
-from .views import HealthcheckView
+from .views import HealthcheckView, RulesView
 from .viewsets import (
     DocumentationLinkViewSet, InfractionViewSet,
     OffTopicChannelNameViewSet, RoleViewSet,
@@ -63,5 +63,6 @@ urlpatterns = (
     # from django_hosts.resolvers import reverse
     # snake_name_endpoint = reverse('bot:snakename-list', host='api')  # `bot/` endpoints
     path('bot/', include((bot_router.urls, 'api'), namespace='bot')),
-    path('healthcheck', HealthcheckView.as_view(), name='healthcheck')
+    path('healthcheck', HealthcheckView.as_view(), name='healthcheck'),
+    path('rules', RulesView.as_view(), name='rules')
 )
diff --git a/api/views.py b/api/views.py
index c5582ec0..6a269618 100644
--- a/api/views.py
+++ b/api/views.py
@@ -1,3 +1,4 @@
+from rest_framework.exceptions import ParseError
 from rest_framework.response import Response
 from rest_framework.views import APIView
 
@@ -17,7 +18,7 @@ class HealthcheckView(APIView):
     Seems to be.
 
     ## Authentication
-    Does not require any authentication nor permissions..
+    Does not require any authentication nor permissions.
     """
 
     authentication_classes = ()
@@ -25,3 +26,135 @@ class HealthcheckView(APIView):
 
     def get(self, request, format=None):  # noqa
         return Response({'status': 'ok'})
+
+
+class RulesView(APIView):
+    """
+    Return a list of the server's rules.
+
+    ## Routes
+    ### GET /rules
+    Returns a JSON array containing the server's rules:
+
+    >>> [
+    ...     "Eat candy.",
+    ...     "Wake up at 4 AM.",
+    ...     "Take your medicine."
+    ... ]
+
+    Since some of the the rules require links, this view
+    gives you the option to return rules in either Markdown
+    or HTML format by specifying the `format`.
+
+    ## Authentication
+    Does not require any authentication nor permissions.
+    """
+
+    authentication_classes = ()
+    permission_classes = ()
+
+    @staticmethod
+    def _format_link(description, link, target):
+        """
+        Build the markup necessary to render `link` with `description`
+        as its description in the given `target` language.
+
+        Arguments:
+            description (str):
+                A textual description of the string. Represents the content
+                between the `<a>` tags in HTML, or the content between the
+                array brackets in Markdown.
+
+            link (str):
+                The resulting link that a user should be redirected to
+                upon clicking the generated element.
+
+            target (str):
+                One of `{'md', 'html'}`, denoting the target format that the
+                link should be rendered in.
+
+        Returns:
+            str:
+                The link, rendered appropriately for the given `target` format
+                using `description` as its textual description.
+
+        Raises:
+            ValueError:
+                If `target` is not `'md'` or `'html'`.
+        """
+
+        if target == 'html':
+            return f'<a href="{link}">{description}</a>'
+        elif target == 'md':
+            return f'[{description}]({link})'
+        else:
+            raise ValueError(
+                f"Can only template links to `html` or `md`, got `{target}`"
+            )
+
+
+    # `format` here is the result format, we have a link format here instead.
+    def get(self, request, format=None):  # noqa
+        link_format = request.query_params.get('link_format', 'md')
+        if link_format not in ('html', 'md'):
+            raise ParseError(
+                f"`format` must be `html` or `md`, got `{format}`."
+            )
+
+        discord_community_guidelines_link = self._format_link(
+            'Discord Community Guidelines',
+            'https://discordapp.com/guidelines',
+            link_format
+        )
+        channels_page_link = self._format_link(
+            'channels page',
+            'https://pythondiscord.com/about/channels',
+            link_format
+        )
+        google_translate_link = self._format_link(
+            'Google Translate',
+            'https://translate.google.com/',
+            link_format
+        )
+
+        return Response([
+            "Be polite, and do not spam.",
+            f"Follow the {discord_community_guidelines_link}.",
+            (
+                "Don't intentionally make other people uncomfortable - if "
+                "someone asks you to stop discussing something, you should stop."
+            ),
+            (
+                "Be patient both with users asking "
+                "questions, and the users answering them."
+            ),
+            (
+                "We will not help you with anything that might break a law or the "
+                "terms of service of any other community, site, service, or "
+                "otherwise - No piracy, brute-forcing, captcha circumvention, "
+                "sneaker bots, or anything else of that nature."
+            ),
+            (
+                "Listen to and respect the staff members - we're "
+                "here to help, but we're all human beings."
+            ),
+            (
+                "All discussion should be kept within the relevant "
+                "channels for the subject - See the "
+                f"{channels_page_link} for more information."
+            ),
+            (
+                "This is an English-speaking server, so please speak English "
+                f"to the best of your ability - {google_translate_link} "
+                "should be fine if you're not sure."
+            ),
+            (
+                "Keep all discussions safe for work - No gore, nudity, sexual "
+                "soliciting, references to suicide, or anything else of that nature"
+            ),
+            (
+                "We do not allow advertisements for communities (including "
+                "other Discord servers) or commercial projects - Contact "
+                "us directly if you want to discuss a partnership!"
+            )
+        ])