From c46a6918165cb2a3851105a679c5567418c15e50 Mon Sep 17 00:00:00 2001
From: YuviPanda <yuvipanda@gmail.com>
Date: Fri, 2 Aug 2024 19:00:28 -0700
Subject: [PATCH] Add OpenGraph social card support

---
 binderhub/app.py              | 19 +++++++++++++++----
 binderhub/main.py             | 33 +++++++++++++++++++++++++++++++--
 binderhub/templates/page.html |  4 ++--
 3 files changed, 48 insertions(+), 8 deletions(-)

diff --git a/binderhub/app.py b/binderhub/app.py
index 50816a59f..2b5e34484 100644
--- a/binderhub/app.py
+++ b/binderhub/app.py
@@ -50,7 +50,7 @@
 from .health import HealthHandler, KubernetesHealthHandler
 from .launcher import Launcher
 from .log import log_request
-from .main import LegacyRedirectHandler, MainHandler
+from .main import LegacyRedirectHandler, RepoLaunchUIHandler, UIHandler
 from .metrics import MetricsHandler
 from .quota import KubernetesLaunchQuota, LaunchQuota
 from .ratelimit import RateLimiter
@@ -989,14 +989,24 @@ def initialize(self, *args, **kwargs):
             (r"/versions", VersionHandler),
             (r"/build/([^/]+)/(.+)", BuildHandler),
             (r"/health", self.health_handler_class, {"hub_url": self.hub_url_local}),
+            (r"/api/repoproviders", RepoProvidersHandlers),
         ]
         if not self.enable_api_only_mode:
             # In API only mode the endpoints in the list below
-            # are unregistered as they don't make sense in a API only scenario
+            # are not registered since they are primarily about providing UI
+
+            for provider_id in self.repo_providers:
+                # Register launchable URLs for all our repo providers
+                # These render social previews, but otherwise redirect to UIHandler
+                handlers += [
+                    (
+                        rf"/v2/({provider_id})/(.+)",
+                        RepoLaunchUIHandler,
+                        {"repo_provider": self.repo_providers[provider_id]},
+                    )
+                ]
             handlers += [
-                (r"/(?:v2/.*|about)?", MainHandler),
                 (r"/repo/([^/]+)/([^/]+)(/.*)?", LegacyRedirectHandler),
-                (r"/api/repoproviders", RepoProvidersHandlers),
                 # for backward-compatible mybinder.org badge URLs
                 # /assets/images/badge.svg
                 (
@@ -1062,6 +1072,7 @@ def initialize(self, *args, **kwargs):
                         )
                     },
                 ),
+                (r"/.*", UIHandler),
             ]
         # This needs to be the last handler in the list, because it needs to match "everything else"
         handlers.append((r".*", Custom404))
diff --git a/binderhub/main.py b/binderhub/main.py
index e42ee8c2d..7d66c5303 100644
--- a/binderhub/main.py
+++ b/binderhub/main.py
@@ -9,8 +9,14 @@
 from .base import BaseHandler
 
 
-class MainHandler(BaseHandler):
-    """Main handler for requests"""
+class UIHandler(BaseHandler):
+    """
+    Responds to most UI Page Requests
+    """
+
+    def initialize(self):
+        self.opengraph_title = "The Binder Project"
+        return super().initialize()
 
     @authenticated
     def get(self):
@@ -32,7 +38,30 @@ def get(self):
             "page.html",
             page_config=page_config,
             extra_footer_scripts=self.settings["extra_footer_scripts"],
+            opengraph_title=self.opengraph_title,
+        )
+
+
+class RepoLaunchUIHandler(UIHandler):
+    """
+    Responds to /v2/ launch URLs only
+
+    Forwards to UIHandler, but puts out an opengraph_title for social previews
+    """
+
+    def initialize(self, repo_provider):
+        self.repo_provider = repo_provider
+        return super().initialize()
+
+    @authenticated
+    def get(self, provider_id, _escaped_spec):
+        prefix = "/v2/" + provider_id
+        spec = self.get_spec_from_request(prefix).rstrip("/")
+
+        self.opengraph_title = (
+            f"{self.repo_provider.display_config['displayName']}: {spec}"
         )
+        return super().get()
 
 
 class LegacyRedirectHandler(BaseHandler):
diff --git a/binderhub/templates/page.html b/binderhub/templates/page.html
index 212d61ef5..6b6780d27 100644
--- a/binderhub/templates/page.html
+++ b/binderhub/templates/page.html
@@ -5,8 +5,8 @@
   <title>{% block title %}Binder{% endblock %}</title>
   {% block meta_social %}
   {# Social media previews #}
-  <meta property="og:title" content="The Binder Project">
-  <meta property="og:image" content="https://mybinder.org/static/images/logo_social.png">
+  <meta property="og:title" content="{{opengraph_title}}">
+  <meta property="og:image" content="{{static_url("images/logo_social.png")}}">
   <meta property="og:description" content="Reproducible, sharable, open, interactive computing environments.">
   <meta property="og:image:width" content="1334">
   <meta property="og:image:height" content="700">