ui: better ogp meta on problem_detail page

packages/ui-default/templates/layout/basic.html

@@ -23,3 +23,5 @@
 </div>
 {% if UserContext and not handler.user._id %}{% include "partials/login_dialog.html" %}{% endif %}
 {% endblock %}
+{% block ogp %}
+{% endblock %}

packages/ui-default/templates/layout/html5.html

@@ -19,12 +19,14 @@
   <link rel="icon" type="image/png" href="{{ UiContext.cdn_prefix }}favicon-16x16.png" sizes="16x16">
   {% if handler.context.request.url %}<link rel="canonical" href="{{ model.system.get('server.url') }}{{ handler.context.request.url.substring(1) }}">{% endif %}
   <meta name="theme-color" content="#56758f">
-  {% block ogp %}
+  {% block ogp_site %}
   <meta property="og:site_name" content="{{ (handler.domain|default({ui:[]})).ui.name|default(model.system.get('server.name')) }}" />
-  <meta property="og:title" content="{{ handler.renderTitle(page_name) }}" />
   <meta property="og:url" content="{{ model.system.get('server.url') }}{{ handler.request.path.slice(1) }}" />
   <meta property="og:image" content="{{ UiContext.cdn_prefix }}favicon-96x96.png" />
   {% endblock %}
+  {% block ogp %}
+  <meta property="og:title" content="{{ handler.renderTitle(page_name) }}" />
+  {% endblock %}
   <title>{{ handler.renderTitle(page_name) }}</title>
   <style>
     body {

packages/ui-default/templates/partials/problem_description.html

@@ -19,5 +19,9 @@
       <p>{{ _('You cannot submit for this problem because the contest is ended. You can click "Open in Problem Set" to view this problem in normal mode.') }}</p>
     </blockquote>
   {% endif %}
-  {{ pdoc.content|content(handler.request.query.lang or handler.user.viewLang or handler.session.viewLang, pdoc.html)|safe }}
+  {% if not renderredContent %}
+    {% set preferredLang = handler.request.query.lang or handler.user.viewLang or handler.session.viewLang %}
+    {% set renderredContent = pdoc.content|content(preferredLang, pdoc.html) %}
+  {% endif %}
+  {{ renderredContent|safe }}
 </div>

packages/ui-default/templates/problem_detail.html

@@ -24,6 +24,22 @@
   {{ set(UiContext, 'pretestConnUrl', "record-conn?pretest=1&uidOrName=" + handler.user._id + "&pid=" + pdoc.docId + "&domainId=" + handler.args.domainId) }}
 {% endif %}
 </script>
+{% if not tdoc %}
+  {% block ogp %}
+    {% set preferredLang = handler.request.query.lang or handler.user.viewLang or handler.session.viewLang %}
+    {% set renderredContent = pdoc.content|content(preferredLang, pdoc.html) %}
+    {% set langs = pdoc.content|contentLang %}
+    {% for k in langs %}
+      {% if k != preferredLang %}
+        <meta property="og:locale:alternate" content="{{ k }}" />
+      {% else %}
+        <meta property="og:locale" content="{{ k }}" />
+      {% endif %}
+    {% endfor %}
+    <meta property="og:title" content="{{ pdoc.pid|default(pdoc.docId) }}. {{ pdoc.title }} - {{ model.system.get('server.name') }}" />
+    <meta property="og:description" content="{{ renderredContent|problemPreview|truncate(100, true) }}" />
+  {% endblock %}
+{% endif %}
 <div class="row" data-sticky-parent>
   <div class="medium-9 columns">
     <div class="section">