add download link in lightbox

app/assets/javascripts/discourse/lib/lightbox.js

@@ -9,7 +9,17 @@ Discourse.Lightbox = {
   apply: function($elem) {
     $LAB.script("/javascripts/jquery.magnific-popup-min.js").wait(function() {
       $('a.lightbox', $elem).each(function(i, e) {
-        $(e).magnificPopup({ type: 'image', closeOnContentClick: true });
+        $(e).magnificPopup({
+          type: 'image',
+          closeOnContentClick: true,
+
+          image: {
+            titleSrc: function(item) {
+              return item.el.attr('title') + ' &middot; <a class="image-source-link" href="' + item.src + '" target="_blank">' + I18n.t("lightbox.download") + '</a>';
+            }
+          }
+
+        });
       });
     });
   }

config/locales/client.en.yml

@@ -1438,3 +1438,6 @@ en:
           rate_limits: 'Rate Limits'
           developer: 'Developer'
           uncategorized: 'Uncategorized'
+
+    lightbox:
+      download: "download"

lib/cooked_post_processor.rb

@@ -170,6 +170,8 @@ class CookedPostProcessor
     informations = "#{original_width}x#{original_height}"
     informations << " #{number_to_human_size(upload.filesize)}" if upload
 
+    a["title"] = filename
+
     meta.add_child create_span_node("filename", filename)
     meta.add_child create_span_node("informations", informations)
     meta.add_child create_span_node("expand")

spec/components/cooked_post_processor_spec.rb

@@ -94,7 +94,7 @@ describe CookedPostProcessor do
 
       it "generates overlay information" do
         cpp.post_process_images
-        cpp.html.should match_html '<div><a href="/uploads/default/1/1234567890123456.jpg" class="lightbox"><img src="/uploads/default/_optimized/da3/9a3/ee5e6b4b0d_690x1380.jpg" width="690" height="1380"><div class="meta">
+        cpp.html.should match_html '<div><a href="/uploads/default/1/1234567890123456.jpg" class="lightbox" title="uploaded.jpg"><img src="/uploads/default/_optimized/da3/9a3/ee5e6b4b0d_690x1380.jpg" width="690" height="1380"><div class="meta">
 <span class="filename">uploaded.jpg</span><span class="informations">1000x2000 1.21 KB</span><span class="expand"></span>
 </div></a></div>'
         cpp.should be_dirty