Add inline pulse rendering

This was broken from the last pulse related refactor. It affects slack
message attachments and the preview section of the pulse screen.

This introduces a render-type argument to some of the pulse rendering
functions where we can use the the correct behavior (bytes + base64
encoding or a URL + references) depending on how the image will be
used.

Testing this is difficult as this is creating images and then
depending on the render-type, encoding that image byte array into a
Base64 string. I added some very basic checks that at least ensures
the byte array is of the approximate right size. If we were rendering
it incorrectly, we'd see the byte array size much smaller. Pretty
fragile, but is the only way I could find to sanity check the results
so we don't introduce a bug like this in the future.

src/metabase/pulse/render.clj

@@ -411,11 +411,6 @@
 (defn- mb-hash-str [image-hash]
   (str image-hash "@metabase"))
 
-(defn- resource-path->content-id-pair [path]
-  (let [external-link-url (io/resource path)]
-    [(mb-hash-str (hash-image-url external-link-url))
-     external-link-url]))
-
 (defn- write-byte-array-to-temp-file
   [^bytes img-bytes]
   (let [f (doto (java.io.File/createTempFile "metabase_pulse_image_" ".png")
@@ -424,22 +419,72 @@
       (.write fos img-bytes))
     f))
 
-(defn- byte-array->content-id-pair
-  [^bytes img-bytes]
-  (let [f (write-byte-array-to-temp-file img-bytes)]
-    [(mb-hash-str (hash-bytes img-bytes))
-     (io/as-url f)]))
+(defn- byte-array->url [^bytes img-bytes]
+  (-> img-bytes write-byte-array-to-temp-file io/as-url))
+
+(defmulti ^:private make-image-bundle
+  "Create an image bundle. An image bundle contains the data needed to either encode the image inline (when
+  `RENDER-TYPE` is `:inline`), or create the hashes/references needed for an attached image (`RENDER-TYPE` of
+  `:attachment`)"
+  (fn [render-type url-or-bytes]
+    [render-type (class url-or-bytes)]))
+
+(defmethod make-image-bundle [:attachment java.net.URL]
+  [render-type ^java.net.URL url]
+  (let [content-id (mb-hash-str (hash-image-url url))]
+    {:content-id  content-id
+     :image-url   url
+     :image-src   (content-id-reference content-id)
+     :render-type render-type}))
+
+(defmethod make-image-bundle [:attachment (class (byte-array 0))]
+  [render-type image-bytes]
+  (let [image-url (byte-array->url image-bytes)
+        content-id (mb-hash-str (hash-bytes image-bytes))]
+    {:content-id  content-id
+     :image-url   image-url
+     :image-src   (content-id-reference content-id)
+     :render-type render-type}))
+
+(defmethod make-image-bundle [:inline java.net.URL]
+  [render-type ^java.net.URL url]
+  {:image-src   (-> url io/input-stream IOUtils/toByteArray render-img-data-uri)
+   :image-url   url
+   :render-type render-type})
+
+(defmethod make-image-bundle [:inline (class (byte-array 0))]
+  [render-type image-bytes]
+  {:image-src   (render-img-data-uri image-bytes)
+   :render-type render-type})
+
+(def ^:private external-link-url (io/resource "frontend_client/app/assets/img/external_link.png"))
+(def ^:private no-results-url    (io/resource "frontend_client/app/assets/img/pulse_no_results@2x.png"))
 
 (def ^:private external-link-image
   (delay
-   (resource-path->content-id-pair "frontend_client/app/assets/img/external_link.png")))
+   (make-image-bundle :attachment external-link-url)))
 
 (def ^:private no-results-image
   (delay
-   (resource-path->content-id-pair "frontend_client/app/assets/img/pulse_no_results@2x.png")))
+   (make-image-bundle :attachment no-results-url)))
+
+(defn- external-link-image-bundle [render-type]
+  (case render-type
+    :attachment @external-link-image
+    :inline (make-image-bundle render-type external-link-url)))
+
+(defn- no-results-image-bundle [render-type]
+  (case render-type
+    :attachment @no-results-image
+    :inline (make-image-bundle render-type no-results-url)))
+
+(defn- image-bundle->attachment [{:keys [render-type content-id image-url]}]
+  (case render-type
+    :attachment {content-id image-url}
+    :inline     nil))
 
 (s/defn ^:private render:sparkline :- RenderedPulseCard
-  [timezone card {:keys [rows cols]}]
+  [render-type timezone card {:keys [rows cols]}]
   (let [ft-row (if (datetime-field? (first cols))
                  #(.getTime ^Date (u/->Timestamp %))
                  identity)
@@ -462,14 +507,14 @@
         rows'  (reverse (take-last 2 rows))
         values (map (comp format-number second) rows')
         labels (format-timestamp-pair timezone (map first rows') (first cols))
-        [content-id png-url] (byte-array->content-id-pair (render-sparkline-to-png xs' ys' 524 130))]
+        image-bundle (make-image-bundle render-type (render-sparkline-to-png xs' ys' 524 130))]
 
-    {:attachments (when (and content-id png-url)
-                    {content-id png-url})
+    {:attachments (when image-bundle
+                    (image-bundle->attachment image-bundle))
      :content     [:div
                    [:img {:style (style {:display :block
                                          :width :100%})
-                          :src   (content-id-reference content-id)}]
+                          :src   (:image-src image-bundle)}]
                    [:table
                     [:tr
                      [:td {:style (style {:color         color-brand
@@ -492,13 +537,12 @@
                       (second labels)]]]]}))
 
 (s/defn ^:private render:empty :- RenderedPulseCard
-  [_ _]
-  (let [[content-id no-results-url] @no-results-image]
-    {:attachments (when (and content-id no-results-url)
-                    {content-id no-results-url})
+  [render-type _ _]
+  (let [image-bundle (no-results-image-bundle render-type)]
+    {:attachments (image-bundle->attachment image-bundle)
      :content     [:div {:style (style {:text-align :center})}
                    [:img {:style (style {:width :104px})
-                          :src   (content-id-reference content-id)}]
+                          :src   (:image-src image-bundle)}]
                    [:div {:style (style {:margin-top :8px
                                          :color      color-gray-4})}
                     "No results"]]}))
@@ -528,12 +572,12 @@
       :else                                                        :table)))
 
 (s/defn ^:private make-title-if-needed :- (s/maybe RenderedPulseCard)
-  [card]
+  [render-type card]
   (when *include-title*
-    (let [[content-id link-url] (when *include-buttons*
-                                  @external-link-image)]
-      {:attachments (when (and content-id link-url)
-                      {content-id link-url})
+    (let [image-bundle (when *include-buttons*
+                         (external-link-image-bundle render-type))]
+      {:attachments (when image-bundle
+                      (image-bundle->attachment image-bundle))
        :content     [:table {:style (style {:margin-bottom :8px
                                             :width         :100%})}
                      [:tbody
@@ -544,18 +588,18 @@
                         (when *include-buttons*
                           [:img {:style (style {:width :16px})
                                  :width 16
-                                 :src   (content-id-reference content-id)}])]]]]})))
+                                 :src   (:image-src image-bundle)}])]]]]})))
 
 (s/defn ^:private render-pulse-card-body :- RenderedPulseCard
-  [timezone card {:keys [data error]}]
+  [render-type timezone card {:keys [data error]}]
   (try
     (when error
       (let [^String msg (tru "Card has errors: {0}" error)]
         (throw (Exception. msg))))
     (case (detect-pulse-card-type card data)
-      :empty     (render:empty     card data)
+      :empty     (render:empty     render-type card data)
       :scalar    (render:scalar    timezone card data)
-      :sparkline (render:sparkline timezone card data)
+      :sparkline (render:sparkline render-type timezone card data)
       :bar       (render:bar       timezone card data)
       :table     (render:table     timezone card data)
       {:attachments nil
@@ -572,11 +616,11 @@
                                           :padding     :16px})}
                      "An error occurred while displaying this card."]})))
 
-(s/defn render-pulse-card :- RenderedPulseCard
+(s/defn ^:private render-pulse-card :- RenderedPulseCard
   "Render a single CARD for a `Pulse` to Hiccup HTML. RESULT is the QP results."
-  [timezone card results]
-  (let [{title :content title-attachments :attachments} (make-title-if-needed card)
-        {pulse-body :content body-attachments :attachments} (render-pulse-card-body timezone card results)]
+  [render-type timezone card results]
+  (let [{title :content title-attachments :attachments} (make-title-if-needed render-type card)
+        {pulse-body :content body-attachments :attachments} (render-pulse-card-body render-type timezone card results)]
     {:attachments (merge title-attachments body-attachments)
      :content     [:a {:href   (card-href card)
                        :target "_blank"
@@ -592,13 +636,13 @@
   "Same as `render-pulse-card` but isn't intended for an email, rather for previewing so there is no need for
   attachments"
   [timezone card results]
-  (:content (render-pulse-card timezone card results)))
+  (:content (render-pulse-card :inline timezone card results)))
 
 (s/defn render-pulse-section :- RenderedPulseCard
   "Render a specific section of a Pulse, i.e. a single Card, to Hiccup HTML."
   [timezone {:keys [card result]}]
   (let [{:keys [attachments content]} (binding [*include-title* true]
-                                        (render-pulse-card timezone card result))]
+                                        (render-pulse-card :attachment timezone card result))]
     {:attachments attachments
      :content     [:div {:style (style {:margin-top       :10px
                                         :margin-bottom    :20px
@@ -611,4 +655,4 @@
 (defn render-pulse-card-to-png
   "Render a PULSE-CARD as a PNG. DATA is the `:data` from a QP result (I think...)"
   ^bytes [timezone pulse-card result]
-  (render-html-to-png (render-pulse-card timezone pulse-card result) card-width))
+  (render-html-to-png (render-pulse-card :inline timezone pulse-card result) card-width))