From 2b35dce0372ea8eab4e034a00f38fe114a503566 Mon Sep 17 00:00:00 2001
From: Andrey Antukh <niwi@niwi.nz>
Date: Thu, 15 Apr 2021 17:33:52 +0200
Subject: [PATCH] :tada: Add cache for font fetching on embedd ns.

---
 frontend/src/app/main/repo.cljs               |  9 ++--
 .../src/app/main/ui/shapes/text/embed.cljs    | 46 ++++++++++++++-----
 2 files changed, 40 insertions(+), 15 deletions(-)

diff --git a/frontend/src/app/main/repo.cljs b/frontend/src/app/main/repo.cljs
index ef9050268..3d2a167a7 100644
--- a/frontend/src/app/main/repo.cljs
+++ b/frontend/src/app/main/repo.cljs
@@ -7,12 +7,13 @@
 (ns app.main.repo
   (:require
    [app.common.data :as d]
-   [beicon.core :as rx]
-   [lambdaisland.uri :as u]
-   [cuerdas.core :as str]
    [app.config :as cfg]
+   [app.util.http :as http]
+   [app.util.time :as dt]
    [app.util.transit :as t]
-   [app.util.http :as http]))
+   [beicon.core :as rx]
+   [cuerdas.core :as str]
+   [lambdaisland.uri :as u]))
 
 (defn- handle-response
   [{:keys [status body] :as response}]
diff --git a/frontend/src/app/main/ui/shapes/text/embed.cljs b/frontend/src/app/main/ui/shapes/text/embed.cljs
index 4e8030497..1b1475a60 100644
--- a/frontend/src/app/main/ui/shapes/text/embed.cljs
+++ b/frontend/src/app/main/ui/shapes/text/embed.cljs
@@ -11,6 +11,7 @@
    [app.common.text :as txt]
    [app.main.fonts :as fonts]
    [app.util.http :as http]
+   [app.util.time :as dt]
    [app.util.webapi :as wapi]
    [app.util.object :as obj]
    [clojure.set :as set]
@@ -19,6 +20,23 @@
    [beicon.core :as rx]
    [rumext.alpha :as mf]))
 
+
+(defonce cache (atom {}))
+
+(defn with-cache
+  [{:keys [key max-age]} observable]
+  (let [entry (get @cache key)
+        age   (when entry
+                (dt/diff (dt/now)
+                         (:created-at entry)))]
+    (if (and (some? entry)
+             (< age max-age))
+      (rx/of (:data entry))
+      (->> observable
+           (rx/tap (fn [data]
+                     (let [entry {:created-at (dt/now) :data data}]
+                       (swap! cache assoc key entry))))))))
+
 (def font-face-template "
 /* latin */
 @font-face {
@@ -63,20 +81,26 @@
               (->> (rx/take 1 observable)
                    (rx/subs resolve reject)))))
 
-(defn get-font-data
+(defn fetch-font-data
   "Parses the CSS and retrieves the font data as DataURI."
   [^string css]
   (let [uris (->> (re-seq #"url\(([^)]+)\)" css)
-                  (map second))]
-    (->> (rx/from (seq uris))
-         (rx/mapcat (fn [uri]
-                      (http/send! {:method :get
-                                   :uri uri
-                                   :response-type :blob})))
-         (rx/map :body)
-         (rx/mapcat wapi/read-file-as-data-url)
-         (rx/reduce conj [])
-         (http/as-promise))))
+                  (mapv second))]
+    (with-cache {:key uris :max-age (dt/duration {:hours 4})}
+      (->> (rx/from (seq uris))
+           (rx/mapcat (fn [uri]
+                        (http/send! {:method :get
+                                     :uri uri
+                                     :response-type :blob})))
+           (rx/map :body)))))
+
+(defn get-font-data
+  "Parses the CSS and retrieves the font data as DataURI."
+  [^string css]
+  (->> (fetch-font-data css)
+       (rx/mapcat wapi/read-file-as-data-url)
+       (rx/reduce conj [])
+       (http/as-promise)))
 
 (defn embed-font
   "Given a font-id and font-variant-id, retrieves the CSS for it and