✨ Add get-file-tokens RPC to read a file's design tokens (#12172)

Clients that only need a file's design tokens, such as a CI job that
syncs them to a git repository after an update-file webhook, had to
download the whole file with get-file.

get-file-tokens returns the file's tokens as a DTCG document, the same
format the token export produces, or nil when the file has none. Active
themes and sets come from the file's tokens status, so they reflect
what is currently active.

The document is returned as a plain map. A bare TokensLib is not a
collection, so the response middleware would hand it to ring unencoded.

Relates to #7091

Signed-off-by: Filip Sajdak <filip.sajdak@siili.com>
Signed-off-by: Andrey Antukh <niwi@niwi.nz>
Co-authored-by: Andrey Antukh <niwi@niwi.nz>

backend/src/app/rpc/commands/files.clj

@@ -746,6 +746,28 @@
       (select-keys plugin-data [namespace])
       (or plugin-data {}))))
 
+;; --- COMMAND QUERY: get-file-tokens
+
+(def ^:private schema:get-file-tokens
+  [:map {:title "get-file-tokens"}
+   [:file-id ::sm/uuid]])
+
+(sv/defmethod ::get-file-tokens
+  "Return the design tokens of a file as a DTCG document, or nil when
+   the file has none. Active themes and sets come from the file's
+   tokens status. Cheap alternative to `get-file` when only the tokens
+   are needed."
+  {::doc/added "2.20"
+   ::sm/params schema:get-file-tokens
+   ::sm/result [:maybe [:map-of :string :any]]}
+  [cfg {:keys [::rpc/profile-id file-id]}]
+  (bfc/check-file-exists cfg file-id)
+  (check-read-permissions! cfg profile-id file-id)
+  (let [{:keys [data]} (bfc/get-file cfg file-id)]
+    (binding [pmap/*load-fn* (partial feat.fdata/load-pointer cfg file-id)]
+      (when-let [tokens-lib (cfo/get-tokens-lib data)]
+        (ctob/export-dtcg-json tokens-lib (cfo/get-tokens-status data))))))
+
 
 ;; --- COMMAND QUERY: get-file-libraries
 

backend/test/backend_tests/rpc_file_test.clj

@@ -2929,3 +2929,68 @@
     (t/is (not (nil? (:error out))))
     (let [edata (-> out :error ex-data)]
       (t/is (= :not-found (:type edata))))))
+
+(t/deftest get-file-tokens-without-tokens
+  (let [profile (th/create-profile* 1 {:is-active true})
+        file    (th/create-file* 1 {:profile-id (:id profile)
+                                    :project-id (:default-project-id profile)
+                                    :is-shared  false})
+        out     (th/command! {::th/type :get-file-tokens
+                              ::rpc/profile-id (:id profile)
+                              :file-id (:id file)})]
+    (t/is (nil? (:error out)))
+    (t/is (nil? (:result out)))))
+
+(t/deftest get-file-tokens-with-tokens
+  (let [profile  (th/create-profile* 1 {:is-active true})
+        file     (th/create-file* 1 {:profile-id (:id profile)
+                                     :project-id (:default-project-id profile)
+                                     :is-shared  false})
+        set-id   (uuid/next)
+        token-id (uuid/next)]
+
+    (update-file!
+     :file-id (:id file)
+     :profile-id (:id profile)
+     :changes
+     [{:type :set-token-set
+       :id set-id
+       :attrs {:id set-id :name "brand-core"}}
+      {:type :set-token
+       :set-id set-id
+       :token-id token-id
+       :attrs {:id token-id
+               :name "color.primary-base"
+               :type :color
+               :value "#ff0000"}}])
+
+    (update-file!
+     :file-id (:id file)
+     :profile-id (:id profile)
+     :revn 1
+     :changes
+     [{:type :set-tokens-status
+       :theme-ids #{}
+       :set-ids #{set-id}}])
+
+    (let [out (th/command! {::th/type :get-file-tokens
+                            ::rpc/profile-id (:id profile)
+                            :file-id (:id file)})
+          dtcg (:result out)]
+      (t/is (nil? (:error out)))
+      (t/is (= "#ff0000" (get-in dtcg ["brand-core" "color" "primary-base" "$value"])))
+      (t/is (= "color" (get-in dtcg ["brand-core" "color" "primary-base" "$type"])))
+      (t/is (= ["brand-core"] (get-in dtcg ["$metadata" "tokenSetOrder"])))
+      (t/is (= #{"brand-core"} (set (get-in dtcg ["$metadata" "activeSets"])))))))
+
+(t/deftest get-file-tokens-forbidden
+  (let [owner (th/create-profile* 1 {:is-active true})
+        other (th/create-profile* 2 {:is-active true})
+        file  (th/create-file* 1 {:profile-id (:id owner)
+                                  :project-id (:default-project-id owner)
+                                  :is-shared  false})
+        out   (th/command! {::th/type :get-file-tokens
+                            ::rpc/profile-id (:id other)
+                            :file-id (:id file)})]
+    (t/is (th/ex-info? (:error out)))
+    (t/is (th/ex-of-type? (:error out) :not-found))))