feat: Show the build date on the loading banner of unreleased builds (#2659)

scripts/build-date-plugin.js

@@ -0,0 +1,40 @@
+/**
+ * Vite plugin: writes the date of the build into the card.
+ */
+
+// Strict length requirement: See below.
+export const BUILD_DATE_PLACEHOLDER = '__BUILD_DATE_SENTINEL___';
+
+/**
+ * The date cannot be handed to the bundler as a substituted name, because the
+ * build configuration is evaluated once and `vite build --watch` reuses it.
+ * As such, every rebuild would report the time the watcher started rather than
+ * the actual build time. Output is generated afresh for each build, so the date
+ * is written here instead.
+ *
+ * @type {() => import('vite').Plugin}
+ */
+export const buildDate = () => ({
+  name: 'build-date',
+
+  renderChunk(code) {
+    if (!code.includes(BUILD_DATE_PLACEHOLDER)) {
+      return null;
+    }
+
+    const date = new Date().toISOString();
+    if (date.length !== BUILD_DATE_PLACEHOLDER.length) {
+      this.error(
+        'The build date must be exactly as long as the placeholder it replaces.',
+      );
+    }
+
+    return {
+      code: code.replaceAll(BUILD_DATE_PLACEHOLDER, date),
+
+      // The replacement is exactly as long as what it replaces, so the existing
+      // sourcemap still describes the code.
+      map: null,
+    };
+  },
+});

scripts/build-defines.js

@@ -1,6 +1,8 @@
 import { execFileSync } from 'node:child_process';
 import { readFileSync } from 'node:fs';
 
+import { BUILD_DATE_PLACEHOLDER } from './build-date-plugin.js';
+
 /**
  * Asks git something or gives back nothing when it cannot be asked.
  */
@@ -23,7 +25,11 @@ const getPackageVersion = () =>
  *
  * `releaseVersion` is the version being released, which only the release
  * workflow knows; a build without one reports the version in `package.json`, or
- * a development build the commit it was made from.
+ * a development build the commit it was made from. Its presence is what makes a
+ * build a released one.
+ *
+ * The build date is a placeholder here, written in for by the `buildDate`
+ * plugin as each build's output is generated.
  *
  * The values are JSON so that a bundler can drop them in as written.
  */
@@ -35,10 +41,11 @@ export const getBuildDefines = ({ dev, releaseVersion }) => {
     __ADVANCED_CAMERA_CARD_RELEASE_VERSION__: JSON.stringify(
       releaseVersion ?? (dev ? developmentVersion : getPackageVersion()),
     ),
+    __ADVANCED_CAMERA_CARD_IS_RELEASE_BUILD__: JSON.stringify(!!releaseVersion),
     __ADVANCED_CAMERA_CARD_GIT_HASH__: JSON.stringify(gitHash),
     __ADVANCED_CAMERA_CARD_GIT_DATE__: JSON.stringify(
       askGit('log', '-1', '--format=%cI'),
     ),
-    __ADVANCED_CAMERA_CARD_BUILD_DATE__: JSON.stringify(new Date().toISOString()),
+    __ADVANCED_CAMERA_CARD_BUILD_DATE__: JSON.stringify(BUILD_DATE_PLACEHOLDER),
   };
 };