Fix theme name requirement regression with efficient lookup by name (#35007)

Co-authored-by: Claire <claire.github-309c@sitedethib.com>

config/vite/plugin-mastodon-themes.ts

@@ -29,7 +29,7 @@ export function MastodonThemes(): Plugin {
         throw new Error('Invalid themes.yml file');
       }
 
-      for (const themePath of Object.values(themes)) {
+      for (const [themeName, themePath] of Object.entries(themes)) {
         if (
           typeof themePath !== 'string' ||
           themePath.split('.').length !== 2 || // Ensure it has exactly one period
@@ -40,7 +40,7 @@ export function MastodonThemes(): Plugin {
           );
           continue;
         }
-        entrypoints[path.basename(themePath)] = path.resolve(
+        entrypoints[`themes/${themeName}`] = path.resolve(
           userConfig.root,
           themePath,
         );

config/vite/plugin-name-lookup.ts

@@ -0,0 +1,68 @@
+import { relative, extname } from 'node:path';
+
+import type { Plugin } from 'vite';
+
+export function MastodonNameLookup(): Plugin {
+  const nameMap: Record<string, string> = {};
+
+  let root = '';
+
+  return {
+    name: 'mastodon-name-lookup',
+    applyToEnvironment(environment) {
+      return !!environment.config.build.manifest;
+    },
+    configResolved(userConfig) {
+      root = userConfig.root;
+    },
+    generateBundle(options, bundle) {
+      if (!root) {
+        throw new Error(
+          'MastodonNameLookup plugin requires the root to be set in the config.',
+        );
+      }
+
+      // Iterate over all chunks in the bundle and create a lookup map
+      for (const file in bundle) {
+        const chunk = bundle[file];
+        if (
+          chunk?.type !== 'chunk' ||
+          !chunk.isEntry ||
+          !chunk.facadeModuleId
+        ) {
+          continue;
+        }
+
+        const relativePath = relative(
+          root,
+          sanitizeFileName(chunk.facadeModuleId),
+        );
+        const ext = extname(relativePath);
+        const name = chunk.name.replace(ext, '');
+
+        if (nameMap[name]) {
+          throw new Error(
+            `Entrypoint ${relativePath} conflicts with ${nameMap[name]}`,
+          );
+        }
+
+        nameMap[name] = relativePath;
+      }
+
+      this.emitFile({
+        type: 'asset',
+        fileName: '.vite/manifest-lookup.json',
+        source: JSON.stringify(nameMap, null, 2),
+      });
+    },
+  };
+}
+
+// Taken from https://github.com/rollup/rollup/blob/4f69d33af3b2ec9320c43c9e6c65ea23a02bdde3/src/utils/sanitizeFileName.ts
+// https://datatracker.ietf.org/doc/html/rfc2396
+// eslint-disable-next-line no-control-regex
+const INVALID_CHAR_REGEX = /[\u0000-\u001F"#$%&*+,:;<=>?[\]^`{|}\u007F]/g;
+
+function sanitizeFileName(name: string): string {
+  return name.replace(INVALID_CHAR_REGEX, '');
+}