Fix co-located components regressions

packages/compat/src/synthesize-template-only-components.ts

@@ -1,16 +1,29 @@
 import Plugin from 'broccoli-plugin';
 import type { Node } from 'broccoli-node-api';
-import { join, basename } from 'path';
-import walkSync from 'walk-sync';
-import { remove, outputFileSync, pathExistsSync } from 'fs-extra';
+import { join, basename, extname } from 'path';
+import walkSync, { type Entry } from 'walk-sync';
+import { removeSync, outputFileSync, pathExistsSync, readFileSync } from 'fs-extra';
 
 const source = `import templateOnlyComponent from '@ember/component/template-only';
 export default templateOnlyComponent();`;
 
 const jsExtensions = ['.js', '.ts', '.mjs', '.mts'];
 
+type Emitted =
+  | { type: 'template-only-component'; outputPath: string }
+  | { type: 'template-import'; outputPath: string; mtime: number };
+
+type TemplateOnly = { template: Entry; javascript: undefined };
+type JavaScriptOnly = { template: undefined; javascript: Entry };
+type Colocated = { template: Entry; javascript: Entry };
+type ComponentFiles = TemplateOnly | JavaScriptOnly | Colocated;
+
+function importTemplate(files: { template: Entry }): string {
+  return `/* import __COLOCATED_TEMPLATE__ from './${basename(files.template.relativePath)}'; */\n`;
+}
+
 export default class SynthesizeTemplateOnlyComponents extends Plugin {
-  private emitted = new Set() as Set<string>;
+  private emitted = new Map() as Map<string, Emitted>;
   private allowedPaths: string[];
   private templateExtensions: string[];
 
@@ -25,54 +38,92 @@ export default class SynthesizeTemplateOnlyComponents extends Plugin {
   }
 
   async build() {
+    let unneeded = new Set(this.emitted.keys());
     for (let dir of this.allowedPaths) {
-      let { needed, seen } = this.crawl(join(this.inputPaths[0], dir));
-      for (let file of needed) {
-        let fullName = join(this.outputPath, dir, file);
-        if (seen.has(file)) {
-          this.remove(fullName);
+      let entries = this.crawl(join(this.inputPaths[0], dir));
+      for (let [name, files] of entries) {
+        let fullName = join(this.outputPath, dir, name);
+        unneeded.delete(fullName);
+        if (files.javascript && files.template) {
+          this.addTemplateImport(fullName, files);
+        } else if (files.template) {
+          this.addTemplateOnlyComponent(fullName, files);
         } else {
-          this.add(fullName);
+          this.remove(fullName);
         }
       }
     }
+    for (let fullName of unneeded) {
+      this.remove(fullName);
+    }
   }
-  private add(filename: string) {
-    if (!this.emitted.has(filename)) {
+
+  private addTemplateOnlyComponent(filename: string, files: TemplateOnly) {
+    const emitted = this.emitted.get(filename);
+
+    if (emitted?.type !== 'template-only-component') {
       // special case: ember-cli doesn't allow template-only components named
       // "template.hbs" because there are too many people doing a "pods-like"
       // layout that happens to match that pattern.🤮
       if (basename(filename) !== 'template') {
-        outputFileSync(filename + '.js', source, 'utf8');
+        const outputPath = filename + '.js';
+        outputFileSync(outputPath, importTemplate(files) + source, 'utf8');
+        this.emitted.set(filename, { type: 'template-only-component', outputPath });
+
+        if (emitted && emitted.outputPath !== outputPath) {
+          removeSync(emitted.outputPath);
+        }
+      }
+    }
+  }
+
+  private addTemplateImport(filename: string, files: Colocated) {
+    const emitted = this.emitted.get(filename);
+    const mtime = files.javascript.mtime;
+
+    if (!(emitted?.type === 'template-import' && emitted.mtime === mtime)) {
+      const inputSource = readFileSync(files.javascript.fullPath, { encoding: 'utf8' });
+      const outputPath = filename + extname(files.javascript.relativePath);
+      // If we are ok with appending instead, copy + append maybe more efficient?
+      outputFileSync(outputPath, importTemplate(files) + inputSource, 'utf8');
+      this.emitted.set(filename, { type: 'template-import', outputPath, mtime });
+
+      if (emitted && emitted.outputPath !== outputPath) {
+        removeSync(emitted.outputPath);
       }
-      this.emitted.add(filename);
     }
   }
 
   private remove(filename: string) {
-    if (this.emitted.has(filename)) {
-      remove(filename + '.js');
+    const emitted = this.emitted.get(filename);
+
+    if (emitted) {
+      removeSync(emitted.outputPath);
       this.emitted.delete(filename);
     }
   }
 
-  private crawl(dir: string) {
-    const needed = new Set<string>();
-    const seen = new Set<string>();
+  private crawl(dir: string): Map<string, ComponentFiles> {
+    const entries = new Map<string, ComponentFiles>();
+
     if (pathExistsSync(dir)) {
-      for (let file of walkSync(dir, { directories: false })) {
-        for (const templateExtension of this.templateExtensions) {
-          if (file.endsWith(templateExtension)) {
-            needed.add(file.slice(0, -1 * templateExtension.length));
-          } else {
-            const jsExtension = jsExtensions.find(ext => file.endsWith(ext));
-            if (jsExtension) {
-              seen.add(file.slice(0, -1 * jsExtension.length));
-            }
-          }
+      for (let entry of walkSync.entries(dir, { directories: false })) {
+        const templateExtension = this.templateExtensions.find(ext => entry.relativePath.endsWith(ext));
+        if (templateExtension) {
+          const key = entry.relativePath.slice(0, -1 * templateExtension.length);
+          entries.set(key, { template: entry, javascript: entries.get(key)?.javascript });
+          continue;
+        }
+
+        const jsExtension = jsExtensions.find(ext => entry.relativePath.endsWith(ext));
+        if (jsExtension) {
+          const key = entry.relativePath.slice(0, -1 * jsExtension.length);
+          entries.set(key, { template: entries.get(key)?.template, javascript: entry });
+          continue;
         }
       }
     }
-    return { needed, seen };
+
+    return entries;
   }
 }