feat: implement resolveModuleNames for type resolution in ERB virtual files (#29)

* Initial plan

* Initial plan for fixing intersection type resolution in ERB virtual files

Co-authored-by: kudoas <45157831+kudoas@users.noreply.github.com>

* feat: implement resolveModuleNames for proper type resolution in ERB virtual files

Co-authored-by: kudoas <45157831+kudoas@users.noreply.github.com>

* fix: remove incorrect cleanup of non-existent test file

Co-authored-by: kudoas <45157831+kudoas@users.noreply.github.com>

* docs: update CHANGELOG with fix for intersection type resolution

Co-authored-by: kudoas <45157831+kudoas@users.noreply.github.com>

* chore: Refactor code structure for improved readability and maintainability

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: kudoas <45157831+kudoas@users.noreply.github.com>
Co-authored-by: Daichi <sakanactor624@gmail.com>

Author: Copilot

src/services/typescriptCompletionService.ts

@@ -91,7 +91,16 @@ export class TypeScriptCompletionService {
       getCompilationSettings: () => this.compilerOptions,
       getDefaultLibFileName: (options) => getDefaultLibFilePath(options),
       fileExists: (fileName) => fileName === this.fileName || sys.fileExists(fileName),
-      readFile: (fileName) => (fileName === this.fileName ? this.content : sys.readFile(fileName))
+      readFile: (fileName) => (fileName === this.fileName ? this.content : sys.readFile(fileName)),
+      resolveModuleNames: (moduleNames, containingFile) => {
+        return moduleNames.map((moduleName) => {
+          const result = ts.resolveModuleName(moduleName, containingFile, this.compilerOptions, {
+            fileExists: sys.fileExists,
+            readFile: sys.readFile
+          });
+          return result.resolvedModule;
+        });
+      }
     };
   }
 }

src/test/unit/typescriptCompletionService.test.ts

@@ -0,0 +1,119 @@
+import { ok, strictEqual } from 'node:assert';
+import * as path from 'node:path';
+import * as fs from 'node:fs';
+import * as os from 'node:os';
+
+import { TypeScriptCompletionService } from '../../services/typescriptCompletionService';
+
+suite('TypeScriptCompletionService', () => {
+  test('provides completions for simple JavaScript', () => {
+    const service = new TypeScriptCompletionService();
+    const jsContent = 'const answer = 42; answer.';
+    service.updateContent(jsContent);
+
+    const completions = service.getCompletions(jsContent.length);
+    ok(completions, 'Expected completions to be defined');
+    ok(completions.entries.length > 0, 'Expected at least one completion');
+
+    // Should have Number methods
+    const hasToFixed = completions.entries.some((e) => e.name === 'toFixed');
+    ok(hasToFixed, 'Expected to find Number.toFixed method');
+  });
+
+  test('provides hover information for variables', () => {
+    const service = new TypeScriptCompletionService();
+    const jsContent = 'const answer = 42;';
+    service.updateContent(jsContent);
+
+    const offset = jsContent.indexOf('answer');
+    const info = service.getQuickInfo(offset);
+    ok(info, 'Expected quick info to be defined');
+    ok(info.displayParts, 'Expected display parts to be defined');
+
+    const display = info.displayParts.map((part) => part.text).join('');
+    ok(display.includes('answer'), 'Expected hover to include variable name');
+  });
+
+  test('resolves module imports with JSDoc types', () => {
+    // Create a temporary directory with a type definition file
+    const tmpDir = fs.mkdtempSync(path.join(os.tmpdir(), 'erb-test-'));
+    const typeDefPath = path.join(tmpDir, 'types.js');
+    const testFilePath = path.join(tmpDir, 'test.js');
+
+    try {
+      // Create a type definition file
+      fs.writeFileSync(
+        typeDefPath,
+        `
+/**
+ * @typedef {Object} User
+ * @property {string} name
+ * @property {number} age
+ */
+
+/**
+ * @typedef {Object} Address
+ * @property {string} street
+ * @property {string} city
+ */
+`
+      );
+
+      // Create a test file that imports and uses intersection types
+      const jsContent = `
+/**
+ * @typedef {import('./types').User} User
+ * @typedef {import('./types').Address} Address
+ * @typedef {User & Address} UserWithAddress
+ */
+
+/** @type {UserWithAddress} */
+const person = { name: 'John', age: 30, street: '123 Main', city: 'NYC' };
+person.
+`;
+
+      const service = new TypeScriptCompletionService();
+      // Update with the full path as the containing file
+      service.updateContent(jsContent.trim(), testFilePath);
+
+      const completions = service.getCompletions(jsContent.trim().length);
+      ok(completions, 'Expected completions to be defined');
+      ok(completions.entries.length > 0, 'Expected at least one completion');
+
+      // Should have properties from both User and Address types
+      const hasName = completions.entries.some((e) => e.name === 'name');
+      const hasAge = completions.entries.some((e) => e.name === 'age');
+      const hasStreet = completions.entries.some((e) => e.name === 'street');
+      const hasCity = completions.entries.some((e) => e.name === 'city');
+
+      ok(hasName, 'Expected to find name property from User type');
+      ok(hasAge, 'Expected to find age property from User type');
+      ok(hasStreet, 'Expected to find street property from Address type');
+      ok(hasCity, 'Expected to find city property from Address type');
+    } finally {
+      // Cleanup
+      try {
+        fs.unlinkSync(typeDefPath);
+        fs.rmdirSync(tmpDir);
+      } catch (e) {
+        // Ignore cleanup errors
+      }
+    }
+  });
+
+  test('updates version when content changes', () => {
+    const service = new TypeScriptCompletionService();
+    const version1 = service.getVirtualFileName();
+
+    service.updateContent('const x = 1;');
+    const completions1 = service.getCompletions(15);
+    ok(completions1, 'Expected first completions to be defined');
+
+    service.updateContent('const y = 2;');
+    const completions2 = service.getCompletions(15);
+    ok(completions2, 'Expected second completions to be defined');
+
+    // Version tracking is internal, but we can verify service still works
+    ok(true, 'Service handled multiple content updates');
+  });
+});