Go to import (#2978)

fix #1294
![Kapture 2024-03-01 at 14 41
07](https://github.com/microsoft/typespec/assets/1031227/8be68f83-4eca-421c-b6dd-27bc1eed141f)

.chronus/changes/goto-import-2024-2-1-22-43-14.md

@@ -0,0 +1,8 @@
+---
+# Change versionKind to one of: internal, fix, dependencies, feature, deprecation, breaking
+changeKind: fix
+packages:
+  - "@typespec/compiler"
+---
+
+[IDE] Go to imports

packages/compiler/src/server/serverlib.ts

@@ -45,8 +45,9 @@ import { CharCode, codePointBefore, isIdentifierContinue } from "../core/charcod
 import { compilerAssert, getSourceLocation } from "../core/diagnostics.js";
 import { formatTypeSpec } from "../core/formatter.js";
 import { getTypeName } from "../core/helpers/type-name-utils.js";
+import { ResolveModuleHost, resolveModule } from "../core/index.js";
 import { getNodeAtPosition, visitChildren } from "../core/parser.js";
-import { ensureTrailingDirectorySeparator } from "../core/path-utils.js";
+import { ensureTrailingDirectorySeparator, getDirectoryPath } from "../core/path-utils.js";
 import { Program } from "../core/program.js";
 import { skipTrivia, skipWhiteSpace } from "../core/scanner.js";
 import { createSourceFile, getSourceFileKindFromExt } from "../core/source-file.js";
@@ -64,7 +65,7 @@ import {
   TypeReferenceNode,
   TypeSpecScriptNode,
 } from "../core/types.js";
-import { getNormalizedRealPath } from "../utils/misc.js";
+import { getNormalizedRealPath, resolveTspMain } from "../utils/misc.js";
 import { getSemanticTokens } from "./classify.js";
 import { createCompileService } from "./compile-service.js";
 import { resolveCompletion } from "./completion.js";
@@ -599,11 +600,47 @@ export function createServer(host: ServerHost): Server {
     if (result === undefined) {
       return [];
     }
-    const id = getNodeAtPosition(result.script, result.document.offsetAt(params.position));
-    const sym =
-      id?.kind === SyntaxKind.Identifier ? result.program.checker.resolveIdentifier(id) : undefined;
-    return getLocations(sym?.declarations);
+    const node = getNodeAtPosition(result.script, result.document.offsetAt(params.position));
+    switch (node?.kind) {
+      case SyntaxKind.Identifier:
+        const sym = result.program.checker.resolveIdentifier(node);
+        return getLocations(sym?.declarations);
+      case SyntaxKind.StringLiteral:
+        if (node.parent?.kind === SyntaxKind.ImportStatement) {
+          return [await getImportLocation(node.value, result.script)];
+        } else {
+          return [];
+        }
+    }
+    return [];
+  }
+
+  async function getImportLocation(
+    importPath: string,
+    currentFile: TypeSpecScriptNode
+  ): Promise<Location> {
+    const host: ResolveModuleHost = {
+      realpath: compilerHost.realpath,
+      readFile: async (path) => {
+        const file = await compilerHost.readFile(path);
+        return file.text;
+      },
+      stat: compilerHost.stat,
+    };
+    const resolved = await resolveModule(host, importPath, {
+      baseDir: getDirectoryPath(currentFile.file.path),
+      resolveMain(pkg) {
+        // this lets us follow node resolve semantics more-or-less exactly
+        // but using tspMain instead of main.
+        return resolveTspMain(pkg) ?? pkg.main;
+      },
+    });
+    return {
+      uri: fileService.getURL(resolved.type === "file" ? resolved.path : resolved.mainFile),
+      range: Range.create(0, 0, 0, 0),
+    };
   }
+
   async function complete(params: CompletionParams): Promise<CompletionList> {
     const completions: CompletionList = {
       isIncomplete: false,

packages/compiler/test/server/goto-definition.test.ts

@@ -0,0 +1,73 @@
+import { pathToFileURL } from "url";
+import { describe, expect, it } from "vitest";
+import { Location } from "vscode-languageserver";
+import {
+  createTestServerHost,
+  extractCursor,
+  resolveVirtualPath,
+} from "../../src/testing/index.js";
+
+function resolveVirtualPathUri(path: string): string {
+  return pathToFileURL(resolveVirtualPath(path)).href;
+}
+
+async function goToDefinitionAtCursor(
+  sourceWithCursor: string,
+  otherFiles: Record<string, string> = {}
+): Promise<Location[]> {
+  const { source, pos } = extractCursor(sourceWithCursor);
+
+  const testHost = await createTestServerHost();
+  for (const [filename, content] of Object.entries(otherFiles)) {
+    testHost.addOrUpdateDocument(filename, content);
+  }
+  const textDocument = testHost.addOrUpdateDocument("main.tsp", source);
+  return await testHost.server.gotoDefinition({
+    textDocument,
+    position: textDocument.positionAt(pos),
+  });
+}
+
+describe("go to imports", () => {
+  it("go to local import", async () => {
+    const locations = await goToDefinitionAtCursor(
+      `
+    import "./othe┆r.tsp";
+  `,
+      { "other.tsp": "model Other {}" }
+    );
+    expect(locations).toEqual([
+      {
+        range: {
+          end: { character: 0, line: 0 },
+          start: { character: 0, line: 0 },
+        },
+        uri: resolveVirtualPathUri("other.tsp"),
+      },
+    ]);
+  });
+
+  it("go to library import", async () => {
+    const locations = await goToDefinitionAtCursor(
+      `
+    import "┆test-lib";
+  `,
+      {
+        "node_modules/test-lib/package.json": JSON.stringify({
+          name: "test-lib",
+          tspMain: "./main.tsp",
+        }),
+        "node_modules/test-lib/main.tsp": "model Other {}",
+      }
+    );
+    expect(locations).toEqual([
+      {
+        range: {
+          end: { character: 0, line: 0 },
+          start: { character: 0, line: 0 },
+        },
+        uri: resolveVirtualPathUri("node_modules/test-lib/main.tsp"),
+      },
+    ]);
+  });
+});