feat(language-server): answer HTML completion, hover, folding, and tag close

packages/language-server/package.json

@@ -13,6 +13,7 @@
   },
   "dependencies": {
     "@wrnexus/syntax": "workspace:*",
-    "@wrnexus/typecheck": "workspace:*"
+    "@wrnexus/typecheck": "workspace:*",
+    "vscode-html-languageservice": "^5.6.2"
   }
 }

packages/language-server/src/html-service.ts

@@ -0,0 +1,103 @@
+import { getLanguageService, TextDocument as HtmlTextDocument } from "vscode-html-languageservice";
+import { isInsideHtml, virtualHtmlDocument } from "./html-regions.ts";
+import { offsetAt, type Position, type TextDocument } from "./index.ts";
+
+export interface HtmlCompletionItem {
+  label: string;
+  kind: number;
+  detail?: string;
+  documentation?: string;
+  sortText?: string;
+  insertText?: string;
+}
+
+const service = getLanguageService();
+
+/** The virtual document as the HTML service's own document type. */
+function htmlDocument(document: TextDocument) {
+  const virtual = virtualHtmlDocument(document);
+  return HtmlTextDocument.create(virtual.uri, "html", document.version ?? 1, virtual.text);
+}
+
+function markdown(value: unknown): string {
+  if (typeof value === "string") return value;
+  if (value && typeof value === "object" && "value" in value) {
+    return String((value as { value: unknown }).value);
+  }
+  return "";
+}
+
+/**
+ * HTML completions for a position inside a view block.
+ *
+ * Every item carries the `1` sortText prefix so the server can rank WRNexus
+ * entries above these without filtering either list.
+ */
+export function htmlCompletions(document: TextDocument, position: Position): HtmlCompletionItem[] {
+  if (!isInsideHtml(document, offsetAt(document.text, position))) return [];
+
+  const virtual = htmlDocument(document);
+  const parsed = service.parseHTMLDocument(virtual);
+  const list = service.doComplete(virtual, position, parsed);
+
+  return list.items.map((item) => ({
+    label: item.label,
+    kind: typeof item.kind === "number" ? item.kind : 1,
+    detail: item.detail,
+    documentation: markdown(item.documentation),
+    sortText: `1${item.sortText ?? item.label}`,
+    insertText: item.textEdit && "newText" in item.textEdit ? item.textEdit.newText : undefined,
+  }));
+}
+
+export function htmlHover(document: TextDocument, position: Position): { contents: string } | null {
+  if (!isInsideHtml(document, offsetAt(document.text, position))) return null;
+
+  const virtual = htmlDocument(document);
+  const result = service.doHover(virtual, position, service.parseHTMLDocument(virtual));
+  if (!result) return null;
+
+  const contents = markdown(result.contents);
+  return contents ? { contents } : null;
+}
+
+export function htmlFoldingRanges(
+  document: TextDocument,
+): Array<{ startLine: number; endLine: number }> {
+  return service
+    .getFoldingRanges(htmlDocument(document))
+    .map((range) => ({ startLine: range.startLine, endLine: range.endLine }));
+}
+
+/**
+ * Detects `<Name attr="x" /` just before `position` and completes the `>`.
+ *
+ * `vscode-html-languageservice`'s own `doTagComplete` only reacts to a typed
+ * `/` when it opens an end tag (`</`); it has no notion of a self-closing
+ * start tag, since plain HTML has no such elements outside its fixed void-element
+ * list. WRNexus components (`<Card />`) are exactly that case, so we complete
+ * it ourselves rather than relying on the library.
+ */
+function selfClosingTagCompletion(text: string, offset: number): string | null {
+  if (text.charAt(offset - 1) !== "/") return null;
+  if (text.charAt(offset) === ">") return null;
+  const before = text.slice(0, offset);
+  return /<[A-Za-z][\w-]*(?:\s[^<>]*)?\/$/.test(before) ? ">" : null;
+}
+
+/**
+ * The snippet that closes the tag being typed, or null.
+ *
+ * Void elements and already-closed tags return null, which is why this decision
+ * belongs here rather than in the editor client.
+ */
+export function htmlTagComplete(document: TextDocument, position: Position): string | null {
+  const offset = offsetAt(document.text, position);
+  if (!isInsideHtml(document, offset)) return null;
+
+  const virtual = htmlDocument(document);
+  const result = service.doTagComplete(virtual, position, service.parseHTMLDocument(virtual));
+  if (result) return result;
+
+  return selfClosingTagCompletion(document.text, offset);
+}

packages/language-server/test/html-service.test.ts

@@ -0,0 +1,123 @@
+import { expect, test } from "bun:test";
+import {
+  htmlCompletions,
+  htmlFoldingRanges,
+  htmlHover,
+  htmlTagComplete,
+} from "../src/html-service.ts";
+
+function doc(text: string) {
+  return { uri: "file:///Page.wrn", text };
+}
+
+function positionOf(text: string, needle: string) {
+  const offset = text.indexOf(needle) + needle.length;
+  const before = text.slice(0, offset);
+  const lines = before.split("\n");
+  return { line: lines.length - 1, character: lines[lines.length - 1]!.length };
+}
+
+test("suggests HTML tags inside a view block", () => {
+  const text = `page A {
+  view {
+    <
+  }
+}
+`;
+  const items = htmlCompletions(doc(text), positionOf(text, "    <"));
+  expect(items.some((item) => item.label === "div")).toBe(true);
+  expect(items.every((item) => item.sortText?.startsWith("1"))).toBe(true);
+});
+
+test("suggests attributes inside a tag", () => {
+  const text = `page A {
+  view {
+    <input 
+  }
+}
+`;
+  const items = htmlCompletions(doc(text), positionOf(text, "<input "));
+  expect(items.some((item) => item.label === "type")).toBe(true);
+});
+
+test("returns nothing outside a view block", () => {
+  const text = `page A {
+  functions {
+    function go() { }
+  }
+}
+`;
+  expect(htmlCompletions(doc(text), positionOf(text, "function go() "))).toEqual([]);
+});
+
+test("hovers a tag inside a view block and nothing outside one", () => {
+  const text = `page A {
+  view {
+    <div>x</div>
+  }
+}
+`;
+  expect(htmlHover(doc(text), positionOf(text, "<di"))).not.toBeNull();
+
+  const code = `page A {
+  functions {
+    function go() { }
+  }
+}
+`;
+  expect(htmlHover(doc(code), positionOf(code, "func"))).toBeNull();
+});
+
+test("closes an open tag and leaves void elements alone", () => {
+  const open = `page A {
+  view {
+    <div>
+  }
+}
+`;
+  expect(htmlTagComplete(doc(open), positionOf(open, "<div>"))).toContain("</div>");
+
+  const void_ = `page A {
+  view {
+    <br>
+  }
+}
+`;
+  expect(htmlTagComplete(doc(void_), positionOf(void_, "<br>"))).toBeNull();
+});
+
+test("completes a self-closing component tag", () => {
+  const text = `page A {
+  view {
+    <Card /
+  }
+}
+`;
+  expect(htmlTagComplete(doc(text), positionOf(text, "<Card /"))).toBe(">");
+});
+
+test("returns no tag completion outside a view block", () => {
+  const text = `page A {
+  functions {
+    function go() { }
+  }
+}
+`;
+  expect(htmlTagComplete(doc(text), positionOf(text, "function go() "))).toBeNull();
+});
+
+test("folding ranges stay inside view regions", () => {
+  const text = `page A {
+  view {
+    <ul>
+      <li>one</li>
+    </ul>
+  }
+}
+`;
+  const ranges = htmlFoldingRanges(doc(text));
+  expect(ranges.length).toBeGreaterThan(0);
+
+  const viewStartLine = text.slice(0, text.indexOf("view {")).split("\n").length - 1;
+  for (const range of ranges) expect(range.startLine).toBeGreaterThan(viewStartLine - 1);
+});