Get definitions (#219)

* Start on css completion

* Support for CSS completions

* Adds support for Go to Definition in TypeScript in Astro

* Run formatting

11 files changed, 430 insertions, 219 deletions

diff --git a/tools/astro-languageserver/src/core/documents/utils.ts b/tools/astro-languageserver/src/core/documents/utils.ts
index 227a76176..eb9d2060d 100644
--- a/tools/astro-languageserver/src/core/documents/utils.ts
+++ b/tools/astro-languageserver/src/core/documents/utils.ts
@@ -1,5 +1,6 @@
 import { HTMLDocument, Node, Position } from 'vscode-html-languageservice';
-import { clamp } from '../../utils';
+import { Range } from 'vscode-languageserver';
+import { clamp, isInRange } from '../../utils';
 import { parseHtml } from './parseHtml';
 
 export interface TagInformation {
@@ -84,6 +85,10 @@ export function isInsideFrontmatter(text: string, offset: number): boolean {
   return start > 1 && start < 3 && end >= 1;
 }
 
+export function isInTag(position: Position, tagInfo: TagInformation | null): tagInfo is TagInformation {
+  return !!tagInfo && isInRange(position, Range.create(tagInfo.startPos, tagInfo.endPos));
+}
+
 /**
  * Get the line and character based on the offset
  * @param offset The index of the position
diff --git a/tools/astro-languageserver/src/index.ts b/tools/astro-languageserver/src/index.ts
index 7c4417d69..e3532f252 100644
--- a/tools/astro-languageserver/src/index.ts
+++ b/tools/astro-languageserver/src/index.ts
@@ -19,6 +19,10 @@ export function startServer() {
   connection.onInitialize((evt) => {
     const workspaceUris = evt.workspaceFolders?.map((folder) => folder.uri.toString()) ?? [evt.rootUri ?? ''];
 
+    pluginHost.initialize({
+      filterIncompleteCompletions: !evt.initializationOptions?.dontFilterIncompleteCompletions,
+      definitionLinkSupport: !!evt.capabilities.textDocument?.definition?.linkSupport,
+    });
     pluginHost.register(new AstroPlugin(docManager, configManager));
     pluginHost.register(new HTMLPlugin(docManager, configManager));
     pluginHost.register(new CSSPlugin(docManager, configManager));
@@ -29,6 +33,7 @@ export function startServer() {
       capabilities: {
         textDocumentSync: TextDocumentSyncKind.Incremental,
         foldingRangeProvider: true,
+        definitionProvider: true,
         completionProvider: {
           resolveProvider: true,
           triggerCharacters: [
@@ -102,6 +107,7 @@ export function startServer() {
 
     return pluginHost.resolveCompletion(data, completionItem);
   });
+  connection.onDefinition((evt) => pluginHost.getDefinitions(evt.textDocument, evt.position));
   connection.onFoldingRanges((evt) => pluginHost.getFoldingRanges(evt.textDocument));
   connection.onRequest(TagCloseRequest, (evt: any) => pluginHost.doTagComplete(evt.textDocument, evt.position));
 
diff --git a/tools/astro-languageserver/src/plugins/PluginHost.ts b/tools/astro-languageserver/src/plugins/PluginHost.ts
index 8d59c9c93..3741845c4 100644
--- a/tools/astro-languageserver/src/plugins/PluginHost.ts
+++ b/tools/astro-languageserver/src/plugins/PluginHost.ts
@@ -1,4 +1,4 @@
-import { CompletionContext, CompletionItem, CompletionList, Position, TextDocumentIdentifier } from 'vscode-languageserver';
+import { CompletionContext, CompletionItem, CompletionList, DefinitionLink, Location, Position, TextDocumentIdentifier } from 'vscode-languageserver';
 import type { DocumentManager } from '../core/documents';
 import type * as d from './interfaces';
 import { flatten } from '../utils';
@@ -10,11 +10,24 @@ enum ExecuteMode {
   Collect,
 }
 
+interface PluginHostConfig {
+  filterIncompleteCompletions: boolean;
+  definitionLinkSupport: boolean;
+}
+
 export class PluginHost {
   private plugins: d.Plugin[] = [];
+  private pluginHostConfig: PluginHostConfig = {
+    filterIncompleteCompletions: true,
+    definitionLinkSupport: false,
+  };
 
   constructor(private documentsManager: DocumentManager) {}
 
+  initialize(pluginHostConfig: PluginHostConfig) {
+    this.pluginHostConfig = pluginHostConfig;
+  }
+
   register(plugin: d.Plugin) {
     this.plugins.push(plugin);
   }
@@ -67,6 +80,21 @@ export class PluginHost {
     return foldingRanges;
   }
 
+  async getDefinitions(textDocument: TextDocumentIdentifier, position: Position): Promise<DefinitionLink[] | Location[]> {
+    const document = this.getDocument(textDocument.uri);
+    if (!document) {
+      throw new Error('Cannot call methods on an unopened document');
+    }
+
+    const definitions = flatten(await this.execute<DefinitionLink[]>('getDefinitions', [document, position], ExecuteMode.Collect));
+
+    if (this.pluginHostConfig.definitionLinkSupport) {
+      return definitions;
+    } else {
+      return definitions.map((def) => <Location>{ range: def.targetSelectionRange, uri: def.targetUri });
+    }
+  }
+
   onWatchFileChanges(onWatchFileChangesParams: any[]): void {
     for (const support of this.plugins) {
       support.onWatchFileChanges?.(onWatchFileChangesParams);
diff --git a/tools/astro-languageserver/src/plugins/typescript/DocumentSnapshot.ts b/tools/astro-languageserver/src/plugins/typescript/DocumentSnapshot.ts
new file mode 100644
index 000000000..04ea170d4
--- /dev/null
+++ b/tools/astro-languageserver/src/plugins/typescript/DocumentSnapshot.ts
@@ -0,0 +1,242 @@
+import * as ts from 'typescript';
+import { TextDocumentContentChangeEvent, Position } from 'vscode-languageserver';
+import { Document, DocumentMapper, IdentityMapper } from '../../core/documents';
+import { isInTag, positionAt, offsetAt } from '../../core/documents/utils';
+import { pathToUrl } from '../../utils';
+import { getScriptKindFromFileName, isAstroFilePath, toVirtualAstroFilePath } from './utils';
+
+/**
+ * The mapper to get from original snapshot positions to generated and vice versa.
+ */
+export interface SnapshotFragment extends DocumentMapper {
+  positionAt(offset: number): Position;
+  offsetAt(position: Position): number;
+}
+
+export interface DocumentSnapshot extends ts.IScriptSnapshot {
+  version: number;
+  filePath: string;
+  scriptKind: ts.ScriptKind;
+  positionAt(offset: number): Position;
+  /**
+   * Instantiates a source mapper.
+   * `destroyFragment` needs to be called when
+   * it's no longer needed / the class should be cleaned up
+   * in order to prevent memory leaks.
+   */
+  getFragment(): Promise<DocumentFragmentSnapshot>;
+  /**
+   * Needs to be called when source mapper
+   * is no longer needed / the class should be cleaned up
+   * in order to prevent memory leaks.
+   */
+  destroyFragment(): void;
+  /**
+   * Convenience function for getText(0, getLength())
+   */
+  getFullText(): string;
+}
+
+export const createDocumentSnapshot = (filePath: string, currentText: string | null, createDocument?: (_filePath: string, text: string) => Document): DocumentSnapshot => {
+  const text = currentText || (ts.sys.readFile(filePath) ?? '');
+
+  if (isAstroFilePath(filePath)) {
+    if (!createDocument) throw new Error('Astro documents require the "createDocument" utility to be provided');
+    const snapshot = new AstroDocumentSnapshot(createDocument(filePath, text));
+    return snapshot;
+  }
+
+  return new TypeScriptDocumentSnapshot(0, filePath, text);
+};
+
+class AstroDocumentSnapshot implements DocumentSnapshot {
+  version = this.doc.version;
+  scriptKind = ts.ScriptKind.Unknown;
+
+  constructor(private doc: Document) {}
+
+  async getFragment(): Promise<DocumentFragmentSnapshot> {
+    const uri = pathToUrl(this.filePath);
+    const mapper = await this.getMapper(uri);
+    return new DocumentFragmentSnapshot(mapper, this.doc);
+  }
+
+  async destroyFragment() {
+    return;
+  }
+
+  get text() {
+    return this.doc.getText();
+  }
+
+  get filePath() {
+    return this.doc.getFilePath() || '';
+  }
+
+  getText(start: number, end: number) {
+    return this.text.substring(start, end);
+  }
+
+  getLength() {
+    return this.text.length;
+  }
+
+  getFullText() {
+    return this.text;
+  }
+
+  getChangeRange() {
+    return undefined;
+  }
+
+  positionAt(offset: number) {
+    return positionAt(offset, this.text);
+  }
+
+  getLineContainingOffset(offset: number) {
+    const chunks = this.getText(0, offset).split('\n');
+    return chunks[chunks.length - 1];
+  }
+
+  offsetAt(position: Position) {
+    return offsetAt(position, this.text);
+  }
+
+  private getMapper(uri: string) {
+    return new IdentityMapper(uri);
+  }
+}
+
+export class DocumentFragmentSnapshot implements Omit<DocumentSnapshot, 'getFragment' | 'destroyFragment'>, SnapshotFragment {
+  version: number;
+  filePath: string;
+  url: string;
+  text: string;
+
+  scriptKind = ts.ScriptKind.TSX;
+  scriptInfo = null;
+
+  constructor(private mapper: any, private parent: Document) {
+    const filePath = parent.getFilePath();
+    if (!filePath) throw new Error('Cannot create a document fragment from a non-local document');
+    const text = parent.getText();
+    this.version = parent.version;
+    this.filePath = toVirtualAstroFilePath(filePath);
+    this.url = toVirtualAstroFilePath(filePath);
+    this.text = this.transformContent(text);
+  }
+
+  /** @internal */
+  private transformContent(content: string) {
+    return content.replace(/---/g, '///');
+  }
+
+  getText(start: number, end: number) {
+    return this.text.substring(start, end);
+  }
+
+  getLength() {
+    return this.text.length;
+  }
+
+  getFullText() {
+    return this.text;
+  }
+
+  getChangeRange() {
+    return undefined;
+  }
+
+  positionAt(offset: number) {
+    return positionAt(offset, this.text);
+  }
+
+  getLineContainingOffset(offset: number) {
+    const chunks = this.getText(0, offset).split('\n');
+    return chunks[chunks.length - 1];
+  }
+
+  offsetAt(position: Position): number {
+    return offsetAt(position, this.text);
+  }
+
+  getOriginalPosition(pos: Position): Position {
+    return this.mapper.getOriginalPosition(pos);
+  }
+
+  getGeneratedPosition(pos: Position): Position {
+    return this.mapper.getGeneratedPosition(pos);
+  }
+
+  isInGenerated(pos: Position): boolean {
+    return !isInTag(pos, this.parent.styleInfo);
+  }
+
+  getURL(): string {
+    return this.url;
+  }
+}
+
+export class TypeScriptDocumentSnapshot implements DocumentSnapshot {
+  scriptKind = getScriptKindFromFileName(this.filePath);
+  scriptInfo = null;
+  url: string;
+
+  constructor(public version: number, public readonly filePath: string, private text: string) {
+    this.url = pathToUrl(filePath);
+  }
+
+  getText(start: number, end: number) {
+    return this.text.substring(start, end);
+  }
+
+  getLength() {
+    return this.text.length;
+  }
+
+  getFullText() {
+    return this.text;
+  }
+
+  getChangeRange() {
+    return undefined;
+  }
+
+  positionAt(offset: number) {
+    return positionAt(offset, this.text);
+  }
+
+  offsetAt(position: Position): number {
+    return offsetAt(position, this.text);
+  }
+
+  async getFragment(): Promise<DocumentFragmentSnapshot> {
+    return (this as unknown) as any;
+  }
+
+  destroyFragment() {
+    // nothing to clean up
+  }
+
+  getLineContainingOffset(offset: number) {
+    const chunks = this.getText(0, offset).split('\n');
+    return chunks[chunks.length - 1];
+  }
+
+  update(changes: TextDocumentContentChangeEvent[]): void {
+    for (const change of changes) {
+      let start = 0;
+      let end = 0;
+      if ('range' in change) {
+        start = this.offsetAt(change.range.start);
+        end = this.offsetAt(change.range.end);
+      } else {
+        end = this.getLength();
+      }
+
+      this.text = this.text.slice(0, start) + change.text + this.text.slice(end);
+    }
+
+    this.version++;
+  }
+}
diff --git a/tools/astro-languageserver/src/plugins/typescript/LanguageServiceManager.ts b/tools/astro-languageserver/src/plugins/typescript/LanguageServiceManager.ts
index 529ab2b4c..d2a5cecff 100644
--- a/tools/astro-languageserver/src/plugins/typescript/LanguageServiceManager.ts
+++ b/tools/astro-languageserver/src/plugins/typescript/LanguageServiceManager.ts
@@ -3,7 +3,8 @@ import type { Document, DocumentManager } from '../../core/documents';
 import type { ConfigManager } from '../../core/config';
 import { urlToPath, pathToUrl, debounceSameArg } from '../../utils';
 import { getLanguageService, getLanguageServiceForDocument, LanguageServiceContainer, LanguageServiceDocumentContext } from './languageService';
-import { DocumentSnapshot, SnapshotManager } from './SnapshotManager';
+import { SnapshotManager } from './SnapshotManager';
+import { DocumentSnapshot } from './DocumentSnapshot';
 
 export class LanguageServiceManager {
   private readonly docManager: DocumentManager;
diff --git a/tools/astro-languageserver/src/plugins/typescript/SnapshotManager.ts b/tools/astro-languageserver/src/plugins/typescript/SnapshotManager.ts
index 4f9e865a1..5a406b945 100644
--- a/tools/astro-languageserver/src/plugins/typescript/SnapshotManager.ts
+++ b/tools/astro-languageserver/src/plugins/typescript/SnapshotManager.ts
@@ -1,9 +1,7 @@
 import * as ts from 'typescript';
-import { TextDocumentContentChangeEvent, Position } from 'vscode-languageserver';
-import { Document } from '../../core/documents';
-import { positionAt, offsetAt } from '../../core/documents/utils';
-import { pathToUrl } from '../../utils';
-import { getScriptKindFromFileName, isAstroFilePath, toVirtualAstroFilePath } from './utils';
+import { TextDocumentContentChangeEvent } from 'vscode-languageserver';
+import { toVirtualAstroFilePath } from './utils';
+import { DocumentSnapshot, TypeScriptDocumentSnapshot, createDocumentSnapshot } from './DocumentSnapshot';
 
 export interface TsFilesSpec {
   include?: readonly string[];
@@ -95,209 +93,3 @@ export class SnapshotManager {
     }
   }
 }
-
-export interface DocumentSnapshot extends ts.IScriptSnapshot {
-  version: number;
-  filePath: string;
-  scriptKind: ts.ScriptKind;
-  positionAt(offset: number): Position;
-  /**
-   * Instantiates a source mapper.
-   * `destroyFragment` needs to be called when
-   * it's no longer needed / the class should be cleaned up
-   * in order to prevent memory leaks.
-   */
-  getFragment(): Promise<DocumentFragmentSnapshot>;
-  /**
-   * Needs to be called when source mapper
-   * is no longer needed / the class should be cleaned up
-   * in order to prevent memory leaks.
-   */
-  destroyFragment(): void;
-  /**
-   * Convenience function for getText(0, getLength())
-   */
-  getFullText(): string;
-}
-
-export const createDocumentSnapshot = (filePath: string, currentText: string | null, createDocument?: (_filePath: string, text: string) => Document): DocumentSnapshot => {
-  const text = currentText || (ts.sys.readFile(filePath) ?? '');
-
-  if (isAstroFilePath(filePath)) {
-    if (!createDocument) throw new Error('Astro documents require the "createDocument" utility to be provided');
-    const snapshot = new AstroDocumentSnapshot(createDocument(filePath, text));
-    return snapshot;
-  }
-
-  return new TypeScriptDocumentSnapshot(0, filePath, text);
-};
-
-class AstroDocumentSnapshot implements DocumentSnapshot {
-  version = this.doc.version;
-  scriptKind = ts.ScriptKind.Unknown;
-
-  constructor(private doc: Document) {}
-
-  async getFragment(): Promise<DocumentFragmentSnapshot> {
-    return new DocumentFragmentSnapshot(this.doc);
-  }
-
-  async destroyFragment() {
-    return;
-  }
-
-  get text() {
-    return this.doc.getText();
-  }
-
-  get filePath() {
-    return this.doc.getFilePath() || '';
-  }
-
-  getText(start: number, end: number) {
-    return this.text.substring(start, end);
-  }
-
-  getLength() {
-    return this.text.length;
-  }
-
-  getFullText() {
-    return this.text;
-  }
-
-  getChangeRange() {
-    return undefined;
-  }
-
-  positionAt(offset: number) {
-    return positionAt(offset, this.text);
-  }
-
-  getLineContainingOffset(offset: number) {
-    const chunks = this.getText(0, offset).split('\n');
-    return chunks[chunks.length - 1];
-  }
-
-  offsetAt(position: Position) {
-    return offsetAt(position, this.text);
-  }
-}
-
-class DocumentFragmentSnapshot implements Omit<DocumentSnapshot, 'getFragment' | 'destroyFragment'> {
-  version: number;
-  filePath: string;
-  url: string;
-  text: string;
-
-  scriptKind = ts.ScriptKind.TSX;
-  scriptInfo = null;
-
-  constructor(private doc: Document) {
-    const filePath = doc.getFilePath();
-    if (!filePath) throw new Error('Cannot create a document fragment from a non-local document');
-    const text = doc.getText();
-    this.version = doc.version;
-    this.filePath = toVirtualAstroFilePath(filePath);
-    this.url = toVirtualAstroFilePath(filePath);
-    this.text = this.transformContent(text);
-  }
-
-  /** @internal */
-  private transformContent(content: string) {
-    return content.replace(/---/g, '///');
-  }
-
-  getText(start: number, end: number) {
-    return this.text.substring(start, end);
-  }
-
-  getLength() {
-    return this.text.length;
-  }
-
-  getFullText() {
-    return this.text;
-  }
-
-  getChangeRange() {
-    return undefined;
-  }
-
-  positionAt(offset: number) {
-    return positionAt(offset, this.text);
-  }
-
-  getLineContainingOffset(offset: number) {
-    const chunks = this.getText(0, offset).split('\n');
-    return chunks[chunks.length - 1];
-  }
-
-  offsetAt(position: Position): number {
-    return offsetAt(position, this.text);
-  }
-}
-
-class TypeScriptDocumentSnapshot implements DocumentSnapshot {
-  scriptKind = getScriptKindFromFileName(this.filePath);
-  scriptInfo = null;
-  url: string;
-
-  constructor(public version: number, public readonly filePath: string, private text: string) {
-    this.url = pathToUrl(filePath);
-  }
-
-  getText(start: number, end: number) {
-    return this.text.substring(start, end);
-  }
-
-  getLength() {
-    return this.text.length;
-  }
-
-  getFullText() {
-    return this.text;
-  }
-
-  getChangeRange() {
-    return undefined;
-  }
-
-  positionAt(offset: number) {
-    return positionAt(offset, this.text);
-  }
-
-  offsetAt(position: Position): number {
-    return offsetAt(position, this.text);
-  }
-
-  async getFragment(): Promise<DocumentFragmentSnapshot> {
-    return (this as unknown) as any;
-  }
-
-  destroyFragment() {
-    // nothing to clean up
-  }
-
-  getLineContainingOffset(offset: number) {
-    const chunks = this.getText(0, offset).split('\n');
-    return chunks[chunks.length - 1];
-  }
-
-  update(changes: TextDocumentContentChangeEvent[]): void {
-    for (const change of changes) {
-      let start = 0;
-      let end = 0;
-      if ('range' in change) {
-        start = this.offsetAt(change.range.start);
-        end = this.offsetAt(change.range.end);
-      } else {
-        end = this.getLength();
-      }
-
-      this.text = this.text.slice(0, start) + change.text + this.text.slice(end);
-    }
-
-    this.version++;
-  }
-}
diff --git a/tools/astro-languageserver/src/plugins/typescript/TypeScriptPlugin.ts b/tools/astro-languageserver/src/plugins/typescript/TypeScriptPlugin.ts
index aab758bdb..30781a508 100644
--- a/tools/astro-languageserver/src/plugins/typescript/TypeScriptPlugin.ts
+++ b/tools/astro-languageserver/src/plugins/typescript/TypeScriptPlugin.ts
@@ -1,12 +1,14 @@
 import type { Document, DocumentManager } from '../../core/documents';
 import type { ConfigManager } from '../../core/config';
 import type { CompletionsProvider, AppCompletionItem, AppCompletionList } from '../interfaces';
-import { CompletionContext, Position, FileChangeType } from 'vscode-languageserver';
+import { CompletionContext, DefinitionLink, FileChangeType, Position, LocationLink } from 'vscode-languageserver';
 import * as ts from 'typescript';
 import { CompletionsProviderImpl, CompletionEntryWithIdentifer } from './features/CompletionsProvider';
 import { LanguageServiceManager } from './LanguageServiceManager';
 import { SnapshotManager } from './SnapshotManager';
-import { getScriptKindFromFileName } from './utils';
+import { convertToLocationRange, isVirtualFilePath, getScriptKindFromFileName } from './utils';
+import { isNoTextSpanInGeneratedCode, SnapshotFragmentMap } from './features/utils';
+import { isNotNullOrUndefined, pathToUrl } from '../../utils';
 
 export class TypeScriptPlugin implements CompletionsProvider {
   private readonly docManager: DocumentManager;
@@ -33,6 +35,40 @@ export class TypeScriptPlugin implements CompletionsProvider {
     return this.completionProvider.resolveCompletion(document, completionItem);
   }
 
+  async getDefinitions(document: Document, position: Position): Promise<DefinitionLink[]> {
+    const { lang, tsDoc } = await this.languageServiceManager.getTypeScriptDoc(document);
+    const mainFragment = await tsDoc.getFragment();
+
+    const filePath = tsDoc.filePath;
+    const tsFilePath = filePath.endsWith('.ts') ? filePath : filePath + '.ts';
+
+    const defs = lang.getDefinitionAndBoundSpan(tsFilePath, mainFragment.offsetAt(mainFragment.getGeneratedPosition(position)));
+
+    if (!defs || !defs.definitions) {
+      return [];
+    }
+
+    const docs = new SnapshotFragmentMap(this.languageServiceManager);
+    docs.set(tsDoc.filePath, { fragment: mainFragment, snapshot: tsDoc });
+
+    const result = await Promise.all(
+      defs.definitions.map(async (def) => {
+        const { fragment, snapshot } = await docs.retrieve(def.fileName);
+
+        if (isNoTextSpanInGeneratedCode(snapshot.getFullText(), def.textSpan)) {
+          const fileName = isVirtualFilePath(def.fileName) ? def.fileName.substr(0, def.fileName.length - 3) : def.fileName;
+          return LocationLink.create(
+            pathToUrl(fileName),
+            convertToLocationRange(fragment, def.textSpan),
+            convertToLocationRange(fragment, def.textSpan),
+            convertToLocationRange(mainFragment, defs.textSpan)
+          );
+        }
+      })
+    );
+    return result.filter(isNotNullOrUndefined);
+  }
+
   async onWatchFileChanges(onWatchFileChangesParams: any[]): Promise<void> {
     const doneUpdateProjectFiles = new Set<SnapshotManager>();
 
diff --git a/tools/astro-languageserver/src/plugins/typescript/features/utils.ts b/tools/astro-languageserver/src/plugins/typescript/features/utils.ts
new file mode 100644
index 000000000..8c87dc5f4
--- /dev/null
+++ b/tools/astro-languageserver/src/plugins/typescript/features/utils.ts
@@ -0,0 +1,54 @@
+import type { SnapshotFragment, DocumentSnapshot } from '../DocumentSnapshot';
+import type { LanguageServiceManager } from '../LanguageServiceManager';
+
+/**
+ * Checks if this a section that should be completely ignored
+ * because it's purely generated.
+ */
+export function isInGeneratedCode(text: string, start: number, end: number) {
+  const lineStart = text.lastIndexOf('\n', start);
+  const lineEnd = text.indexOf('\n', end);
+  const lastStart = text.substring(lineStart, start).lastIndexOf('/*Ωignore_startΩ*/');
+  const lastEnd = text.substring(lineStart, start).lastIndexOf('/*Ωignore_endΩ*/');
+  return lastStart > lastEnd && text.substring(end, lineEnd).includes('/*Ωignore_endΩ*/');
+}
+
+/**
+ * Checks that this isn't a text span that should be completely ignored
+ * because it's purely generated.
+ */
+export function isNoTextSpanInGeneratedCode(text: string, span: ts.TextSpan) {
+  return !isInGeneratedCode(text, span.start, span.start + span.length);
+}
+
+export class SnapshotFragmentMap {
+  private map = new Map<string, { fragment: SnapshotFragment; snapshot: DocumentSnapshot }>();
+  constructor(private languageServiceManager: LanguageServiceManager) {}
+
+  set(fileName: string, content: { fragment: SnapshotFragment; snapshot: DocumentSnapshot }) {
+    this.map.set(fileName, content);
+  }
+
+  get(fileName: string) {
+    return this.map.get(fileName);
+  }
+
+  getFragment(fileName: string) {
+    return this.map.get(fileName)?.fragment;
+  }
+
+  async retrieve(fileName: string) {
+    let snapshotFragment = this.get(fileName);
+    if (!snapshotFragment) {
+      const snapshot = await this.languageServiceManager.getSnapshot(fileName);
+      const fragment = await snapshot.getFragment();
+      snapshotFragment = { fragment, snapshot };
+      this.set(fileName, snapshotFragment);
+    }
+    return snapshotFragment;
+  }
+
+  async retrieveFragment(fileName: string) {
+    return (await this.retrieve(fileName)).fragment;
+  }
+}
diff --git a/tools/astro-languageserver/src/plugins/typescript/languageService.ts b/tools/astro-languageserver/src/plugins/typescript/languageService.ts
index 0db9e66cc..b7ff6df20 100644
--- a/tools/astro-languageserver/src/plugins/typescript/languageService.ts
+++ b/tools/astro-languageserver/src/plugins/typescript/languageService.ts
@@ -4,7 +4,8 @@ import * as ts from 'typescript';
 import { basename } from 'path';
 import { ensureRealAstroFilePath, findTsConfigPath } from './utils';
 import { Document } from '../../core/documents';
-import { createDocumentSnapshot, SnapshotManager, DocumentSnapshot } from './SnapshotManager';
+import { SnapshotManager } from './SnapshotManager';
+import { createDocumentSnapshot, DocumentSnapshot } from './DocumentSnapshot';
 import { createAstroModuleLoader } from './module-loader';
 
 const services = new Map<string, Promise<LanguageServiceContainer>>();
diff --git a/tools/astro-languageserver/src/plugins/typescript/utils.ts b/tools/astro-languageserver/src/plugins/typescript/utils.ts
index da4e37c84..b212d9cd3 100644
--- a/tools/astro-languageserver/src/plugins/typescript/utils.ts
+++ b/tools/astro-languageserver/src/plugins/typescript/utils.ts
@@ -1,7 +1,9 @@
 import * as ts from 'typescript';
-import { CompletionItemKind, DiagnosticSeverity } from 'vscode-languageserver';
+import { CompletionItemKind, DiagnosticSeverity, Position, Range } from 'vscode-languageserver';
 import { dirname } from 'path';
 import { pathToUrl } from '../../utils';
+import { mapRangeToOriginal } from '../../core/documents';
+import { SnapshotFragment } from './DocumentSnapshot';
 
 export function scriptElementKindToCompletionItemKind(kind: ts.ScriptElementKind): CompletionItemKind {
   switch (kind) {
@@ -127,12 +129,52 @@ export function getExtensionFromScriptKind(kind: ts.ScriptKind | undefined): ts.
   }
 }
 
+export function convertRange(document: { positionAt: (offset: number) => Position }, range: { start?: number; length?: number }): Range {
+  return Range.create(document.positionAt(range.start || 0), document.positionAt((range.start || 0) + (range.length || 0)));
+}
+
+export function convertToLocationRange(defDoc: SnapshotFragment, textSpan: ts.TextSpan): Range {
+  const range = mapRangeToOriginal(defDoc, convertRange(defDoc, textSpan));
+  // Some definition like the svelte component class definition don't exist in the original, so we map to 0,1
+  if (range.start.line < 0) {
+    range.start.line = 0;
+    range.start.character = 1;
+  }
+  if (range.end.line < 0) {
+    range.end = range.start;
+  }
+
+  return range;
+}
+
+type FrameworkExt = 'astro' | 'vue' | 'jsx' | 'tsx' | 'svelte';
+
+export function isVirtualFrameworkFilePath(ext: FrameworkExt, filePath: string) {
+  return filePath.endsWith('.' + ext + '.ts');
+}
+
 export function isAstroFilePath(filePath: string) {
   return filePath.endsWith('.astro');
 }
 
 export function isVirtualAstroFilePath(filePath: string) {
-  return filePath.endsWith('.astro.ts');
+  return isVirtualFrameworkFilePath('astro', filePath);
+}
+
+export function isVirtualVueFilePath(filePath: string) {
+  return isVirtualFrameworkFilePath('vue', filePath);
+}
+
+export function isVirtualJsxFilePath(filePath: string) {
+  return isVirtualFrameworkFilePath('jsx', filePath) || isVirtualFrameworkFilePath('tsx', filePath);
+}
+
+export function isVirtualSvelteFilePath(filePath: string) {
+  return isVirtualFrameworkFilePath('svelte', filePath);
+}
+
+export function isVirtualFilePath(filePath: string) {
+  return isVirtualAstroFilePath(filePath) || isVirtualVueFilePath(filePath) || isVirtualSvelteFilePath(filePath) || isVirtualJsxFilePath(filePath);
 }
 
 export function toVirtualAstroFilePath(filePath: string) {
diff --git a/tools/astro-languageserver/src/utils.ts b/tools/astro-languageserver/src/utils.ts
index f9f1acf34..ba3d9366e 100644
--- a/tools/astro-languageserver/src/utils.ts
+++ b/tools/astro-languageserver/src/utils.ts
@@ -51,6 +51,10 @@ export function clamp(num: number, min: number, max: number): number {
   return Math.max(min, Math.min(max, num));
 }
 
+export function isNotNullOrUndefined<T>(val: T | undefined | null): val is T {
+  return val !== undefined && val !== null;
+}
+
 /** Checks if a position is inside range */
 export function isInRange(positionToTest: Position, range: Range): boolean {
   return isBeforeOrEqualToPosition(range.end, positionToTest) && isBeforeOrEqualToPosition(positionToTest, range.start);