feat(vscode-ext): support source opening (#817)

## What does this PR do?

It enables quick opening of the source file in VSCode using CMD+click
with the Extension.

### Preview

<img width="1270" height="524" alt="image"
src="https://github.com/user-attachments/assets/5cfe6730-dfcd-449d-ae98-059b6b8115b4"
/>

Author: Binlogo

vscode-insta/src/SnapshotDocumentLinkProvider.ts

@@ -0,0 +1,134 @@
+import * as path from "path";
+import {
+  DocumentLink,
+  DocumentLinkProvider,
+  Position,
+  Range,
+  Selection,
+  TextDocument,
+  Uri,
+  window,
+  workspace,
+} from "vscode";
+
+type SourceLink = {
+  sourcePath: string;
+  range: Range;
+  line?: number;
+};
+
+export const SOURCE_COMMAND = "mitsuhiko.insta.open-source-location";
+
+function extractSourceLink(document: TextDocument): SourceLink | undefined {
+  let sourcePath: string | undefined;
+  let lineNumber: number | undefined;
+  let sourceLineIndex = -1;
+
+  // Simple pass through all lines
+  for (let i = 0; i < document.lineCount; i++) {
+    const text = document.lineAt(i).text;
+    
+    // Find source path
+    if (text.startsWith("source:")) {
+      sourcePath = text.slice(7).trim(); // "source:" is 7 characters
+      sourceLineIndex = i;
+    }
+    
+    // Find assertion line (optional)
+    if (text.startsWith("assertion_line:")) {
+      const lineStr = text.slice(15).trim(); // "assertion_line:" is 15 characters
+      lineNumber = parseInt(lineStr, 10);
+    }
+  }
+
+  if (sourcePath && sourceLineIndex >= 0) {
+    // Create a simple range for the entire source line
+    const line = document.lineAt(sourceLineIndex);
+    const range = new Range(
+      new Position(sourceLineIndex, 0),
+      new Position(sourceLineIndex, line.text.length)
+    );
+    
+    return {
+      sourcePath,
+      range,
+      line: lineNumber,
+    };
+  }
+
+  return undefined;
+}
+
+async function resolveSourceUri(
+  document: TextDocument,
+  sourcePath: string
+): Promise<Uri | undefined> {
+  // Handle absolute paths
+  if (path.isAbsolute(sourcePath)) {
+    return Uri.file(sourcePath);
+  }
+
+  // For relative paths, resolve against workspace root
+  // Insta snapshots are always workspace-relative
+  const workspaceFolder = workspace.getWorkspaceFolder(document.uri);
+  if (workspaceFolder) {
+    return Uri.file(path.join(workspaceFolder.uri.fsPath, sourcePath));
+  }
+
+  return undefined;
+}
+
+export class SnapshotDocumentLinkProvider implements DocumentLinkProvider {
+  async provideDocumentLinks(
+    document: TextDocument
+  ): Promise<DocumentLink[]> {
+    const info = extractSourceLink(document);
+    if (!info) {
+      return [];
+    }
+
+    const target = await resolveSourceUri(document, info.sourcePath);
+    if (!target) {
+      return [];
+    }
+
+    const payload = encodeURIComponent(
+      JSON.stringify({
+        target: target.toString(true),
+        line: info.line,
+      })
+    );
+
+    const link = new DocumentLink(
+      info.range,
+      Uri.parse(`command:${SOURCE_COMMAND}?${payload}`)
+    );
+    link.tooltip = "Open snapshot source";
+    return [link];
+  }
+}
+
+export async function openSourceDocument(payload?: {
+  target?: string;
+  line?: number;
+}) {
+  if (!payload?.target) {
+    return;
+  }
+
+  const uri = Uri.parse(payload.target);
+  try {
+    const document = await workspace.openTextDocument(uri);
+    const editor = await window.showTextDocument(document, { preview: true });
+    if (payload.line !== undefined) {
+      const zeroBasedLine = Math.max(payload.line - 1, 0);
+      const position = new Position(zeroBasedLine, 0);
+      editor.selection = new Selection(position, position);
+      editor.revealRange(new Range(position, position));
+    }
+  } catch (error) {
+    const message =
+      error instanceof Error ? error.message : "Unknown error opening file";
+    window.showErrorMessage(`Could not open source file: ${message}`);
+  }
+}

vscode-insta/src/extension.ts

@@ -13,6 +13,11 @@ import { InlineSnapshotProvider } from "./InlineSnapshotProvider";
 import { PendingSnapshotsProvider } from "./PendingSnapshotsProvider";
 import { Snapshot } from "./Snapshot";
 import { SnapshotPathProvider } from "./SnapshotPathProvider";
+import {
+  SnapshotDocumentLinkProvider,
+  openSourceDocument,
+  SOURCE_COMMAND
+} from "./SnapshotDocumentLinkProvider";
 import { findCargoRoots, projectUsesInsta } from "./cargo";
 import { processAllSnapshots, processInlineSnapshot } from "./insta";
 
@@ -201,6 +206,7 @@ function performOnAllSnapshots(op: "accept" | "reject") {
 export function activate(context: ExtensionContext): void {
   const pendingSnapshots = new PendingSnapshotsProvider();
   const snapshotPathProvider = new SnapshotPathProvider();
+  const snapshotDocumentLinkProvider = new SnapshotDocumentLinkProvider();
 
   const snapWatcher = workspace.createFileSystemWatcher(
     "**/*.{snap,snap.new,pending-snap}"
@@ -224,6 +230,14 @@ export function activate(context: ExtensionContext): void {
     snapWatcher,
     cargoLockWatcher,
     window.registerTreeDataProvider("pendingInstaSnapshots", pendingSnapshots),
+    languages.registerDocumentLinkProvider(
+      { language: "insta-snapshots" },
+      snapshotDocumentLinkProvider
+    ),
+    languages.registerDocumentLinkProvider(
+      { scheme: "instaInlineSnapshot" },
+      snapshotDocumentLinkProvider
+    ),
     workspace.registerTextDocumentContentProvider(
       "instaInlineSnapshot",
       new InlineSnapshotProvider(pendingSnapshots)
@@ -267,6 +281,7 @@ export function activate(context: ExtensionContext): void {
     ),
     commands.registerCommand("mitsuhiko.insta.reject-all-snapshots", () =>
       performOnAllSnapshots("reject")
-    )
+    ),
+    commands.registerCommand(SOURCE_COMMAND, openSourceDocument)
   );
 }