Add Swiftly installation support

Author: roulpriya

package-lock.json

@@ -1083,6 +1083,13 @@
             "order": 4,
             "scope": "machine-overridable"
           },
+          "swift.suppressSwiftlyInstallPrompt": {
+            "type": "boolean",
+            "default": false,
+            "markdownDescription": "Suppress the automatic Swiftly installation prompt when no Swift toolchain is found.",
+            "order": 98,
+            "scope": "application"
+          },
           "swift.diagnostics": {
             "type": "boolean",
             "default": false,
@@ -2081,6 +2088,7 @@
     "fast-glob": "^3.3.3",
     "lcov-parse": "^1.0.0",
     "plist": "^3.1.0",
+    "tar": "^7.5.1",
     "vscode-languageclient": "^9.0.1",
     "xml2js": "^0.6.2",
     "zod": "^4.1.5"

package.json

@@ -17,8 +17,10 @@ import * as vscode from "vscode";
 
 import { FolderContext } from "./FolderContext";
 import { FolderOperation } from "./WorkspaceContext";
+import { handleMissingSwiftly } from "./commands/installSwiftly";
 import { SwiftLogger } from "./logging/SwiftLogger";
 import { BuildFlags } from "./toolchain/BuildFlags";
+import { handleMissingSwiftlyToolchain } from "./toolchain/swiftly";
 import { showReloadExtensionNotification } from "./ui/ReloadExtension";
 import { fileExists } from "./utilities/filesystem";
 import { Version } from "./utilities/version";
@@ -140,6 +142,30 @@ export class PackageWatcher {
     async handleSwiftVersionFileChange() {
         const version = await this.readSwiftVersionFile();
         if (version?.toString() !== this.currentVersion?.toString()) {
+            if (version) {
+                const swiftlyInstalled = await handleMissingSwiftly(this.logger);
+                if (swiftlyInstalled) {
+                    const toolchainInstalled = await handleMissingSwiftlyToolchain(
+                        version.toString(),
+                        this.logger,
+                        this.folderContext.folder
+                    );
+                    if (toolchainInstalled) {
+                        // Build dynamic message based on installation results
+                        const message =
+                            "Swiftly and Swift toolchain have been installed. Please reload the extension to use the new toolchain.";
+                        await showReloadExtensionNotification(message);
+                        return;
+                    } else {
+                        // Only Swiftly was installed
+                        const message =
+                            "Swiftly has been installed. Please reload the extension to continue.";
+                        await showReloadExtensionNotification(message);
+                        return;
+                    }
+                }
+            }
+
             await this.folderContext.fireEvent(FolderOperation.swiftVersionUpdated);
             await showReloadExtensionNotification(
                 "Changing the swift toolchain version requires the extension to be reloaded"