(CAT-1669) - Fix hashrocket allignment on completion item select

Prior to this commit, when selecting a param/prop from the dropdown
completion list in puppet-vscode, the hash rocket would not be formatted
inline with the rest of the document.

This commit implements a middleware to the language client, and adds a
vscode API item command which allows us to execute a vscode command
after the selection of the param/prop from the dropdown list. So when an
param/prop is selected, we send a callback event to the language server
to format the document.

This is only possible on the vscode side thanks to the vscode API,
unfortunately there is no suitable events to implement this into the
langauge server.

Author: jordanbreen28

src/extension.ts

@@ -133,6 +133,17 @@ export function activate(context: vscode.ExtensionContext) {
     extensionFeatures.push(new PuppetModuleHoverFeature(extContext, logger));
   }
 
+  // if formatting is enabled, add a middleware to the language client to format the document on insert
+  if (settings.format.enable) {
+    vscode.commands.registerCommand('editor.action.formatDocumentAndMoveCursor', async () => {
+      vscode.commands.executeCommand('editor.action.formatDocument').then(() => {
+        vscode.commands.executeCommand('cursorMove', { to: 'left' });
+      });
+    });
+    // add middleware to Intercept the provideCompletionItem method
+    connectionHandler.languageClient.clientOptions.middleware = provideCompletionItemMiddleware;
+  }
+
   const facts = new PuppetFactsProvider(connectionHandler);
   vscode.window.registerTreeDataProvider('puppetFacts', facts);
 
@@ -359,3 +370,28 @@ function setLanguageConfiguration() {
     },
   });
 }
+
+export const provideCompletionItemMiddleware = {
+  provideCompletionItem: async (document, position, context, token, next) => {
+    // Get the completion list from the language server
+    const result = await next(document, position, context, token);
+    let items: vscode.CompletionItem[];
+    if (Array.isArray(result)) {
+      items = result;
+    } else {
+      items = result.items;
+    }
+    // Add command to be executed after completion item is selected
+    items.forEach(item => {
+      // check completion item is a prop or param, as this dictates which command to use
+      const isPropOrParam = item.detail === 'Property' || item.detail === 'Parameter';
+      // additional cursor cmd on the insertion of a property/param (UX)
+      const command = isPropOrParam ? 'editor.action.formatDocumentAndMoveCursor' : 'editor.action.formatDocument';
+      item.command = {
+        title: 'format document',
+        command: command
+      };
+    });
+    return items;
+  }
+};