(#70) Add current Language Server code

This code has been taken from the develop branch, so that we can
continue the development of the language server portion of the extension
without preventing other ongoing work from going out the door.

We will get to this at some point, but for now, this should be regarded
as a nice have.

Author: gep13

package-lock.json

@@ -84,6 +84,29 @@
 								}
 							}
 						}
+					},
+					"chocolatey.language": {
+						"type": "object",
+						"properties": {
+							"allowSuppressionOfRequirements": {
+								"title": "Allow requirements suppression",
+								"type": "boolean",
+								"default": false,
+								"description": "Allow the suppression of rules that are marked as requirements"
+							},
+							"disableLanguageService": {
+								"title": "Disable language service",
+								"type": "boolean",
+								"default": false,
+								"description": "Prevent the Chocolatey Language Service from starting up"
+							},
+							"suppressedRules": {
+								"title": "Suppress Rules",
+								"type": "array",
+								"description": "The codes for the Chocolatey Language Service rules that should be suppressed",
+								"default": []
+							}
+						}
 					}
 				}
 			}
@@ -153,6 +176,7 @@
 		"typescript": "^3.8.3"
 	},
 	"dependencies": {
+		"vscode-languageclient": "^6.1.3",
 		"xml2js": "^0.4.23"
 	},
 	"extensionPack": [

package.json

@@ -1,4 +1,6 @@
 import { window, commands, workspace, QuickPickItem, ExtensionContext, Uri } from "vscode";
+import { LanguageClient, LanguageClientOptions, ServerOptions } from 'vscode-languageclient';
+import { Trace } from 'vscode-jsonrpc';
 import * as chocolateyCli from "./ChocolateyCliManager";
 import * as chocolateyOps from "./ChocolateyOperation";
 import * as path from "path";
@@ -7,6 +9,13 @@ import * as fs from "fs";
 var chocolateyManager : chocolateyCli.ChocolateyCliManager;
 var installed : boolean = false;
 
+const languageServerPaths = [
+    // TODO: Change path to the actually expected location of the language server
+    "out/.server/Chocolatey.Language.Server.dll",
+    "./src/Chocolatey.Language.Server/bin/Release/netcoreapp2.1/Chocolatey.Language.Server.dll",
+    "./src/Chocolatey.Language.Server/bin/Debug/netcoreapp2.1/Chocolatey.Language.Server.dll"
+];
+
 export function activate(context: ExtensionContext): void {
     // register Commands
     context.subscriptions.push(
@@ -18,6 +27,65 @@ export function activate(context: ExtensionContext): void {
         commands.registerCommand("chocolatey.apikey", () => execute("apikey")),
         commands.registerCommand("chocolatey.open", async (uri: string) => await commands.executeCommand('vscode.open', Uri.parse(uri)))
     );
+
+    let config = workspace.getConfiguration("chocolatey.language");
+    let disableLanguageService: boolean | undefined = false;
+
+    if(config !== undefined) {
+        disableLanguageService = config.get("disableLanguageService")
+    }
+
+    // Only start the Language Service if configured to do so
+    if(!disableLanguageService) {
+        let serverExe = 'dotnet';
+        let serverModule: string | null = null;
+        for (let p of languageServerPaths) {
+            p = context.asAbsolutePath(p);
+            // console.log/p);
+            if (fs.existsSync(p)) {
+                serverModule = p;
+                break;
+            }
+        }
+
+        // TODO: Decision need to be made if the Language Server should
+        // be packed inside the vsix file, or downloaded during runtime.
+
+        if (!serverModule) { throw new URIError("Cannot find the language server module."); }
+        let workPath = path.dirname(serverModule);
+        console.log(`Use ${serverModule} as server module.`);
+        console.log(`Work path: ${workPath}`);
+
+        // If the extension is launched in debug mode then the debug server options are used
+        // Otherwise the run options are used
+        let serverOptions: ServerOptions = {
+            run: { command: serverExe, args: [serverModule], options: { cwd: workPath } },
+            debug: { command: serverExe, args: [serverModule, "--debug"], options: { cwd: workPath } }
+        };
+
+        // Options to control the language client
+        let clientOptions: LanguageClientOptions = {
+            // Register the server for plain text documents
+            documentSelector: [
+                {
+                    pattern: '**/*.nuspec',
+                }
+            ],
+            synchronize: {
+                configurationSection: 'chocolatey',
+                fileEvents: workspace.createFileSystemWatcher('**/*.nuspec')
+            },
+        }
+
+        // Create the language client and start the client.
+        const client = new LanguageClient('chocolatey', 'Chocolatey Language Server', serverOptions, clientOptions);
+        client.trace = Trace.Verbose;
+        let disposable = client.start();
+
+        // Push the disposable to the context's subscriptions so that the
+        // client can be deactivated on extension deactivation
+        context.subscriptions.push(disposable);
+    }
 }
 
 function deleteNupkgs():void {