add third option: never check for newer versions

Shouldn't save too much bandwidth, but why not?

Also fix default option

Author: WorldSEnder

package.json

@@ -157,13 +157,15 @@
           "type": "string",
           "enum": [
             "keep-up-to-date",
-            "prompt"
+            "prompt",
+            "never-check"
           ],
           "enumDescriptions": [
             "Always download the latest available version when it is published",
-            "Prompt before downloading a newer version"
+            "Prompt before upgrading to a newer version",
+            "Don't check for newer versions"
           ],
-          "default": true,
+          "default": "keep-up-to-date",
           "markdownDescription": "Only applicable with `#haskell.languageServerVariant#` set to `haskell-language-server`. Determine what to do when a new version of the language server is available."
         }
       }

src/hlsBinaries.ts

@@ -20,7 +20,7 @@ interface IAsset {
   name: string;
 }
 
-type UpdateBehaviour = 'keep-up-to-date' | 'prompt';
+type UpdateBehaviour = 'keep-up-to-date' | 'prompt' | 'never-check';
 
 const assetValidator: validate.Validator<IAsset> = validate.object({
   browser_download_url: validate.string(),
@@ -179,14 +179,18 @@ async function getLatestReleaseMetadata(context: ExtensionContext): Promise<IRel
       throw err;
     }
   }
+  // Not all users want to upgrade right away, in that case prompt
+  const updateBehaviour = workspace.getConfiguration('haskell').get('hlsUpdateBehavior') as UpdateBehaviour;
+
+  if (updateBehaviour === 'never-check') {
+    return readCachedReleaseData();
+  }
 
   try {
     const releaseInfo = await httpsGetSilently(opts);
     const latestInfoParsed =
       validate.parseAndValidate(releaseInfo, githubReleaseApiValidator).find((x) => !x.prerelease) || null;
 
-    // Not all users want to upgrade right away, in that case prompt
-    const updateBehaviour = workspace.getConfiguration('haskell').get('hlsUpdateBehavior') as UpdateBehaviour;
     if (updateBehaviour === 'prompt') {
       const cachedInfoParsed = await readCachedReleaseData();
 
@@ -248,7 +252,12 @@ export async function downloadHaskellLanguageServer(
   // Fetch the latest release from GitHub or from cache
   const release = await getLatestReleaseMetadata(context);
   if (!release) {
-    window.showErrorMessage("Couldn't find any pre-built haskell-language-server binaries");
+    let message = "Couldn't find any pre-built haskell-language-server binaries";
+    const updateBehaviour = workspace.getConfiguration('haskell').get('hlsUpdateBehavior') as UpdateBehaviour;
+    if (updateBehaviour === 'never-check') {
+      message += ' (and checking for newer versions is disabled)';
+    }
+    window.showErrorMessage(message);
     return null;
   }
 

src/utils.ts

@@ -6,6 +6,7 @@ import * as http from 'http';
 import * as https from 'https';
 import { extname } from 'path';
 import * as url from 'url';
+import { promisify } from 'util';
 import { ProgressLocation, window } from 'vscode';
 import * as yazul from 'yauzl';
 import { createGunzip } from 'zlib';
@@ -50,6 +51,13 @@ export async function httpsGetSilently(options: https.RequestOptions): Promise<s
   });
 }
 
+async function ignoreFileNotExists(err: NodeJS.ErrnoException): Promise<void> {
+  if (err.code === 'ENOENT') {
+    return;
+  }
+  throw err;
+}
+
 export async function downloadFile(titleMsg: string, src: string, dest: string): Promise<void> {
   // Check to see if we're already in the process of downloading the same thing
   const inFlightDownload = inFlightDownloads.get(src)?.get(dest);
@@ -158,10 +166,10 @@ export async function downloadFile(titleMsg: string, src: string, dest: string):
     } else {
       inFlightDownloads.set(src, new Map([[dest, downloadTask]]));
     }
-    return downloadTask;
+    return await downloadTask;
   } catch (e) {
-    fs.unlinkSync(downloadDest);
-    throw new Error(`Failed to download ${url}`);
+    await promisify(fs.unlink)(downloadDest).catch(ignoreFileNotExists);
+    throw new Error(`Failed to download ${src}:\n${e.message}`);
   }
 }