use which to search nu location, add icon too. (#153)

* use `which` to search `nu` location, add icon too.

* also use `env:CARGO_HOME` and fallback to `~/.cargo/`

* change behavior in case `nu` cannot be found.

if the profile provider returns undefined, users will get a confusing error message:

```
No terminal profile options provided for id "nushell_default"
```

if we instead just return a program name "nu", the error message became:

```
path to shell executable "nu" does not exist
```

which should give the user more clue what went wrong.

* add detailed error message on failure.

the error message also guide the user to install `nushell` from website and reload vscode.

* fix CI failure caused by empty function lint

Author: nerditation

client/package.json

@@ -13,7 +13,8 @@
     "vscode": "^1.75.0"
   },
   "dependencies": {
-    "vscode-languageclient": "^8.1.0"
+    "vscode-languageclient": "^8.1.0",
+    "which": "^4.0.0"
   },
   "devDependencies": {
     "@types/vscode": "^1.75.1",

client/src/extension.ts

@@ -24,31 +24,31 @@ export function activate(context: vscode.ExtensionContext) {
       provideTerminalProfile(
         token: vscode.CancellationToken
       ): vscode.ProviderResult<vscode.TerminalProfile> {
+        const which = require("which");
         const path = require("path");
-        const fs = require("fs");
-        const glob = require("glob");
-        const os = require("os");
 
+        const PATH_FROM_ENV = process.env["PATH"];
         const pathsToCheck = [
+          PATH_FROM_ENV,
           // cargo install location
-          "~/.cargo/bin/nu",
-          "~/.cargo/bin/nu.exe",
+          (process.env["CARGO_HOME"] || "~/.cargo") + "/bin",
 
           // winget on Windows install location
-          "c:\\program files\\nu\\bin\\nu.exe",
+          "c:\\program files\\nu\\bin",
           // just add a few other drives for fun
-          "d:\\program files\\nu\\bin\\nu.exe",
-          "e:\\program files\\nu\\bin\\nu.exe",
-          "f:\\program files\\nu\\bin\\nu.exe",
+          "d:\\program files\\nu\\bin",
+          "e:\\program files\\nu\\bin",
+          "f:\\program files\\nu\\bin",
 
           // SCOOP:TODO
           // all user installed programs and scoop itself install to
           // c:\users\<user>\scoop\ unless SCOOP env var is set
           // globally installed programs go in
           // c:\programdata\scoop unless SCOOP_GLOBAL env var is set
           // scoop install location
-          "~/scoop/apps/nu/*/nu.exe",
-          "~/scoop/shims/nu.exe",
+          // SCOOP should already set up the correct `PATH` env var
+          //"~/scoop/apps/nu/*/nu.exe",
+          //"~/scoop/shims/nu.exe",
 
           // chocolatey install location - same as winget
           // 'c:\\program files\\nu\\bin\\nu.exe',
@@ -60,59 +60,57 @@ export function activate(context: vscode.ExtensionContext) {
 
           // brew install location mac
           // intel
-          "/usr/local/bin/nu",
+          "/usr/local/bin",
           // arm
-          "/opt/homebrew/bin/nu",
+          "/opt/homebrew/bin",
 
           // native package manager install location
-          "/usr/bin/nu",
+          // standard location should be in `PATH` env var
+          //"/usr/bin/nu",
         ];
 
-        let found_nushell_path = "";
-        const home = os.homedir();
-
-        for (const cur_val of pathsToCheck) {
-          // console.log("Inspecting location: " + cur_val);
-          let constructed_file = "";
-          if (cur_val.startsWith("~/scoop")) {
-            // console.log("Found scoop: " + cur_val);
-            const p = path.join(home, cur_val.slice(1));
-            // console.log("Expanded ~: " + p);
-            const file = glob.sync(p, "debug").toString();
-            // console.log("Glob for files: " + file);
-
-            if (file) {
-              // console.log("Found some file: " + file);
-              // if there are slashes, reverse them to back slashes
-              constructed_file = file.replace(/\//g, "\\");
+        const found_nushell_path = which.sync("nu", {
+          nothrow: true,
+          path: pathsToCheck.join(path.delimiter),
+        });
+
+        if (found_nushell_path == null) {
+          console.log(
+            "Nushell not found in env:PATH or any of the heuristic locations."
+          );
+          // use an async arrow funciton to use `await` inside
+          return (async () => {
+            if (
+              (await vscode.window.showErrorMessage(
+                "We cannot find a nushell executable in your path or pre-defined locations",
+                "install from website"
+              )) &&
+              (await vscode.env.openExternal(
+                vscode.Uri.parse("https://www.nushell.sh/")
+              )) &&
+              (await vscode.window.showInformationMessage(
+                "after you install nushell, you might need to reload vscode",
+                "reload now"
+              ))
+            ) {
+              vscode.commands.executeCommand("workbench.action.reloadWindow");
             }
-          } else if (cur_val.startsWith("~")) {
-            constructed_file = path.join(home, cur_val.slice(1));
-            // console.log("Found ~, constructing path: " + constructed_file);
-          } else {
-            constructed_file = cur_val;
-          }
-
-          if (fs.existsSync(constructed_file)) {
-            // console.log("File exists, returning: " + constructed_file);
-            found_nushell_path = constructed_file;
-            break;
-          } else {
-            // console.log("File not found: " + constructed_file);
-          }
+            // user has already seen error messages, but they didn't click through
+            // return a promise that never resolve to supress the confusing error
+            return await new Promise(() => undefined);
+          })();
         }
 
-        if (found_nushell_path.length > 0) {
-          return {
-            options: {
-              name: "Nushell",
-              shellPath: found_nushell_path,
-            },
-          };
-        } else {
-          console.log("Nushell not found, returning undefined");
-          return undefined;
-        }
+        return {
+          options: {
+            name: "Nushell",
+            shellPath: found_nushell_path,
+            iconPath: vscode.Uri.joinPath(
+              context.extensionUri,
+              "assets/nu.svg"
+            ),
+          },
+        };
       },
     })
   );