Adopt Terminal Shell Type API from VSCode with legacy fallback (#153)

@anthonykim1 The VSCode shell type is missing following types:
`tcshell`, `wsl`, `xonsh`

Author: karthiknadig

package.json

@@ -519,6 +519,7 @@
     "enabledApiProposals": [
         "chatParticipantPrivate",
         "chatParticipantAdditions",
-        "chatVariableResolver"
+        "chatVariableResolver",
+        "terminalShellType"
     ]
-}
+}

src/features/common/shellDetector.ts

@@ -1,4 +1,4 @@
-import { Terminal } from 'vscode';
+import { Terminal, TerminalShellType as TerminalShellTypeVscode } from 'vscode';
 import { isWindows } from '../../managers/common/utils';
 import * as os from 'os';
 import { vscodeShell } from '../../common/vscodeEnv.apis';
@@ -32,22 +32,24 @@ const IS_NUSHELL = /(nu$)/i;
 const IS_XONSH = /(xonsh$)/i;
 
 type KnownShellType = Exclude<TerminalShellType, TerminalShellType.unknown>;
-const detectableShells = new Map<KnownShellType, RegExp>(unsafeEntries({
-    [TerminalShellType.powershell]: IS_POWERSHELL,
-    [TerminalShellType.gitbash]: IS_GITBASH,
-    [TerminalShellType.bash]: IS_BASH,
-    [TerminalShellType.wsl]: IS_WSL,
-    [TerminalShellType.zsh]: IS_ZSH,
-    [TerminalShellType.ksh]: IS_KSH,
-    [TerminalShellType.commandPrompt]: IS_COMMAND,
-    [TerminalShellType.fish]: IS_FISH,
-    [TerminalShellType.tcshell]: IS_TCSHELL,
-    [TerminalShellType.cshell]: IS_CSHELL,
-    [TerminalShellType.nushell]: IS_NUSHELL,
-    [TerminalShellType.powershellCore]: IS_POWERSHELL_CORE,
-    [TerminalShellType.xonsh]: IS_XONSH,
-// This `satisfies` makes sure all shells are covered
-} satisfies Record<KnownShellType, RegExp>));
+const detectableShells = new Map<KnownShellType, RegExp>(
+    unsafeEntries({
+        [TerminalShellType.powershell]: IS_POWERSHELL,
+        [TerminalShellType.gitbash]: IS_GITBASH,
+        [TerminalShellType.bash]: IS_BASH,
+        [TerminalShellType.wsl]: IS_WSL,
+        [TerminalShellType.zsh]: IS_ZSH,
+        [TerminalShellType.ksh]: IS_KSH,
+        [TerminalShellType.commandPrompt]: IS_COMMAND,
+        [TerminalShellType.fish]: IS_FISH,
+        [TerminalShellType.tcshell]: IS_TCSHELL,
+        [TerminalShellType.cshell]: IS_CSHELL,
+        [TerminalShellType.nushell]: IS_NUSHELL,
+        [TerminalShellType.powershellCore]: IS_POWERSHELL_CORE,
+        [TerminalShellType.xonsh]: IS_XONSH,
+        // This `satisfies` makes sure all shells are covered
+    } satisfies Record<KnownShellType, RegExp>),
+);
 
 function identifyShellFromShellPath(shellPath: string): TerminalShellType {
     // Remove .exe extension so shells can be more consistently detected
@@ -122,8 +124,38 @@ function identifyShellFromSettings(): TerminalShellType {
     return shellPath ? identifyShellFromShellPath(shellPath) : TerminalShellType.unknown;
 }
 
+function fromShellTypeApi(terminal: Terminal): TerminalShellType {
+    switch (terminal.state.shellType) {
+        case TerminalShellTypeVscode.Sh:
+        case TerminalShellTypeVscode.Bash:
+            return TerminalShellType.bash;
+        case TerminalShellTypeVscode.Fish:
+            return TerminalShellType.fish;
+        case TerminalShellTypeVscode.Csh:
+            return TerminalShellType.cshell;
+        case TerminalShellTypeVscode.Ksh:
+            return TerminalShellType.ksh;
+        case TerminalShellTypeVscode.Zsh:
+            return TerminalShellType.zsh;
+        case TerminalShellTypeVscode.CommandPrompt:
+            return TerminalShellType.commandPrompt;
+        case TerminalShellTypeVscode.GitBash:
+            return TerminalShellType.gitbash;
+        case TerminalShellTypeVscode.PowerShell:
+            return TerminalShellType.powershellCore;
+        case TerminalShellTypeVscode.NuShell:
+            return TerminalShellType.nushell;
+        default:
+            return TerminalShellType.unknown;
+    }
+}
+
 export function identifyTerminalShell(terminal: Terminal): TerminalShellType {
-    let shellType = identifyShellFromTerminalName(terminal);
+    let shellType = fromShellTypeApi(terminal);
+
+    if (shellType === TerminalShellType.unknown) {
+        shellType = identifyShellFromTerminalName(terminal);
+    }
 
     if (shellType === TerminalShellType.unknown) {
         shellType = identifyShellFromSettings();

src/vscode.proposed.terminalShellType.d.ts

@@ -0,0 +1,38 @@
+/*---------------------------------------------------------------------------------------------
+ *  Copyright (c) Microsoft Corporation. All rights reserved.
+ *  Licensed under the MIT License. See License.txt in the project root for license information.
+ *--------------------------------------------------------------------------------------------*/
+
+declare module 'vscode' {
+    // https://github.com/microsoft/vscode/issues/230165
+
+    /**
+     * Known terminal shell types.
+     */
+    export enum TerminalShellType {
+        Sh = 1,
+        Bash = 2,
+        Fish = 3,
+        Csh = 4,
+        Ksh = 5,
+        Zsh = 6,
+        CommandPrompt = 7,
+        GitBash = 8,
+        PowerShell = 9,
+        Python = 10,
+        Julia = 11,
+        NuShell = 12,
+        Node = 13,
+    }
+
+    // Part of TerminalState since the shellType can change multiple times and this comes with an event.
+    export interface TerminalState {
+        /**
+         * The current detected shell type of the terminal. New shell types may be added in the
+         * future in which case they will be returned as a number that is not part of
+         * {@link TerminalShellType}.
+         * Includes number type to prevent the breaking change when new enum members are added?
+         */
+        readonly shellType?: TerminalShellType | number | undefined;
+    }
+}