import { commandHostEnvironment } from '@agent-device/host-kit/command';

/**

* Shared Linux environment detection — display server and input tool.

*

* Results are cached after the first probe so that every action

* (press, type, scroll…) does not re-run `which` on every call.

*/

import { AppError } from '@agent-device/kernel/errors';

import { resolveLinuxToolProvider, type LinuxToolProvider } from './tool-provider.ts';

export type DisplayServer = 'wayland' | 'x11';

export type InputTool = 'xdotool' | 'ydotool';

function detectDisplayServer(): DisplayServer {

const environment = commandHostEnvironment().env;

if (environment['WAYLAND_DISPLAY']) return 'wayland';

if (environment['XDG_SESSION_TYPE'] === 'wayland') return 'wayland';

return 'x11';

}

// ── Cached input tool resolution ───────────────────────────────────────

let cachedInputTool: {

tool: InputTool;

display: DisplayServer;

provider: LinuxToolProvider;

} | null = null;

export async function ensureInputTool(): Promise<{

tool: InputTool;

display: DisplayServer;

}> {

const provider = resolveLinuxToolProvider();

if (cachedInputTool?.provider === provider) return cachedInputTool;

const display = detectDisplayServer();

if (display === 'wayland') {

if (await provider.whichCommand('ydotool')) {

cachedInputTool = { tool: 'ydotool', display, provider };

return cachedInputTool;

}

throw new AppError(

'TOOL_MISSING',

'ydotool is required for input synthesis on Wayland (xdotool does not work on Wayland). Install it via your package manager.',

);

}

if (await provider.whichCommand('xdotool')) {

cachedInputTool = { tool: 'xdotool', display, provider };

return cachedInputTool;

}

throw new AppError(

'TOOL_MISSING',

'xdotool is required for input synthesis on X11. Install it via your package manager.',

);

}

/**

* @internal Test isolation hook for the cached Linux input tool.

*/

export function resetInputToolCache(): void {

cachedInputTool = null;

}