/**
 * The scheduled task that starts an instance inside the signed-in Windows
 * desktop. Programs started straight from an SSH session run in a session
 * with no desktop, where OBS, osu! and window capture cannot work; a task
 * with LogonType Interactive runs in the user's own desktop session instead,
 * and keeps running when the SSH connection closes.
 */

export const taskName = (instance: string) => `Vash Broadcast (${instance})`;

/** Runs a PowerShell script with values passed as environment variables (no quoting problems). */
export async function powershell(script: string, env: Record<string, string> = {}) {
	if (process.platform !== 'win32') throw new Error('Scheduled tasks exist only on Windows');
	// -EncodedCommand (UTF-16LE, base64) sidesteps Windows command-line quoting entirely.
	const encoded = Buffer.from(
		`$ProgressPreference = 'SilentlyContinue'\n${script}`,
		'utf16le'
	).toString('base64');
	const child = Bun.spawn(
		[
			'powershell.exe',
			'-NoProfile',
			'-NonInteractive',
			'-ExecutionPolicy',
			'Bypass',
			'-EncodedCommand',
			encoded
		],
		{ stdout: 'pipe', stderr: 'pipe', env: { ...process.env, ...env }, windowsHide: true }
	);
	const [stdout, stderr, code] = await Promise.all([
		new Response(child.stdout).text(),
		new Response(child.stderr).text(),
		child.exited
	]);
	if (code !== 0)
		throw new Error(
			stderr.trim().split(/\r?\n/).slice(0, 3).join(' ') || `PowerShell exited with ${code}`
		);
	return stdout.trim();
}

export async function registerTask(options: {
	instance: string;
	exe: string;
	cwd: string;
	autostart: boolean;
}) {
	await powershell(
		`$ErrorActionPreference = 'Stop'
$user = [System.Security.Principal.WindowsIdentity]::GetCurrent().Name
$action = New-ScheduledTaskAction -Execute $env:VASH_EXE -Argument $env:VASH_ARGS -WorkingDirectory $env:VASH_CWD
$principal = New-ScheduledTaskPrincipal -UserId $user -LogonType Interactive -RunLevel Limited
# Priority 4 is normal; the default (7) would slow OBS and osu! down.
$settings = New-ScheduledTaskSettingsSet -AllowStartIfOnBatteries -DontStopIfGoingOnBatteries -ExecutionTimeLimit ([TimeSpan]::Zero) -MultipleInstances IgnoreNew -StartWhenAvailable -Priority 4
$task = @{ Action = $action; Principal = $principal; Settings = $settings; Description = 'Vash broadcast worker. Manage it with vash-broadcast.exe.' }
if ($env:VASH_AUTOSTART -eq '1') { $task.Trigger = New-ScheduledTaskTrigger -AtLogOn -User $user }
$definition = New-ScheduledTask @task
Register-ScheduledTask -TaskName $env:VASH_TASK -InputObject $definition -Force | Out-Null`,
		{
			VASH_TASK: taskName(options.instance),
			VASH_EXE: options.exe,
			VASH_ARGS: `task --instance ${options.instance}`,
			VASH_CWD: options.cwd,
			VASH_AUTOSTART: options.autostart ? '1' : '0'
		}
	);
}

export async function runTask(instance: string) {
	await powershell(`Start-ScheduledTask -TaskName $env:VASH_TASK`, {
		VASH_TASK: taskName(instance)
	});
}

export async function endTask(instance: string) {
	await powershell(`Stop-ScheduledTask -TaskName $env:VASH_TASK -ErrorAction SilentlyContinue`, {
		VASH_TASK: taskName(instance)
	}).catch(() => {});
}

export async function unregisterTask(instance: string) {
	await powershell(
		`Unregister-ScheduledTask -TaskName $env:VASH_TASK -Confirm:$false -ErrorAction SilentlyContinue`,
		{ VASH_TASK: taskName(instance) }
	).catch(() => {});
}

export interface TaskInfo {
	exists: boolean;
	state: string | null;
	lastRunTime: string | null;
	lastTaskResult: number | null;
	autostart: boolean;
}

export async function taskInfo(instance: string): Promise<TaskInfo> {
	const output = await powershell(
		`$task = Get-ScheduledTask -TaskName $env:VASH_TASK -ErrorAction SilentlyContinue
if ($null -eq $task) { '{"exists":false}'; exit }
$info = $task | Get-ScheduledTaskInfo
@{ exists = $true; state = [string]$task.State; lastRunTime = if ($info.LastRunTime) { $info.LastRunTime.ToString('o') } else { $null }; lastTaskResult = [long]$info.LastTaskResult; autostart = @($task.Triggers).Count -gt 0 } | ConvertTo-Json -Compress`,
		{ VASH_TASK: taskName(instance) }
	);
	const info = JSON.parse(output) as Partial<TaskInfo>;
	return {
		exists: !!info.exists,
		state: info.state ?? null,
		lastRunTime: info.lastRunTime ?? null,
		lastTaskResult: info.lastTaskResult ?? null,
		autostart: !!info.autostart
	};
}

/** Who is signed in at the PC's own screen, if anyone. */
export async function consoleUser() {
	const output = await powershell(`(Get-CimInstance Win32_ComputerSystem).UserName`).catch(
		() => ''
	);
	return output || null;
}

export async function currentUser() {
	return powershell(`[System.Security.Principal.WindowsIdentity]::GetCurrent().Name`);
}

export async function gpuNames() {
	const output = await powershell(
		`(Get-CimInstance Win32_VideoController | Select-Object -ExpandProperty Name) -join "\`n"`
	).catch(() => '');
	return output.split(/\r?\n/).filter(Boolean);
}