# Set-EventSaverDisable.ps1
#
# Turn the EventSaver shopfloor screensaver OFF fleet-wide and undo its
# side effects. Runs under GE-Enforce (SYSTEM) every cycle. Idempotent +
# silent (SYSTEM context - no window).
#
# Self-excludes the canary test host: pass -ExceptHost <name> and this script
# does nothing on that PC, so the (canary-gated) enable entries keep it on
# there while every other shopfloor PC is cleaned.
#
# Undoes: screensaver registry (per-user), the EventSaver-Enable fallback
# task, the never-off power policy, and the staged .scr/.ini.

[CmdletBinding()]
param(
    [string]$ExceptHost     = '',
    [string]$ScrPath        = 'C:\Windows\System32\EventSaver.scr',
    [string]$TaskName       = 'EventSaver-Enable',
    [int]   $MonitorMinutes = 15,   # restore a sane monitor-off (was Never)
    [int]   $StandbyMinutes = 20    # restore a sane sleep (was Never)
)

$ErrorActionPreference = 'Continue'

# leave the canary host alone - the enable entries own it there
if ($ExceptHost -and ($env:COMPUTERNAME -ieq $ExceptHost)) { exit 0 }

function Disable-Saver($deskKey) {
    if (Test-Path $deskKey) {
        Set-ItemProperty -Path $deskKey -Name 'ScreenSaveActive' -Value '0' -Type String -Force -ErrorAction SilentlyContinue
        Remove-ItemProperty -Path $deskKey -Name 'SCRNSAVE.EXE' -ErrorAction SilentlyContinue
    }
}

# 1. screensaver off in the default profile + every loaded user hive
Disable-Saver 'Registry::HKEY_USERS\.DEFAULT\Control Panel\Desktop'
Get-ChildItem 'Registry::HKEY_USERS' -ErrorAction SilentlyContinue |
    Where-Object { $_.PSChildName -match '^S-1-5-21' -and $_.PSChildName -notmatch '_Classes$' } |
    ForEach-Object { Disable-Saver "Registry::HKEY_USERS\$($_.PSChildName)\Control Panel\Desktop" }

# 2. remove the self-clearing fallback task if present
if (Get-ScheduledTask -TaskName $TaskName -ErrorAction SilentlyContinue) {
    Unregister-ScheduledTask -TaskName $TaskName -Confirm:$false -ErrorAction SilentlyContinue
}

# 3. restore power (undo the EventSaver never-off)
& powercfg /change monitor-timeout-ac $MonitorMinutes 2>&1 | Out-Null
& powercfg /change standby-timeout-ac $StandbyMinutes 2>&1 | Out-Null

# 4. remove staged binary + config (harmless if already gone)
Remove-Item -LiteralPath $ScrPath -Force -ErrorAction SilentlyContinue
Remove-Item -LiteralPath ($ScrPath -replace '\.scr$', '.ini') -Force -ErrorAction SilentlyContinue

exit 0