param([switch]$UpdateIcon)
$ErrorActionPreference = 'Stop'

$shortcutProject = $PSScriptRoot
$shortcutMarker = Join-Path $shortcutProject 'runtime\desktop-shortcut-created.txt'
if ((Test-Path -LiteralPath $shortcutMarker) -and -not $UpdateIcon) { return }

try {
    # Resolves the real Desktop, including a redirected/OneDrive Desktop.
    $shortcutDesktop = [Environment]::GetFolderPath('DesktopDirectory')
    if (-not $shortcutDesktop) { throw 'Windows Desktop folder is unavailable.' }
    $shortcutPath = Join-Path $shortcutDesktop 'SUB Control.lnk'

    # Never replace a shortcut the user already has.
    if (-not (Test-Path -LiteralPath $shortcutPath)) {
        $shortcutShell = New-Object -ComObject WScript.Shell
        $shortcutLink = $shortcutShell.CreateShortcut($shortcutPath)
        $shortcutLink.TargetPath = Join-Path $env:SystemRoot 'System32\WindowsPowerShell\v1.0\powershell.exe'
        $shortcutLink.Arguments = '-NoProfile -WindowStyle Hidden -File "' + (Join-Path $shortcutProject 'run.ps1') + '"'
        $shortcutLink.WorkingDirectory = $shortcutProject
        $shortcutLink.Description = 'Launch SUB Control'
        $shortcutLink.WindowStyle = 7
        $shortcutIcon = Join-Path $shortcutProject 'assets\sub-control.ico'
        if (Test-Path -LiteralPath $shortcutIcon) { $shortcutLink.IconLocation = "$shortcutIcon,0" }
        $shortcutLink.Save()
    } elseif ($UpdateIcon) {
        $shortcutShell = New-Object -ComObject WScript.Shell
        $shortcutLink = $shortcutShell.CreateShortcut($shortcutPath)
        $expectedScript = '"' + (Join-Path $shortcutProject 'run.ps1') + '"'
        if ($shortcutLink.Arguments.Contains($expectedScript)) {
            $shortcutLink.IconLocation = (Join-Path $shortcutProject 'assets\sub-control.ico') + ',0'
            $shortcutLink.Save()
        } else {
            throw 'Existing shortcut belongs to another installation; left unchanged.'
        }
    }

    New-Item -ItemType Directory -Path (Split-Path -Parent $shortcutMarker) -Force | Out-Null
    Set-Content -LiteralPath $shortcutMarker -Value $shortcutPath
} catch {
    # Desktop permissions must not prevent the controller from starting.
    Write-Warning "Could not create the SUB Control desktop shortcut: $_"
}