function Get-NextFreePort {
    param([int]$Start = $Script:Port)
    for ($p = [Math]::Max(1024,$Start); $p -lt 65535; $p++) {
        $l = [System.Net.Sockets.TcpListener]::new([Net.IPAddress]::Loopback, $p)
        try { $l.Start(); $l.Stop(); return $p } catch {}
    }
    throw "No free TCP port available."
}

function Start-Server {
    $Global:Listener = [System.Net.HttpListener]::new()
    $primaryPrefix  = "http://localhost:$Script:Port/"
    $wildcardPrefix = "http://+:$Script:Port/"

    try {
        $Global:Listener.Prefixes.Add($primaryPrefix)
        $Global:Listener.Start()
        Write-LogHybrid "Listening on $primaryPrefix" Info Server -LogToEvent
    }
    catch [System.Net.HttpListenerException] {
        if ($_.Exception.ErrorCode -eq 5) {
            Write-LogHybrid "Access denied on $primaryPrefix. Attempting URL ACL…" Warning Server -LogToEvent
            try {
                $user = "$env:USERDOMAIN\$env:USERNAME"
                if (-not $user.Trim()) { $user = $env:USERNAME }
                Start-Process -FilePath "netsh" -ArgumentList "http add urlacl url=$wildcardPrefix user=`"$user`" listen=yes" -Verb RunAs -WindowStyle Hidden -Wait
                $Global:Listener = [System.Net.HttpListener]::new()
                $Global:Listener.Prefixes.Add($wildcardPrefix)
                $Global:Listener.Start()
                Write-LogHybrid "Listening on $wildcardPrefix (URL ACL added for $user)" Success Server -LogToEvent
            } catch {
                Write-LogHybrid "URL ACL registration failed: $($_.Exception.Message)" Error Server -LogToEvent
                return
            }
        }
        elseif ($_.Exception.NativeErrorCode -in 32,183) {
            $old = $Script:Port
            $Script:Port = Get-NextFreePort -Start ($Script:Port + 1)
            $Global:Listener = [System.Net.HttpListener]::new()
            $primaryPrefix = "http://localhost:$Script:Port/"
            $Global:Listener.Prefixes.Add($primaryPrefix)
            $Global:Listener.Start()
            Write-LogHybrid "Port $old busy. Listening on $primaryPrefix" Warning Server -LogToEvent
        }
        else {
            Write-LogHybrid "HttpListener start failed: $($_.Exception.Message)" Error Server -LogToEvent
            return
        }
    }

    try {
        while ($Global:Listener.IsListening) {
            $ctx = $Global:Listener.GetContext()
            try { Dispatch-Request $ctx }
            catch {
                $msg = $_.Exception.Message
                $pos = if ($_.InvocationInfo) { $_.InvocationInfo.PositionMessage } else { "" }
                $stk = if ($_.ScriptStackTrace) { $_.ScriptStackTrace } else { "" }

                Write-LogHybrid "Dispatch error: $msg`n$pos`n$stk" Error Server -LogToEvent
            }

        }
    }
    finally {
        $Global:Listener.Close()
        Write-LogHybrid "Listener closed." Info Server -LogToEvent
    }
}