param(
    [string]$Scanner1Host = "192.168.1.13",
    [int]$Scanner1Port = 2001,
    [string]$Scanner2Host = "192.168.1.14",
    [int]$Scanner2Port = 2001,
    [int]$TimeoutMs = 5000,
    [switch]$Parallel
)

$ErrorActionPreference = "Stop"

function Test-TcpClientConnection {
    param(
        [Parameter(Mandatory = $true)]
        [string]$Name,

        [Parameter(Mandatory = $true)]
        [string]$HostName,

        [Parameter(Mandatory = $true)]
        [int]$Port,

        [Parameter(Mandatory = $true)]
        [int]$ConnectTimeoutMs
    )

    $client = [System.Net.Sockets.TcpClient]::new()
    $stopwatch = [System.Diagnostics.Stopwatch]::StartNew()
    try {
        Write-Host "[$Name] Connecting to $HostName`:$Port, TimeoutMs=$ConnectTimeoutMs ..."
        $connectTask = $client.ConnectAsync($HostName, $Port)
        $timeoutTask = [System.Threading.Tasks.Task]::Delay($ConnectTimeoutMs)
        $completedTask = [System.Threading.Tasks.Task]::WhenAny($connectTask, $timeoutTask).GetAwaiter().GetResult()
        $stopwatch.Stop()

        if ($completedTask -ne $connectTask) {
            return [pscustomobject]@{
                Name = $Name
                Target = "$HostName`:$Port"
                Succeeded = $false
                ElapsedMs = $stopwatch.ElapsedMilliseconds
                LocalEndPoint = ""
                RemoteEndPoint = ""
                ErrorType = "Timeout"
                ErrorMessage = "ConnectAsync did not complete within $ConnectTimeoutMs ms."
            }
        }

        if ($connectTask.IsFaulted) {
            $exception = $connectTask.Exception.GetBaseException()
            return [pscustomobject]@{
                Name = $Name
                Target = "$HostName`:$Port"
                Succeeded = $false
                ElapsedMs = $stopwatch.ElapsedMilliseconds
                LocalEndPoint = ""
                RemoteEndPoint = ""
                ErrorType = $exception.GetType().FullName
                ErrorMessage = $exception.Message
            }
        }

        return [pscustomobject]@{
            Name = $Name
            Target = "$HostName`:$Port"
            Succeeded = $client.Connected
            ElapsedMs = $stopwatch.ElapsedMilliseconds
            LocalEndPoint = $client.Client.LocalEndPoint.ToString()
            RemoteEndPoint = $client.Client.RemoteEndPoint.ToString()
            ErrorType = ""
            ErrorMessage = ""
        }
    }
    catch {
        $stopwatch.Stop()
        return [pscustomobject]@{
            Name = $Name
            Target = "$HostName`:$Port"
            Succeeded = $false
            ElapsedMs = $stopwatch.ElapsedMilliseconds
            LocalEndPoint = ""
            RemoteEndPoint = ""
            ErrorType = $_.Exception.GetType().FullName
            ErrorMessage = $_.Exception.Message
        }
    }
    finally {
        $client.Dispose()
    }
}

Write-Host "=== Scanner TCP Client Diagnostic ==="
Write-Host "Machine: $env:COMPUTERNAME"
Write-Host "User: $env:USERNAME"
Write-Host "Time: $(Get-Date -Format 'yyyy-MM-dd HH:mm:ss.fff')"
Write-Host "Mode: $(if ($Parallel) { 'Parallel' } else { 'Sequential' })"
Write-Host ""

if ($Parallel) {
    $job1 = Start-Job -ScriptBlock ${function:Test-TcpClientConnection} -ArgumentList "Scanner1", $Scanner1Host, $Scanner1Port, $TimeoutMs
    $job2 = Start-Job -ScriptBlock ${function:Test-TcpClientConnection} -ArgumentList "Scanner2", $Scanner2Host, $Scanner2Port, $TimeoutMs
    $results = Receive-Job -Job $job1, $job2 -Wait
    Remove-Job -Job $job1, $job2
}
else {
    $results = @(
        Test-TcpClientConnection -Name "Scanner1" -HostName $Scanner1Host -Port $Scanner1Port -ConnectTimeoutMs $TimeoutMs
        Test-TcpClientConnection -Name "Scanner2" -HostName $Scanner2Host -Port $Scanner2Port -ConnectTimeoutMs $TimeoutMs
    )
}

foreach ($result in $results) {
    Write-Host "--- $($result.Name) ---"
    $result | Format-List
}

Write-Host ""
Write-Host "Tip: if Sequential succeeds but Parallel times out, the device or network may reject concurrent short connections."
Write-Host "Tip: close TCP debugging tools before running this script, because some scanners allow only one client connection."