<#
.SYNOPSIS
    Checks a list of computers for a Windows service and reports its state, startup type and account.
.DESCRIPTION
    Connects to each computer with a CIM session (WinRM by default, DCOM if you ask for it) and
    looks up the service by name or display name. Every computer gets a row: found, not installed,
    or unreachable, so the report accounts for the whole list. Read-only.
.PARAMETER ComputerName
    Computers to check. Accepts pipeline input, so Get-Content .\computers.txt | ... works.
.PARAMETER Name
    Service name or display name. Wildcards are fine, for example '*Spooler*'.
.PARAMETER Protocol
    Wsman (the default, needs WinRM) or Dcom (older machines, needs RPC/WMI through the firewall).
.PARAMETER Credential
    Credentials for the remote connection.
.PARAMETER CsvPath
    Also save the results to this CSV file.
.EXAMPLE
    Get-Content .\computers.txt | .\Get-ServiceAudit.ps1 -Name Spooler -CsvPath .\spooler.csv
#>
[CmdletBinding()]
param(
    [Parameter(ValueFromPipeline, ValueFromPipelineByPropertyName)]
    [Alias('CN', 'DNSHostName')]
    [string[]]$ComputerName = $env:COMPUTERNAME,
    [Parameter(Mandatory)][ValidateNotNullOrEmpty()][string]$Name,
    [ValidateSet('Wsman', 'Dcom')][string]$Protocol = 'Wsman',
    [pscredential]$Credential,
    [string]$CsvPath
)

begin {
    $results = [System.Collections.Generic.List[object]]::new()
    $wql = $Name.Replace('\', '\\').Replace("'", "\'").Replace('[', '[[]').Replace('_', '[_]').Replace('*', '%')
    $query = "SELECT Name, DisplayName, State, StartMode, StartName, PathName FROM Win32_Service WHERE Name LIKE '$wql' OR DisplayName LIKE '$wql'"

    function New-Row($Computer, $Status, $Service) {
        [pscustomobject]@{
            ComputerName = $Computer
            Status       = $Status
            ServiceName  = $Service.Name
            DisplayName  = $Service.DisplayName
            State        = $Service.State
            StartMode    = $Service.StartMode
            RunAs        = $Service.StartName
            Path         = $Service.PathName
        }
    }
}

process {
    foreach ($computer in $ComputerName) {
        $computer = $computer.Trim()
        if (-not $computer -or $computer.StartsWith('#')) { continue }

        $session = $null
        try {
            $sessionArgs = @{
                ComputerName  = $computer
                SessionOption = New-CimSessionOption -Protocol $Protocol
                ErrorAction   = 'Stop'
            }
            if ($Credential) { $sessionArgs.Credential = $Credential }
            $session = New-CimSession @sessionArgs

            $services = @(Get-CimInstance -CimSession $session -Query $query -ErrorAction Stop)
            if ($services.Count -eq 0) {
                $results.Add((New-Row $computer 'Not installed' $null))
            }
            foreach ($svc in $services) {
                $results.Add((New-Row $computer 'Found' $svc))
            }
        }
        catch {
            Write-Warning "$computer : $($_.Exception.Message)"
            $results.Add((New-Row $computer 'Unreachable' $null))
        }
        finally {
            if ($session) { Remove-CimSession -CimSession $session }
        }
    }
}

end {
    if ($CsvPath) {
        $results | Export-Csv -LiteralPath $CsvPath -NoTypeInformation
        Write-Verbose "Saved $($results.Count) row(s) to $CsvPath"
    }
    $results
}