# sn-uuid.ps1 (ConstrainedLanguage-safe)

# Options via environment variables:
# $env:SNUUID_CSVONLY      = "1"  -> only prints CSV header+row
# $env:SNUUID_OUTFILE      = "C:\path\file.csv" -> writes CSV there
# $env:SNUUID_APPEND       = "1"  -> append row to existing file
# $env:SNUUID_SERIALSOURCE = "BIOS" or "CSP" -> which serial to use (default BIOS)

function Escape-Csv([string]$s) {
    if ($null -eq $s) {
        return ""
    }

    $s = [string]$s

    if ($s -match '[",\r\n]') {
        return '"' + ($s -replace '"', '""') + '"'
    }

    return $s
}

# Read options

$CsvOnly      = ($env:SNUUID_CSVONLY -eq "1")
$OutFile      = $env:SNUUID_OUTFILE
$Append       = ($env:SNUUID_APPEND -eq "1")
$SerialSource = $env:SNUUID_SERIALSOURCE

if ([string]::IsNullOrWhiteSpace($SerialSource)) {
    $SerialSource = "BIOS"
}

# Prefer CIM, fall back to WMI

try {
    $cs = Get-CimInstance -ClassName Win32_ComputerSystem -ErrorAction Stop
}
catch {
    $cs = Get-WmiObject -Class Win32_ComputerSystem
}

try {
    $csp = Get-CimInstance -ClassName Win32_ComputerSystemProduct -ErrorAction Stop
}
catch {
    $csp = Get-WmiObject -Class Win32_ComputerSystemProduct
}

try {
    $bios = Get-CimInstance -ClassName Win32_BIOS -ErrorAction Stop
}
catch {
    $bios = Get-WmiObject -Class Win32_BIOS
}

# Get active network adapters with a MAC address

try {
    $netAdapters = Get-CimInstance -ClassName Win32_NetworkAdapterConfiguration -ErrorAction Stop |
        Where-Object {
            $_.IPEnabled -eq $true -and
            -not [string]::IsNullOrWhiteSpace($_.MACAddress)
        }
}
catch {
    $netAdapters = Get-WmiObject -Class Win32_NetworkAdapterConfiguration |
        Where-Object {
            $_.IPEnabled -eq $true -and
            -not [string]::IsNullOrWhiteSpace($_.MACAddress)
        }
}

# Join MAC addresses if multiple adapters are active

$mac = ""

foreach ($adapter in $netAdapters) {
    if (-not [string]::IsNullOrWhiteSpace($adapter.MACAddress)) {

        if ([string]::IsNullOrWhiteSpace($mac)) {
            $mac = $adapter.MACAddress
        }
        else {
            $mac = $mac + " | " + $adapter.MACAddress
        }
    }
}

# Select serial source

if ($SerialSource -match '^(?i)csp$') {
    $serial = $csp.IdentifyingNumber
}
else {
    $serial = $bios.SerialNumber
}

# Pretty output

if (-not $CsvOnly) {
    "ComputerName`t{0}"  -f $cs.Name
    "UUID`t`t{0}"        -f $csp.UUID
    "MAC`t`t{0}"         -f $mac
    "Manufacturer`t{0}"  -f $cs.Manufacturer
    "Model`t`t{0}"       -f $cs.Model
    "Serial (BIOS)`t{0}" -f $bios.SerialNumber
    "Serial (CSP)`t{0}"  -f $csp.IdentifyingNumber
    "Vendor`t`t{0}"      -f $csp.Vendor
    "Name`t`t{0}"        -f $csp.Name
    ""
    "--- Corporate Identifier CSV ---"
}

# CSV output

$header = "Manufacturer,Model,SerialNumber,UUID,MACAddress"

$row = "{0},{1},{2},{3},{4}" -f `
    (Escape-Csv $cs.Manufacturer), `
    (Escape-Csv $cs.Model), `
    (Escape-Csv $serial), `
    (Escape-Csv $csp.UUID), `
    (Escape-Csv $mac)

$csvText = $header + "`r`n" + $row

# Optionally write to file

if (-not [string]::IsNullOrWhiteSpace($OutFile)) {

    $fileExists = Test-Path -LiteralPath $OutFile

    if ($Append -and $fileExists) {
        # Append only the row to avoid duplicate header
        Add-Content -LiteralPath $OutFile -Value $row -Encoding UTF8
    }
    else {
        # Create/overwrite with header + row
        Set-Content -LiteralPath $OutFile -Value $csvText -Encoding UTF8
    }
}

# Always print CSV

$header
$row