# 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 (also prints unless CSVONLY=1)
#   $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 (env vars)
$CsvOnly      = ($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 }

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

# Pretty output (unless CSV-only)
if (-not $CsvOnly) {
  "ComputerName`t{0}"       -f $cs.Name
  "UUID`t`t{0}"             -f $csp.UUID
  "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"
$row    = "{0},{1},{2}" -f (Escape-Csv $cs.Manufacturer), (Escape-Csv $cs.Model), (Escape-Csv $serial)

$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 (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 (so you can copy/paste or pipe to clipboard)
$header
$row