[CmdletBinding()]
param (
    [Parameter(Mandatory = $false)]
    [String]$filePath
)

$metrics = Get-CimInstance Win32_ReliabilityStabilityMetrics -ErrorAction SilentlyContinue
if ($metrics.Count -ge 1) {
  $metric = $metrics | Sort-Object TimeGenerated -Descending | Select-Object -First 1
} else {
  throw ("Get-CimInstance")
}

if ($filePath) {
  $records = Get-CimInstance -ClassName Win32_ReliabilityRecords |Where-Object {($_.TimeGenerated -ge $metric.StartMeasurementDate) -and ($_.TimeGenerated -lt $metric.EndMeasurementDate)} | Sort-Object TimeGenerated |Select ComputerName, EventIdentifier, LogFile, Message,ProductName,RecordNumber,SourceName,TimeGenerated,User
  if ($records.Count -eq 0) {
    $records = "信頼性に関連するログは記録されていません。期間:$($metric.StartMeasurementDate)～$($metric.EndMeasurementDate)"
  }
  # -Encoding UTF8|UTF8BOM|UTF8NOBOM|ANSI（シフトJIS）|ASCII|UNICODE
  $records | Out-File -FilePath $filePath -Encoding UTF8 -Force
}
return [Math]::Round($metric.SystemStabilityIndex * 10)