[CmdletBinding()]
Param (
    [ValidateScript({ Test-Path $_ } )]
    [string]$ChessMatchesPath = 'C:\Users\Irwin\Downloads\ChessData-master\ChessData-master',

    [switch]$DisplaySumTotal
)

#region Define regex results. Make search case-insensitive just incase.
[regex]$whiteWin = '(?i)result\s+"1-0"'
[regex]$blackWin = '(?i)Result\s+"0-1"'
[regex]$Tie      = '(?i)result\s+"1/2.*'
#endregion

#region Main Process All pgn files
Get-ChildItem -Path $ChessMatchesPath -File *.pgn -Recurse |
ForEach-Object {
   $pgnFile = Get-Content $_.FullName -Raw
   [PSCustomObject]@{
      FileReference = $_.Name
      WhiteWin = @($whiteWin.Matches($pgnFile)).Count
      BlackWin = @($blackWin.Matches($pgnFile)).Count
      Tie      = @($Tie.Matches($pgnFile)).Count
   }
} -OutVariable ChessResults

If($DisplaySumTotal){
  "`n`r"
  'Total wins White: {0}' -f ($ChessResults.WhiteWin | Measure-Object -Sum).Sum
  'Total wins Black: {0}' -f ($ChessResults.BlackWin | Measure-Object -Sum).Sum
  'Total ties:       {0}' -f ($ChessResults.Tie      | Measure-Object -Sum).Sum
}
#endregion