Git local pre-commit hook script that ensures correct file encoding

pre-commit-encoding.ps1

function Get-FileEncoding {
  [CmdletBinding()] 
  Param (
    [Parameter(Mandatory = $True, ValueFromPipelineByPropertyName = $True)] [string]$Path
  ) 
  [byte[]]$byte = get-content -Encoding byte -ReadCount 4 -TotalCount 4 -Path $Path
  $encoding = 'utf8';    
  if ( $byte[0] -eq 0xef -and $byte[1] -eq 0xbb -and $byte[2] -eq 0xbf )
  { $encoding = 'utf8-with-bom'; }
  elseif (($byte[0] -eq 0xfe -and $byte[1] -eq 0xff) <#big endian#>) 
  { $encoding = 'bigendian-unicode'; }
  elseif (($byte[0] -eq 0xff -and $byte[1] -eq 0xfe) <#lower endian#>)
  { $encoding = 'unicode'; }
  elseif ($byte[0] -eq 0 -and $byte[1] -eq 0 -and $byte[2] -eq 0xfe -and $byte[3] -eq 0xff <#big endian#>) 
  { $encoding = 'bigendian-utf32' }
  elseif ($byte[0] -eq 0 -and $byte[1] -eq 0 -and $byte[2] -eq 0xff -and $byte[3] -eq 0xfe <#lower endian#>)
  { $encoding = 'utf32'; }
  elseif ($byte[0] -eq 0x2b -and $byte[1] -eq 0x2f -and $byte[2] -eq 0x76)
  { $encoding = 'utf7'; }    
  return $encoding;
}

$files = (& cmd /c "git diff --name-only --diff-filter=ACM | git check-attr --stdin encoding");
$split = $files | ForEach-Object { 
  $s = $_.Split(":"); 
  $set = @{ File=$s[0].Trim();Attr=$s[1].Trim();Info=$s[2].Trim(); };
  if($set.Info -match "unspecified" -or $set.Info -match "unset") { return; }  
  $guessed = (Get-FileEncoding -Path $set.File);
  $allowed = @("utf8","utf8-with-bom","bigendian-unicode","unicode","bigendian-utf32","utf32","utf7");
  if($allowed -notcontains $set.Info) {
    Write-Error "Target encoding $($set.Info) for $($set.File) is unknown allowed are: $([string]::Join(',', $allowed)).";
    exit 1;
  }
  if($guessed -notmatch $set.Info) {
    Write-Host $($set.File);
    Write-Host ": Encoding $($guessed) -> $($set.Info).";
    $content = Get-Content -Path $set.File -Encoding $($guessed.Replace("-",""));    
    if($set.Info -match "utf8") {
      $Utf8NoBomEncoding = New-Object System.Text.UTF8Encoding($False);
      $p = Join-Path $(Get-Location).Path $set.File;
      [System.IO.File]::WriteAllLines($p, $content, $Utf8NoBomEncoding);
    } elseif($set.Info -match "utf8-with-bom") {
      Set-Content -Path $set.File -Encoding UTF8 -Value $content;
    } else {
      Set-Content -Path $set.File -Encoding $($set.Info.Replace("-","")) -Value $content;
    }
  }
}