param (
    [string]$ImagePath,
    [string]$OutputDir,
    [string]$Prefix
)

Add-Type -AssemblyName System.Drawing

$img = [System.Drawing.Image]::FromFile($ImagePath)
$w = $img.Width
$h = $img.Height

$targetWidth = $w
$targetHeight = [math]::Floor($w / 3.0)

$left = 0
$top = 0

if ($targetHeight -gt $h) {
    $targetHeight = $h
    $targetWidth = $h * 3
    $left = [math]::Floor(($w - $targetWidth) / 2.0)
} else {
    $top = [math]::Floor(($h - $targetHeight) / 2.0)
}

[int]$sqSize = [math]::Floor($targetWidth / 3.0)

[int]$leftInt = $left
[int]$topInt = $top

for ($i = 0; $i -lt 3; $i++) {
    $bmp = New-Object System.Drawing.Bitmap -ArgumentList $sqSize, $sqSize
    $g = [System.Drawing.Graphics]::FromImage($bmp)
    
    [int]$rx = $leftInt + ($i * $sqSize)
    $srcRect = New-Object System.Drawing.Rectangle -ArgumentList $rx, $topInt, $sqSize, $sqSize
    $destRect = New-Object System.Drawing.Rectangle -ArgumentList 0, 0, $sqSize, $sqSize
    
    $g.DrawImage($img, $destRect, $srcRect, [System.Drawing.GraphicsUnit]::Pixel)
    $g.Dispose()
    
    $outFile = Join-Path $OutputDir ("{0}_part{1}.png" -f $Prefix, ($i + 1))
    $bmp.Save($outFile, [System.Drawing.Imaging.ImageFormat]::Png)
    $bmp.Dispose()
}

$img.Dispose()
Write-Output "Successfully split the image into 3 pieces."