param(
  [Parameter(Mandatory = $true)][string]$Output,
  [Parameter(Mandatory = $true)][string[]]$InputPaths
)

$ErrorActionPreference = 'Stop'
Add-Type -AssemblyName System.Drawing

if ($InputPaths.Count -lt 2) { throw 'Contact sheet requires at least two images.' }

$images = @()
try {
  foreach ($inputPath in $InputPaths) {
    $resolved = (Resolve-Path -LiteralPath $inputPath).Path
    $images += [System.Drawing.Bitmap]::FromFile($resolved)
  }

  $width = ($images | Measure-Object -Property Width -Sum).Sum
  $height = ($images | Measure-Object -Property Height -Maximum).Maximum
  $canvas = [System.Drawing.Bitmap]::new($width, $height, [System.Drawing.Imaging.PixelFormat]::Format32bppArgb)
  try {
    $graphics = [System.Drawing.Graphics]::FromImage($canvas)
    try {
      $graphics.Clear([System.Drawing.Color]::FromArgb(247, 240, 228))
      $offsetX = 0
      foreach ($image in $images) {
        $graphics.DrawImageUnscaled($image, $offsetX, 0)
        $offsetX += $image.Width
      }
    } finally {
      $graphics.Dispose()
    }

    $outputPath = [System.IO.Path]::GetFullPath($Output)
    [System.IO.Directory]::CreateDirectory([System.IO.Path]::GetDirectoryName($outputPath)) | Out-Null
    $canvas.Save($outputPath, [System.Drawing.Imaging.ImageFormat]::Png)
    Write-Output "CONTACT-SHEET $outputPath"
  } finally {
    $canvas.Dispose()
  }
} finally {
  foreach ($image in $images) { $image.Dispose() }
}