$ErrorActionPreference = 'Stop'

Add-Type -AssemblyName System.Drawing

$root = Split-Path -Parent $PSScriptRoot
$screenshots = Join-Path $root 'docs/design/screens/handoff/2026-07-14'
$files = [ordered]@{
  initial = Join-Path $screenshots 'G06-selected-strip-final-initial-recheck-360x800.png'
  results = Join-Path $screenshots 'G06-selected-strip-final-results-360x800.png'
  empty = Join-Path $screenshots 'G06-selected-strip-final-empty-360x800.png'
}
$images = @{}

try {
  foreach ($state in $files.Keys) {
    $file = $files[$state]
    if (-not (Test-Path -LiteralPath $file)) {
      throw "Missing G06 $state screenshot: $file"
    }

    $image = [System.Drawing.Bitmap]::new($file)
    $images[$state] = $image
    if ($image.Width -ne 360 -or $image.Height -ne 800) {
      throw "G06 $state screenshot must be 360x800, got $($image.Width)x$($image.Height)"
    }

    foreach ($point in @(@(0, 0), @(359, 0), @(0, 799), @(359, 799))) {
      if ($image.GetPixel($point[0], $point[1]).A -ne 255) {
        throw "G06 $state screenshot must have an opaque viewport"
      }
    }
  }

  foreach ($state in @('results', 'empty')) {
    $stableDifferenceCount = 0
    $fullDifferenceCount = 0
    for ($y = 0; $y -lt 800; $y++) {
      for ($x = 0; $x -lt 360; $x++) {
        if ($images.initial.GetPixel($x, $y).ToArgb() -ne $images[$state].GetPixel($x, $y).ToArgb()) {
          $fullDifferenceCount++
          if ($y -lt 150) { $stableDifferenceCount++ }
        }
      }
    }

    if ($stableDifferenceCount -ne 0) {
      throw "G06 $state screenshot changed $stableDifferenceCount pixels in the stable header/title region"
    }
    if ($fullDifferenceCount -lt 100) {
      throw "G06 $state screenshot does not visibly differ from the initial state"
    }
  }
}
finally {
  foreach ($image in $images.Values) { $image.Dispose() }
}

Write-Output 'G06-SCREENSHOT-CONSISTENCY PASS'