$ErrorActionPreference = 'Stop'

$root = Split-Path -Parent $PSScriptRoot
Add-Type -AssemblyName System.Drawing

$backgrounds = @(
  'static/assets/backgrounds/auth-ancestral-header-v1.png',
  'static/assets/backgrounds/auth-rice-paper-v1.jpg',
  'static/assets/backgrounds/auth-ink-scenery-v1.png'
)
$icons = @(
  'static/assets/icons/auth/login-outline-v1.png',
  'static/assets/icons/auth/wechat-licensed-v1.png',
  'static/assets/icons/auth/auth-button-corner-v1.png',
  'static/assets/icons/auth/auth-divider-knot-v1.png',
  'static/assets/icons/auth/auth-title-cloud-v1.png'
)

foreach ($asset in $backgrounds + $icons) {
  if (-not (Test-Path -LiteralPath (Join-Path $root $asset))) {
    throw "Missing A01 asset: $asset"
  }
}

foreach ($asset in $icons) {
  $bitmap = [System.Drawing.Bitmap]::FromFile((Join-Path $root $asset))
  $width = [int]$bitmap.Width
  $height = [int]$bitmap.Height
  $corners = @(
    $bitmap.GetPixel(0, 0).A,
    $bitmap.GetPixel(($width - 1), 0).A,
    $bitmap.GetPixel(0, ($height - 1)).A,
    $bitmap.GetPixel(($width - 1), ($height - 1)).A
  )
  $visiblePixels = 0
  for ($y = 0; $y -lt $height; $y++) {
    for ($x = 0; $x -lt $width; $x++) {
      if ($bitmap.GetPixel($x, $y).A -gt 24) { $visiblePixels++ }
    }
  }
  $bitmap.Dispose()

  $expectedSize = switch ($asset) {
    'static/assets/icons/auth/auth-button-corner-v1.png' { @(160, 160) }
    'static/assets/icons/auth/auth-divider-knot-v1.png' { @(160, 96) }
    'static/assets/icons/auth/auth-title-cloud-v1.png' { @(200, 120) }
    default { @(96, 96) }
  }
  if ($width -ne $expectedSize[0] -or $height -ne $expectedSize[1]) { throw "$asset must be $($expectedSize[0]) x $($expectedSize[1])px." }
  if (($corners | Where-Object { $_ -ne 0 }).Count -ne 0) { throw "$asset has opaque outer corners." }
  if ($visiblePixels -lt 80) { throw "$asset has no usable visible artwork." }
  Write-Output "PASS $asset transparent corners and visible artwork"
}

Write-Output 'A01-ASSET-ALPHA-AUDIT PASS'