param(
    [Parameter(Mandatory=$true)][string]$Out,
    [string]$Match = "DOSBox-X"
)

Add-Type @"
using System;
using System.Runtime.InteropServices;
public class W {
    [DllImport("user32.dll")] public static extern bool GetWindowRect(IntPtr h, out RECT r);
    [DllImport("user32.dll")] public static extern bool SetForegroundWindow(IntPtr h);
    [DllImport("user32.dll")] public static extern bool IsWindowVisible(IntPtr h);
    [DllImport("user32.dll")] public static extern bool PrintWindow(IntPtr h, IntPtr hdc, uint flags);
    [DllImport("user32.dll", CharSet=CharSet.Auto)] public static extern int GetWindowText(IntPtr h, System.Text.StringBuilder s, int n);
    [DllImport("user32.dll")] public static extern bool EnumWindows(EnumProc cb, IntPtr p);
    public delegate bool EnumProc(IntPtr h, IntPtr p);
    [StructLayout(LayoutKind.Sequential)] public struct RECT { public int L, T, R, B; }
}
"@

$found = @()
$cb = [W+EnumProc]{
    param($h, $p)
    if ([W]::IsWindowVisible($h)) {
        $sb = New-Object System.Text.StringBuilder 512
        [void][W]::GetWindowText($h, $sb, 512)
        $t = $sb.ToString()
        if ($t -like "*$Match*") { $script:found += ,@($h, $t) }
    }
    return $true
}
[void][W]::EnumWindows($cb, [IntPtr]::Zero)
if ($found.Count -eq 0) { Write-Output "NO-WINDOW"; exit 1 }

Add-Type -AssemblyName System.Drawing

function Test-Blank($bmp) {
    # sample a grid; blank/uniform => PrintWindow failed on this surface
    $seen = @{}
    for ($y = 10; $y -lt $bmp.Height - 10; $y += 23) {
        for ($x = 10; $x -lt $bmp.Width - 10; $x += 29) {
            $seen[$bmp.GetPixel($x, $y).ToArgb()] = $true
            if ($seen.Count -gt 6) { return $false }
        }
    }
    return $true
}

$i = 0
foreach ($f in $found) {
    $h = $f[0]; $title = $f[1]
    [void][W]::SetForegroundWindow($h)
    Start-Sleep -Milliseconds 600
    $r = New-Object W+RECT
    [void][W]::GetWindowRect($h, [ref]$r)
    $w = $r.R - $r.L; $ht = $r.B - $r.T
    if ($w -le 0 -or $ht -le 0) { continue }

    # PRIMARY: PrintWindow(PW_RENDERFULLCONTENT) -- immune to occlusion
    $bmp = New-Object System.Drawing.Bitmap $w, $ht
    $g = [System.Drawing.Graphics]::FromImage($bmp)
    $hdc = $g.GetHdc()
    $ok = [W]::PrintWindow($h, $hdc, 2)
    $g.ReleaseHdc($hdc)
    $method = "PrintWindow"

    if (-not $ok -or (Test-Blank $bmp)) {
        # FALLBACK: screen copy (only valid if nothing is in front)
        $g.Dispose(); $bmp.Dispose()
        $bmp = New-Object System.Drawing.Bitmap $w, $ht
        $g = [System.Drawing.Graphics]::FromImage($bmp)
        $g.CopyFromScreen($r.L, $r.T, 0, 0, (New-Object System.Drawing.Size $w, $ht))
        $method = "CopyFromScreen(FALLBACK -- occlusion-sensitive)"
    }

    $path = if ($found.Count -eq 1) { $Out } else { $Out -replace '\.png$', "_$i.png" }
    $bmp.Save($path, [System.Drawing.Imaging.ImageFormat]::Png)
    $g.Dispose(); $bmp.Dispose()
    Write-Output "SAVED $path  ${w}x${ht}  via $method  [$title]"
    $i++
}