import Cocoa
let pid = pid_t(CommandLine.arguments[1])!
let out = CommandLine.arguments[2]
guard let wins = CGWindowListCopyWindowInfo([.optionOnScreenOnly], kCGNullWindowID) as? [[String: Any]] else { exit(1) }
for w in wins {
    if (w[kCGWindowOwnerPID as String] as? Int) == pid,
       (w[kCGWindowLayer as String] as? Int) == 0,
       let wid = w[kCGWindowNumber as String] as? Int,
       let bd = w[kCGWindowBounds as String] as? [String: Any],
       (bd["Width"] as! Double) > 400 {
        if let img = CGWindowListCreateImage(.null, .optionIncludingWindow, CGWindowID(wid), [.boundsIgnoreFraming]) {
            let url = URL(fileURLWithPath: out)
            if let dest = CGImageDestinationCreateWithURL(url as CFURL, "public.png" as CFString, 1, nil) {
                CGImageDestinationAddImage(dest, img, nil)
                CGImageDestinationFinalize(dest)
                print("saved \(out) size=\(img.width)x\(img.height)")
            }
        } else { print("capture failed") }
        exit(0)
    }
}
print("no window found")