import CoreGraphics
import Foundation

// Lists on-screen windows, optionally filtered by owning PID.
// Usage: swift list-windows.swift [pid]

let filterPid: Int? = CommandLine.arguments.count > 1 ? Int(CommandLine.arguments[1]) : nil

guard
  let windows = CGWindowListCopyWindowInfo(
    [.optionOnScreenOnly, .excludeDesktopElements], kCGNullWindowID) as? [[String: Any]]
else {
  FileHandle.standardError.write(Data("window list unavailable\n".utf8))
  exit(1)
}

for window in windows {
  guard let pid = window[kCGWindowOwnerPID as String] as? Int else { continue }
  if let filterPid, pid != filterPid { continue }
  let id = window[kCGWindowNumber as String] as? Int ?? -1
  let owner = window[kCGWindowOwnerName as String] as? String ?? "?"
  let name = window[kCGWindowName as String] as? String ?? ""
  let layer = window[kCGWindowLayer as String] as? Int ?? -1
  let bounds = window[kCGWindowBounds as String] as? [String: Any] ?? [:]
  print("windowId=\(id) pid=\(pid) layer=\(layer) owner=\(owner) name=\(name) bounds=\(bounds)")
}