Allow SwiftUI to modifier NSWindow

NSWindowAdaptorModifier.swift

//
// NSWindowAdaptorModifier.swift
// Copyright (c) 2023 BrightDigit.
//

import AppKit
import Foundation
import SwiftUI

// swiftlint:disable strict_fileprivate

private struct NSWindowAdaptorHostingView: NSViewRepresentable {
  private var callback: (NSWindow?) -> Void

  fileprivate init(callback: @escaping (NSWindow?) -> Void) {
    self.callback = callback
  }

  fileprivate func makeNSView(context _: Self.Context) -> NSView {
    let view = NSView()
    DispatchQueue.main.async { [weak view] in
      self.callback(view?.window)
    }
    view.setFrameSize(.zero)
    view.isHidden = true
    view.frame = CGRect.zero
    return view
  }

  fileprivate func updateNSView(_: NSView, context _: Context) {}
}

private struct NSWindowAdaptorModifier: ViewModifier {
  private var callback: (NSWindow?) -> Void

  fileprivate init(callback: @escaping (NSWindow?) -> Void) {
    self.callback = callback
  }

  fileprivate func body(content: Content) -> some View {
    content
      .overlay(
        NSWindowAdaptorHostingView(callback: callback)
          .frame(width: 0, height: 0)
      )
  }
}

public extension View {
  func nsWindowAdaptor(_ callback: @escaping (NSWindow?) -> Void) -> some View {
    self.modifier(NSWindowAdaptorModifier(callback: callback))
  }
}