persephone/Persephone/Preferences/Controllers/PreferencesViewController.swift

//
//  PreferencesController.swift
//  Persephone
//
//  Created by Daniel Barber on 2019/2/23.
//  Copyright © 2019 Dan Barber. All rights reserved.
//

import Cocoa

class PreferencesViewController: NSTabViewController {

  private lazy var tabViewSizes: [String : NSSize] = [:]

  override func viewDidLoad() {
    if let viewController = self.tabViewItems.first?.viewController, let title = viewController.title {
      tabViewSizes[title] = viewController.view.frame.size
    }
    
    super.viewDidLoad()
  }

  override func transition(from fromViewController: NSViewController, to toViewController: NSViewController, options: NSViewController.TransitionOptions, completionHandler completion: (() -> Void)?) {

    NSAnimationContext.runAnimationGroup({ context in
      context.duration = 0.5
      self.updateWindowFrameAnimated(viewController: toViewController)
      super.transition(
        from: fromViewController,
        to: toViewController,
        options: [.crossfade, .allowUserInteraction],
        completionHandler: completion
      )
    }, completionHandler: nil)
  }

  func updateWindowFrameAnimated(viewController: NSViewController) {
    guard let title = viewController.title, let window = view.window
      else { return }

    let contentSize: NSSize

    if tabViewSizes.keys.contains(title) {
      contentSize = tabViewSizes[title]!
    } else {
      contentSize = viewController.view.frame.size
      tabViewSizes[title] = contentSize
    }

    let newWindowSize = window.frameRect(forContentRect: NSRect(origin: NSPoint.zero, size: contentSize)).size

    var frame = window.frame
    frame.origin.y += frame.height
    frame.origin.y -= newWindowSize.height
    frame.size = newWindowSize
    window.animator().setFrame(frame, display: false)
  }
}