ManagerViewController

//
//  ManagerViewController.swift
//  Skillshare
//
//  Created by Stillalive on 5/29/17.
//  Copyright © 2017 Stillalive. All rights reserved.
//

import UIKit

open class ManagerViewController: UIViewController {
    
    fileprivate var cachedViewControllers = [String: UIViewController]()
    fileprivate var activeViewControllerIdentifier = ""
    
    fileprivate let CHILD_KEY = 1000000
    fileprivate let CHILD_LOGIN_KEY = "NavLogin"
    fileprivate let CHILD_MAIN_KEY = "MainTabBar"
    
    // MARK: - View Lifecycles
    
    override open func viewDidLoad() {
        super.viewDidLoad()
        
        print("[ Info ] Manager Screen Loaded")
        if UserDefaults.standard.bool(forKey: SSPreferences.isLoggedIn) {
            showMainScreen()
        }else {
            showLoginScreen()
        }
        
        (UIApplication.shared.delegate as! AppDelegate).managerVC = self
    }
    
    override open func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }
    
    
    // MARK: - View Controller Management Methods
    func showLoginScreen() {
        displayContentViewController(CHILD_LOGIN_KEY)
    }
    
    func showMainScreen() {
        displayContentViewController(CHILD_MAIN_KEY)
    }
    
    
    func displayContentViewController(_ identifier: String) {
        var vc: UIViewController?
        if let cachedVC = cachedViewControllers[identifier] {
            vc = cachedVC
        }else if let vendorTabVC = storyboard?.instantiateViewController(withIdentifier: identifier) {
            cachedViewControllers[identifier] = vendorTabVC
            vc = vendorTabVC
        }
        
        self.addChildViewController(vc!)
        
        
        let existingView = view.viewWithTag(CHILD_KEY)
        if view.viewWithTag(CHILD_KEY) != nil {
            vc?.view.alpha = 0
        }
        
        vc!.view.frame = view.bounds
        view.addSubview(vc!.view)
        
        if identifier == "Main" {
            (vc as! UITabBarController).selectedIndex = 0
        }
        
        if existingView != nil {
            UIView.animate(withDuration: 0.25, delay: 0, options: .curveEaseIn, animations: {
                existingView?.alpha = 0
            }, completion: { finished in
                UIView.animate(withDuration: 0.25, delay: 0, options: .curveEaseOut, animations: {
                    vc?.view.alpha = 1
                }, completion: { finished in
                    if finished {
                        existingView?.removeFromSuperview()
                        let firstVC = self.childViewControllers.first
                        firstVC?.removeFromParentViewController()
                        firstVC?.didMove(toParentViewController: nil)
                    }
                })
            })
        }
        
        vc!.view.tag = CHILD_KEY
        vc!.view.setNeedsLayout()
        vc!.view.layoutIfNeeded()
        vc!.didMove(toParentViewController: self)
    }
    
    /*
     // MARK: - Navigation
     
     // In a storyboard-based application, you will often want to do a little preparation before navigation
     override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
     // Get the new view controller using segue.destinationViewController.
     // Pass the selected object to the new view controller.
     }
     */
    
}

public extension UIViewController {
    
    public var managerViewController: ManagerViewController? {
        return managerViewControllerForViewController(self)
    }
    
    fileprivate func managerViewControllerForViewController(_ controller : UIViewController) -> ManagerViewController?
    {
        if let managerController = controller as? ManagerViewController {
            return managerController
        }
        
        if let parent = controller.parent {
            return managerViewControllerForViewController(parent)
        } else {
            return nil
        }
    }
}