//
//  SEUIChildManagingViewController.swift
//  ThreePanelSplitViewController
//
//  Created by Brian Nickel on 6/21/17.
//  Copyright © 2017 Brian Nickel. All rights reserved.
//

import UIKit

public enum AppearanceState {
    case disappeared, appeared
    case appearing(Bool)
    case disappearing(Bool)

    public var isAnimating: Bool {
        switch self {
        case .disappeared, .appeared:
            return false
        case .appearing(let animating):
            return animating
        case .disappearing(let animating):
            return animating
        }
    }
}

open class SEUIChildManagingViewController: UIViewController {

    private(set) public var childViewControllerContainers: [SEUIChildViewControllerContainer] = []

    public func add(_ childViewControllerContainer: SEUIChildViewControllerContainer, to superview: UIView) {
        childViewControllerContainers.append(childViewControllerContainer)
        superview.addSubview(childViewControllerContainer.containerView)
        childViewControllerContainer.parentTransitioned(to: appearanceState)
    }

    private(set) public var appearanceState: AppearanceState = .disappeared {
        didSet {
            for container in childViewControllerContainers {
                container.parentTransitioned(to: appearanceState)
            }
        }
    }

    open override var shouldAutomaticallyForwardAppearanceMethods: Bool {
        return false
    }

    open override func viewWillAppear(_ animated: Bool) {
        super.viewWillAppear(animated)
        appearanceState = .appearing(animated)
    }

    open override func viewDidAppear(_ animated: Bool) {
        super.viewDidAppear(animated)
        appearanceState = .appeared
    }

    open override func viewWillDisappear(_ animated: Bool) {
        super.viewWillDisappear(animated)
        appearanceState = .disappearing(animated)
    }

    open override func viewDidDisappear(_ animated: Bool) {
        appearanceState = .disappeared
    }
}