/*

 Copyright (C) 2016 Apple Inc. All Rights Reserved.

 See LICENSE.txt for this sample’s licensing information

 Abstract:

 The animator used when the ChatReplyViewController is presented.

 */

import UIKit

private enum AnimationParameters {

    static let duration = 0.4

    static let damping: CGFloat = 0.7

}

class ChatReplyPresentAnimator: NSObject, UIViewControllerAnimatedTransitioning {    

    func transitionDuration(using transitionContext: UIViewControllerContextTransitioning?) -> TimeInterval {

        return AnimationParameters.duration

    }

    func animateTransition(using transitionContext: UIViewControllerContextTransitioning) {

        if let replyView = transitionContext.view(forKey: UITransitionContextViewKey.to) {

            transitionContext.containerView.addSubview(replyView)

            replyView.layoutIfNeeded()

            replyView.alpha = 1.0

        }

        let replyViewController = transitionContext.viewController(forKey: UITransitionContextViewControllerKey.to) as! ChatReplyViewController

        let animations = {

            replyViewController.isExpanded = true

        }

        let completion = { (finished: Bool) in

            transitionContext.completeTransition(finished)

        }

        replyViewController.isExpanded = false

        if transitionContext.isAnimated {

            let duration = transitionDuration(using: transitionContext)

            let runAnimations = {

                UIView.animate(withDuration: duration, delay: 0, usingSpringWithDamping: AnimationParameters.damping, initialSpringVelocity: 0, options: [], animations: animations, completion: completion)

            }

            if transitionContext.isInteractive {

                UIView.animate(withDuration: duration, delay: 0, options: [], animations: {}, completion: { (finished) in

                    if transitionContext.transitionWasCancelled {

                        completion(false)

                    }

                    else {

                        runAnimations()

                    }

                })

            }

            else {

                runAnimations()

            }

        }

        else {

            animations()

            completion(true)

        }

    }

}