import UIKit

class AnimatorVC: UIViewController {
    @IBOutlet weak var stackView: UIStackView!

    init() {
        super.init(nibName: "AnimatorVC", bundle: nil)
    }

    required init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }

    override func viewDidLoad() {
        super.viewDidLoad()

        _ = (0..<5).map {
            let progressView = UIProgressView()
            progressView.tag = $0
            stackView.addArrangedSubview(progressView)
        }
    }

    var animator: UIViewPropertyAnimator = UIViewPropertyAnimator(duration: 5.0, curve: .easeInOut)
    var currentIndex = 0


    @IBAction func reset(_ sender: Any) {
        currentIndex = 0
        stackView.arrangedSubviews.forEach {
            if let progressView = $0 as? UIProgressView {
                progressView.setProgress(0, animated: false)
            }
        }
    }

    @IBAction func start(_ sender: Any) {
        print(#function, animator.state, animator.state.rawValue)

        animator.addAnimations {
            self.stackView.arrangedSubviews.forEach {
                if let progressView = $0 as? UIProgressView {
                    if progressView.tag == self.currentIndex {
                        progressView.setProgress(1.0, animated: true)
                    }

                }
            }
        }
        animator.addCompletion { _ in
            self.complete()
        }
        animator.startAnimation()
    }

    private func complete() {
        animator.stopAnimation(true)

        DispatchQueue.main.asyncAfter(deadline: .now() + 0.1) { [weak self] in
            guard let self = self else { return }
            if self.currentIndex == 4 {
                self.reset(true)
            } else {
                self.currentIndex += 1
                self.start(true)
            }
        }
    }

    @IBAction func pause(_ sender: Any) {
    }


    @IBAction func stop(_ sender: Any) {
    }

    @IBAction func next(_ sender: Any) {
        print(#function, animator.state, animator.state.rawValue)

        animator.stopAnimation(true)

        currentIndex += 1

        DispatchQueue.main.asyncAfter(deadline: .now() + 0.1) { [weak self] in
            self?.start(sender)
        }
    }

    @IBAction func prev(_ sender: Any) {
        animator.stopAnimation(true)

        currentIndex -= 1

        stackView.arrangedSubviews.forEach {
            if let progressView = $0 as? UIProgressView {
                let progress: Float = progressView.tag < currentIndex ? 1.0 : 0
                progressView.setProgress(progress, animated: false)
            }
        }

        DispatchQueue.main.asyncAfter(deadline: .now() + 0.1) { [weak self] in
            self?.start(sender)
        }
    }
}