//: A UIKit based Playground for presenting user interface

import UIKit
import PlaygroundSupport

class MyViewController : UIViewController {

    // Timer to record the length of time between debounced calls
    var timer: Timer? = nil

    override func loadView() {
        super.loadView()

        let view = UIView()
        view.backgroundColor = .white

        // Set up the slider
        let slider = UISlider(frame: CGRect(x: 100, y: 100, width: 200, height: 50))
        slider.minimumValue = 0
        slider.maximumValue = 100
        slider.isContinuous = true
        slider.addTarget(self, action: #selector(sliderValueDidChange(_:)), for: .valueChanged)
        self.view.addSubview(slider)
    }

    @objc func sliderValueDidChange(_ sender: UISlider) {
        // Coalesce the calls until the slider valude has not changed for 0.2 seconds
        debounce(seconds: 0.2) {
            print("slider value: (sender.value)")
        }
    }

    // Debounce function taking a time interval to wait before firing after user input has stopped
    // and a function to execute when debounce has stopped being called for a period of time.
    func debounce(seconds: TimeInterval, function: @escaping () -> Swift.Void ) {
        timer?.invalidate()
        timer = Timer.scheduledTimer(withTimeInterval: seconds, repeats: false, block: { _ in
            function()
        })
    }
}

// Present the view controller in the Live View window
PlaygroundPage.current.liveView = MyViewController()
PlaygroundPage.current.needsIndefiniteExecution = true

func debounce(seconds: TimeInterval, function: @escaping () -> Swift.Void ) {
    timer?.invalidate()
    timer = Timer.scheduledTimer(withTimeInterval: seconds, repeats: false, block: { _ in
        function()
    })
}