/*

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

 See LICENSE.txt for this sample’s licensing information

 Abstract:

 A button subclass used to display a single large emoji, which can be sent as a reply to a received chat.

 */

import UIKit

class ChatReplyButton : UIButton {

    var action: ((_ button: UIButton) -> Void)?

    var pulses = false

    private var isPulsing = false

    convenience init(title: String, pulses: Bool = false, action: ((_ button: UIButton) -> Void)? = nil) {

        self.init(frame: CGRect.zero)

        self.setTitle(title, for: [])

        self.titleLabel?.font = UIFont.systemFont(ofSize: 50)

        self.sizeToFit()

        self.pulses = pulses

        self.action = action

        self.addTarget(self, action: #selector(handleTap), for: .primaryActionTriggered)

        startPulsing()

    }

    func handleTap() {

        action?(self)

    }

    override var isHighlighted: Bool {

        didSet {

            if isHighlighted {

                stopPulsing()

                animate(toScale: 1.4)

            }

            else {

                startPulsing()

                animateToDefaultScale()

            }

        }

    }

    private func animateToDefaultScale() {

        guard !isHighlighted && !pulses else { return }

        animate(toScale: 1.0)

    }

    private func animate(toScale: CGFloat) {

        UIView.animate(withDuration: 0.3, delay: 0, usingSpringWithDamping: 0.5, initialSpringVelocity: 0, options: [.allowUserInteraction, .beginFromCurrentState], animations: {

            self.transform = CGAffineTransform(scaleX: toScale, y: toScale)

        })

    }

    private func stopPulsing() {

        guard pulses else { return }

        isPulsing = false

        layer.removeAllAnimations()

    }

    private func startPulsing() {

        guard pulses && !isPulsing else { return }

        isPulsing = true

        let minScale = CGFloat(0.95)

        let maxScale = CGFloat(1.05)

        let pulseDuration = 0.5

        UIView.animate(withDuration: pulseDuration / 2.0, delay: 0, options: [.allowUserInteraction], animations: {

            self.transform = CGAffineTransform(scaleX: minScale, y: minScale)

            }, completion: { _ in

                UIView.animate(withDuration: pulseDuration, delay: 0, options: [.allowUserInteraction, .repeat, .autoreverse], animations: {

                    self.transform = CGAffineTransform(scaleX: maxScale, y: maxScale)

                })

        })

    }

}