Privado-iOS/iOS/Privado/Sources/Common/View/SmoothTransition.swift

//
//  SmoothTransition.swift
//  Privado
//
//  Created by Viktor on 30.06.2020.
//  Copyright © 2020 Privado LLC. All rights reserved.
//

import Foundation
import UIKit

class SmoothTransition: NSObject, UIViewControllerAnimatedTransitioning {
    
    private enum Constants {
        static let duration: TimeInterval = 0.2
        static let dy: CGFloat = 0
    }
    
    var popStyle: Bool = false

    private var duration: TimeInterval = Constants.duration
    private var dy: CGFloat = Constants.dy
    
    init(duration: TimeInterval = Constants.duration, dy: CGFloat = Constants.dy) {
        super.init()
        self.duration = duration
        self.dy = dy
    }
    
    func transitionDuration(
        using transitionContext: UIViewControllerContextTransitioning?) -> TimeInterval {
        return self.duration
    }
    
    func animateTransition(using transitionContext: UIViewControllerContextTransitioning) {
        
        if popStyle {
            
            animatePop(using: transitionContext)
            return
        }
        
        guard let fz = transitionContext.viewController(forKey: UITransitionContextViewControllerKey.from) else {
            return
        }
        guard let tz = transitionContext.viewController(forKey: UITransitionContextViewControllerKey.to) else {
            return
        }
        
        let f = transitionContext.finalFrame(for: tz)
        
        let fOff = f.offsetBy(dx: f.width, dy: self.dy)
        tz.view.frame = fOff
        
        transitionContext.containerView.insertSubview(tz.view, aboveSubview: fz.view)
        
        UIView.animate(
            withDuration: transitionDuration(using: transitionContext),
            animations: {
                tz.view.frame = f
        }, completion: {_ in
                transitionContext.completeTransition(true)
        })
    }
    
    func animatePop(using transitionContext: UIViewControllerContextTransitioning) {
        
        let fz = transitionContext.viewController(forKey: UITransitionContextViewControllerKey.from)!
        let tz = transitionContext.viewController(forKey: UITransitionContextViewControllerKey.to)!
        
        let f = transitionContext.initialFrame(for: fz)
        let fOffPop = f.offsetBy(dx: f.width, dy: self.dy)
        
        transitionContext.containerView.insertSubview(tz.view, belowSubview: fz.view)
        
        UIView.animate(
            withDuration: transitionDuration(using: transitionContext),
            animations: {
                fz.view.frame = fOffPop
        }, completion: {_ in
                transitionContext.completeTransition(true)
        })
    }
}