Tusker/Tusker/Screens/Gallery/Transitions/GalleryShrinkAnimationController.swift

//  GalleryShrinkAnimationController.swift
//  Tusker
//
//  Created by Shadowfacts on 6/14/19.
//  Copyright © 2019 Shadowfacts. All rights reserved.
//

import UIKit
import Gifu

class GalleryShrinkAnimationController: NSObject, UIViewControllerAnimatedTransitioning {
    
    let interactionController: LargeImageInteractionController?
    
    init(interactionController: LargeImageInteractionController?) {
        self.interactionController = interactionController
    }
    
    func transitionDuration(using transitionContext: UIViewControllerContextTransitioning?) -> TimeInterval {
        return 0.2
    }
    
    func animateTransition(using transitionContext: UIViewControllerContextTransitioning) {
        guard let fromVC = transitionContext.viewController(forKey: .from) as? GalleryViewController,
            let toVC = transitionContext.viewController(forKey: .to) else {
                return
        }
        
        let (sourceFrame, sourceCornerRadius) = fromVC.sourcesInfo[fromVC.currentIndex]
        let originalVCFrame = fromVC.view.frame
        
        let attachment = fromVC.attachments[fromVC.currentIndex]
        
        guard let data = ImageCache.attachments.get(attachment.url),
            let image = UIImage(data: data) else {
                transitionContext.completeTransition(!transitionContext.transitionWasCancelled)
                return
        }
        
        let ratio = image.size.width / image.size.height
        var width = originalVCFrame.width
        var height = width / ratio
        let maxHeight = fromVC.view.bounds.height - fromVC.view.safeAreaInsets.top - fromVC.view.safeAreaInsets.bottom
        if height > maxHeight {
            let scaleFactor = maxHeight / height
            width *= scaleFactor
            height = maxHeight
        }
        let originalFrame = CGRect(x: originalVCFrame.midX - width / 2, y: originalVCFrame.midY - height / 2, width: width, height: height)
        
        let imageView = GIFImageView(frame: originalFrame)
        imageView.image = image
        if attachment.url.pathExtension == "gif" {
            imageView.animate(withGIFData: data)
        }
        imageView.contentMode = .scaleAspectFill
        imageView.layer.cornerRadius = 0
        imageView.layer.masksToBounds = true
        
        let blackView = UIView(frame: originalVCFrame)
        blackView.backgroundColor = .black
        blackView.alpha = 1
        
        let containerView = transitionContext.containerView
        containerView.addSubview(toVC.view)
        containerView.addSubview(blackView)
        containerView.addSubview(imageView)
        
        let duration = transitionDuration(using: transitionContext)
        UIView.animate(withDuration: duration, animations: {
            imageView.frame = sourceFrame
            imageView.layer.cornerRadius = sourceCornerRadius
            blackView.alpha = 0
        }, completion: { _ in
            blackView.removeFromSuperview()
            imageView.removeFromSuperview()
            
            if transitionContext.transitionWasCancelled {
                toVC.view.removeFromSuperview()
            }
            
            transitionContext.completeTransition(!transitionContext.transitionWasCancelled)
        })
    }
}