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

import UIKit
import Gifu

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