//
//  LargeImageViewController.swift
//  Tusker
//
//  Created by Shadowfacts on 8/31/18.
//  Copyright © 2018 Shadowfacts. All rights reserved.
//

import UIKit

class LargeImageViewController: UIViewController, UIScrollViewDelegate {

    @IBOutlet weak var scrollView: UIScrollView!
    @IBOutlet weak var imageView: UIImageView!
    @IBOutlet weak var imageViewLeadingConstraint: NSLayoutConstraint!
    @IBOutlet weak var imageViewTopConstraint: NSLayoutConstraint!

    var image: UIImage? {
        didSet {
            imageView.image = image
            if oldValue == nil, let image = image {
                imageView.bounds = CGRect(origin: .zero, size: image.size)
                view.setNeedsLayout()
            }
        }
    }

    var prevZoomScale: CGFloat?
    
    init() {
        super.init(nibName: "LargeImageViewController", bundle: nil)
    }
    
    required init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
    
    override func viewDidLoad() {
        super.viewDidLoad()

//        imageView.image = image
        
        scrollView.delegate = self
//        imageView.bounds = CGRect(origin: .zero, size: imageView.image!.size)
        
//        view.addGestureRecognizer(UITapGestureRecognizer(target: self, action: #selector(scrollViewPressed(_:))))
        let doubleTap = UITapGestureRecognizer(target: self, action: #selector(scrollViewDoubleTapped(_:)))
        doubleTap.numberOfTapsRequired = 2
        view.addGestureRecognizer(doubleTap)
    }
    
    
    override func viewDidLayoutSubviews() {
        super.viewDidLayoutSubviews()
        
        let maxHeight = view.bounds.height - view.safeAreaInsets.top - view.safeAreaInsets.bottom
        let heightScale = maxHeight / imageView.bounds.height
        let widthScale = view.bounds.width / imageView.bounds.width
        let minScale = min(widthScale, heightScale)
        scrollView.minimumZoomScale = minScale
        scrollView.zoomScale = minScale
        scrollView.maximumZoomScale = minScale * 4
        
        centerImage()
    }

    func viewForZooming(in scrollView: UIScrollView) -> UIView? {
        return imageView
    }
    
    func scrollViewDidZoom(_ scrollView: UIScrollView) {
        centerImage()
        
//        let prevZoomScale = self.prevZoomScale ?? scrollView.minimumZoomScale
//        if scrollView.zoomScale <= scrollView.minimumZoomScale {
//            controlsVisible = true
//        } else if scrollView.zoomScale > prevZoomScale {
//            controlsVisible = false
//        }
//        self.prevZoomScale = scrollView.zoomScale
    }
    
    func centerImage() {
        let yOffset = max(0, (view.bounds.size.height - imageView.frame.height - scrollView.contentInset.top - scrollView.contentInset.bottom) / 2)
        imageViewTopConstraint.constant = yOffset

        let xOffset = max(0, (view.bounds.size.width - imageView.frame.width - scrollView.contentInset.left - scrollView.contentInset.right) / 2)
        imageViewLeadingConstraint.constant = xOffset
    }
    
    func zoomRectFor(scale: CGFloat, center: CGPoint) -> CGRect {
        var zoomRect = CGRect.zero
        zoomRect.size.width = imageView.frame.width / scale
        zoomRect.size.height = imageView.frame.height / scale
        let newCenter = scrollView.convert(center, to: imageView)
        zoomRect.origin.x = newCenter.x - (zoomRect.width / 2)
        zoomRect.origin.y = newCenter.y - (zoomRect.height / 2)
        return zoomRect
    }
    
    func animateZoomOut() {
        UIView.animate(withDuration: 0.3, animations: {
            self.scrollView.zoomScale = self.scrollView.minimumZoomScale
            self.view.layoutIfNeeded()
        })
    }
    
//    @objc func scrollViewPressed(_ sender: UITapGestureRecognizer) {
//        if scrollView.zoomScale > scrollView.minimumZoomScale {
//            animateZoomOut()
//        } else {
////            setControlsVisible(!controlsVisible, animated: true)
//        }
//    }
    
    @objc func scrollViewDoubleTapped(_ recognizer: UITapGestureRecognizer) {
        if scrollView.zoomScale <= scrollView.minimumZoomScale {
            let point = recognizer.location(in: recognizer.view)
            let scale: CGFloat
            if scrollView.minimumZoomScale < 1 {
                if 1 - scrollView.zoomScale <= 0.5 {
                    scale = scrollView.zoomScale + 1
                } else {
                    scale = 1
                }
            } else {
                scale = scrollView.maximumZoomScale
            }
            let rect = zoomRectFor(scale: scale, center: point)
            UIView.animate(withDuration: 0.3) {
                self.scrollView.zoom(to: rect, animated: false)
                self.view.layoutIfNeeded()
            }
        } else {
            animateZoomOut()
        }
    }
    
//    @IBAction func closeButtonPressed(_ sender: Any) {
//        dismiss(animated: true)
//    }
//
//    @IBAction func sharePressed(_ sender: Any) {
//        guard let image = image else { return }
//        let activityVC = UIActivityViewController(activityItems: [image], applicationActivities: nil)
//        present(activityVC, animated: true)
//    }
    
}