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

import UIKit
import Photos

protocol LargeImageViewControllerDelegate {
    func closeLargeImage()
}

class LargeImageViewController: UIViewController, UIScrollViewDelegate {

    static func create(image: UIImage, description: String?, sourceView: UIView, sourceViewController: UIViewController) -> LargeImageViewController {
        guard let vc = UIStoryboard(name: "LargeImage", bundle: nil).instantiateInitialViewController() as? LargeImageViewController else { fatalError() }
        vc.image = image
        vc.imageDescription = description
        var frame = sourceView.convert(sourceView.bounds, to: sourceViewController.view)
        if let scrollView = sourceViewController.view as? UIScrollView {
            let scale = scrollView.zoomScale
            let width = frame.width * scale
            let height = frame.height * scale
            let x = frame.minX * scale - scrollView.contentOffset.x + scrollView.frame.minX
            let y = frame.minY * scale - scrollView.contentOffset.y + scrollView.frame.minY
            frame = CGRect(x: x, y: y, width: width, height: height)
        }
        vc.originFrame = frame
        vc.originCornerRadius = sourceView.layer.cornerRadius
        vc.transitioningDelegate = sourceViewController
        return vc
    }

    var delegate: LargeImageViewControllerDelegate?
    
    var originFrame: CGRect?
    var originCornerRadius: CGFloat?
    var dismissInteractionController: LargeImageInteractionController?
    
    @IBOutlet weak var scrollView: UIScrollView!
    @IBOutlet weak var imageView: UIImageView!
    @IBOutlet weak var imageViewLeadingConstraint: NSLayoutConstraint!
    @IBOutlet weak var imageViewTrailingConstraint: NSLayoutConstraint!
    @IBOutlet weak var imageViewTopConstraint: NSLayoutConstraint!
    @IBOutlet weak var imageViewBottomConstraint: NSLayoutConstraint!
    
    @IBOutlet weak var topControlsView: UIView!
    @IBOutlet weak var topControlsHeightConstraint: NSLayoutConstraint!
    @IBOutlet weak var downloadButton: UIButton!
    @IBOutlet weak var downloadButtonTopConstraint: NSLayoutConstraint!
    @IBOutlet weak var downloadButtonLeadingConstraint: NSLayoutConstraint!
    @IBOutlet weak var closeButton: UIButton!
    @IBOutlet weak var closeButtonTopConstraint: NSLayoutConstraint!
    @IBOutlet weak var closeButtonTrailingConstraint: NSLayoutConstraint!
    
    @IBOutlet weak var bottomControlsView: UIView!
    @IBOutlet weak var descriptionLabel: UILabel!
    
    var initializedTopControlsConstrains = false
    
    var image: UIImage?
    var imageDescription: String?
    
    var controlsVisible = true {
        didSet {
            UIView.animate(withDuration: 0.2) {
                let topOffset = self.controlsVisible ? 0 : -self.topControlsView.bounds.height
                self.topControlsView.transform = CGAffineTransform(translationX: 0, y: topOffset)
                if self.imageDescription != nil {
                    let bottomOffset = self.controlsVisible ? 0 : self.bottomControlsView.bounds.height + self.view.safeAreaInsets.bottom
                    self.bottomControlsView.transform = CGAffineTransform(translationX: 0, y: bottomOffset)
                }
            }
        }
    }
    
    var prevZoomScale: CGFloat?
    
    override var prefersStatusBarHidden: Bool {
        return true
    }
    
    override func viewDidLoad() {
        super.viewDidLoad()

        imageView.image = image
        scrollView.delegate = self
        imageView.bounds = CGRect(origin: .zero, size: image!.size)
        
        if let imageDescription = imageDescription {
            descriptionLabel.text = imageDescription
        } else {
            bottomControlsView.isHidden = true
        }
        
        dismissInteractionController = LargeImageInteractionController(viewController: self)
    }
    
    
    override func viewDidLayoutSubviews() {
        super.viewDidLayoutSubviews()
        
        let widthScale = view.bounds.size.width / imageView.bounds.width
        let heightScale = view.bounds.size.height / imageView.bounds.height
        let minScale = min(widthScale, heightScale)
        scrollView.minimumZoomScale = minScale
        scrollView.zoomScale = minScale
        scrollView.maximumZoomScale = minScale >= 1 ? minScale + 2 : 2
        
        if !initializedTopControlsConstrains {
            initializedTopControlsConstrains = true
            if view.safeAreaInsets.top == 44 {
                // running on iPhone X style notched device
                let notchWidth: CGFloat = 209
                let earWidth = (view.bounds.width - notchWidth) / 2
                let offset = (earWidth - downloadButton.bounds.width) / 2
                downloadButtonLeadingConstraint.constant = offset
                closeButtonTrailingConstraint.constant = offset
            }
        }
    }
    
    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) / 2)
        imageViewTopConstraint.constant = yOffset
        imageViewBottomConstraint.constant = yOffset
        
        let xOffset = max(0, (view.bounds.size.width - imageView.frame.width) / 2)
        imageViewLeadingConstraint.constant = xOffset
        imageViewTrailingConstraint.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()
        })
    }

    /*
    // MARK: - Navigation

    // In a storyboard-based application, you will often want to do a little preparation before navigation
    override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
        // Get the new view controller using segue.destination.
        // Pass the selected object to the new view controller.
    }
    */
    
    @IBAction func scrollViewPressed(_ sender: UITapGestureRecognizer) {
        if scrollView.zoomScale > scrollView.minimumZoomScale {
            animateZoomOut()
        } else {
            controlsVisible = !controlsVisible
        }
    }
    
    @IBAction 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) {
        delegate?.closeLargeImage()
    }
    
    @IBAction func downloadPressed(_ sender: Any) {
        guard let image = image else { return }
        PHPhotoLibrary.shared().performChanges({
            PHAssetChangeRequest.creationRequestForAsset(from: image)
        }, completionHandler: { success, error in
            if success {
                return
            } else if let error = error {
                print("Couldn't save photo: \(error)")
            } else {
                return
            }
        })
    }
    
}