import UIKit

class BrosweingImageViewController: UIViewController, UIScrollViewDelegate{

    @IBOutlet var backgroundView: UIView!
    @IBOutlet weak var productScrollView: UIScrollView!

    var productImages = Array<UIImage>()
    var singleImgView: UIImageView!
    var currentPageIndex: Int = 0

    var imgViewArray = Array<UIImageView>()

    override func viewDidLoad() {
        super.viewDidLoad()

        self.productScrollView.delegate = self
        self.productScrollView.isPagingEnabled = true
        self.productScrollView.bounces = false
        self.productScrollView.bouncesZoom = false
        self.productScrollView.scrollsToTop = false
        self.productScrollView.maximumZoomScale = 2.5
        self.productScrollView.minimumZoomScale = 1.0
        self.productScrollView.zoomScale = 1.0


        self.productImages = [UIImage(named: "pic_colorful_officeSolutions")!, UIImage(named: "pic_colorful_networking")!, UIImage(named: "pic_colorful_homeTools")!]

        self.productScrollView.contentSize.width = productScrollView.frame.width * CGFloat(self.productImages.count)
        for i in 0 ..< 3 {
            singleImgView = UIImageView(frame: CGRect(x: CGFloat(i) *  self.productScrollView.frame.width, y: 0, width: productScrollView.frame.size.width, height: productScrollView.frame.size.height))
            singleImgView.image = productImages[i]
            singleImgView.isUserInteractionEnabled = false
            imgViewArray.append(singleImgView)
            productScrollView.addSubview(singleImgView)
        }

//        self.productScrollView.contentSize.width = productScrollView.frame.width * CGFloat(0)
//        singleImgView = UIImageView(frame: CGRect(x: CGFloat(0) *  self.productScrollView.frame.width, y: 0, width: productScrollView.frame.size.width, height: productScrollView.frame.size.height))
//        singleImgView.image = productImages[0]
//        singleImgView.isUserInteractionEnabled = false
//        self.productScrollView.addSubview(singleImgView)

        setupGestureRecognizer()

    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }

    // MARK : - Private Method

    func scrollViewDidEndDecelerating(_ scrollView: UIScrollView) {
        //計算出目前滑動的頁數
        let currentPageNumber = Int(round(productScrollView.contentOffset.x / productScrollView.frame.size.width))
        print("***",currentPageNumber)
        //設定pageControl顯示的頁數
        self.currentPageIndex = currentPageNumber
    }

    // MARK : - Setup Gestures

    func setupGestureRecognizer() {
        //init Tap Gesture
        let tapGesture = UITapGestureRecognizer(target: self, action: #selector(handleDoubleTapGesture(_:)))
        tapGesture.numberOfTapsRequired = 2
        self.productScrollView.addGestureRecognizer(tapGesture)

        //init Pan Gesture
        let panGestureRecognizer = UIPanGestureRecognizer(target: self, action: #selector(handlePanGesture(_:)))
        panGestureRecognizer.minimumNumberOfTouches = 1
        panGestureRecognizer.maximumNumberOfTouches = 1
        self.backgroundView.addGestureRecognizer(panGestureRecognizer)
    }

    func handleDoubleTapGesture(_ recognizer: UITapGestureRecognizer) {

        if (self.productScrollView.zoomScale > self.productScrollView.minimumZoomScale) {
            self.productScrollView.setZoomScale(self.productScrollView.minimumZoomScale, animated: true)
        } else {
            self.productScrollView.setZoomScale(self.productScrollView.maximumZoomScale, animated: true)
        }
    }


    public func viewForZooming(in scrollView: UIScrollView) -> UIView?
    {
//        return self.imgViewArray[currentPageIndex]
//        return self.productScrollView.subviews[currentPageIndex]
        return singleImgView
    }

    func handlePanGesture(_ sender: UIPanGestureRecognizer) {
        if let direction = sender.direction {
            if direction.isVertical {
                // pan is vertical
                self.dismiss(animated: true, completion: {
                    let vc = self.storyboard?.instantiateViewController(withIdentifier: "ProductViewController")
                    self.present(vc!, animated: true, completion: nil)
                })
            }
        }
    }
}

public enum PanDirection: Int {
    case up, down, left, right
    public var isVertical: Bool { return [.up, .down].contains(self) }
    public var isHorizontal: Bool { return !isVertical }
}

public extension UIPanGestureRecognizer {

    public var direction: PanDirection? {
        let velocity = self.velocity(in: view)
        let isVertical = fabs(velocity.y) > fabs(velocity.x)
        switch (isVertical, velocity.x, velocity.y) {
        case (true, _, let y) where y < 0: return .up
        case (true, _, let y) where y > 0: return .down
        case (false, let x, _) where x > 0: return .right
        case (false, let x, _) where x < 0: return .left
        default: return nil
        }
    }
}