//
//  NavigationBarInteractivePopDeletegate.swift
//  PaiaiUIKit
//
//  Created by ffib on 2019/1/15.
//  Copyright © 2019 yb. All rights reserved.
//

import Foundation

public protocol NavigationBarInteractivePopDeletegate: class {
    func setupNavigationBarInteractivePopDelegate()
}

public extension NavigationBarInteractivePopDeletegate where Self: UIViewController & NavigationBarInOutAnimator {
    func setupNavigationBarInteractivePopDelegate() {
        guard let nav = navigationController else { return }
        nav.interactivePopGestureRecognizer?.addTarget(self, action: #selector(interactivePopAnimation(gesture:)))
    }
}

extension UIViewController {
    @objc func interactivePopAnimation(gesture: UIPanGestureRecognizer) {
        guard let `self` =  self as? (NavigationBarInOutAnimator & UIViewController) else { return }
        let point = gesture.translation(in: view)
        let percentage = calculatePercentageOfOffsets(point: point)
        
        /// naivgationController == nil  popped viewController
        /// navigationController?.visibleViewController == self pop to viewController
        
        let percentageAnimation: ((CGFloat) -> Void)
        let fadeInAnimation: (() -> Void)
        let fadeOutAnimation: (() -> Void)
        if navigationController == nil {
            percentageAnimation = self.navigationBarFadeOutWithPercentage
            fadeInAnimation = self.navigationBarFadeAndMoveIn
            fadeOutAnimation = self.navigationBarFadeAndMoveOut
        } else if navigationController?.visibleViewController == self {
            percentageAnimation = self.navigationBarFadeInWithPercentage
            fadeInAnimation = self.navigationBarFadeIn
            fadeOutAnimation = self.navigationBarFadeOut
        } else {
            return
        }
        
        percentageAnimation(percentage)
        
        guard gesture.state == .ended else { return }

        if (percentage > 0.5 && navigationController == nil) ||
            (percentage < 0.5 && navigationController?.visibleViewController == self) {
            fadeOutAnimation()
        } else if (percentage < 0.5 && navigationController == nil) ||
            (percentage > 0.5 && navigationController?.visibleViewController == self) {
            fadeInAnimation()
        }
    }
    
    private func calculatePercentageOfOffsets(point: CGPoint) -> CGFloat {
        return point.x / view.bounds.width
    }
}