paiai_ios/PaiAi/PaiaiUIKit/Reusable/UIKit/NavigationController/NavigationController.swift

//
//  NavigationController.swift
//  PaiaiUIKit
//
//  Created by FFIB on 2019/4/23.
//  Copyright © 2019 FFIB. All rights reserved.
//

import UIKit

public class NavigationController: UINavigationController {

    override public init(rootViewController: UIViewController) {
        super.init(navigationBarClass: NavigationBar.classForCoder(), toolbarClass: nil)
        self.viewControllers = [rootViewController]
    }

    required init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
    }

    override public init(nibName nibNameOrNil: String?, bundle nibBundleOrNil: Bundle?) {
        super.init(nibName: nibNameOrNil, bundle: nibBundleOrNil)
    }

    override public func viewDidLoad() {
        super.viewDidLoad()
        delegate = self
        interactivePopGestureRecognizer?.delegate = self
        interactivePopGestureRecognizer?.isEnabled = true

        interactivePopGestureRecognizer?.addTarget(self,
                                                   action: #selector(handlePop(gestureRecognizer:)))
    }

    @objc
    private func handlePop(gestureRecognizer: UIPanGestureRecognizer) {
        guard let navBar = navigationBar as? NavigationBar else { return }
        if gestureRecognizer.state == .began { navBar.isPush = false }

        guard navBar.needsInteractive else { return }

        let percent = gestureRecognizer.translation(in: view).x / view.bounds.width

        if gestureRecognizer.state == .began || gestureRecognizer.state == .changed {
            navBar.transitionAnimationWithPercent(percent)
        }

        guard gestureRecognizer.state == .ended
            || gestureRecognizer.state == .cancelled
            || gestureRecognizer.state == .failed,
            let coordinator = transitionCoordinator else { return }

        navBar.bounce = percent < 0.5 ? .backward : .forward
        let durationPercent = Double(percent < 0.5 ? coordinator.percentComplete : (1 - coordinator.percentComplete))
        UIView.animate(withDuration: coordinator.transitionDuration * durationPercent,
                       delay: 0,
                       usingSpringWithDamping: 1,
                       initialSpringVelocity: coordinator.completionVelocity,
                       options: [],
                       animations: {
                        navBar.transitionAnimationWithPercent(1)
        }, completion: { _ in
            navBar.clear()
        })
    }
}

extension NavigationController: UINavigationControllerDelegate {

    public func navigationController(_ navigationController: UINavigationController,
                                     animationControllerFor operation: UINavigationController.Operation,
                                     from fromVC: UIViewController,
                                     to toVC: UIViewController) -> UIViewControllerAnimatedTransitioning? {
        (navigationBar as? NavigationBar)?.isPush = operation == .push
        return nil
    }

    public func navigationController(_ navigationController: UINavigationController,
                                     willShow viewController: UIViewController,
                                     animated: Bool) {
        guard let navBar = navigationBar as? NavigationBar,
            navBar.needsInteractive else { return }

        guard let coordinator = transitionCoordinator,
            animated else {
                navBar.setBackgroundImage()
                navBar.clear()
                return
        }

        navBar.constructViewHierarchy()

        guard !coordinator.isInteractive else { return }

        coordinator.animate(alongsideTransition: { (transitionContext) in
            DispatchQueue.main.async {
                UIView.beginAnimations(nil, context: nil)
                UIView.setAnimationCurve(transitionContext.completionCurve)
                UIView.setAnimationDuration(transitionContext.transitionDuration)
                navBar.transitionAnimation()
                UIView.commitAnimations()
            }
        }, completion: { (_) in
            navBar.clear()
        })
    }
}

extension NavigationController: UIGestureRecognizerDelegate {
    public func gestureRecognizerShouldBegin(_ gestureRecognizer: UIGestureRecognizer) -> Bool {
        if gestureRecognizer == interactivePopGestureRecognizer {
            return viewControllers.count > 1
        }
        return true
    }
}