//
//  BrowserNavigationController.swift
//  Gemini-iOS
//
//  Created by Shadowfacts on 12/16/20.
//

import UIKit
import BrowserCore
import Combine

class BrowserNavigationController: UINavigationController {

    let navigator: NavigationManager
    
    var poppedViewControllers = [UIViewController]()
    var skipResetPoppedOnNextPush = false
    
    private var interactivePushTransition: InteractivePushTransition!
    
    private var cancellables = [AnyCancellable]()
    
    init(navigator: NavigationManager) {
        self.navigator = navigator
        
        super.init(nibName: nil, bundle: nil)
        
        navigator.$currentURL
            .sink { [weak self] (newURL) in
                self?.pushViewController(BrowserWebViewController(navigator: navigator, url: newURL), animated: true)
            }
            .store(in: &cancellables)
    }
    
    required init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
    
    override func viewDidLoad() {
        super.viewDidLoad()

        interactivePushTransition = InteractivePushTransition(navigationController: self)
    }
    
    override func popViewController(animated: Bool) -> UIViewController? {
        if let popped = super.popViewController(animated: animated) {
            poppedViewControllers.insert(popped, at: 0)
            return popped
        } else {
            return nil
        }
    }
    
    override func popToRootViewController(animated: Bool) -> [UIViewController]? {
        if let popped = super.popToRootViewController(animated: animated) {
            poppedViewControllers = popped
            return popped
        } else {
            return nil
        }
    }
    
    override func popToViewController(_ viewController: UIViewController, animated: Bool) -> [UIViewController]? {
        if let popped = super.popToViewController(viewController, animated: animated) {
            poppedViewControllers.insert(contentsOf: popped, at: 0)
            return popped
        } else {
            return nil
        }
    }
    
    override func pushViewController(_ viewController: UIViewController, animated: Bool) {
        if skipResetPoppedOnNextPush {
            skipResetPoppedOnNextPush = false
        } else {
            self.poppedViewControllers = []
        }
        super.pushViewController(viewController, animated: animated)
    }
    
    func onWillShow() {
        self.transitionCoordinator?.notifyWhenInteractionChanges({ (context) in
            if context.isCancelled {
                if self.interactivePushTransition.interactive {
                    // when an interactive push gesture is cancelled, make sure to adding the VC that was being pushed back onto the popped stack so it doesn't disappear
                    self.poppedViewControllers.insert(self.interactivePushTransition.pushingViewController!, at: 0)
                } else {
                    // when an interactive pop gesture is cancelled (i.e. the user lifts their finger before it triggers),
                    // the popViewController(animated:) method has already been called so the VC has already been added to the popped stack
                    // so we make sure to remove it, otherwise there could be duplicate VCs on the navigation stasck
                    self.poppedViewControllers.remove(at: 0)
                }
            }
        })
    }
    
}