OnboardingViewController.swift

//
//  OnboardingViewController.swift
//  PWMe
//
//  Created by Stephen lee on 8/22/19.
//  Copyright © 2019 Stephen lee. All rights reserved.
//

import UIKit

class OnboardingViewController: UIViewController, UIPageViewControllerDataSource {
    
    static var storyboardID : String {
        return "OnboardingStoryboardID"
    }
    
    weak var pvc : UIPageViewController!
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        self.pvc = self.children[0] as? UIPageViewController
        self.pvc.dataSource = self
        let p = SingleInputPage(num: 1, total: ONBOARDING_COUNT)
        pvc.setViewControllers([p], direction: .forward, animated: false, completion: nil)
        self.removeSwipeGesture()
    }
    
    private func removeSwipeGesture(){
        for view in self.pvc!.view.subviews {
            if let subView = view as? UIScrollView {
                subView.isScrollEnabled = false
            }
        }
    }
    
    private func getPageClass() -> Page? {
        let vc = self.pvc.viewControllers![0]
        
        // SetUsername page
        if let current = vc as? SingleInputPage {
            return current
        }
        
        // SetSkillLevels page
        if let current = vc as? SkillLevelsPage {
            return current
        }
        
        return nil
    }
    
    func pageViewController(_ p: UIPageViewController, viewControllerAfter vc: UIViewController) -> UIViewController? {
        if let cur = getPageClass() {
            let num = cur.num

            switch num {
            case 1:
                return SkillLevelsPage(num: num+1, total: ONBOARDING_COUNT)
            case ONBOARDING_COUNT:
                return AppStoryboard.Main.instance.instantiateInitialViewController()
            default:
                print("Unexpected behavior in viewControllerAfter. num:\(num) ONBOARDING_COUNT \(ONBOARDING_COUNT)")
                return SingleInputPage(num: num+1, total: ONBOARDING_COUNT)
            }
        }

        return nil
    }

    func pageViewController(_ p: UIPageViewController, viewControllerBefore vc: UIViewController) -> UIViewController? {
        if let cur = getPageClass() {
            let num = cur.num
            if num == 1 {
                return nil
            }
            return SingleInputPage(num: num-1, total: ONBOARDING_COUNT)
        }
        
        return nil
    }
    
    @objc func goNextPage(_:AnyObject) {
        if let current = getPageClass() {
            current.view.isUserInteractionEnabled = false
            DispatchQueue.main.asyncAfter(deadline: .now() + 1.0) {
                current.view.isUserInteractionEnabled = true
                let p = self.pageViewController(self.pvc, viewControllerAfter: current)
                self.pvc.setViewControllers([p!], direction: .forward, animated: true, completion: nil)
            }
        }
    }
}