NewsBlur/clients/ios/Classes/HorizontalPageDelegate.swift

//
//  HorizontalPageDelegate.swift
//  NewsBlur
//
//  Created by David Sinclair on 2020-09-24.
//  Copyright © 2020 NewsBlur. All rights reserved.
//

import UIKit

//#warning("hack: this function is just for testing")
//func storyViewController() -> OriginalStoryViewController {
//    let viewController = OriginalStoryViewController()
//
//    if let appDelegate = UIApplication.shared.delegate as? NewsBlurAppDelegate {
//        let urls = ["https://dejal.com/", "https://dejus.com/", "https://yellowcottagehomestead.com/", "https://apple.com", "https://amazon.com"]
//
//        appDelegate.activeOriginalStoryURL = URL(string: urls.randomElement() ?? "https://dejal.com/")
//    }
//
//    _ = viewController.view
//    viewController.loadInitialStory()
//
//    return viewController
//}

/// Delegate and data source of the story horizontal page view controller.
class HorizontalPageDelegate: NSObject {
}

extension HorizontalPageDelegate: UIPageViewControllerDataSource {
    func pageViewController(_ pageViewController: UIPageViewController, viewControllerBefore viewController: UIViewController) -> UIViewController? {
        guard let pageViewController = pageViewController as? HorizontalPageViewController, let currentViewController = viewController as? VerticalPageViewController, let detailViewController = pageViewController.detailViewController else {
            return nil
        }
        
        let pageIndex = (currentViewController.pageIndex ?? -1) - 1
        let previousViewController = detailViewController.pageIndexIsValid(pageIndex) ? Storyboards.shared.controller(withIdentifier: .verticalPages) as? VerticalPageViewController : nil
        
        pageViewController.previousController = previousViewController
        previousViewController?.horizontalPageViewController = pageViewController
        previousViewController?.currentController = detailViewController.makeStoryController(for: pageIndex)
        
        return previousViewController
    }
    
    func pageViewController(_ pageViewController: UIPageViewController, viewControllerAfter viewController: UIViewController) -> UIViewController? {
        guard let pageViewController = pageViewController as? HorizontalPageViewController, let currentViewController = viewController as? VerticalPageViewController, let detailViewController = pageViewController.detailViewController else {
            return nil
        }
        
        var pageIndex = (currentViewController.pageIndex ?? -1) + 1
        
        if pageIndex == -1 {
            pageIndex = 0
        }
        
        let nextViewController = detailViewController.pageIndexIsValid(pageIndex) ? Storyboards.shared.controller(withIdentifier: .verticalPages) as? VerticalPageViewController : nil

        pageViewController.nextController = nextViewController
        nextViewController?.horizontalPageViewController = pageViewController
        nextViewController?.currentController = detailViewController.makeStoryController(for: pageIndex)
        
        return nextViewController
    }
}

extension HorizontalPageDelegate: UIPageViewControllerDelegate {
    func pageViewController(_ pageViewController: UIPageViewController, didFinishAnimating finished: Bool, previousViewControllers: [UIViewController], transitionCompleted completed: Bool) {
        guard let pageViewController = pageViewController as? HorizontalPageViewController, let detailViewController = pageViewController.detailViewController else {
            return
        }
        
        detailViewController.setStoryFromScroll(false)
    }
}