elpha-ios/elpha-ios/AttachmentPageViewController.swift

//
//  AttachmentPageViewController.swift
//  elpha-ios
//
//  Created by Dwayne Harris on 11/1/18.
//  Copyright © 2018 Elpha. All rights reserved.
//

import UIKit

class AttachmentPageViewController: UIPageViewController {
    var status: StatusMO?
    var controllers: [UIViewController] = []
    var attachmentIndex = 0
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        self.presentingViewController?.tabBarController?.tabBar.isHidden = true
        
        self.delegate = self
        self.dataSource = self
        
        if let status = status, let attachments = status.attachments {
            attachments.forEach { attachment in
                if let controller = UIStoryboard(name: "Main", bundle: nil).instantiateViewController(withIdentifier: "AttachmentViewController") as? AttachmentViewController {
                    controller.attachment = attachment as? AttachmentMO
                    controllers.append(controller)
                }
            }
        }
        
        setViewControllers([controllers[attachmentIndex]], direction: .forward, animated: true, completion: nil)
    }
    
    func dismissController() {
        self.presentingViewController?.tabBarController?.tabBar.isHidden = false
        dismiss(animated: false)
    }
    
    override var preferredStatusBarStyle: UIStatusBarStyle {
        return .lightContent
    }
    
    override var prefersStatusBarHidden: Bool {
        return true
    }
    
    override func viewDidLayoutSubviews() {
        super.viewDidLayoutSubviews()
        
        for view in view.subviews {
            if view is UIScrollView {
                view.frame = UIScreen.main.bounds
            } else if view is UIPageControl {
                view.backgroundColor = UIColor.clear
            }
        }
    }
}

extension AttachmentPageViewController: UIPageViewControllerDataSource, UIPageViewControllerDelegate {
    func presentationCount(for pageViewController: UIPageViewController) -> Int {
        return controllers.count
    }
    
    func presentationIndex(for pageViewController: UIPageViewController) -> Int {
        return attachmentIndex
    }
    
    func pageViewController(_ pageViewController: UIPageViewController, viewControllerBefore viewController: UIViewController) -> UIViewController? {
        guard let index = controllers.index(of: viewController) else {
            return nil
        }
        
        if controllers.count == 1 {
            return nil
        }
        
        if index == 0 {
            return controllers.last
        }
        
        return controllers[index - 1]
    }
    
    func pageViewController(_ pageViewController: UIPageViewController, viewControllerAfter viewController: UIViewController) -> UIViewController? {
        guard let index = controllers.index(of: viewController) else {
            return nil
        }
        
        if controllers.count == 1 {
            return nil
        }
        
        if index == controllers.count - 1 {
            return controllers.first
        }
        
        return controllers[index + 1]
    }
}