session-ios/Session/Media Viewing & Editing/AllMediaViewController.swift

// Copyright © 2022 Rangeproof Pty Ltd. All rights reserved.

import UIKit
import QuartzCore
import GRDB
import DifferenceKit
import SessionUIKit
import SignalUtilitiesKit

public class AllMediaViewController: UIViewController, UIPageViewControllerDataSource, UIPageViewControllerDelegate {
    private let pageVC = UIPageViewController(transitionStyle: .scroll, navigationOrientation: .horizontal, options: nil)
    private var pages: [UIViewController] = []
    private var targetVCIndex: Int?
    
    // MARK: Components
    private lazy var tabBar: TabBar = {
        let tabs = [
            TabBar.Tab(title: MediaStrings.media) { [weak self] in
                guard let self = self else { return }
                self.pageVC.setViewControllers([ self.pages[0] ], direction: .forward, animated: false, completion: nil)
            },
            TabBar.Tab(title: MediaStrings.document) { [weak self] in
                guard let self = self else { return }
                self.pageVC.setViewControllers([ self.pages[1] ], direction: .forward, animated: false, completion: nil)
            }
        ]
        return TabBar(tabs: tabs)
    }()
    
    private var mediaTitleViewController: MediaTileViewController
    private var documentTitleViewController: DocumentTileViewController
    
    init(mediaTitleViewController: MediaTileViewController, documentTitleViewController: DocumentTileViewController) {
        self.mediaTitleViewController = mediaTitleViewController
        self.documentTitleViewController = documentTitleViewController
        super.init(nibName: nil, bundle: nil)
    }
    
    required init?(coder: NSCoder) {
        notImplemented()
    }
    
    // MARK: Lifecycle
    public override func viewDidLoad() {
        super.viewDidLoad()
        
        // Add a custom back button if this is the only view controller
        if self.navigationController?.viewControllers.first == self {
            let backButton = OWSViewController.createOWSBackButton(withTarget: self, selector: #selector(didPressDismissButton))
            self.navigationItem.leftBarButtonItem = backButton
        }
        
        ViewControllerUtilities.setUpDefaultSessionStyle(
            for: self,
            title: MediaStrings.allMedia,
            hasCustomBackButton: false
        )
        
        // Set up page VC
        pages = [ mediaTitleViewController, documentTitleViewController ]
        pageVC.dataSource = self
        pageVC.delegate = self
        pageVC.setViewControllers([ mediaTitleViewController ], direction: .forward, animated: false, completion: nil)
        // Set up tab bar
        view.addSubview(tabBar)
        tabBar.pin([ UIView.HorizontalEdge.leading, UIView.HorizontalEdge.trailing, UIView.VerticalEdge.top ], to: view)
        // Set up page VC constraints
        let pageVCView = pageVC.view!
        view.addSubview(pageVCView)
        pageVCView.pin([ UIView.HorizontalEdge.leading, UIView.HorizontalEdge.trailing, UIView.VerticalEdge.bottom ], to: view)
        pageVCView.pin(.top, to: .bottom, of: tabBar)
    }
    
    // MARK: General
    public func pageViewController(_ pageViewController: UIPageViewController, viewControllerBefore viewController: UIViewController) -> UIViewController? {
        guard let index = pages.firstIndex(of: viewController), index != 0 else { return nil }
        return pages[index - 1]
    }
    
    public func pageViewController(_ pageViewController: UIPageViewController, viewControllerAfter viewController: UIViewController) -> UIViewController? {
        guard let index = pages.firstIndex(of: viewController), index != (pages.count - 1) else { return nil }
        return pages[index + 1]
    }
    
    // MARK: Updating
    public func pageViewController(_ pageViewController: UIPageViewController, willTransitionTo pendingViewControllers: [UIViewController]) {
        guard let targetVC = pendingViewControllers.first, let index = pages.firstIndex(of: targetVC) else { return }
        targetVCIndex = index
    }
    
    public func pageViewController(_ pageViewController: UIPageViewController, didFinishAnimating isFinished: Bool, previousViewControllers: [UIViewController], transitionCompleted isCompleted: Bool) {
        guard isCompleted, let index = targetVCIndex else { return }
        tabBar.selectTab(at: index)
    }
    
    // MARK: Interaction
    @objc public func didPressDismissButton() {
        dismiss(animated: true, completion: nil)
    }
}