mastodon-ios/Mastodon/Scene/HomeTimeline/HomeTimelineViewController.swift

//
//  HomeTimelineViewController.swift
//  Mastodon
//
//  Created by sxiaojian on 2021/2/5.
//

import os.log
import UIKit
import AVKit
import Combine
import CoreData
import CoreDataStack
import GameplayKit
import MastodonSDK
import AlamofireImage
import StoreKit
import MastodonAsset
import MastodonCore
import MastodonUI
import MastodonLocalization

final class HomeTimelineViewController: UIViewController, NeedsDependency, MediaPreviewableViewController {
    
    let logger = Logger(subsystem: "HomeTimelineViewController", category: "UI")
    
    weak var context: AppContext! { willSet { precondition(!isViewLoaded) } }
    weak var coordinator: SceneCoordinator! { willSet { precondition(!isViewLoaded) } }
    
    var disposeBag = Set<AnyCancellable>()
    var viewModel: HomeTimelineViewModel!
    
    let mediaPreviewTransitionController = MediaPreviewTransitionController()

    let friendsAssetImageView: UIImageView = {
        let imageView = UIImageView()
        imageView.image = Asset.Asset.friends.image
        imageView.contentMode = .scaleAspectFill
        return imageView
    }()
    
    lazy var emptyView: UIStackView = {
        let emptyView = UIStackView()
        emptyView.axis = .vertical
        emptyView.distribution = .fill
        emptyView.isLayoutMarginsRelativeArrangement = true
        return emptyView
    }()
    
    let titleView = HomeTimelineNavigationBarTitleView()
    
    let settingBarButtonItem: UIBarButtonItem = {
        let barButtonItem = UIBarButtonItem()
        barButtonItem.tintColor = ThemeService.tintColor
        barButtonItem.image = Asset.ObjectsAndTools.gear.image.withRenderingMode(.alwaysTemplate)
        barButtonItem.accessibilityLabel = L10n.Common.Controls.Actions.settings
        return barButtonItem
    }()
    
    let tableView: UITableView = {
        let tableView = ControlContainableTableView()
        tableView.register(StatusTableViewCell.self, forCellReuseIdentifier: String(describing: StatusTableViewCell.self))
        tableView.register(TimelineMiddleLoaderTableViewCell.self, forCellReuseIdentifier: String(describing: TimelineMiddleLoaderTableViewCell.self))
        tableView.register(TimelineBottomLoaderTableViewCell.self, forCellReuseIdentifier: String(describing: TimelineBottomLoaderTableViewCell.self))
        tableView.rowHeight = UITableView.automaticDimension
        tableView.separatorStyle = .none
        tableView.backgroundColor = .clear
        return tableView
    }()
    
    let publishProgressView: UIProgressView = {
        let progressView = UIProgressView(progressViewStyle: .bar)
        progressView.alpha = 0
        return progressView
    }()
    
    let refreshControl = RefreshControl()
    
    deinit {
        os_log(.info, log: .debug, "%{public}s[%{public}ld], %{public}s:", ((#file as NSString).lastPathComponent), #line, #function)
    }
    
}

extension HomeTimelineViewController {
    
    override func viewDidLoad() {
        super.viewDidLoad()

        title = L10n.Scene.HomeTimeline.title
        view.backgroundColor = ThemeService.shared.currentTheme.value.secondarySystemBackgroundColor
        ThemeService.shared.currentTheme
            .receive(on: RunLoop.main)
            .sink { [weak self] theme in
                guard let self = self else { return }
                self.view.backgroundColor = theme.secondarySystemBackgroundColor
            }
            .store(in: &disposeBag)
        viewModel.$displaySettingBarButtonItem
            .receive(on: DispatchQueue.main)
            .sink { [weak self] displaySettingBarButtonItem in
                guard let self = self else { return }
                #if DEBUG
                // display debug menu
                self.navigationItem.rightBarButtonItem = {
                    let barButtonItem = UIBarButtonItem()
                    barButtonItem.image = UIImage(systemName: "ellipsis.circle")
                    barButtonItem.menu = self.debugMenu
                    return barButtonItem
                }()
                #else
                self.navigationItem.rightBarButtonItem = displaySettingBarButtonItem ? self.settingBarButtonItem : nil
                #endif
            }
            .store(in: &disposeBag)
        #if DEBUG
        // long press to trigger debug menu
        settingBarButtonItem.menu = debugMenu
        #else
        settingBarButtonItem.target = self
        settingBarButtonItem.action = #selector(HomeTimelineViewController.settingBarButtonItemPressed(_:))
        #endif
        
        #if SNAPSHOT
        titleView.logoButton.menu = self.debugMenu
        titleView.button.menu = self.debugMenu
        #endif
        
        navigationItem.titleView = titleView
        titleView.delegate = self
        
        viewModel.homeTimelineNavigationBarTitleViewModel.state
            .removeDuplicates()
            .receive(on: DispatchQueue.main)
            .sink { [weak self] state in
                guard let self = self else { return }
                self.titleView.configure(state: state)
            }
            .store(in: &disposeBag)
        
        viewModel.homeTimelineNavigationBarTitleViewModel.state
            .removeDuplicates()
            .filter { $0 == .publishedButton }
            .receive(on: DispatchQueue.main)
            .sink { [weak self] _ in
                guard let self = self else { return }
                guard UserDefaults.shared.lastVersionPromptedForReview == nil else { return }
                guard UserDefaults.shared.processCompletedCount > 3 else { return }
                guard let windowScene = self.view.window?.windowScene else { return }
                let version = UIApplication.appVersion()
                UserDefaults.shared.lastVersionPromptedForReview = version
                SKStoreReviewController.requestReview(in: windowScene)
            }
            .store(in: &disposeBag)
        
        tableView.refreshControl = refreshControl
        refreshControl.addTarget(self, action: #selector(HomeTimelineViewController.refreshControlValueChanged(_:)), for: .valueChanged)

        tableView.translatesAutoresizingMaskIntoConstraints = false
        view.addSubview(tableView)
        tableView.pinToParent()
        
        // // layout publish progress
        publishProgressView.translatesAutoresizingMaskIntoConstraints = false
        view.addSubview(publishProgressView)
        NSLayoutConstraint.activate([
            publishProgressView.topAnchor.constraint(equalTo: view.layoutMarginsGuide.topAnchor),
            publishProgressView.leadingAnchor.constraint(equalTo: view.leadingAnchor),
            publishProgressView.trailingAnchor.constraint(equalTo: view.trailingAnchor),
        ])

        viewModel.tableView = tableView
        tableView.delegate = self
        viewModel.setupDiffableDataSource(
            tableView: tableView,
            statusTableViewCellDelegate: self,
            timelineMiddleLoaderTableViewCellDelegate: self
        )
        
        // setup batch fetch
        viewModel.listBatchFetchViewModel.setup(scrollView: tableView)
        viewModel.listBatchFetchViewModel.shouldFetch
            .receive(on: DispatchQueue.main)
            .sink { [weak self] _ in
                guard let self = self else { return }
                guard self.view.window != nil else { return }
                self.viewModel.loadOldestStateMachine.enter(HomeTimelineViewModel.LoadOldestState.Loading.self)
            }
            .store(in: &disposeBag)
        
        // bind refresh control
        viewModel.didLoadLatest
            .receive(on: DispatchQueue.main)
            .sink { [weak self] _ in
                guard let self = self else { return }
                UIView.animate(withDuration: 0.5) { [weak self] in
                    guard let self = self else { return }
                    self.refreshControl.endRefreshing()
                } completion: { _ in }
            }
            .store(in: &disposeBag)
        
        context.publisherService.$currentPublishProgress
            .receive(on: DispatchQueue.main)
            .sink { [weak self] progress in
                guard let self = self else { return }
                let progress = Float(progress)

                guard progress > 0 else {
                    let dismissAnimator = UIViewPropertyAnimator(duration: 0.1, curve: .easeInOut)
                    dismissAnimator.addAnimations {
                        self.publishProgressView.alpha = 0
                    }
                    dismissAnimator.addCompletion { _ in
                        self.publishProgressView.setProgress(0, animated: false)
                    }
                    dismissAnimator.startAnimation()
                    return
                }
                if self.publishProgressView.alpha == 0 {
                    let progressAnimator = UIViewPropertyAnimator(duration: 0.1, curve: .easeOut)
                    progressAnimator.addAnimations {
                        self.publishProgressView.alpha = 1
                    }
                    progressAnimator.startAnimation()
                }
                
                self.publishProgressView.setProgress(progress, animated: true)
            }
            .store(in: &disposeBag)
        
        viewModel.timelineIsEmpty
            .receive(on: DispatchQueue.main)
            .sink { [weak self] isEmpty in
                if isEmpty {
                    self?.showEmptyView()
                } else {
                    self?.emptyView.removeFromSuperview()
                }
            }
            .store(in: &disposeBag)
        
        NotificationCenter.default
            .publisher(for: .statusBarTapped, object: nil)
            .throttle(for: 0.5, scheduler: DispatchQueue.main, latest: false)
            .sink { [weak self] notification in
                guard let self = self else { return }
                guard let _ = self.view.window else { return } // displaying
                
                // https://developer.limneos.net/index.php?ios=13.1.3&framework=UIKitCore.framework&header=UIStatusBarTapAction.h
                guard let action = notification.object as AnyObject?,
                    let xPosition = action.value(forKey: "xPosition") as? Double
                else { return }
                
                let viewFrameInWindow = self.view.convert(self.view.frame, to: nil)
                guard xPosition >= viewFrameInWindow.minX && xPosition <= viewFrameInWindow.maxX else { return }
                        
                // works on iOS 14
                self.logger.log(level: .debug, "\((#file as NSString).lastPathComponent, privacy: .public)[\(#line, privacy: .public)], \(#function, privacy: .public): receive notification \(xPosition)")

                // check if scroll to top
                guard self.shouldRestoreScrollPosition() else { return }
                self.restorePositionWhenScrollToTop()
            }
            .store(in: &disposeBag)

    }
    
    override func viewWillAppear(_ animated: Bool) {
        super.viewWillAppear(animated)
        
        refreshControl.endRefreshing()
        tableView.deselectRow(with: transitionCoordinator, animated: animated)
        
        // needs trigger manually after onboarding dismiss
        setNeedsStatusBarAppearanceUpdate()
    }

    override func viewDidAppear(_ animated: Bool) {
        super.viewDidAppear(animated)
        
        viewModel.viewDidAppear.send()

        if let timestamp = viewModel.lastAutomaticFetchTimestamp {
            let now = Date()
            if now.timeIntervalSince(timestamp) > 60 {
                self.viewModel.lastAutomaticFetchTimestamp = now
                self.viewModel.homeTimelineNeedRefresh.send()
            } else {
                // do nothing
            }
        } else {
            self.viewModel.homeTimelineNeedRefresh.send()
        }
    }

    override func viewWillTransition(to size: CGSize, with coordinator: UIViewControllerTransitionCoordinator) {
        super.viewWillTransition(to: size, with: coordinator)

        coordinator.animate { _ in
            // do nothing
        } completion: { _ in
            // fix AutoLayout cell height not update after rotate issue
            self.viewModel.cellFrameCache.removeAllObjects()
            self.tableView.reloadData()
        }
    }
}

extension HomeTimelineViewController {
    func showEmptyView() {
        if emptyView.superview != nil {
            return
        }
        view.addSubview(emptyView)
        emptyView.translatesAutoresizingMaskIntoConstraints = false
        NSLayoutConstraint.activate([
            emptyView.topAnchor.constraint(equalTo: view.layoutMarginsGuide.topAnchor),
            emptyView.leadingAnchor.constraint(equalTo: view.leadingAnchor),
            emptyView.trailingAnchor.constraint(equalTo: view.trailingAnchor),
            emptyView.bottomAnchor.constraint(equalTo: view.layoutMarginsGuide.bottomAnchor)
        ])
        
        if emptyView.arrangedSubviews.count > 0 {
            return
        }
        let findPeopleButton: PrimaryActionButton = {
            let button = PrimaryActionButton()
            button.setTitle(L10n.Common.Controls.Actions.findPeople, for: .normal)
            button.addTarget(self, action: #selector(HomeTimelineViewController.findPeopleButtonPressed(_:)), for: .touchUpInside)
            return button
        }()
        NSLayoutConstraint.activate([
            findPeopleButton.heightAnchor.constraint(equalToConstant: 46)
        ])
        
        let manuallySearchButton: HighlightDimmableButton = {
            let button = HighlightDimmableButton()
            button.titleLabel?.font = UIFontMetrics(forTextStyle: .headline).scaledFont(for: .systemFont(ofSize: 15, weight: .semibold))
            button.setTitle(L10n.Common.Controls.Actions.manuallySearch, for: .normal)
            button.setTitleColor(Asset.Colors.brand.color, for: .normal)
            button.addTarget(self, action: #selector(HomeTimelineViewController.manuallySearchButtonPressed(_:)), for: .touchUpInside)
            return button
        }()

        let topPaddingView = UIView()
        let bottomPaddingView = UIView()

        emptyView.addArrangedSubview(topPaddingView)
        emptyView.addArrangedSubview(friendsAssetImageView)
        emptyView.addArrangedSubview(bottomPaddingView)

        topPaddingView.translatesAutoresizingMaskIntoConstraints = false
        bottomPaddingView.translatesAutoresizingMaskIntoConstraints = false
        NSLayoutConstraint.activate([
            topPaddingView.heightAnchor.constraint(equalTo: bottomPaddingView.heightAnchor, multiplier: 0.8),
        ])

        let buttonContainerStackView = UIStackView()
        emptyView.addArrangedSubview(buttonContainerStackView)
        buttonContainerStackView.isLayoutMarginsRelativeArrangement = true
        buttonContainerStackView.layoutMargins = UIEdgeInsets(top: 0, left: 32, bottom: 22, right: 32)
        buttonContainerStackView.axis = .vertical
        buttonContainerStackView.spacing = 17

        buttonContainerStackView.addArrangedSubview(findPeopleButton)
        buttonContainerStackView.addArrangedSubview(manuallySearchButton)
    }
}

extension HomeTimelineViewController {
    
    @objc private func findPeopleButtonPressed(_ sender: PrimaryActionButton) {
        let suggestionAccountViewModel = SuggestionAccountViewModel(context: context, authContext: viewModel.authContext)
        suggestionAccountViewModel.delegate = viewModel
        _ = coordinator.present(
            scene: .suggestionAccount(viewModel: suggestionAccountViewModel),
            from: self,
            transition: .modal(animated: true, completion: nil)
        )
    }
    
    @objc private func manuallySearchButtonPressed(_ sender: UIButton) {
        os_log(.info, log: .debug, "%{public}s[%{public}ld], %{public}s", ((#file as NSString).lastPathComponent), #line, #function)
        let searchDetailViewModel = SearchDetailViewModel(authContext: viewModel.authContext)
        _ = coordinator.present(scene: .searchDetail(viewModel: searchDetailViewModel), from: self, transition: .modal(animated: true, completion: nil))
    }
    
    @objc private func settingBarButtonItemPressed(_ sender: UIBarButtonItem) {
        os_log(.info, log: .debug, "%{public}s[%{public}ld], %{public}s", ((#file as NSString).lastPathComponent), #line, #function)
        guard let setting = context.settingService.currentSetting.value else { return }
        let settingsViewModel = SettingsViewModel(context: context, authContext: viewModel.authContext, setting: setting)
        _ = coordinator.present(scene: .settings(viewModel: settingsViewModel), from: self, transition: .modal(animated: true, completion: nil))
    }

    @objc private func refreshControlValueChanged(_ sender: RefreshControl) {
        guard viewModel.loadLatestStateMachine.enter(HomeTimelineViewModel.LoadLatestState.Loading.self) else {
            sender.endRefreshing()
            return
        }
    }
    
    @objc func signOutAction(_ sender: UIAction) {
        Task { @MainActor in
            try await context.authenticationService.signOutMastodonUser(authenticationBox: viewModel.authContext.mastodonAuthenticationBox)
            self.coordinator.setup()
        }
    }

}
// MARK: - UIScrollViewDelegate
extension HomeTimelineViewController {
    func scrollViewDidScroll(_ scrollView: UIScrollView) {
        switch scrollView {
        case tableView:
            viewModel.homeTimelineNavigationBarTitleViewModel.handleScrollViewDidScroll(scrollView)
        default:
            break
        }
    }
    
    func scrollViewShouldScrollToTop(_ scrollView: UIScrollView) -> Bool {
        switch scrollView {
        case tableView:
            
            let indexPath = IndexPath(row: 0, section: 0)
            guard viewModel.diffableDataSource?.itemIdentifier(for: indexPath) != nil else {
                return true
            }
            // save position
            savePositionBeforeScrollToTop()
            // override by custom scrollToRow
            tableView.scrollToRow(at: indexPath, at: .top, animated: true)
            return false
        default:
            assertionFailure()
            return true
        }
    }
    
    private func savePositionBeforeScrollToTop() {
        // check save action interval
        // should not fast than 0.5s to prevent save when scrollToTop on-flying
        if let record = viewModel.scrollPositionRecord {
            let now = Date()
            guard now.timeIntervalSince(record.timestamp) > 0.5 else {
                // skip this save action
                return
            }
        }
        
        guard let diffableDataSource = viewModel.diffableDataSource else { return }
        guard let anchorIndexPaths = tableView.indexPathsForVisibleRows?.sorted() else { return }
        guard !anchorIndexPaths.isEmpty else { return }
        let anchorIndexPath = anchorIndexPaths[anchorIndexPaths.count / 2]
        guard let anchorItem = diffableDataSource.itemIdentifier(for: anchorIndexPath) else { return }
        
        let offset: CGFloat = {
            guard let anchorCell = tableView.cellForRow(at: anchorIndexPath) else { return 0 }
            let cellFrameInView = tableView.convert(anchorCell.frame, to: view)
            return cellFrameInView.origin.y
        }()
        logger.log(level: .debug, "\((#file as NSString).lastPathComponent, privacy: .public)[\(#line, privacy: .public)], \(#function, privacy: .public): save position record for \(anchorIndexPath) with offset: \(offset)")
        viewModel.scrollPositionRecord = HomeTimelineViewModel.ScrollPositionRecord(
            item: anchorItem,
            offset: offset,
            timestamp: Date()
        )
    }
    
    private func shouldRestoreScrollPosition() -> Bool {
        // check if scroll to top
        guard self.tableView.safeAreaInsets.top > 0 else { return false }
        let zeroOffset = -self.tableView.safeAreaInsets.top
        return abs(self.tableView.contentOffset.y - zeroOffset) < 2.0
    }
    
    private func restorePositionWhenScrollToTop() {
        guard let diffableDataSource = self.viewModel.diffableDataSource else { return }
        guard let record = self.viewModel.scrollPositionRecord,
              let indexPath = diffableDataSource.indexPath(for: record.item)
        else { return }
        
        tableView.scrollToRow(at: indexPath, at: .middle, animated: true)
        viewModel.scrollPositionRecord = nil
    }
}

// MARK: - AuthContextProvider
extension HomeTimelineViewController: AuthContextProvider {
    var authContext: AuthContext { viewModel.authContext }
}

// MARK: - UITableViewDelegate
extension HomeTimelineViewController: UITableViewDelegate, AutoGenerateTableViewDelegate {
    // sourcery:inline:HomeTimelineViewController.AutoGenerateTableViewDelegate

    // Generated using Sourcery
    // DO NOT EDIT
    func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
        aspectTableView(tableView, didSelectRowAt: indexPath)
    }

    func tableView(_ tableView: UITableView, contextMenuConfigurationForRowAt indexPath: IndexPath, point: CGPoint) -> UIContextMenuConfiguration? {
        return aspectTableView(tableView, contextMenuConfigurationForRowAt: indexPath, point: point)
    }

    func tableView(_ tableView: UITableView, previewForHighlightingContextMenuWithConfiguration configuration: UIContextMenuConfiguration) -> UITargetedPreview? {
        return aspectTableView(tableView, previewForHighlightingContextMenuWithConfiguration: configuration)
    }

    func tableView(_ tableView: UITableView, previewForDismissingContextMenuWithConfiguration configuration: UIContextMenuConfiguration) -> UITargetedPreview? {
        return aspectTableView(tableView, previewForDismissingContextMenuWithConfiguration: configuration)
    }

    func tableView(_ tableView: UITableView, willPerformPreviewActionForMenuWith configuration: UIContextMenuConfiguration, animator: UIContextMenuInteractionCommitAnimating) {
        aspectTableView(tableView, willPerformPreviewActionForMenuWith: configuration, animator: animator)
    }

    // sourcery:end
}

// MARK: - TimelineMiddleLoaderTableViewCellDelegate
extension HomeTimelineViewController: TimelineMiddleLoaderTableViewCellDelegate {
    func timelineMiddleLoaderTableViewCell(_ cell: TimelineMiddleLoaderTableViewCell, loadMoreButtonDidPressed button: UIButton) {
        guard let diffableDataSource = viewModel.diffableDataSource else { return }
        guard let indexPath = tableView.indexPath(for: cell) else { return }
        guard let item = diffableDataSource.itemIdentifier(for: indexPath) else { return }

        Task {
            await viewModel.loadMore(item: item)
        }
    }
}

// MARK: - ScrollViewContainer
extension HomeTimelineViewController: ScrollViewContainer {
    
    var scrollView: UIScrollView { return tableView }
    
    func scrollToTop(animated: Bool) {
        if scrollView.contentOffset.y < scrollView.frame.height,
           viewModel.loadLatestStateMachine.canEnterState(HomeTimelineViewModel.LoadLatestState.Loading.self),
           (scrollView.contentOffset.y + scrollView.adjustedContentInset.top) == 0.0,
           !refreshControl.isRefreshing {
            scrollView.scrollRectToVisible(CGRect(origin: CGPoint(x: 0, y: -refreshControl.frame.height), size: CGSize(width: 1, height: 1)), animated: animated)
            DispatchQueue.main.async { [weak self] in
                guard let self = self else { return }
                self.refreshControl.beginRefreshing()
                self.refreshControl.sendActions(for: .valueChanged)
            }
        } else {
            let indexPath = IndexPath(row: 0, section: 0)
            guard viewModel.diffableDataSource?.itemIdentifier(for: indexPath) != nil else { return }
            // save position
            savePositionBeforeScrollToTop()
            tableView.scrollToRow(at: indexPath, at: .top, animated: true)
        }
    }
    
}

// MARK: - StatusTableViewCellDelegate
extension HomeTimelineViewController: StatusTableViewCellDelegate { }

// MARK: - HomeTimelineNavigationBarTitleViewDelegate
extension HomeTimelineViewController: HomeTimelineNavigationBarTitleViewDelegate {
    func homeTimelineNavigationBarTitleView(_ titleView: HomeTimelineNavigationBarTitleView, logoButtonDidPressed sender: UIButton) {
        if shouldRestoreScrollPosition() {
            restorePositionWhenScrollToTop()
        } else {
            savePositionBeforeScrollToTop()
            scrollToTop(animated: true)
        }
    }
    
    func homeTimelineNavigationBarTitleView(_ titleView: HomeTimelineNavigationBarTitleView, buttonDidPressed sender: UIButton) {
        switch titleView.state {
        case .newPostButton:
            guard let diffableDataSource = viewModel.diffableDataSource else { return }
            let indexPath = IndexPath(row: 0, section: 0)
            guard diffableDataSource.itemIdentifier(for: indexPath) != nil else { return }
        
            savePositionBeforeScrollToTop()
            tableView.scrollToRow(at: indexPath, at: .top, animated: true)
        case .offlineButton:
            // TODO: retry
            break
        case .publishedButton:
            break
        default:
            break
        }
    }
}

extension HomeTimelineViewController {
    override var keyCommands: [UIKeyCommand]? {
        return navigationKeyCommands + statusNavigationKeyCommands
    }
}

// MARK: - StatusTableViewControllerNavigateable
extension HomeTimelineViewController: StatusTableViewControllerNavigateable {
    @objc func navigateKeyCommandHandlerRelay(_ sender: UIKeyCommand) {
        navigateKeyCommandHandler(sender)
    }

    @objc func statusKeyCommandHandlerRelay(_ sender: UIKeyCommand) {
        statusKeyCommandHandler(sender)
    }
}