Try to resolve statuses from links that match known patterns

Tusker/Screens/Conversation/ConversationCollectionViewController.swift

@@ -94,6 +94,9 @@ class ConversationCollectionViewController: UIViewController, CollectionViewCont
         let expandThreadCell = UICollectionView.CellRegistration<ExpandThreadCollectionViewCell, ([ConversationNode], Bool)> { cell, indexPath, item in
             cell.updateUI(childThreads: item.0, inline: item.1)
         }
+        let loadingCell = UICollectionView.CellRegistration<LoadingCollectionViewCell, Void> { cell, indexPath, itemIdentifier in
+            cell.indicator.startAnimating()
+        }
         return UICollectionViewDiffableDataSource(collectionView: collectionView) { [unowned self] collectionView, indexPath, itemIdentifier in
             switch itemIdentifier {
             case let .status(id: id, state: state, prevLink: prevLink, nextLink: nextLink):
@@ -104,17 +107,31 @@ class ConversationCollectionViewController: UIViewController, CollectionViewCont
                 }
             case .expandThread(childThreads: let childThreads, inline: let inline):
                 return collectionView.dequeueConfiguredReusableCell(using: expandThreadCell, for: indexPath, item: (childThreads, inline))
+            case .loadingIndicator:
+                return collectionView.dequeueConfiguredReusableCell(using: loadingCell, for: indexPath, item: ())
             }
         }
     }
     
+    override func viewWillAppear(_ animated: Bool) {
+        super.viewWillAppear(animated)
+        
+        clearSelectionOnAppear(animated: animated)
+    }
+    
     func addMainStatus(_ status: StatusMO) {
         loadViewIfNeeded()
         
         var snapshot = NSDiffableDataSourceSnapshot<Section, Item>()
         snapshot.appendSections([.statuses])
+        
+        if status.inReplyToID != nil {
+            snapshot.appendItems([.loadingIndicator], toSection: .statuses)
+        }
+        
         let mainStatusItem = Item.status(id: mainStatusID, state: mainStatusState, prevLink: status.inReplyToID != nil, nextLink: false)
         snapshot.appendItems([mainStatusItem], toSection: .statuses)
+        
         dataSource.apply(snapshot, animatingDifferences: false)
     }
     
@@ -125,6 +142,7 @@ class ConversationCollectionViewController: UIViewController, CollectionViewCont
         await mastodonController.persistentContainer.addAll(statuses: parentStatuses + context.descendants)
         
         var snapshot = dataSource.snapshot()
+        snapshot.deleteItems([.loadingIndicator])
         let mainStatusItem = Item.status(id: mainStatusID, state: mainStatusState, prevLink: mainStatus.inReplyToID != nil, nextLink: false)
         let parentItems = parentIDs.enumerated().map { index, id in
             Item.status(id: id, state: .unknown, prevLink: index > 0, nextLink: true)
@@ -299,6 +317,7 @@ extension ConversationCollectionViewController {
     enum Item: Hashable {
         case status(id: String, state: CollapseState, prevLink: Bool, nextLink: Bool)
         case expandThread(childThreads: [ConversationNode], inline: Bool)
+        case loadingIndicator
         
         static func ==(lhs: Item, rhs: Item) -> Bool {
             switch (lhs, rhs) {
@@ -306,6 +325,8 @@ extension ConversationCollectionViewController {
                 return a == b && aPrev == bPrev && aNext == bNext
             case let (.expandThread(childThreads: a, inline: aInline), .expandThread(childThreads: b, inline: bInline)):
                 return a.count == b.count && zip(a, b).allSatisfy { $0.status.id == $1.status.id } && aInline == bInline
+            case (.loadingIndicator, .loadingIndicator):
+                return true
             default:
                 return false
             }
@@ -324,6 +345,8 @@ extension ConversationCollectionViewController {
                     hasher.combine(thread.status.id)
                 }
                 hasher.combine(inline)
+            case .loadingIndicator:
+                hasher.combine(2)
             }
         }
     }
@@ -331,11 +354,13 @@ extension ConversationCollectionViewController {
 
 extension ConversationCollectionViewController: UICollectionViewDelegate {
     func collectionView(_ collectionView: UICollectionView, shouldSelectItemAt indexPath: IndexPath) -> Bool {
-        if case .status(id: let id, _, _, _) = dataSource.itemIdentifier(for: indexPath),
-           id == mainStatusID {
-            return false
-        } else {
+        switch dataSource.itemIdentifier(for: indexPath) {
+        case .status(id: let id, state: _, prevLink: _, nextLink: _):
+            return id != mainStatusID
+        case .expandThread(childThreads: _, inline: _):
             return true
+        default:
+            return false
         }
     }
     
@@ -343,6 +368,8 @@ extension ConversationCollectionViewController: UICollectionViewDelegate {
         switch dataSource.itemIdentifier(for: indexPath) {
         case nil:
             break
+        case .loadingIndicator:
+            break
         case .status(id: let id, state: let state, _, _):
             selected(status: id, state: state.copy())
         case .expandThread(childThreads: let childThreads, inline: _):

Tusker/Screens/Conversation/ConversationViewController.swift

@@ -8,20 +8,16 @@
 
 import UIKit
 import Pachyderm
+import WebURL
+import WebURLFoundationExtras
 
 class ConversationViewController: UIViewController {
     
     weak var mastodonController: MastodonController!
     
-    let mainStatusID: String
+    private(set) var mode: Mode
     let mainStatusState: CollapseState
-    var statusIDToScrollToOnLoad: String {
-        didSet {
-            if case .displaying(let vc) = state {
-                vc.statusIDToScrollToOnLoad = statusIDToScrollToOnLoad
-            }
-        }
-    }
+    var statusIDToScrollToOnLoad: String?
     var showStatusesAutomatically = false {
         didSet {
             if case .displaying(let vc) = state {
@@ -57,6 +53,8 @@ class ConversationViewController: UIViewController {
                 embedChild(vc)
             case .notFound:
                 showMainStatusNotFound()
+            case .unableToResolve(let error):
+                showUnableToResolve(error)
             }
             
             updateVisibilityBarButtonItem()
@@ -64,9 +62,16 @@ class ConversationViewController: UIViewController {
     }
     
     init(for mainStatusID: String, state mainStatusState: CollapseState, mastodonController: MastodonController) {
-        self.mainStatusID = mainStatusID
+        self.mode = .localID(mainStatusID)
         self.mainStatusState = mainStatusState
-        self.statusIDToScrollToOnLoad = mainStatusID
+        self.mastodonController = mastodonController
+        
+        super.init(nibName: nil, bundle: nil)
+    }
+    
+    init(resolving url: URL, mastodonController: MastodonController) {
+        self.mode = .resolve(url)
+        self.mainStatusState = .unknown
         self.mastodonController = mastodonController
         
         super.init(nibName: nil, bundle: nil)
@@ -121,7 +126,8 @@ class ConversationViewController: UIViewController {
         guard let userInfo = notification.userInfo,
               let accountID = mastodonController.accountInfo?.id,
               userInfo["accountID"] as? String == accountID,
-              let statusIDs = userInfo["statusIDs"] as? [String] else {
+              let statusIDs = userInfo["statusIDs"] as? [String],
+              case .localID(let mainStatusID) = mode else {
             return
         }
         if statusIDs.contains(mainStatusID) {
@@ -137,6 +143,10 @@ class ConversationViewController: UIViewController {
     // MARK: Loading
     
     private func loadMainStatus() async {
+        guard let mainStatusID = await resolveStatusIfNecessary() else {
+            return
+        }
+        
         @MainActor
         func doLoadMainStatus() async -> StatusMO? {
             switch await FetchStatusService(statusID: mainStatusID, mastodonController: mastodonController).run() {
@@ -169,10 +179,37 @@ class ConversationViewController: UIViewController {
         }
     }
     
+    @MainActor
+    private func resolveStatusIfNecessary() async -> String? {
+        switch mode {
+        case .localID(let id):
+            return id
+        case .resolve(let url):
+            let indicator = UIActivityIndicatorView(style: .medium)
+            indicator.startAnimating()
+            state = .loading(indicator)
+            
+            let url = WebURL(url)!
+            let request = Client.search(query: url.serialized(), types: [.statuses], resolve: true)
+            do {
+                let (results, _) = try await mastodonController.run(request)
+                guard let status = results.statuses.first(where: { $0.url == url }) else {
+                    throw UnableToResolveError()
+                }
+                _ = mastodonController.persistentContainer.addOrUpdateOnViewContext(status: status)
+                mode = .localID(status.id)
+                return status.id
+            } catch {
+                state = .unableToResolve(error)
+                return nil
+            }
+        }
+    }
+    
     @MainActor
     private func mainStatusLoaded(_ mainStatus: StatusMO) async {
-        let vc = ConversationCollectionViewController(for: mainStatusID, state: mainStatusState, mastodonController: mastodonController)
-        vc.statusIDToScrollToOnLoad = statusIDToScrollToOnLoad
+        let vc = ConversationCollectionViewController(for: mainStatus.id, state: mainStatusState, mastodonController: mastodonController)
+        vc.statusIDToScrollToOnLoad = statusIDToScrollToOnLoad ?? mainStatus.id
         vc.showStatusesAutomatically = showStatusesAutomatically
         vc.addMainStatus(mainStatus)
         state = .displaying(vc)
@@ -227,6 +264,66 @@ class ConversationViewController: UIViewController {
         self.showToast(configuration: config, animated: true)
     }
     
+    private func showUnableToResolve(_ error: Error) {
+        let image = UIImageView(image: UIImage(systemName: "exclamationmark.triangle.fill")!)
+        image.tintColor = .secondaryLabel
+        image.contentMode = .scaleAspectFit
+        
+        let title = UILabel()
+        title.textColor = .secondaryLabel
+        title.font = .preferredFont(forTextStyle: .title1).withTraits(.traitBold)!
+        title.adjustsFontForContentSizeCategory = true
+        title.text = "Couldn't Load Post"
+        
+        let subtitle = UILabel()
+        subtitle.textColor = .secondaryLabel
+        subtitle.font = .preferredFont(forTextStyle: .body)
+        subtitle.adjustsFontForContentSizeCategory = true
+        subtitle.numberOfLines = 0
+        subtitle.textAlignment = .center
+        if let error = error as? UnableToResolveError {
+            subtitle.text = error.localizedDescription
+        } else if let error = error as? Client.Error {
+            subtitle.text = error.localizedDescription
+        } else {
+            subtitle.text = error.localizedDescription
+        }
+        
+        var config = UIButton.Configuration.plain()
+        config.title = "Open in Safari"
+        config.image = UIImage(systemName: "safari")
+        config.imagePadding = 4
+        let button = UIButton(configuration: config, primaryAction: UIAction(handler: { [unowned self] _ in
+            guard case .resolve(let url) = self.mode else {
+                return
+            }
+            self.selected(url: url, allowResolveStatuses: false)
+        }))
+        
+        let stack = UIStackView(arrangedSubviews: [
+            image,
+            title,
+            subtitle,
+            button,
+        ])
+        stack.axis = .vertical
+        stack.alignment = .center
+        stack.spacing = 8
+        stack.isAccessibilityElement = true
+        stack.accessibilityLabel = "\(title.text!). \(subtitle.text!)"
+        
+        stack.translatesAutoresizingMaskIntoConstraints = false
+        view.addSubview(stack)
+        NSLayoutConstraint.activate([
+            image.widthAnchor.constraint(equalToConstant: 64),
+            image.heightAnchor.constraint(equalToConstant: 64),
+            
+            stack.leadingAnchor.constraint(equalToSystemSpacingAfter: view.safeAreaLayoutGuide.leadingAnchor, multiplier: 1),
+            view.safeAreaLayoutGuide.trailingAnchor.constraint(equalToSystemSpacingAfter: stack.trailingAnchor, multiplier: 1),
+            stack.centerYAnchor.constraint(equalTo: view.safeAreaLayoutGuide.centerYAnchor),
+        ])
+    }
+    
     // MARK: Interaction
     
     @objc func toggleCollapseButtonPressed() {
@@ -240,15 +337,35 @@ class ConversationViewController: UIViewController {
 
 }
 
+extension ConversationViewController {
+    enum Mode {
+        case localID(String)
+        case resolve(URL)
+    }
+}
+
+extension ConversationViewController {
+    struct UnableToResolveError: Error {
+        var localizedDescription: String {
+            "Unable to resolve status from URL"
+        }
+    }
+}
+
 extension ConversationViewController {
     enum State {
         case unloaded
         case loading(UIActivityIndicatorView)
         case displaying(ConversationCollectionViewController)
         case notFound
+        case unableToResolve(Error)
     }
 }
 
+extension ConversationViewController: TuskerNavigationDelegate {
+    var apiController: MastodonController! { mastodonController }
+}
+
 extension ConversationViewController: ToastableViewController {
     var toastScrollView: UIScrollView? {
         if case .displaying(let vc) = state {

Tusker/Screens/Conversation/ExpandThreadCollectionViewCell.swift

@@ -8,7 +8,7 @@
 
 import UIKit
 
-class ExpandThreadCollectionViewCell: UICollectionViewCell {
+class ExpandThreadCollectionViewCell: UICollectionViewListCell {
     
     private var avatarContainerView: UIView!
     private var avatarContainerWidthConstraint: NSLayoutConstraint!
@@ -46,8 +46,6 @@ class ExpandThreadCollectionViewCell: UICollectionViewCell {
         contentView.addSubview(hStack)
         stackViewLeadingConstraint = hStack.leadingAnchor.constraint(equalTo: contentView.leadingAnchor, constant: 16)
         
-        // TODO: separator
-        
         threadLinkView = UIView()
         threadLinkView.backgroundColor = .tintColor.withAlphaComponent(0.5)
         threadLinkView.layer.cornerRadius = 2.5
@@ -142,4 +140,19 @@ class ExpandThreadCollectionViewCell: UICollectionViewCell {
         }
     }
     
+    override func updateConfiguration(using state: UICellConfigurationState) {
+        var config = UIBackgroundConfiguration.listPlainCell()
+        if state.isSelected || state.isHighlighted {
+            var hue: CGFloat = 0
+            var saturation: CGFloat = 0
+            var brightness: CGFloat = 0
+            UIColor.secondarySystemBackground.getHue(&hue, saturation: &saturation, brightness: &brightness, alpha: nil)
+            let sign: CGFloat = traitCollection.userInterfaceStyle == .dark ? 1 : -1
+            config.backgroundColor = UIColor(hue: hue, saturation: saturation, brightness: max(0, brightness + sign * 0.1), alpha: 1)
+        } else {
+            config.backgroundColor = .secondarySystemBackground
+        }
+        backgroundConfiguration = config.updated(for: state)
+    }
+    
 }

Tusker/TuskerNavigationDelegate.swift

@@ -44,7 +44,7 @@ extension TuskerNavigationDelegate {
         show(HashtagTimelineViewController(for: tag, mastodonController: apiController), sender: self)
     }
     
-    func selected(url: URL, allowUniversalLinks: Bool = true) {
+    func selected(url: URL, allowResolveStatuses: Bool = true, allowUniversalLinks: Bool = true) {
         func openSafari() {
             if Preferences.shared.useInAppSafari,
                url.scheme == "https" || url.scheme == "http" {
@@ -66,8 +66,12 @@ extension TuskerNavigationDelegate {
             }
         }
         
-        if allowUniversalLinks && Preferences.shared.openLinksInApps,
-           url.scheme == "https" || url.scheme == "http" {
+        if allowResolveStatuses,
+           isLikelyResolvableAsStatus(url) {
+            show(ConversationViewController(resolving: url, mastodonController: apiController))
+        } else if allowUniversalLinks,
+                  Preferences.shared.openLinksInApps,
+                  url.scheme == "https" || url.scheme == "http" {
             UIApplication.shared.open(url, options: [.universalLinksOnly: true]) { (success) in
                 if (!success) {
                     openSafari()
@@ -217,3 +221,21 @@ enum PopoverSource {
         .barButtonItem(WeakHolder(item))
     }
 }
+
+private let statusPathRegex = try! NSRegularExpression(
+    pattern:
+           "(^/@[a-z0-9_]+/\\d{18})"       // mastodon
+        + "|(^/notice/[a-z0-9]{18})"       // pleroma
+        + "|(^/p/[a-z0-9_]+/\\d{18})"      // pixelfed
+        + "|(^/i/web/post/\\d{18})"        // pixelfed web frontend
+        + "|(^/u/.+/h/[a-z0-9]{18})"       // honk
+        + "|(^/@.+/statuses/[a-z0-9]{26})" // gotosocial
+    ,
+    options: .caseInsensitive
+)
+
+private func isLikelyResolvableAsStatus(_ url: URL) -> Bool {
+    let path = url.path
+    let range = NSRange(location: 0, length: path.utf16.count)
+    return statusPathRegex.numberOfMatches(in: path, range: range) == 1
+}