Indicate when a followed hashtag caused a post to appear in the home timeline

Tusker/Screens/Timeline/TimelineViewController.swift

@@ -101,6 +101,11 @@ class TimelineViewController: UIViewController, TimelineLikeCollectionViewContro
     // separate method because InstanceTimelineViewController needs to be able to customize it
     func configureStatusCell(_ cell: TimelineStatusCollectionViewCell, id: String, state: StatusState) {
         cell.delegate = self
+        if case .home = timeline {
+            cell.showFollowedHashtags = true
+        } else {
+            cell.showFollowedHashtags = false
+        }
         cell.updateUI(statusID: id, state: state)
     }
     

Tusker/Views/Status/TimelineStatusCollectionViewCell.swift

@@ -10,23 +10,26 @@ import UIKit
 import Pachyderm
 import Combine
 
+private let reblogIcon = UIImage(systemName: "repeat")
+private let hashtagIcon = UIImage(systemName: "number")
+
 class TimelineStatusCollectionViewCell: UICollectionViewListCell, StatusCollectionViewCell {
     
     static let separatorInsets = NSDirectionalEdgeInsets(top: 0, leading: 16, bottom: 0, trailing: 0)
     
     // MARK: Subviews
     
-    private lazy var rebloggerLabel = EmojiLabel().configure {
+    private lazy var timelineReasonLabel = EmojiLabel().configure {
         $0.textColor = .secondaryLabel
         $0.font = .preferredFont(forTextStyle: .body)
         $0.adjustsFontForContentSizeCategory = true
     }
-    private let reblogIcon = UIImageView(image: UIImage(systemName: "repeat")).configure {
+    private let timelineReasonIcon = UIImageView(image: reblogIcon).configure {
         $0.tintColor = .secondaryLabel
     }
-    private lazy var reblogHStack = UIStackView(arrangedSubviews: [
+    private lazy var timelineReasonHStack = UIStackView(arrangedSubviews: [
-        reblogIcon,
+        timelineReasonIcon,
-        rebloggerLabel,
+        timelineReasonLabel,
     ]).configure {
         $0.axis = .horizontal
         $0.spacing = 8
@@ -258,6 +261,7 @@ class TimelineStatusCollectionViewCell: UICollectionViewListCell, StatusCollecti
         true
     }
     var showPinned: Bool = false
+    var showFollowedHashtags: Bool = false
     
     // alas these need to be internal so they're accessible from the protocol extensions
     var statusID: String!
@@ -275,12 +279,12 @@ class TimelineStatusCollectionViewCell: UICollectionViewListCell, StatusCollecti
     override init(frame: CGRect) {
         super.init(frame: frame)
         
-        for subview in [reblogHStack, mainContainer, actionsContainer] {
+        for subview in [timelineReasonHStack, mainContainer, actionsContainer] {
             subview.translatesAutoresizingMaskIntoConstraints = false
             contentView.addSubview(subview)
         }
         
-        mainContainerTopToReblogLabelConstraint = mainContainer.topAnchor.constraint(equalTo: reblogHStack.bottomAnchor, constant: 4)
+        mainContainerTopToReblogLabelConstraint = mainContainer.topAnchor.constraint(equalTo: timelineReasonHStack.bottomAnchor, constant: 4)
         mainContainerTopToSelfConstraint = mainContainer.topAnchor.constraint(equalTo: contentView.topAnchor, constant: 8)
         mainContainerBottomToActionsConstraint = mainContainer.bottomAnchor.constraint(equalTo: actionsContainer.topAnchor, constant: -4)
         mainContainerBottomToSelfConstraint = mainContainer.bottomAnchor.constraint(equalTo: contentView.bottomAnchor, constant: -6)
@@ -291,9 +295,9 @@ class TimelineStatusCollectionViewCell: UICollectionViewListCell, StatusCollecti
         
         NSLayoutConstraint.activate([
             // why is this 4 but the mainContainerTopSelfConstraint constant 8? because this looks more balanced
-            reblogHStack.topAnchor.constraint(equalTo: contentView.topAnchor, constant: 4),
+            timelineReasonHStack.topAnchor.constraint(equalTo: contentView.topAnchor, constant: 4),
-            rebloggerLabel.leadingAnchor.constraint(equalTo: contentVStack.leadingAnchor),
+            timelineReasonLabel.leadingAnchor.constraint(equalTo: contentVStack.leadingAnchor),
-            reblogHStack.trailingAnchor.constraint(lessThanOrEqualTo: contentView.trailingAnchor, constant: -16),
+            timelineReasonHStack.trailingAnchor.constraint(lessThanOrEqualTo: contentView.trailingAnchor, constant: -16),
             
             mainContainer.leadingAnchor.constraint(equalTo: contentView.leadingAnchor, constant: 16),
             mainContainer.trailingAnchor.constraint(equalTo: contentView.trailingAnchor, constant: -16),
@@ -427,23 +431,35 @@ class TimelineStatusCollectionViewCell: UICollectionViewListCell, StatusCollecti
         
         self.statusState = state
         
+        var hideTimelineReason = true
+        
         if let rebloggedStatus = status.reblog {
             reblogStatusID = statusID
             rebloggerID = status.account.id
-            reblogHStack.isHidden = false
-            mainContainerTopToReblogLabelConstraint.isActive = true
-            mainContainerTopToSelfConstraint.isActive = false
-            updateRebloggerLabel(reblogger: status.account)
             
+            hideTimelineReason = false
+            timelineReasonIcon.image = reblogIcon
+            updateRebloggerLabel(reblogger: status.account)
             status = rebloggedStatus
         } else {
             reblogStatusID = nil
             rebloggerID = nil
-            reblogHStack.isHidden = true
-            mainContainerTopToReblogLabelConstraint.isActive = false
-            mainContainerTopToSelfConstraint.isActive = true
         }
         
+        if showFollowedHashtags {
+            let hashtags = mastodonController.followedHashtags.filter({ followed in status.hashtags.contains(where: { followed.name == $0.name }) })
+            if !hashtags.isEmpty {
+                hideTimelineReason = false
+                timelineReasonIcon.image = hashtagIcon
+                timelineReasonLabel.text = hashtags.map(\.name).formatted(.list(type: .and, width: .narrow))
+                timelineReasonLabel.removeEmojis()
+            }
+        }
+        
+        timelineReasonHStack.isHidden = hideTimelineReason
+        mainContainerTopToReblogLabelConstraint.isActive = !hideTimelineReason
+        mainContainerTopToSelfConstraint.isActive = hideTimelineReason
+        
         doUpdateUI(status: status)
         
         doUpdateTimestamp(status: status)
@@ -523,11 +539,11 @@ class TimelineStatusCollectionViewCell: UICollectionViewListCell, StatusCollecti
     
     private func updateRebloggerLabel(reblogger: AccountMO) {
         if Preferences.shared.hideCustomEmojiInUsernames {
-            rebloggerLabel.text = "\(reblogger.displayNameWithoutCustomEmoji) reblogged"
+            timelineReasonLabel.text = "\(reblogger.displayNameWithoutCustomEmoji) reblogged"
-            rebloggerLabel.removeEmojis()
+            timelineReasonLabel.removeEmojis()
         } else {
-            rebloggerLabel.text = "\(reblogger.displayOrUserName) reblogged"
+            timelineReasonLabel.text = "\(reblogger.displayOrUserName) reblogged"
-            rebloggerLabel.setEmojis(reblogger.emojis, identifier: reblogger.id)
+            timelineReasonLabel.setEmojis(reblogger.emojis, identifier: reblogger.id)
         }
     }
     
@@ -566,10 +582,13 @@ class TimelineStatusCollectionViewCell: UICollectionViewListCell, StatusCollecti
     // MARK: Interaction
     
     @objc private func reblogLabelPressed() {
-        guard let rebloggerID else {
+        if let rebloggerID {
-            return
-        }
             delegate?.selected(account: rebloggerID)
+        } else if showFollowedHashtags,
+                  let status = mastodonController.persistentContainer.status(for: statusID),
+                  let hashtag = mastodonController.followedHashtags.first(where: { followed in status.hashtags.contains(where: { followed.name == $0.name }) }) {
+            delegate?.selected(tag: Hashtag(name: hashtag.name, url: hashtag.url))
+        }
     }
     
     @objc private func accountPressed() {