Extract a bunch of timeline view controller stuff to separate protocol

Tusker.xcodeproj/project.pbxproj

@@ -35,6 +35,7 @@
 		D611C2D0232DC61100C86A49 /* HashtagTableViewCell.xib in Resources */ = {isa = PBXBuildFile; fileRef = D611C2CE232DC61100C86A49 /* HashtagTableViewCell.xib */; };
 		D61A45E628DC0F2F002BE511 /* ConfirmLoadMoreCollectionViewCell.swift in Sources */ = {isa = PBXBuildFile; fileRef = D61A45E528DC0F2F002BE511 /* ConfirmLoadMoreCollectionViewCell.swift */; };
 		D61A45E828DF477D002BE511 /* LoadingCollectionViewCell.swift in Sources */ = {isa = PBXBuildFile; fileRef = D61A45E728DF477D002BE511 /* LoadingCollectionViewCell.swift */; };
+		D61A45EA28DF51EE002BE511 /* TimelineLikeCollectionViewController.swift in Sources */ = {isa = PBXBuildFile; fileRef = D61A45E928DF51EE002BE511 /* TimelineLikeCollectionViewController.swift */; };
 		D61AC1D5232E9FA600C54D2D /* InstanceSelectorTableViewController.swift in Sources */ = {isa = PBXBuildFile; fileRef = D61AC1D4232E9FA600C54D2D /* InstanceSelectorTableViewController.swift */; };
 		D61AC1D8232EA42D00C54D2D /* InstanceTableViewCell.swift in Sources */ = {isa = PBXBuildFile; fileRef = D61AC1D6232EA42D00C54D2D /* InstanceTableViewCell.swift */; };
 		D61AC1D9232EA42D00C54D2D /* InstanceTableViewCell.xib in Resources */ = {isa = PBXBuildFile; fileRef = D61AC1D7232EA42D00C54D2D /* InstanceTableViewCell.xib */; };
@@ -380,6 +381,7 @@
 		D611C2CE232DC61100C86A49 /* HashtagTableViewCell.xib */ = {isa = PBXFileReference; lastKnownFileType = file.xib; path = HashtagTableViewCell.xib; sourceTree = "<group>"; };
 		D61A45E528DC0F2F002BE511 /* ConfirmLoadMoreCollectionViewCell.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = ConfirmLoadMoreCollectionViewCell.swift; sourceTree = "<group>"; };
 		D61A45E728DF477D002BE511 /* LoadingCollectionViewCell.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = LoadingCollectionViewCell.swift; sourceTree = "<group>"; };
+		D61A45E928DF51EE002BE511 /* TimelineLikeCollectionViewController.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = TimelineLikeCollectionViewController.swift; sourceTree = "<group>"; };
 		D61AC1D4232E9FA600C54D2D /* InstanceSelectorTableViewController.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = InstanceSelectorTableViewController.swift; sourceTree = "<group>"; };
 		D61AC1D6232EA42D00C54D2D /* InstanceTableViewCell.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = InstanceTableViewCell.swift; sourceTree = "<group>"; };
 		D61AC1D7232EA42D00C54D2D /* InstanceTableViewCell.xib */ = {isa = PBXFileReference; lastKnownFileType = file.xib; path = InstanceTableViewCell.xib; sourceTree = "<group>"; };
@@ -1298,6 +1300,7 @@
 				D6412B0224AFF6A600F5412E /* TabBarScrollableViewController.swift */,
 				D6B22A0E2560D52D004D82EF /* TabbedPageViewController.swift */,
 				D6538944214D6D7500E3CEFC /* TableViewSwipeActionProvider.swift */,
+				D61A45E928DF51EE002BE511 /* TimelineLikeCollectionViewController.swift */,
 				D6DFC69D242C490400ACC392 /* TrackpadScrollGestureRecognizer.swift */,
 				D6B8DB332182A59300424AF7 /* UIAlertController+Visibility.swift */,
 				D6C693FD2162FEEA007D6A6D /* UIViewController+Children.swift */,
@@ -1900,6 +1903,7 @@
 				D66C900B28DAB7FD00217BF2 /* TimelineViewController.swift in Sources */,
 				D6AEBB432321685E00E5038B /* OpenInSafariActivity.swift in Sources */,
 				D6C693FE2162FEEA007D6A6D /* UIViewController+Children.swift in Sources */,
+				D61A45EA28DF51EE002BE511 /* TimelineLikeCollectionViewController.swift in Sources */,
 				D64D0AB12128D9AE005A6F37 /* OnboardingViewController.swift in Sources */,
 				D67C1795266D57D10070F250 /* FastAccountSwitcherIndicatorView.swift in Sources */,
 				D627FF76217E923E00CC0648 /* DraftsManager.swift in Sources */,

Tusker/Screens/Timeline/TimelineViewController.swift

@@ -14,20 +14,19 @@ import SwiftSoup
 
 // TODO: gonna need a thing to replicate all of EnhancedTableViewController
 
-class TimelineViewController: UIViewController {
+class TimelineViewController: UIViewController, TimelineLikeCollectionViewController {
-    
     let timeline: Timeline
     weak var mastodonController: MastodonController!
     
-    private var controller: TimelineLikeController<TimelineItem>!
+    private(set) var controller: TimelineLikeController<TimelineItem>!
-    private var confirmLoadMore = PassthroughSubject<Void, Never>()
+    let confirmLoadMore = PassthroughSubject<Void, Never>()
     private var newer: RequestRange?
     private var older: RequestRange?
     
-    private var collectionView: UICollectionView {
+    var collectionView: UICollectionView {
         view as! UICollectionView
     }
-    private var dataSource: UICollectionViewDiffableDataSource<Section, Item>!
+    private(set) var dataSource: UICollectionViewDiffableDataSource<Section, Item>!
     
     init(for timeline: Timeline, mastodonController: MastodonController!) {
         self.timeline = timeline
@@ -135,18 +134,26 @@ class TimelineViewController: UIViewController {
 }
 
 extension TimelineViewController {
-    enum Section: Hashable {
+    enum Section: TimelineLikeCollectionViewSection {
         case header
         case statuses
         case footer
+        
+        static var entries: Self { .statuses }
     }
-    enum Item: Hashable {
+    enum Item: TimelineLikeCollectionViewItem {
+        typealias TimelineItem = String // status ID
+        
         case status(id: String, state: StatusState)
         case loadingIndicator
         case confirmLoadMore
 //        // TODO: remove local param from this
 //        case publicTimelineDescription(local: Bool)
         
+        static func fromTimelineItem(_ id: String) -> Self {
+            return .status(id: id, state: .unknown)
+        }
+        
         static func ==(lhs: Item, rhs: Item) -> Bool {
             switch (lhs, rhs) {
             case let (.status(id: a, state: _), .status(id: b, state: _)):
@@ -188,7 +195,8 @@ extension TimelineViewController {
     }
 }
 
-extension TimelineViewController: TimelineLikeControllerDelegate {
+// MARK: - TimelineLikeControllerDelegate
+extension TimelineViewController {
     typealias TimelineItem = String // status ID
     
     func loadInitial() async throws -> [TimelineItem] {
@@ -255,120 +263,7 @@ extension TimelineViewController: TimelineLikeControllerDelegate {
         }
     }
     
-    func canLoadOlder() async -> Bool {
+    enum Error: TimelineLikeCollectionViewError {
-        if Preferences.shared.disableInfiniteScrolling {
-            var snapshot = dataSource.snapshot()
-            if !snapshot.itemIdentifiers.contains(.confirmLoadMore) {
-                if !snapshot.sectionIdentifiers.contains(.footer) {
-                    snapshot.appendSections([.footer])
-                }
-                snapshot.appendItems([.confirmLoadMore], toSection: .footer)
-                await dataSource.apply(snapshot, animatingDifferences: false)
-            }
-            for await _ in self.confirmLoadMore.values {
-                return true
-            }
-            fatalError("unreachable")
-        } else {
-            return true
-        }
-    }
-    
-    func handleEvent(_ event: TimelineLikeController<TimelineItem>.Event) async {
-        switch event {
-        case .addLoadingIndicator:
-            var snapshot = dataSource.snapshot()
-            if !snapshot.sectionIdentifiers.contains(.footer) {
-                snapshot.appendSections([.footer])
-            }
-            if snapshot.itemIdentifiers.contains(.confirmLoadMore) {
-                snapshot.reconfigureItems([.confirmLoadMore])
-            } else {
-                snapshot.appendItems([.loadingIndicator], toSection: .footer)
-            }
-            await dataSource.apply(snapshot, animatingDifferences: false)
-            
-        case .removeLoadingIndicator:
-            let oldContentOffset = collectionView.contentOffset
-            var snapshot = dataSource.snapshot()
-            snapshot.deleteSections([.footer])
-            await dataSource.apply(snapshot, animatingDifferences: false)
-            collectionView.contentOffset = oldContentOffset
-            
-        case .loadAllError(let error, _):
-            let config = ToastConfiguration(from: error, with: "Error Loading", in: self) { [weak self] (toast: ToastView) in
-                toast.dismissToast(animated: true)
-                Task {
-                    await self?.controller.loadInitial()
-                }
-            }
-            self.showToast(configuration: config, animated: true)
-
-        case .replaceAllItems(let ids, _):
-            var snapshot = dataSource.snapshot()
-            if snapshot.sectionIdentifiers.contains(.statuses) {
-                snapshot.deleteSections([.statuses])
-            }
-            snapshot.appendSections([.statuses])
-            snapshot.appendItems(ids.map { .status(id: $0, state: .unknown) }, toSection: .statuses)
-            await dataSource.apply(snapshot, animatingDifferences: false)
-            
-        case .loadNewerError(Error.allCaughtUp, _):
-            var config = ToastConfiguration(title: "You're all caught up")
-            config.edge = .top
-            config.dismissAutomaticallyAfter = 2
-            config.action = { (toast) in
-                toast.dismissToast(animated: true)
-            }
-            self.showToast(configuration: config, animated: true)
-            
-        case .loadNewerError(let error, _):
-            let config = ToastConfiguration(from: error, with: "Error Loading Newer", in: self) { [weak self] (toast: ToastView) in
-                toast.dismissToast(animated: true)
-                Task {
-                    await self?.controller.loadNewer()
-                }
-            }
-            self.showToast(configuration: config, animated: true)
-            
-        case .prependItems(let ids, _):
-            var snapshot = dataSource.snapshot()
-            let items = ids.map { Item.status(id: $0, state: .unknown) }
-            let first = snapshot.itemIdentifiers(inSection: .statuses).first
-            if let first {
-                snapshot.insertItems(items, beforeItem: first)
-            } else {
-                snapshot.appendItems(items, toSection: .statuses)
-            }
-            await dataSource.apply(snapshot, animatingDifferences: false)
-            
-            if let first,
-               let indexPath = dataSource.indexPath(for: first) {
-                // TODO: i can't tell if this actually works or not
-                // maintain the current position in the list (don't scroll to top)
-                collectionView.scrollToItem(at: indexPath, at: .top, animated: false)
-            }
-            
-        case .loadOlderError(let error, _):
-            let config = ToastConfiguration(from: error, with: "Error Loading Older", in: self) { [weak self] (toast: ToastView) in
-                toast.dismissToast(animated: true)
-                Task {
-                    await self?.controller.loadOlder()
-                }
-            }
-            self.showToast(configuration: config, animated: true)
-
-        case .appendItems(let ids, _):
-            var snapshot = dataSource.snapshot()
-            if snapshot.itemIdentifiers.contains(.confirmLoadMore) {
-                snapshot.deleteItems([.confirmLoadMore])
-            }
-            snapshot.appendItems(ids.map { .status(id: $0, state: .unknown) }, toSection: .statuses)
-            await dataSource.apply(snapshot, animatingDifferences: false)
-        }
-    }
-    
-    enum Error: Swift.Error {
         case noClient
         case noNewer
         case noOlder
@@ -391,6 +286,3 @@ extension TimelineViewController: UICollectionViewDelegate {
         }
     }
 }
-
-extension TimelineViewController: ToastableViewController {
-}

Tusker/Screens/Utilities/TimelineLikeCollectionViewController.swift

@@ -0,0 +1,187 @@
+//
+//  TimelineLikeCollectionViewController.swift
+//  Tusker
+//
+//  Created by Shadowfacts on 9/24/22.
+//  Copyright © 2022 Shadowfacts. All rights reserved.
+//
+
+import UIKit
+import Combine
+
+@MainActor
+protocol TimelineLikeCollectionViewController: UIViewController, TimelineLikeControllerDelegate, ToastableViewController {
+    associatedtype Section: TimelineLikeCollectionViewSection
+    associatedtype Item: TimelineLikeCollectionViewItem where Item.TimelineItem == Self.TimelineItem
+    associatedtype Error: TimelineLikeCollectionViewError
+    
+    // this needs to be an IUO because it can't be set until after the super init is called, so that self can be passed as the delegate param
+    var controller: TimelineLikeController<TimelineItem>! { get }
+    var confirmLoadMore: PassthroughSubject<Void, Never> { get }
+    
+    var collectionView: UICollectionView { get }
+    var dataSource: UICollectionViewDiffableDataSource<Section, Item>! { get }
+}
+
+protocol TimelineLikeCollectionViewSection: Hashable {
+    static var entries: Self { get }
+    static var footer: Self { get }
+}
+
+protocol TimelineLikeCollectionViewItem: Hashable {
+    associatedtype TimelineItem
+    
+    static var loadingIndicator: Self { get }
+    static var confirmLoadMore: Self { get }
+    
+    static func fromTimelineItem(_ item: TimelineItem) -> Self
+}
+
+// TODO: equatable might not be the best for this?
+protocol TimelineLikeCollectionViewError: Error, Equatable {
+    static var allCaughtUp: Self { get }
+}
+
+extension TimelineLikeCollectionViewController {
+    func canLoadOlder() async -> Bool {
+        if Preferences.shared.disableInfiniteScrolling {
+            var snapshot = dataSource.snapshot()
+            if !snapshot.itemIdentifiers.contains(.confirmLoadMore) {
+                if !snapshot.sectionIdentifiers.contains(.footer) {
+                    snapshot.appendSections([.footer])
+                }
+                snapshot.appendItems([.confirmLoadMore], toSection: .footer)
+                await dataSource.apply(snapshot, animatingDifferences: false)
+            }
+            for await _ in confirmLoadMore.values {
+                return true
+            }
+            fatalError("unreachable")
+        } else {
+            return true
+        }
+    }
+    
+    func handleEvent(_ event: TimelineLikeController<TimelineItem>.Event) async {
+        switch event {
+        case .addLoadingIndicator:
+            await handleAddLoadingIndicator()
+        case .removeLoadingIndicator:
+            await handleRemoveLoadingIndicator()
+        case .loadAllError(let error, _):
+            await handleLoadAllError(error)
+        case .replaceAllItems(let items, _):
+            await handleReplaceAllItems(items)
+        case .loadNewerError(let error, _):
+            await handleLoadNewerError(error)
+        case .prependItems(let items, _):
+            await handlePrependItems(items)
+        case .loadOlderError(let error, _):
+            await handleLoadOlderError(error)
+        case .appendItems(let items, _):
+            await handleAppendItems(items)
+        }
+    }
+    
+    func handleAddLoadingIndicator() async {
+        var snapshot = dataSource.snapshot()
+        if !snapshot.sectionIdentifiers.contains(.footer) {
+            snapshot.appendSections([.footer])
+        }
+        if snapshot.itemIdentifiers.contains(.confirmLoadMore) {
+            snapshot.reconfigureItems([.confirmLoadMore])
+        } else {
+            snapshot.appendItems([.loadingIndicator], toSection: .footer)
+        }
+        await dataSource.apply(snapshot, animatingDifferences: false)
+    }
+    
+    func handleRemoveLoadingIndicator() async {
+        let oldContentOffset = collectionView.contentOffset
+        var snapshot = dataSource.snapshot()
+        snapshot.deleteSections([.footer])
+        await dataSource.apply(snapshot, animatingDifferences: false)
+        // prevent the collection view from scrolling as we remove the loading indicator and add the timeline items
+        collectionView.contentOffset = oldContentOffset
+    }
+    
+    func handleLoadAllError(_ error: Swift.Error) async {
+        let config = ToastConfiguration(from: error, with: "Error Loading", in: self) { [weak self] toast in
+            toast.dismissToast(animated: true)
+            Task {
+                await self?.controller.loadInitial()
+            }
+        }
+        self.showToast(configuration: config, animated: true)
+    }
+    
+    func handleReplaceAllItems(_ timelineItems: [TimelineItem]) async {
+        var snapshot = dataSource.snapshot()
+        if snapshot.sectionIdentifiers.contains(.entries) {
+            snapshot.deleteSections([.entries])
+        }
+        snapshot.appendSections([.entries])
+        snapshot.appendItems(timelineItems.map { .fromTimelineItem($0) }, toSection: .entries)
+        await dataSource.apply(snapshot, animatingDifferences: false)
+    }
+    
+    func handleLoadNewerError(_ error: Swift.Error) async {
+        var config: ToastConfiguration
+        if let error = error as? Self.Error,
+           error == .allCaughtUp {
+            config = ToastConfiguration(title: "You're all caught up")
+            config.edge = .top
+            config.dismissAutomaticallyAfter = 2
+            config.action = { toast in
+                toast.dismissToast(animated: true)
+            }
+        } else {
+            config = ToastConfiguration(from: error, with: "Error Loading Newer", in: self) { [weak self] toast in
+                toast.dismissToast(animated: true)
+                Task {
+                    await self?.controller.loadNewer()
+                }
+            }
+        }
+        self.showToast(configuration: config, animated: true)
+    }
+    
+    func handlePrependItems(_ timelineItems: [TimelineItem]) async {
+        let items = timelineItems.map { Item.fromTimelineItem($0) }
+        var snapshot = dataSource.snapshot()
+        let first = snapshot.itemIdentifiers(inSection: .entries).first
+        if let first {
+            snapshot.insertItems(items, beforeItem: first)
+        } else {
+            snapshot.appendItems(items, toSection: .entries)
+        }
+        await dataSource.apply(snapshot, animatingDifferences: false)
+        
+        if let first,
+           let indexPath = dataSource.indexPath(for: first) {
+            // TODO: i can't tell if this actually works or not
+            // maintain the current scroll position in the list (don't scroll to top)
+            collectionView.scrollToItem(at: indexPath, at: .top, animated: false)
+        }
+    }
+    
+    func handleLoadOlderError(_ error: Swift.Error) async {
+        let config = ToastConfiguration(from: error, with: "Error Loading Older", in: self) { [weak self] toast in
+            toast.dismissToast(animated: true)
+            Task {
+                await self?.controller.loadOlder()
+            }
+        }
+        self.showToast(configuration: config, animated: true)
+    }
+    
+    func handleAppendItems(_ timelineItems: [TimelineItem]) async {
+        var snapshot = dataSource.snapshot()
+        // TODO: this might not be necessary, isn't the confirm item removed separately?
+        if snapshot.itemIdentifiers.contains(.confirmLoadMore) {
+            snapshot.deleteItems([.confirmLoadMore])
+        }
+        snapshot.appendItems(timelineItems.map { .fromTimelineItem($0) }, toSection: .entries)
+        await dataSource.apply(snapshot, animatingDifferences: false)
+    }
+}