From ea85b1194552e837f28b3d867e43d94a5da43bf3 Mon Sep 17 00:00:00 2001
From: Shadowfacts <me@shadowfacts.net>
Date: Sat, 11 Feb 2023 10:09:56 -0500
Subject: [PATCH] Use cards for trending links screen, and add pagination

See #355
---
 .../Pachyderm/Sources/Pachyderm/Client.swift  |  13 +-
 .../TrendingLinkCardCollectionViewCell.swift  |  31 +++
 .../TrendingLinkCardCollectionViewCell.xib    |   6 +-
 .../Explore/TrendingLinksViewController.swift | 259 +++++++++++++++---
 .../ConfirmLoadMoreCollectionViewCell.swift   |   2 +-
 5 files changed, 256 insertions(+), 55 deletions(-)

diff --git a/Packages/Pachyderm/Sources/Pachyderm/Client.swift b/Packages/Pachyderm/Sources/Pachyderm/Client.swift
index 57422227..cd6c3889 100644
--- a/Packages/Pachyderm/Sources/Pachyderm/Client.swift
+++ b/Packages/Pachyderm/Sources/Pachyderm/Client.swift
@@ -437,12 +437,13 @@ public class Client {
         return Request(method: .get, path: "/api/v1/trends/statuses", queryParameters: parameters)
     }
     
-    public static func getTrendingLinks(limit: Int? = nil) -> Request<[Card]> {
-        let parameters: [Parameter]
-        if let limit = limit {
-            parameters = ["limit" => limit]
-        } else {
-            parameters = []
+    public static func getTrendingLinks(limit: Int? = nil, offset: Int? = nil) -> Request<[Card]> {
+        var parameters: [Parameter] = []
+        if let limit {
+            parameters.append("limit" => limit)
+        }
+        if let offset {
+            parameters.append("offset" => offset)
         }
         return Request(method: .get, path: "/api/v1/trends/links", queryParameters: parameters)
     }
diff --git a/Tusker/Screens/Explore/TrendingLinkCardCollectionViewCell.swift b/Tusker/Screens/Explore/TrendingLinkCardCollectionViewCell.swift
index 98bea58c..1a88dec3 100644
--- a/Tusker/Screens/Explore/TrendingLinkCardCollectionViewCell.swift
+++ b/Tusker/Screens/Explore/TrendingLinkCardCollectionViewCell.swift
@@ -21,6 +21,29 @@ class TrendingLinkCardCollectionViewCell: UICollectionViewCell {
     @IBOutlet weak var providerLabel: UILabel!
     @IBOutlet weak var activityLabel: UILabel!
     @IBOutlet weak var historyView: TrendHistoryView!
+    private var thumbnailAspectRatioConstraint: NSLayoutConstraint?
+    
+    var verticalSize: VerticalSize! {
+        didSet {
+            guard oldValue != verticalSize else {
+                return
+            }
+            switch verticalSize {
+            case nil:
+                fatalError()
+            case .regular:
+                thumbnailAspectRatioConstraint?.isActive = false
+                thumbnailAspectRatioConstraint = thumbnailView.widthAnchor.constraint(equalTo: thumbnailView.heightAnchor, multiplier: 4/3)
+                thumbnailAspectRatioConstraint!.isActive = true
+                descriptionLabel.numberOfLines = 3
+            case .compact:
+                thumbnailAspectRatioConstraint?.isActive = false
+                thumbnailAspectRatioConstraint = thumbnailView.widthAnchor.constraint(equalTo: thumbnailView.heightAnchor, multiplier: 2/1)
+                thumbnailAspectRatioConstraint!.isActive = true
+                descriptionLabel.numberOfLines = 5
+            }
+        }
+    }
     
     private var hoverGestureAnimator: UIViewPropertyAnimator?
     
@@ -37,6 +60,8 @@ class TrendingLinkCardCollectionViewCell: UICollectionViewCell {
         contentView.backgroundColor = .appGroupedCellBackground
         updateLayerColors()
         
+        verticalSize = .regular
+        
         addGestureRecognizer(UIHoverGestureRecognizer(target: self, action: #selector(hoverRecognized)))
     }
     
@@ -137,3 +162,9 @@ class TrendingLinkCardCollectionViewCell: UICollectionViewCell {
     }
     
 }
+
+extension TrendingLinkCardCollectionViewCell {
+    enum VerticalSize {
+        case regular, compact
+    }
+}
diff --git a/Tusker/Screens/Explore/TrendingLinkCardCollectionViewCell.xib b/Tusker/Screens/Explore/TrendingLinkCardCollectionViewCell.xib
index 23391e6d..3a111877 100644
--- a/Tusker/Screens/Explore/TrendingLinkCardCollectionViewCell.xib
+++ b/Tusker/Screens/Explore/TrendingLinkCardCollectionViewCell.xib
@@ -21,7 +21,7 @@
                     <imageView clipsSubviews="YES" userInteractionEnabled="NO" contentMode="scaleAspectFill" horizontalHuggingPriority="251" verticalHuggingPriority="251" translatesAutoresizingMaskIntoConstraints="NO" id="h3b-Mf-lD6" customClass="CachedImageView" customModule="Tusker" customModuleProvider="target">
                         <rect key="frame" x="0.0" y="0.0" width="300" height="225"/>
                         <constraints>
-                            <constraint firstAttribute="width" secondItem="h3b-Mf-lD6" secondAttribute="height" multiplier="4:3" id="QDY-8a-LYC"/>
+                            <constraint firstAttribute="width" secondItem="h3b-Mf-lD6" secondAttribute="height" multiplier="4:3" placeholder="YES" id="QDY-8a-LYC"/>
                         </constraints>
                     </imageView>
                     <stackView opaque="NO" contentMode="scaleToFill" axis="vertical" alignment="top" spacing="4" translatesAutoresizingMaskIntoConstraints="NO" id="LpU-m4-guC">
@@ -56,9 +56,9 @@
                         </constraints>
                     </view>
                     <visualEffectView opaque="NO" contentMode="scaleToFill" translatesAutoresizingMaskIntoConstraints="NO" id="cWo-9n-z42">
-                        <rect key="frame" x="0.0" y="196.33333333333334" width="300" height="28.666666666666657"/>
+                        <rect key="frame" x="0.0" y="196.66666666666666" width="300" height="28.333333333333343"/>
                         <view key="contentView" opaque="NO" clipsSubviews="YES" multipleTouchEnabled="YES" contentMode="center" insetsLayoutMarginsFromSafeArea="NO" id="ktv-3s-cp9">
-                            <rect key="frame" x="0.0" y="0.0" width="300" height="28.666666666666657"/>
+                            <rect key="frame" x="0.0" y="0.0" width="300" height="28.333333333333343"/>
                             <autoresizingMask key="autoresizingMask" widthSizable="YES" heightSizable="YES"/>
                             <subviews>
                                 <label opaque="NO" userInteractionEnabled="NO" contentMode="left" horizontalHuggingPriority="251" verticalHuggingPriority="251" text="Title" textAlignment="natural" lineBreakMode="tailTruncation" numberOfLines="2" baselineAdjustment="alignBaselines" adjustsLetterSpacingToFitWidth="YES" showsExpansionTextWhenTruncated="YES" adjustsFontForContentSizeCategory="YES" adjustsFontSizeToFit="NO" translatesAutoresizingMaskIntoConstraints="NO" id="Ho3-cU-IGi">
diff --git a/Tusker/Screens/Explore/TrendingLinksViewController.swift b/Tusker/Screens/Explore/TrendingLinksViewController.swift
index 9eebeb8a..89e09f48 100644
--- a/Tusker/Screens/Explore/TrendingLinksViewController.swift
+++ b/Tusker/Screens/Explore/TrendingLinksViewController.swift
@@ -10,19 +10,22 @@ import UIKit
 import Pachyderm
 import WebURLFoundationExtras
 import SafariServices
+import Combine
 
-class TrendingLinksViewController: EnhancedTableViewController {
+class TrendingLinksViewController: UIViewController, CollectionViewController {
     
     weak var mastodonController: MastodonController!
     
-    private var dataSource: UITableViewDiffableDataSource<Section, Item>!
+    var collectionView: UICollectionView!
+    private var dataSource: UICollectionViewDiffableDataSource<Section, Item>!
+    
+    private var state = State.unloaded
+    private let confirmLoadMore = PassthroughSubject<Void, Never>()
     
     init(mastodonController: MastodonController) {
         self.mastodonController = mastodonController
         
-        super.init(style: .grouped)
-        
-        dragEnabled = true
+        super.init(nibName: nil, bundle: nil)
     }
     
     required init?(coder: NSCoder) {
@@ -34,73 +37,239 @@ class TrendingLinksViewController: EnhancedTableViewController {
 
         title = NSLocalizedString("Trending Links", comment: "trending links screen title")
         
-        tableView.register(TrendingLinkTableViewCell.self, forCellReuseIdentifier: "trendingLinkCell")
-        tableView.estimatedRowHeight = 100
-        tableView.allowsFocus = true
-        tableView.backgroundColor = .appGroupedBackground
+        let layout = UICollectionViewCompositionalLayout { [unowned self] sectionIndex, environment in
+            switch dataSource.sectionIdentifier(for: sectionIndex) {
+            case nil:
+                fatalError()
+                
+            case .loadingIndicator, .confirmLoadMore:
+                var config = UICollectionLayoutListConfiguration(appearance: .grouped)
+                config.backgroundColor = .appGroupedBackground
+                config.showsSeparators = false
+                let section = NSCollectionLayoutSection.list(using: config, layoutEnvironment: environment)
+                if UIDevice.current.userInterfaceIdiom == .pad || UIDevice.current.userInterfaceIdiom == .mac {
+                    section.contentInsetsReference = .readableContent
+                }
+                return section
+                
+            case .links:
+                let size = NSCollectionLayoutSize(widthDimension: .fractionalWidth(1), heightDimension: .estimated(280))
+                let item = NSCollectionLayoutItem(layoutSize: size)
+                let item2 = NSCollectionLayoutItem(layoutSize: size)
+                let group = NSCollectionLayoutGroup.vertical(layoutSize: size, subitems: [item, item2])
+                group.contentInsets = NSDirectionalEdgeInsets(top: 0, leading: 16, bottom: 0, trailing: 16)
+                group.interItemSpacing = .fixed(16)
+                let section = NSCollectionLayoutSection(group: group)
+                section.interGroupSpacing = 16
+                section.contentInsets = NSDirectionalEdgeInsets(top: 16, leading: 0, bottom: 16, trailing: 0)
+                return section
+            }
+        }
+        collectionView = UICollectionView(frame: .zero, collectionViewLayout: layout)
+        collectionView.translatesAutoresizingMaskIntoConstraints = false
+        collectionView.delegate = self
+        collectionView.dragDelegate = self
+        collectionView.backgroundColor = .appGroupedBackground
+        collectionView.allowsFocus = true
+        view.addSubview(collectionView)
+        NSLayoutConstraint.activate([
+            collectionView.leadingAnchor.constraint(equalTo: view.leadingAnchor),
+            collectionView.trailingAnchor.constraint(equalTo: view.trailingAnchor),
+            collectionView.topAnchor.constraint(equalTo: view.topAnchor),
+            collectionView.bottomAnchor.constraint(equalTo: view.bottomAnchor),
+        ])
         
-        dataSource = UITableViewDiffableDataSource(tableView: tableView, cellProvider: { tableView, indexPath, item in
-            let cell = tableView.dequeueReusableCell(withIdentifier: "trendingLinkCell", for: indexPath) as! TrendingLinkTableViewCell
-            cell.updateUI(card: item.card)
-            return cell
-        })
+        dataSource = createDataSource()
+    }
+    
+    private func createDataSource() -> UICollectionViewDiffableDataSource<Section, Item> {
+        let loadingCell = UICollectionView.CellRegistration<LoadingCollectionViewCell, Void> { cell, indexPath, itemIdentifier in
+            cell.indicator.startAnimating()
+        }
+        let linkCell = UICollectionView.CellRegistration<TrendingLinkCardCollectionViewCell, Card>(cellNib: UINib(nibName: "TrendingLinkCardCollectionViewCell", bundle: .main)) { cell, indexPath, item in
+            cell.verticalSize = .compact
+            cell.updateUI(card: item)
+        }
+        let confirmLoadMoreCell = UICollectionView.CellRegistration<ConfirmLoadMoreCollectionViewCell, Bool> { cell, indexPath, isLoading in
+            cell.confirmLoadMore = self.confirmLoadMore
+            cell.isLoading = isLoading
+        }
+        return UICollectionViewDiffableDataSource(collectionView: collectionView) { collectionView, indexPath, itemIdentifier in
+            switch itemIdentifier {
+            case .loadingIndicator:
+                return collectionView.dequeueConfiguredReusableCell(using: loadingCell, for: indexPath, item: ())
+            case .link(let card):
+                return collectionView.dequeueConfiguredReusableCell(using: linkCell, for: indexPath, item: card)
+            case .confirmLoadMore(let loading):
+                return collectionView.dequeueConfiguredReusableCell(using: confirmLoadMoreCell, for: indexPath, item: loading)
+            }
+        }
     }
     
     override func viewWillAppear(_ animated: Bool) {
         super.viewWillAppear(animated)
         
-        let request = Client.getTrendingLinks()
         Task {
-            guard let (links, _) = try? await mastodonController.run(request) else {
-                return
-            }
-            var snapshot = NSDiffableDataSourceSnapshot<Section, Item>()
-            snapshot.appendSections([.links])
-            snapshot.appendItems(links.map(Item.init))
-            await dataSource.apply(snapshot)
+            await loadInitial()
         }
     }
     
-    // MARK: - Table View Delegate
+    @MainActor
+    private func loadInitial() async {
+        guard case .unloaded = state else {
+            return
+        }
+        state = .loading
+        
+        var snapshot = NSDiffableDataSourceSnapshot<Section, Item>()
+        snapshot.appendSections([.loadingIndicator])
+        snapshot.appendItems([.loadingIndicator])
+        await dataSource.apply(snapshot)
+        
+        let request = Client.getTrendingLinks()
+        guard let (links, _) = try? await mastodonController.run(request) else {
+            return
+        }
+        snapshot.deleteSections([.loadingIndicator])
+        snapshot.appendSections([.links])
+        snapshot.appendItems(links.map { .link($0) })
+        await dataSource.apply(snapshot)
+        
+        state = .loaded
+    }
     
-    override func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
-        guard let item = dataSource.itemIdentifier(for: indexPath),
-              let url = URL(item.card.url) else {
+    @MainActor
+    private func loadOlder() async {
+        guard case .loaded = state else {
+            return
+        }
+        state = .loadingOlder
+        
+        let origSnapshot = dataSource.snapshot()
+        var snapshot = origSnapshot
+        if Preferences.shared.disableInfiniteScrolling {
+            snapshot.appendSections([.confirmLoadMore])
+            snapshot.appendItems([.confirmLoadMore(false)], toSection: .confirmLoadMore)
+            await dataSource.apply(snapshot)
+            
+            for await _ in confirmLoadMore.values {
+                break
+            }
+            
+            snapshot.deleteItems([.confirmLoadMore(false)])
+            snapshot.appendItems([.confirmLoadMore(true)], toSection: .confirmLoadMore)
+            await dataSource.apply(snapshot, animatingDifferences: false)
+        } else {
+            snapshot.appendSections([.loadingIndicator])
+            snapshot.appendItems([.loadingIndicator], toSection: .confirmLoadMore)
+            await dataSource.apply(snapshot)
+        }
+        
+        let request = Client.getTrendingLinks(offset: snapshot.itemIdentifiers.count)
+        guard let (links, _) = try? await mastodonController.run(request) else {
+            return
+        }
+        snapshot = origSnapshot
+        snapshot.appendItems(links.map { .link($0) }, toSection: .links)
+        await dataSource.apply(snapshot)
+        
+        state = .loaded
+    }
+    
+}
+
+extension TrendingLinksViewController {
+    enum State {
+        case unloaded
+        case loading
+        case loaded
+        case loadingOlder
+    }
+}
+
+extension TrendingLinksViewController {
+    enum Section {
+        case loadingIndicator
+        case links
+        case confirmLoadMore
+    }
+    enum Item: Hashable {
+        case loadingIndicator
+        case link(Card)
+        case confirmLoadMore(Bool)
+        
+        static func ==(lhs: Item, rhs: Item) -> Bool {
+            switch (lhs, rhs) {
+            case (.loadingIndicator, .loadingIndicator):
+                return true
+            case (.link(let a), .link(let b)):
+                return a.url == b.url
+            case (.confirmLoadMore(let a), .confirmLoadMore(let b)):
+                return a == b
+            default:
+                return false
+            }
+        }
+        
+        func hash(into hasher: inout Hasher) {
+            switch self {
+            case .loadingIndicator:
+                hasher.combine(0)
+            case .link(let card):
+                hasher.combine(1)
+                hasher.combine(card.url)
+            case .confirmLoadMore(let loading):
+                hasher.combine(2)
+                hasher.combine(loading)
+            }
+        }
+    }
+}
+
+extension TrendingLinksViewController: UICollectionViewDelegate {
+    func collectionView(_ collectionView: UICollectionView, willDisplay cell: UICollectionViewCell, forItemAt indexPath: IndexPath) {
+        if indexPath.section == collectionView.numberOfSections - 1,
+           indexPath.row == collectionView.numberOfItems(inSection: indexPath.section) - 1 {
+            Task {
+                await loadOlder()
+            }
+        }
+    }
+    
+    func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
+        guard case .link(let card) = dataSource.itemIdentifier(for: indexPath),
+              let url = URL(card.url) else {
             return
         }
         selected(url: url)
     }
     
-    override func tableView(_ tableView: UITableView, contextMenuConfigurationForRowAt indexPath: IndexPath, point: CGPoint) -> UIContextMenuConfiguration? {
-        guard let item = dataSource.itemIdentifier(for: indexPath),
-              let url = URL(item.card.url) else {
+    func collectionView(_ collectionView: UICollectionView, contextMenuConfigurationForItemAt indexPath: IndexPath, point: CGPoint) -> UIContextMenuConfiguration? {
+        guard case .link(let card) = dataSource.itemIdentifier(for: indexPath),
+              let url = URL(card.url) else {
             return nil
         }
-        return UIContextMenuConfiguration(identifier: nil) {
+        return UIContextMenuConfiguration {
             let vc = SFSafariViewController(url: url)
             vc.preferredControlTintColor = Preferences.shared.accentColor.color
             return vc
         } actionProvider: { _ in
-            return UIMenu(children: self.actionsForTrendingLink(card: item.card))
+            UIMenu(children: self.actionsForTrendingLink(card: card))
         }
     }
-
+    
+    func collectionView(_ collectionView: UICollectionView, willPerformPreviewActionForMenuWith configuration: UIContextMenuConfiguration, animator: UIContextMenuInteractionCommitAnimating) {
+        MenuPreviewHelper.willPerformPreviewAction(animator: animator, presenter: self)
+    }
 }
 
-extension TrendingLinksViewController {
-    enum Section {
-        case links
-    }
-    struct Item: Hashable {
-        let card: Card
-        
-        static func ==(lhs: Item, rhs: Item) -> Bool {
-            return lhs.card.url == rhs.card.url
-        }
-        
-        func hash(into hasher: inout Hasher) {
-            hasher.combine(card.url)
+extension TrendingLinksViewController: UICollectionViewDragDelegate {
+    func collectionView(_ collectionView: UICollectionView, itemsForBeginning session: UIDragSession, at indexPath: IndexPath) -> [UIDragItem] {
+        guard case .link(let card) = dataSource.itemIdentifier(for: indexPath),
+              let url = URL(card.url) else {
+            return []
         }
+        return [UIDragItem(itemProvider: NSItemProvider(object: url as NSURL))]
     }
 }
 
diff --git a/Tusker/Views/Confirm Load More Cell/ConfirmLoadMoreCollectionViewCell.swift b/Tusker/Views/Confirm Load More Cell/ConfirmLoadMoreCollectionViewCell.swift
index 0c5514bd..57ab54ef 100644
--- a/Tusker/Views/Confirm Load More Cell/ConfirmLoadMoreCollectionViewCell.swift	
+++ b/Tusker/Views/Confirm Load More Cell/ConfirmLoadMoreCollectionViewCell.swift	
@@ -28,7 +28,7 @@ class ConfirmLoadMoreCollectionViewCell: UICollectionViewCell {
     override init(frame: CGRect) {
         super.init(frame: frame)
         
-        backgroundColor = .systemGroupedBackground
+        backgroundColor = .appGroupedBackground
         
         let label = UILabel()
         label.text = "Infinite scrolling is off. Do you want to keep going?"