SPT-1556 refactoring pagination plugin

Example/ReactiveDataDisplayManager/Collection.storyboard

@@ -55,6 +55,7 @@
                         <segue destination="EB6-CQ-xkp" kind="show" identifier="refreshingCollection" id="RIR-tI-dAc"/>
                         <segue destination="dcC-YA-wFj" kind="show" identifier="twoDirectionPaginatableCollection" id="EKN-aB-kFO"/>
                         <segue destination="WXf-rM-5r7" kind="show" identifier="stackCellCollectionViewController" id="ljM-KS-ixh"/>
+                        <segue destination="hKO-Fp-O7f" kind="show" identifier="horizontalTwoDirectionPaginatableCollection" id="HOF-Cl-xHy"/>
                     </connections>
                 </viewController>
                 <placeholder placeholderIdentifier="IBFirstResponder" id="4hK-7m-aH1" userLabel="First Responder" sceneMemberID="firstResponder"/>
@@ -882,6 +883,50 @@
             </objects>
             <point key="canvasLocation" x="-719" y="2248"/>
         </scene>
+        <!--Horizontal Two Direction Paginatable Collection View Controller-->
+        <scene sceneID="XXX-DU-TWm">
+            <objects>
+                <viewController id="hKO-Fp-O7f" customClass="HorizontalTwoDirectionPaginatableCollectionViewController" customModule="ReactiveDataDisplayManagerExample_iOS" customModuleProvider="target" sceneMemberID="viewController">
+                    <view key="view" contentMode="scaleToFill" id="ZaG-oG-SJ4">
+                        <rect key="frame" x="0.0" y="0.0" width="414" height="896"/>
+                        <autoresizingMask key="autoresizingMask" widthSizable="YES" heightSizable="YES"/>
+                        <subviews>
+                            <collectionView clipsSubviews="YES" multipleTouchEnabled="YES" contentMode="scaleToFill" dataMode="prototypes" translatesAutoresizingMaskIntoConstraints="NO" id="cxu-Ea-CM2">
+                                <rect key="frame" x="0.0" y="92" width="414" height="721"/>
+                                <color key="backgroundColor" systemColor="systemBackgroundColor"/>
+                                <collectionViewFlowLayout key="collectionViewLayout" minimumLineSpacing="10" minimumInteritemSpacing="10" id="ts6-eB-wfW">
+                                    <size key="itemSize" width="200" height="44"/>
+                                    <size key="estimatedItemSize" width="200" height="44"/>
+                                    <size key="headerReferenceSize" width="0.0" height="0.0"/>
+                                    <size key="footerReferenceSize" width="0.0" height="0.0"/>
+                                    <inset key="sectionInset" minX="0.0" minY="0.0" maxX="0.0" maxY="0.0"/>
+                                </collectionViewFlowLayout>
+                                <cells/>
+                            </collectionView>
+                            <activityIndicatorView opaque="NO" contentMode="scaleToFill" horizontalHuggingPriority="750" verticalHuggingPriority="750" style="medium" id="zm3-wO-NvS">
+                                <rect key="frame" x="0.0" y="87" width="414" height="721"/>
+                                <autoresizingMask key="autoresizingMask" flexibleMaxX="YES" flexibleMaxY="YES"/>
+                            </activityIndicatorView>
+                        </subviews>
+                        <viewLayoutGuide key="safeArea" id="JA2-N8-uyI"/>
+                        <color key="backgroundColor" systemColor="systemBackgroundColor"/>
+                        <constraints>
+                            <constraint firstItem="cxu-Ea-CM2" firstAttribute="leading" secondItem="JA2-N8-uyI" secondAttribute="leading" id="6kJ-6j-osI"/>
+                            <constraint firstItem="cxu-Ea-CM2" firstAttribute="top" secondItem="JA2-N8-uyI" secondAttribute="top" id="N6v-T2-rir"/>
+                            <constraint firstItem="JA2-N8-uyI" firstAttribute="bottom" secondItem="cxu-Ea-CM2" secondAttribute="bottom" id="vAG-C2-xWy"/>
+                            <constraint firstItem="JA2-N8-uyI" firstAttribute="trailing" secondItem="cxu-Ea-CM2" secondAttribute="trailing" id="ynm-EV-4bv"/>
+                        </constraints>
+                    </view>
+                    <navigationItem key="navigationItem" id="Fi2-lE-HDS"/>
+                    <connections>
+                        <outlet property="activityIndicator" destination="zm3-wO-NvS" id="WYz-NN-qBg"/>
+                        <outlet property="collectionView" destination="cxu-Ea-CM2" id="bll-ee-4dw"/>
+                    </connections>
+                </viewController>
+                <placeholder placeholderIdentifier="IBFirstResponder" id="MkR-Rn-Nbi" userLabel="First Responder" customClass="UIResponder" sceneMemberID="firstResponder"/>
+            </objects>
+            <point key="canvasLocation" x="5842" y="3025"/>
+        </scene>
     </scenes>
     <resources>
         <image name="table.fill" catalog="system" width="128" height="93"/>

Example/ReactiveDataDisplayManager/Collection/MainCollectionViewController/MainCollectionViewController.swift

@@ -35,6 +35,7 @@ final class MainCollectionViewController: UIViewController {
         case alignedCollection
         case dynamicHeightViewController
         case twoDirectionPaginatableCollection
+        case horizontalTwoDirectionPaginatableCollection
     }
 
     // MARK: - Constants
@@ -53,6 +54,7 @@ final class MainCollectionViewController: UIViewController {
             ("Collection with diffableDataSource", .diffableCollection),
             ("Collection with pagination", .paginatableCollection),
             ("Collection with two direction pagination", .twoDirectionPaginatableCollection),
+            ("Collection with two direction horizontal pagination", .horizontalTwoDirectionPaginatableCollection),
             ("Collection with compositional layout", .compositionalCollection),
             ("Collection with DifferenceKit", .differenceCollection),
             ("List Appearances with swipeable items", .swipeableListAppearances),

Example/ReactiveDataDisplayManager/Collection/PaginatableCollectionViewController/PaginatableCollectionViewController.swift

@@ -28,7 +28,7 @@ final class PaginatableCollectionViewController: UIViewController {
     private lazy var progressView = PaginatorView(frame: .init(x: 0, y: 0, width: collectionView.frame.width, height: 80))
 
     private lazy var adapter = collectionView.rddm.baseBuilder
-        .add(plugin: .paginatable(progressView: progressView, output: self))
+        .add(plugin: .bottomPaginatable(progressView: progressView, output: self))
         .build()
 
     private weak var paginatableInput: PaginatableInput?
@@ -72,8 +72,8 @@ private extension PaginatableCollectionViewController {
         activityIndicator.startAnimating()
 
         // hide footer
-        paginatableInput?.updatePagination(canIterate: false)
-        paginatableInput?.updateProgress(isLoading: false)
+        paginatableInput?.updatePaginationEnabled(false, at: .forward(.bottom))
+        paginatableInput?.updatePaginationState(.idle, at: .forward(.bottom))
 
         // imitation of loading first page
         delay(.now() + .seconds(3)) { [weak self] in
@@ -84,7 +84,7 @@ private extension PaginatableCollectionViewController {
             self?.activityIndicator?.stopAnimating()
 
             // show footer
-            self?.paginatableInput?.updatePagination(canIterate: true)
+            self?.paginatableInput?.updatePaginationEnabled(true, at: .forward(.bottom))
         }
     }
 
@@ -137,24 +137,23 @@ private extension PaginatableCollectionViewController {
 
 extension PaginatableCollectionViewController: PaginatableOutput {
 
-    func onPaginationInitialized(with input: PaginatableInput) {
+    func onPaginationInitialized(with input: PaginatableInput, at direction: PagingDirection) {
         paginatableInput = input
     }
 
-    func loadNextPage(with input: PaginatableInput) {
+    func loadNextPage(with input: PaginatableInput, at direction: PagingDirection) {
 
-        input.updateProgress(isLoading: true)
+        input.updatePaginationState(.loading, at: direction)
 
         delay(.now() + .seconds(3)) { [weak self, weak input] in
             let canFillNext = self?.canFillNext() ?? false
             if canFillNext {
                 let canIterate = self?.fillNext() ?? false
 
-                input?.updateProgress(isLoading: false)
-                input?.updatePagination(canIterate: canIterate)
+                input?.updatePaginationState(.idle, at: direction)
+                input?.updatePaginationEnabled(canIterate, at: direction)
             } else {
-                input?.updateProgress(isLoading: false)
-                input?.updateError(SampleError.sample)
+                input?.updatePaginationState(.error(SampleError.sample), at: direction)
             }
         }
     }

Example/ReactiveDataDisplayManager/Collection/TwoDirectionPaginatableCollectionViewController/HorizontalTwoDirectionPaginatableCollectionViewController.swift

@@ -0,0 +1,229 @@
+//
+//  HorizontalTwoDirectionPaginatableCollectionViewController.swift
+//  ReactiveDataDisplayManagerExample_iOS
+//
+//  Created by Konstantin Porokhov on 30.08.2023.
+//
+
+import UIKit
+import ReactiveDataDisplayManager
+import ReactiveDataComponents
+
+final class HorizontalTwoDirectionPaginatableCollectionViewController: UIViewController {
+
+    // MARK: - Nested types
+
+    private enum ScrollDirection {
+        case left
+        case right
+    }
+
+    // MARK: - Constants
+
+    private enum Constants {
+        static let maxPagesCount = 5
+        static let pageSize = 20
+        static let paginatorHeight: CGFloat = 80
+        static let firstPageMiddleIndexPath = IndexPath(row: Constants.pageSize / 2, section: 0)
+    }
+
+    // MARK: - IBOutlet
+
+    @IBOutlet private weak var collectionView: UICollectionView!
+    @IBOutlet private weak var activityIndicator: UIActivityIndicatorView!
+
+    // MARK: - Private Properties
+
+    private lazy var leftProgressView = PaginatorView(frame: .init(x: 0,
+                                                                   y: 0,
+                                                                   width: 200,
+                                                                   height: collectionView.frame.height))
+    private lazy var rightProgressView = PaginatorView(frame: .init(x: 0,
+                                                                    y: 0,
+                                                                    width: 200,
+                                                                    height: collectionView.frame.height))
+
+    private lazy var adapter = collectionView.rddm.baseBuilder
+        .add(plugin: .leftPaginatable(progressView: leftProgressView, output: self))
+        .add(plugin: .rightPaginatable(progressView: rightProgressView, output: self))
+        .build()
+
+    private weak var bottomPaginatableInput: PaginatableInput?
+    private weak var topPaginatableInput: PaginatableInput?
+
+    private var isFirstPageLoading = true
+    private var currentLeftPage = 0
+    private var currentRightPage = 0
+
+    private lazy var emptyCell = CollectionSpacerCell.rddm.baseGenerator(with: CollectionSpacerCell.Model(height: 0), and: .class)
+
+    // MARK: - UIViewController
+
+    override func viewDidLoad() {
+        super.viewDidLoad()
+        title = "Collection with two direction pagination"
+
+        configureActivityIndicatorIfNeeded()
+        configureCollectionView()
+        loadFirstPage()
+    }
+
+}
+
+// MARK: - Configuration
+
+private extension HorizontalTwoDirectionPaginatableCollectionViewController {
+
+    func configureActivityIndicatorIfNeeded() {
+        if #available(iOS 13.0, tvOS 13.0, *) {
+            activityIndicator.style = .medium
+        }
+    }
+
+}
+
+// MARK: - Private Methods
+
+private extension HorizontalTwoDirectionPaginatableCollectionViewController {
+
+    func configureCollectionView() {
+        let layout = UICollectionViewFlowLayout()
+        layout.scrollDirection = .horizontal
+        layout.itemSize = .init(width: 300, height: 200)
+        collectionView.setCollectionViewLayout(layout, animated: true)
+    }
+
+    func loadFirstPage() {
+
+        // show loader
+        activityIndicator.isHidden = false
+        activityIndicator.hidesWhenStopped = true
+        activityIndicator.startAnimating()
+
+        // hide footer
+        bottomPaginatableInput?.updatePaginationEnabled(false, at: .forward(.bottom))
+        topPaginatableInput?.updatePaginationEnabled(false, at: .backward(.top))
+        bottomPaginatableInput?.updatePaginationState(.idle, at: .forward(.bottom))
+        topPaginatableInput?.updatePaginationState(.loading, at: .backward(.top))
+
+        // imitation of loading first page
+        delay(.now() + .seconds(3)) { [weak self] in
+            // fill table
+            self?.fillAdapter()
+
+            // hide loader
+            self?.activityIndicator?.stopAnimating()
+
+            // scroll to middle
+            self?.collectionView.scrollToItem(at: Constants.firstPageMiddleIndexPath, at: .centeredVertically, animated: false)
+
+            // show pagination loader if update is needed
+            self?.bottomPaginatableInput?.updatePaginationEnabled(true, at: .forward(.bottom))
+            self?.topPaginatableInput?.updatePaginationEnabled(true, at: .backward(.top))
+        }
+    }
+
+    /// This method is used to fill adapter
+    func fillAdapter() {
+        adapter += emptyCell
+
+        for _ in 0...Constants.pageSize {
+            adapter += makeGenerator()
+        }
+
+        adapter => .reload
+    }
+
+    private func makeGenerator(for scrollDirection: ScrollDirection? = nil) -> CollectionCellGenerator {
+        var currentPage = 0
+        if let scrollDirection = scrollDirection {
+            switch scrollDirection {
+            case .left:
+                currentPage = currentLeftPage
+            case .right:
+                currentPage = currentRightPage
+            }
+        }
+
+        let title = "Random cell \(Int.random(in: 0...1000)) from page \(currentPage)"
+        return TitleCollectionViewCell.rddm.baseGenerator(with: title)
+    }
+
+    func canFillPages() -> Bool {
+        if isFirstPageLoading {
+            isFirstPageLoading.toggle()
+            return false
+        } else {
+            return true
+        }
+    }
+
+    func fillNext() -> Bool {
+        currentRightPage += 1
+
+        var newGenerators = [CollectionCellGenerator]()
+
+        for _ in 0...Constants.pageSize {
+            newGenerators.append(makeGenerator(for: .right))
+        }
+
+        if let lastGenerator = adapter.sections.last?.generators.last {
+            adapter.insert(after: lastGenerator, new: newGenerators)
+        } else {
+            adapter += newGenerators
+            adapter => .reload
+        }
+
+        return currentRightPage != Constants.maxPagesCount
+    }
+
+    func fillPrev() -> Bool {
+        currentLeftPage -= 1
+
+        let newGenerators = (0...Constants.pageSize).map { _ in
+            return makeGenerator(for: .left)
+        }
+        adapter.insert(after: emptyCell, new: newGenerators, with: nil)
+
+        return abs(currentLeftPage) != Constants.maxPagesCount
+    }
+
+}
+
+// MARK: - PaginatableOutput
+
+extension HorizontalTwoDirectionPaginatableCollectionViewController: PaginatableOutput {
+
+    func onPaginationInitialized(with input: PaginatableInput, at direction: PagingDirection) {
+        switch direction {
+        case .backward:
+            topPaginatableInput = input
+        case .forward:
+            bottomPaginatableInput = input
+        }
+    }
+
+    func loadNextPage(with input: PaginatableInput, at direction: PagingDirection) {
+
+        input.updatePaginationState(.loading, at: direction)
+
+        delay(.now() + .seconds(3)) { [weak self, weak input] in
+            let canFillNext = self?.canFillPages() ?? false
+            if canFillNext {
+                let canIterate: Bool
+                switch direction {
+                case .backward:
+                    canIterate = self?.fillPrev() ?? false
+                case .forward:
+                    canIterate = self?.fillNext() ?? false
+                }
+
+                input?.updatePaginationState(.idle, at: direction)
+                input?.updatePaginationEnabled(canIterate, at: direction)
+            } else {
+                input?.updatePaginationState(.error(SampleError.sample), at: direction)
+            }
+        }
+    }
+
+}