[Widgets]: (complete) Fixed previous pagination issues for ActiveAppsWidget

AltWidget/Widgets/ActiveAppsWidget.swift

@@ -1,5 +1,5 @@
 //
-//  HomeScreenWidget.swift
+//  ActiveAppsWidget.swift
 //  AltWidgetExtension
 //
 //  Created by Riley Testut on 8/16/23.
@@ -8,10 +8,6 @@
 
 import SwiftUI
 import WidgetKit
-import CoreData
-
-import AltStoreCore
-import AltSign
 
 private extension Color
 {
@@ -24,24 +20,40 @@ private extension Color
 //@available(iOS 17, *)
 struct ActiveAppsWidget: Widget
 {
-    private var viewModel = PaginationViewModel.getNewInstance(
-        "ActiveApps" + UUID().uuidString
-    )
+    // only constants/singleton what needs to be for the life of all widgets of ActiveAppsWidget type
+    // should be declared as instance or class fields for ActiveAppWidgets
     
+    // NOTE: The computed property (widget)body is recomputed/re-run for every
+    //       'type' refers to struct/class types and 'kind' refers to the tag which the widget is marked with
+    //       multiple instances of same type or multiple types can be tagged with same 'kind'
+    //       or each instance of same kind too, can be tagged as different(unique) 'kind'
+    // 1. widget-resizing(of same type)
+    // 2. new widget addition(of same type)
     public var body: some WidgetConfiguration {
         if #available(iOS 17, *)
         {
+            let kind = "ActiveApps"
+            let widgetID = kind + "-" + UUID().uuidString
+
+            let holder = PaginationDataHolder.instance(widgetID)
+            let timelineProvider = AppsTimelineProvider(holder)             // pass the holder
+            
+            // each instance of this widget type is identified by unique 'kind' tag
+            // so that a reloadTimelineFor(kind:) will trigger reload only for that instance
             let staticConfig =  StaticConfiguration(
-                kind: viewModel.widgetID,
-                provider: AppsTimelineProvider(viewModel)
+                kind: widgetID,
+                provider: timelineProvider
             ) { entry in
-                ActiveAppsWidgetView(entry: entry, viewModel: viewModel)
+                // actual view of the widget
+                // this gets recreated for each trigger from the scheduled timeline entries provided by the timeline provider
+                // NOTE: widget views do not adhere to statefulness
+                // so, Combine constructs such as @State, @StateObject, @ObservedObject etc are simply ignored
+                ActiveAppsWidgetView(entry: entry, widgetID: widgetID)
             }
             .supportedFamilies([.systemMedium])
             .configurationDisplayName("Active Apps")
             .description("View remaining days until your active apps expire. Tap the countdown timers to refresh them in the background.")
             
-            // this widgetConfiguration is requested/drawn once per widget per process lifecycle
             return staticConfig
         }
         else
@@ -57,17 +69,11 @@ struct ActiveAppsWidget: Widget
 private struct ActiveAppsWidgetView: View
 {
     var entry: AppsEntry
-    
-    @ObservedObject private var viewModel: PaginationViewModel
+    var widgetID: String
     
     @Environment(\.colorScheme)
     private var colorScheme
-    
-    init(entry: AppsEntry, viewModel: PaginationViewModel){
-        self.entry = entry
-        self.viewModel = viewModel
-    }
-    
+        
     var body: some View {
         Group {
             if entry.apps.isEmpty
@@ -95,17 +101,14 @@ private struct ActiveAppsWidgetView: View
     private var content: some View {
         GeometryReader { (geometry) in
             
-            let MAX_ROWS_PER_PAGE = PaginationViewModel.MAX_ROWS_PER_PAGE
+            let MAX_ROWS_PER_PAGE = PaginationDataHolder.MAX_ROWS_PER_PAGE
             
             let preferredRowHeight = (geometry.size.height / Double(MAX_ROWS_PER_PAGE)) - 8
             let rowHeight = min(preferredRowHeight, geometry.size.height / 2)
             
             HStack(alignment: .center) {
-                
-//                VStack(spacing: 12) {
                 LazyVStack(spacing: 12) {
-                    ForEach($viewModel.sliding_window, id: \.bundleIdentifier) { app in
-                        let app = app.wrappedValue      // remove the binding
+                    ForEach(Array(entry.apps.enumerated()), id: \.offset) { index, app in
                         
                         let icon: UIImage = app.icon ?? UIImage(named: "SideStore")!
                         
@@ -160,6 +163,8 @@ private struct ActiveAppsWidgetView: View
                                     .padding(.all, -5)
                             }
                             .font(.system(size: 16, weight: .semibold, design: .rounded))
+                            // this modifier invalidates the view (disables userinteraction and shows a blinking effect)
+                            // until new timeline events occur, unless a observable boolean state is presented as parameter
                             .invalidatableContent()
                             .activatesRefreshAllAppsIntent()
                         }
@@ -174,9 +179,9 @@ private struct ActiveAppsWidgetView: View
                     Image(systemName: "arrow.up")
                         .resizable()
                         .frame(width: buttonWidth, height: buttonWidth)
-                        .mask(Capsule())
                         .opacity(0.3)
-                        .pageUpButton(widgetID: viewModel.widgetID)
+                        // .mask(Capsule())
+                        .pageUpButton(widgetID)
                     
                     Spacer()
                     
@@ -184,8 +189,8 @@ private struct ActiveAppsWidgetView: View
                         .resizable()
                         .frame(width: buttonWidth, height: buttonWidth)
                         .opacity(0.3)
-                        .mask(Capsule())
-                        .pageDownButton(widgetID: viewModel.widgetID)
+                        // .mask(Capsule())
+                        .pageDownButton(widgetID)
                 }
                 .padding(.vertical)
             }

AltWidget/Widgets/PaginationDataHolder.swift

@@ -0,0 +1,72 @@
+//
+//  PaginationViewModel.swift
+//  AltStore
+//
+//  Created by Magesh K on 09/01/25.
+//  Copyright © 2025 SideStore. All rights reserved.
+//
+
+import Foundation
+
+class PaginationDataHolder: ObservableObject {
+    
+    public static let MAX_ROWS_PER_PAGE: UInt = 3
+
+    private static var instances: [String:PaginationDataHolder] = [:]
+    
+    public static func instance(_ widgetID: String) -> PaginationDataHolder {
+        let instance = PaginationDataHolder(widgetID)
+        Self.instances[widgetID] = instance
+        return instance
+    }
+
+    public static func holder(for widgetID: String) -> PaginationDataHolder? {
+        return Self.instances[widgetID]
+    }
+    
+    private lazy var serializationQ = {
+        DispatchQueue(label: widgetID)
+    }()
+
+    public let widgetID: String
+    private var currentPageindex: UInt = 0
+    
+    private init(_ widgetID: String){
+        self.widgetID = widgetID
+    }
+    
+    deinit {
+        Self.instances.removeValue(forKey: widgetID)
+    }
+    
+    public func updateDirection(_ direction: Direction) {
+        switch(direction){
+        case .up:
+            let pageIndex = Int(currentPageindex)
+            currentPageindex = UInt(max(0, pageIndex-1))
+        case .down:
+            // upper-bounds is checked when computing targetPageIndex in getUpdatedData
+            currentPageindex+=1
+        }
+    }
+    
+    public func getUpdatedData(entries: [AppSnapshot]) -> [AppSnapshot] {
+        let count = UInt(entries.count)
+        
+        if(count == 0) { return entries }
+        
+        let availablePages = UInt(ceil(Double(entries.count) / Double(Self.MAX_ROWS_PER_PAGE)))
+        let targetPageIndex: UInt = currentPageindex < availablePages ? currentPageindex : availablePages-1
+
+        // do blocking update
+        serializationQ.sync {
+            self.currentPageindex = targetPageIndex     // preserve it
+        }
+        
+        let startIndex = targetPageIndex * Self.MAX_ROWS_PER_PAGE
+        let estimatedEndIndex = startIndex + (Self.MAX_ROWS_PER_PAGE-1)
+        let endIndex: UInt = min(count-1, estimatedEndIndex)
+        let currentPageEntries = entries[Int(startIndex) ... Int(endIndex)]
+        return Array(currentPageEntries)
+    }
+}

AltWidget/Widgets/PaginationViewModel.swift

@@ -1,105 +0,0 @@
-//
-//  PaginationViewModel.swift
-//  AltStore
-//
-//  Created by Magesh K on 09/01/25.
-//  Copyright © 2025 SideStore. All rights reserved.
-//
-
-import Foundation
-import Combine
-
-class PaginationViewModel: ObservableObject {
-    
-    private static var instances: [String:PaginationViewModel] = [:]
-    
-    public static let MAX_ROWS_PER_PAGE = 3
-    
-    @Published public var sliding_window: [AppSnapshot] = []
-    @Published public var refreshed: Bool = false
-    
-    private init(){}
-    
-    private var _widgetID: String?
-    public lazy var widgetID: String = {
-        return _widgetID!
-    }()
-    
-    public static func getNewInstance(_ widgetID: String) -> PaginationViewModel {
-        let instance = PaginationViewModel()
-        PaginationViewModel.instances[widgetID] = instance
-        instance._widgetID = widgetID
-        return instance
-    }
-
-    public static func instance(_ widgetID: String) -> PaginationViewModel? {
-        return PaginationViewModel.instances[widgetID]
-    }
-    
-    public private(set) var backup_entries: [AppSnapshot] = []
-    
-    private var r_queue: [AppSnapshot] = []
-    private var l_queue: [AppSnapshot] = []
-    
-    private var lastIndex: Int { r_queue.count - 1 }
-
-    public func setEntries(_ entries: [AppSnapshot]) {
-        r_queue = entries
-        backup_entries = entries
-    }
-    
-    public func handlePagination(_ direction: Direction) {
-        
-        var sliding_window = Array(sliding_window)
-        var l_queue = Array(l_queue)
-        var r_queue = Array(r_queue)
-        
-        // If entries is empty, do nothing
-        guard !backup_entries.isEmpty else {
-            sliding_window.removeAll()
-            return
-        }
-        
-        switch direction {
-        case .up:
-            // move window contents to left-q since we are moving right side
-            if !sliding_window.isEmpty {
-                // take the window as-is and put it to right of l_queue
-                l_queue.append(contentsOf: sliding_window)
-            }
-            
-            // clear the window
-            sliding_window.removeAll()
-        
-            let size = min(r_queue.count, Self.MAX_ROWS_PER_PAGE)
-            for _ in 0..<size {
-                if !r_queue.isEmpty {
-                    sliding_window.append(r_queue.removeFirst())
-                }
-            }
-            
-        case .down:
-            // move window contents to right-q since we are moving left side
-            if !sliding_window.isEmpty {
-                // take the window as-is and put it to left of r_queue
-                r_queue.insert(contentsOf: sliding_window, at: 0)
-            }
-            
-            // clear the window
-            sliding_window.removeAll()
-            
-            let size = min(l_queue.count, Self.MAX_ROWS_PER_PAGE)
-            for _ in 0..<size {
-                sliding_window.insert(l_queue.removeLast(), at: 0)
-            }
-        }
-        
-        if !sliding_window.isEmpty {
-            // commit
-            self.sliding_window = sliding_window
-            self.l_queue = l_queue
-            self.r_queue = r_queue
-            self.refreshed = true
-        }
-    }
-}