Update download-all progress view to use gauge.

Author: CalebRas

Shared/Supporting Files/Views/DownloadOfflineResourcesView.swift

@@ -22,17 +22,26 @@ struct DownloadOfflineResourcesView: View {
     /// The action to dismiss the view.
     @Environment(\.dismiss) private var dismiss
 
+    /// The progress of a download-all operation.
+    @State private var downloadAllProgress: Progress?
+    
     /// The view models for the on-demand resource requests.
     @State private var onDemandResources: [String: OnDemandResource] = [:]
 
-    /// The current state of the "download all on-demand resources" request.
-    @State private var downloadAllRequestState: OnDemandResource.RequestState = .notStarted
-    
     /// A Boolean value indicating whether all of the `onDemandResources` have successfully downloaded.
-    private var allResourcesAreDownloaded: Bool {
-        guard !onDemandResources.isEmpty else { return false }
-        return onDemandResources.values
-            .allSatisfy { $0.requestState == .downloaded }
+    private var allResourcesAreDownloaded: Bool { uniqueRequestStates == [.downloaded] }
+    
+    /// A Boolean value indicating whether there is an on going download-all operation.
+    private var isDownloadingAll: Bool { downloadAllProgress != nil }
+    
+    /// A Boolean value indicating whether there is an in progress download.
+    private var isDownloadingResource: Bool { uniqueRequestStates.contains(.inProgress) }
+    
+    /// The distinct request states of all on-demand resources.
+    private var uniqueRequestStates: Set<OnDemandResource.RequestState> {
+        onDemandResources.values.reduce(into: Set()) { result, resource in
+            result.insert(resource.requestState)
+        }
     }
 
     /// Returns the on-demand resource for the given sample.
@@ -45,24 +54,24 @@ struct DownloadOfflineResourcesView: View {
             Form {
                 Section {
                     Button {
-                        downloadAllRequestState = .inProgress
+                        downloadAllProgress = Progress()
                     } label: {
                         Label {
                             Text("Download All")
                         } icon: {
-                            switch downloadAllRequestState {
-                            case .inProgress:
-                                ProgressView()
-                            case .downloaded:
+                            if let downloadAllProgress {
+                                ProgressView(downloadAllProgress)
+                                    .progressViewStyle(GaugeProgressViewStyle())
+                            } else if allResourcesAreDownloaded {
                                 Image(systemName: "checkmark.circle")
                                     .foregroundStyle(.secondary)
-                            default:
+                            } else {
                                 Image(systemName: "arrow.down.circle")
                             }
                         }
                         .frame(maxWidth: .infinity)
                     }
-                    .disabled(onDemandResources.isEmpty || downloadAllRequestState != .notStarted || allResourcesAreDownloaded)
+                    .disabled(onDemandResources.isEmpty || isDownloadingAll || allResourcesAreDownloaded)
                 }
                 Section {
                     List(samples, id: \.name) { sample in
@@ -78,7 +87,7 @@ struct DownloadOfflineResourcesView: View {
             .navigationBarTitleDisplayMode(.inline)
             .toolbar {
                 ToolbarItem(placement: .confirmationAction) {
-                    if onDemandResources.values.contains(where: { $0.requestState == .inProgress }) {
+                    if isDownloadingResource {
                         Button("Cancel") {
                             for resource in onDemandResources.values where resource.requestState == .inProgress {
                                 resource.cancel()
@@ -108,13 +117,13 @@ struct DownloadOfflineResourcesView: View {
                     return resources
                 }
             }
-            .task(id: downloadAllRequestState) {
-                guard downloadAllRequestState == .inProgress else { return }
+            .task(id: isDownloadingAll) {
+                guard isDownloadingAll else { return }
                 await downloadAll()
             }
-            .onChange(of: allResourcesAreDownloaded) {
-                guard allResourcesAreDownloaded else { return }
-                downloadAllRequestState = .downloaded
+            .onChange(of: isDownloadingResource) {
+                guard isDownloadingAll, !isDownloadingResource else { return }
+                downloadAllProgress = nil
             }
         }
     }
@@ -123,8 +132,13 @@ struct DownloadOfflineResourcesView: View {
     /// - Note: The system may purge the resources at any time after the request object is deallocated.
     private func downloadAll() async {
         await withTaskGroup { group in
-            for resource in onDemandResources.values where resource.isDownloadable {
-                group.addTask(operation: resource.download)
+            for resource in onDemandResources.values {
+                if resource.isDownloadable {
+                    group.addTask(operation: resource.download)
+                    downloadAllProgress?.addChildUnits(resource.progress)
+                } else if resource.requestState == .inProgress {
+                    downloadAllProgress?.addChildUnits(resource.progress)
+                }
             }
         }
 
@@ -197,3 +211,12 @@ private struct GaugeProgressViewStyle: ProgressViewStyle {
         }
     }
 }
+
+private extension Progress {
+    /// Adds a process object and its unit count as a suboperation of a progress tree.
+    /// - Parameter progress: The progress instance to add to the progress tree.
+    func addChildUnits(_ progress: Progress) {
+        addChild(progress, withPendingUnitCount: progress.totalUnitCount)
+        totalUnitCount += progress.totalUnitCount
+    }
+}