Queue vote actions while requests run

Author: weiran

DesignSystem/Sources/DesignSystem/Components/PostDisplayView.swift

@@ -27,6 +27,12 @@ public struct PostDisplayView: View {
     @State private var displayedUpvoted: Bool
     @State private var displayedBookmarked: Bool
     @State private var displayedVoteLinks: VoteLinks?
+    @State private var pendingVoteIntent: VoteIntent?
+
+    private enum VoteIntent {
+        case upvote
+        case unvote
+    }
 
     public init(
         post: Post,
@@ -127,6 +133,11 @@ public struct PostDisplayView: View {
                 displayedUpvoted = newValue
             }
         }
+        .onChange(of: votingState?.canUnvote) { _ in
+            if let voteLinks = post.voteLinks {
+                displayedVoteLinks = voteLinks
+            }
+        }
     }
 
     private var upvotePill: some View {
@@ -221,58 +232,91 @@ public struct PostDisplayView: View {
 
     private func makeUpvoteAction() -> (() -> Void)? {
         return {
-            guard !isSubmittingUpvote else { return }
-
-            let isCurrentlyUpvoted = displayedUpvoted
             let currentVoteLinks = displayedVoteLinks ?? post.voteLinks
             let canUnvote = currentVoteLinks?.unvote != nil
+            let intent: VoteIntent = (displayedUpvoted && canUnvote) ? .unvote : .upvote
+            Task { @MainActor in
+                handleVoteIntent(intent)
+            }
+        }
+    }
 
-            // If already upvoted and can unvote, perform unvote
-            if isCurrentlyUpvoted && canUnvote {
-                guard let onUnvoteTap else { return }
-                isSubmittingUpvote = true
-                let previousScore = displayedScore
-                let previousUpvoted = displayedUpvoted
-                let previousVoteLinks = currentVoteLinks
-                displayedUpvoted = false
-                displayedScore -= 1
-                displayedVoteLinks = VoteLinks(upvote: previousVoteLinks?.upvote, unvote: nil)
-                Task {
-                    let success = await onUnvoteTap()
-                    await MainActor.run {
-                        if !success {
-                            displayedScore = previousScore
-                            displayedUpvoted = previousUpvoted
-                            displayedVoteLinks = previousVoteLinks
-                        }
-                        isSubmittingUpvote = false
+    @MainActor
+    private func handleVoteIntent(_ intent: VoteIntent) {
+        if isSubmittingUpvote {
+            pendingVoteIntent = intent
+            return
+        }
+        executeVoteIntent(intent)
+    }
+
+    @MainActor
+    private func executeVoteIntent(_ intent: VoteIntent) {
+        pendingVoteIntent = nil
+
+        let currentVoteLinks = displayedVoteLinks ?? post.voteLinks
+        let previousScore = displayedScore
+        let previousUpvoted = displayedUpvoted
+        let previousVoteLinks = currentVoteLinks
+
+        switch intent {
+        case .unvote:
+            guard let onUnvoteTap else { return }
+            guard displayedUpvoted else { return }
+
+            isSubmittingUpvote = true
+            displayedUpvoted = false
+            displayedScore -= 1
+            displayedVoteLinks = VoteLinks(upvote: previousVoteLinks?.upvote, unvote: nil)
+
+            Task {
+                let success = await onUnvoteTap()
+                await MainActor.run {
+                    if !success {
+                        displayedScore = previousScore
+                        displayedUpvoted = previousUpvoted
+                        displayedVoteLinks = previousVoteLinks
                     }
+                    isSubmittingUpvote = false
+                    processPendingVoteIntentIfNeeded()
                 }
-            } else {
-                // Perform upvote
-                guard let onUpvoteTap else { return }
-                isSubmittingUpvote = true
-                let previousScore = displayedScore
-                let previousUpvoted = displayedUpvoted
-                let previousVoteLinks = currentVoteLinks
-                displayedUpvoted = true
-                displayedScore += 1
-                displayedVoteLinks = derivedVoteLinks(afterUpvoteFrom: previousVoteLinks)
-                Task {
-                    let success = await onUpvoteTap()
-                    await MainActor.run {
-                        if !success {
-                            displayedScore = previousScore
-                            displayedUpvoted = previousUpvoted
-                            displayedVoteLinks = previousVoteLinks
-                        }
-                        isSubmittingUpvote = false
+            }
+
+        case .upvote:
+            guard let onUpvoteTap else { return }
+            guard !displayedUpvoted else { return }
+            guard currentVoteLinks?.upvote != nil else { return }
+
+            isSubmittingUpvote = true
+            displayedUpvoted = true
+            displayedScore += 1
+            displayedVoteLinks = derivedVoteLinks(afterUpvoteFrom: previousVoteLinks)
+
+            Task {
+                let success = await onUpvoteTap()
+                await MainActor.run {
+                    if !success {
+                        displayedScore = previousScore
+                        displayedUpvoted = previousUpvoted
+                        displayedVoteLinks = previousVoteLinks
+                    } else {
+                        displayedVoteLinks = derivedVoteLinks(afterUpvoteFrom: displayedVoteLinks ?? previousVoteLinks)
                     }
+                    isSubmittingUpvote = false
+                    processPendingVoteIntentIfNeeded()
                 }
             }
         }
     }
 
+    @MainActor
+    private func processPendingVoteIntentIfNeeded() {
+        if let nextIntent = pendingVoteIntent {
+            pendingVoteIntent = nil
+            handleVoteIntent(nextIntent)
+        }
+    }
+
     private func derivedVoteLinks(afterUpvoteFrom voteLinks: VoteLinks?) -> VoteLinks? {
         guard let voteLinks else { return nil }
         if voteLinks.unvote != nil {