feat: make image attachments uploading in the queue

Mastodon/Scene/Compose/ComposeViewController.swift

@@ -147,8 +147,9 @@ extension ComposeViewController {
         ])
         
         collectionView.delegate = self
-        let longPressReorderGesture = UILongPressGestureRecognizer(target: self, action: #selector(ComposeViewController.longPressReorderGestureHandler(_:)))
+        // Note: do not allow reorder due to the images display order following the upload time
-        collectionView.addGestureRecognizer(longPressReorderGesture)
+        // let longPressReorderGesture = UILongPressGestureRecognizer(target: self, action: #selector(ComposeViewController.longPressReorderGestureHandler(_:)))
+        // collectionView.addGestureRecognizer(longPressReorderGesture)
         viewModel.setupDiffableDataSource(
             for: collectionView,
             dependency: self,
@@ -321,7 +322,7 @@ extension ComposeViewController {
         dismiss(animated: true, completion: nil)
     }
     
-    
+    /* Do not allow reorder image due to image display order following the update time
     @objc private func longPressReorderGestureHandler(_ sender: UILongPressGestureRecognizer) {
         switch(sender.state) {
         case .began:
@@ -347,6 +348,7 @@ extension ComposeViewController {
             collectionView.cancelInteractiveMovement()
         }
     }
+     */
     
 }
 

Mastodon/Scene/Compose/ComposeViewModel+Diffable.swift

@@ -24,27 +24,29 @@ extension ComposeViewModel {
             textEditorViewTextAttributesDelegate: textEditorViewTextAttributesDelegate,
             composeStatusAttachmentTableViewCellDelegate: composeStatusAttachmentTableViewCellDelegate
         )
+
+        // Note: do not allow reorder due to the images display order following the upload time
+        // diffableDataSource.reorderingHandlers.canReorderItem = { item in
+        //     switch item {
+        //     case .attachment:       return true
+        //     default:                return false
+        //     }
+        //
+        // }
+        // diffableDataSource.reorderingHandlers.didReorder = { [weak self] transaction in
+        //     guard let self = self else { return }
+        //
+        //     let items = transaction.finalSnapshot.itemIdentifiers
+        //     var attachmentServices: [MastodonAttachmentService] = []
+        //     for item in items {
+        //         guard case let .attachment(attachmentService) = item else { continue }
+        //         attachmentServices.append(attachmentService)
+        //     }
+        //     self.attachmentServices.value = attachmentServices
+        // }
+        //
         
-        diffableDataSource.reorderingHandlers.canReorderItem = { item in
-            switch item {
-            case .attachment:       return true
-            default:                return false
-            }
-            
-        }
-        diffableDataSource.reorderingHandlers.didReorder = { [weak self] transaction in
-            guard let self = self else { return }
-            
-            let items = transaction.finalSnapshot.itemIdentifiers
-            var attachmentServices: [MastodonAttachmentService] = []
-            for item in items {
-                guard case let .attachment(attachmentService) = item else { continue }
-                attachmentServices.append(attachmentService)
-            }
-            self.attachmentServices.value = attachmentServices
-        }
         self.diffableDataSource = diffableDataSource
-        
         var snapshot = NSDiffableDataSourceSnapshot<ComposeStatusSection, ComposeStatusItem>()
         snapshot.appendSections([.repliedTo, .status, .attachment])
         switch composeKind {

Mastodon/Scene/Compose/ComposeViewModel.swift

@@ -137,7 +137,7 @@ final class ComposeViewModel {
             }
             .store(in: &disposeBag)
         
-        // bind snapshot
+        // bind snapshot and drive service upload state
         attachmentServices
             .receive(on: DispatchQueue.main)
             .sink { [weak self] attachmentServices in
@@ -154,6 +154,26 @@ final class ComposeViewModel {
                 snapshot.appendItems(items, toSection: .attachment)
                 
                 diffableDataSource.apply(snapshot)
+                
+                // make image upload in the queue
+                for attachmentService in attachmentServices {
+                    // skip when prefix N task when task finish OR fail OR uploading
+                    guard let currentState = attachmentService.uploadStateMachine.currentState else { break }
+                    if currentState is MastodonAttachmentService.UploadState.Fail {
+                        continue
+                    }
+                    if currentState is MastodonAttachmentService.UploadState.Finish {
+                        continue
+                    }
+                    if currentState is MastodonAttachmentService.UploadState.Uploading {
+                        break
+                    }
+                    // trigger uploading one by one
+                    if currentState is MastodonAttachmentService.UploadState.Initial {
+                        attachmentService.uploadStateMachine.enter(MastodonAttachmentService.UploadState.Uploading.self)
+                        break
+                    }
+                }
             }
             .store(in: &disposeBag)
     }

Mastodon/Service/MastodonAttachmentService/MastodonAttachmentService+UploadState.swift

@@ -31,8 +31,15 @@ extension MastodonAttachmentService.UploadState {
     class Initial: MastodonAttachmentService.UploadState {
         override func isValidNextState(_ stateClass: AnyClass) -> Bool {
             guard service?.authenticationBox != nil else { return false }
-            guard service?.imageData.value != nil else { return false }
+            if stateClass == Initial.self {
-            return stateClass == Uploading.self
+                return true
+            }
+
+            if service?.imageData.value != nil {
+                return stateClass == Uploading.self
+            } else {
+                return stateClass == Fail.self
+            }
         }
     }
     

Mastodon/Service/MastodonAttachmentService/MastodonAttachmentService.swift

@@ -64,15 +64,14 @@ final class MastodonAttachmentService {
                 switch completion {
                 case .failure(let error):
                     self.error.value = error
+                    self.uploadStateMachine.enter(UploadState.Fail.self)
                 case .finished:
                     break
                 }
             } receiveValue: { [weak self] imageData in
                 guard let self = self else { return }
                 self.imageData.value = imageData
-                
+                self.uploadStateMachine.enter(UploadState.Initial.self)
-                // Try pre-upload attachment for current active user
-                self.uploadStateMachine.enter(UploadState.Uploading.self)
             }
             .store(in: &disposeBag)
     }
@@ -89,9 +88,7 @@ final class MastodonAttachmentService {
         setupServiceObserver()
         
         imageData.value = image.jpegData(compressionQuality: 0.75)
-
+        uploadStateMachine.enter(UploadState.Initial.self)
-        // Try pre-upload attachment for current active user
-        uploadStateMachine.enter(UploadState.Uploading.self)
     }
     
     init(
@@ -106,9 +103,7 @@ final class MastodonAttachmentService {
         setupServiceObserver()
         
         self.imageData.value = imageData
-
+        uploadStateMachine.enter(UploadState.Initial.self)
-        // Try pre-upload attachment for current active user
-        uploadStateMachine.enter(UploadState.Uploading.self)
     }
     
     private func setupServiceObserver() {