feat: add Idempotency-Key` header for status

Mastodon/Diffiable/Item/ComposeStatusPollItem.swift

@@ -70,7 +70,7 @@ extension ComposeStatusPollItem {
             hasher.combine(id)
         }
 
-        enum ExpiresOption: Equatable, Hashable, CaseIterable {
+        enum ExpiresOption: String, Equatable, Hashable, CaseIterable {
             case thirtyMinutes
             case oneHour
             case sixHours

Mastodon/Scene/Compose/ComposeViewModel+PublishState.swift

@@ -107,6 +107,8 @@ extension ComposeViewModel.PublishState {
                 return subscriptions
             }()
             
+            let idempotencyKey = viewModel.idempotencyKey.value
+            
             publishingSubscription = Publishers.MergeMany(updateMediaQuerySubscriptions)
                 .collect()
                 .flatMap { attachments -> AnyPublisher<Mastodon.Response.Content<Mastodon.Entity.Status>, Error> in
@@ -122,6 +124,7 @@ extension ComposeViewModel.PublishState {
                     )
                     return viewModel.context.apiService.publishStatus(
                         domain: domain,
+                        idempotencyKey: idempotencyKey,
                         query: query,
                         mastodonAuthenticationBox: mastodonAuthenticationBox
                     )

Mastodon/Scene/Compose/ComposeViewModel.swift

@@ -58,7 +58,10 @@ final class ComposeViewModel: NSObject {
     }()
     private(set) lazy var publishStateMachinePublisher = CurrentValueSubject<PublishState?, Never>(nil)
     private(set) var publishDate = Date()   // update it when enter Publishing state
-
+    
+    // TODO: group post material into Hashable class
+    var idempotencyKey = CurrentValueSubject<String, Never>(UUID().uuidString)
+    
     // UI & UX
     let title: CurrentValueSubject<String, Never>
     let shouldDismiss = CurrentValueSubject<Bool, Never>(true)
@@ -383,6 +386,56 @@ final class ComposeViewModel: NSObject {
             self.isPollToolbarButtonEnabled.value = !shouldPollDisable
         })
         .store(in: &disposeBag)
+        
+        // calculate `Idempotency-Key`
+        let content = Publishers.CombineLatest3(
+            composeStatusAttribute.isContentWarningComposing,
+            composeStatusAttribute.contentWarningContent,
+            composeStatusAttribute.composeContent
+        )
+        .map { isContentWarningComposing, contentWarningContent, composeContent -> String in
+            if isContentWarningComposing {
+                return contentWarningContent + (composeContent ?? "")
+            } else {
+                return composeContent ?? ""
+            }
+        }
+        let attachmentIDs = attachmentServices.map { attachments -> String in
+            let attachmentIDs = attachments.compactMap { $0.attachment.value?.id }
+            return attachmentIDs.joined(separator: ",")
+        }
+        let pollOptionsAndDuration = Publishers.CombineLatest3(
+            isPollComposing,
+            pollOptionAttributes,
+            pollExpiresOptionAttribute.expiresOption
+        )
+        .map { isPollComposing, pollOptionAttributes, expiresOption -> String in
+            guard isPollComposing else {
+                return ""
+            }
+            
+            let pollOptions = pollOptionAttributes.map { $0.option.value }.joined(separator: ",")
+            return pollOptions + expiresOption.rawValue
+        }
+        
+        Publishers.CombineLatest4(
+            content,
+            attachmentIDs,
+            pollOptionsAndDuration,
+            selectedStatusVisibility
+        )
+        .map { content, attachmentIDs, pollOptionsAndDuration, selectedStatusVisibility -> String in
+            var hasher = Hasher()
+            hasher.combine(content)
+            hasher.combine(attachmentIDs)
+            hasher.combine(pollOptionsAndDuration)
+            hasher.combine(selectedStatusVisibility.visibility.rawValue)
+            let hashValue = hasher.finalize()
+            return "\(hashValue)"
+        }
+        .assign(to: \.value, on: idempotencyKey)
+        .store(in: &disposeBag)
+        
     }
     
     deinit {

Mastodon/Service/APIService/APIService+Status+Publish.swift

@@ -16,6 +16,7 @@ extension APIService {
 
     func publishStatus(
         domain: String,
+        idempotencyKey: String?,
         query: Mastodon.API.Statuses.PublishStatusQuery,
         mastodonAuthenticationBox: MastodonAuthenticationBox
     ) -> AnyPublisher<Mastodon.Response.Content<Mastodon.Entity.Status>, Error> {
@@ -24,6 +25,7 @@ extension APIService {
         return Mastodon.API.Statuses.publishStatus(
             session: session,
             domain: domain,
+            idempotencyKey: idempotencyKey,
             query: query,
             authorization: authorization
         )

MastodonIntent/SendPostIntentHandler.swift

@@ -55,9 +55,12 @@ final class SendPostIntentHandler: NSObject, SendPostIntentHandling {
                 spoilerText: nil,
                 visibility: visibility
             )
+            
+            let idempotencyKey = UUID().uuidString
 
             APIService.shared.publishStatus(
                 domain: box.domain,
+                idempotencyKey: idempotencyKey,
                 query: query,
                 mastodonAuthenticationBox: box
             )

MastodonSDK/Sources/MastodonSDK/API/Mastodon+API+Statuses.swift

@@ -77,14 +77,18 @@ extension Mastodon.API.Statuses {
     public static func publishStatus(
         session: URLSession,
         domain: String,
+        idempotencyKey: String?,
         query: PublishStatusQuery,
         authorization: Mastodon.API.OAuth.Authorization?
     ) -> AnyPublisher<Mastodon.Response.Content<Mastodon.Entity.Status>, Error>  {
-        let request = Mastodon.API.post(
+        var request = Mastodon.API.post(
             url: publishNewStatusEndpointURL(domain: domain),
             query: query,
             authorization: authorization
         )
+        if let idempotencyKey = idempotencyKey {
+            request.setValue(idempotencyKey, forHTTPHeaderField: "Idempotency-Key")
+        }
         return session.dataTaskPublisher(for: request)
             .tryMap { data, response in
                 let value = try Mastodon.API.decode(type: Mastodon.Entity.Status.self, from: data, response: response)

ShareActionExtension/Scene/ShareViewModel.swift

@@ -346,6 +346,7 @@ extension ShareViewModel {
                 )
                 return APIService.shared.publishStatus(
                     domain: domain,
+                    idempotencyKey: nil,    // FIXME:
                     query: query,
                     mastodonAuthenticationBox: mastodonAuthenticationBox
                 )