Cache active account ID in CoreData

See #251

Tusker/API/MastodonController.swift

@@ -23,6 +23,7 @@ class MastodonController: ObservableObject {
     @available(*, message: "do something less dumb")
     static var first: MastodonController { all.first!.value }
     
+    @MainActor
     static func getForAccount(_ account: UserAccountInfo) -> MastodonController {
         if let controller = all[account] {
             return controller
@@ -51,6 +52,7 @@ class MastodonController: ObservableObject {
     let client: Client!
     let instanceFeatures = InstanceFeatures()
     
+    @Published private(set) var accountID: String?
     @Published private(set) var account: Account!
     @Published private(set) var instance: Instance?
     @Published private(set) var instanceInfo: InstanceInfo!
@@ -69,6 +71,8 @@ class MastodonController: ObservableObject {
         accountInfo != nil
     }
 
+    // main-actor b/c fetchActiveAccountID and fetchActiveInstance use the viewContext
+    @MainActor
     init(instanceURL: URL, accountInfo: UserAccountInfo?) {
         self.instanceURL = instanceURL
         self.accountInfo = accountInfo
@@ -81,6 +85,7 @@ class MastodonController: ObservableObject {
         self.client.accessToken = accountInfo?.accessToken
         
         if !transient {
+            fetchActiveAccountID()
             fetchActiveInstance()
         }
         
@@ -119,6 +124,7 @@ class MastodonController: ObservableObject {
             .store(in: &cancellables)
     }
     
+    @MainActor
     convenience init(instanceURL: URL, transient: Bool) {
         precondition(transient, "account info must be provided if transient is false")
         self.init(instanceURL: instanceURL, accountInfo: nil)
@@ -242,13 +248,14 @@ class MastodonController: ObservableObject {
                     DispatchQueue.main.async {
                         self.account = account
                     }
-                    self.persistentContainer.backgroundContext.perform {
-                        if let accountMO = self.persistentContainer.account(for: account.id, in: self.persistentContainer.backgroundContext) {
+                    let context = self.persistentContainer.backgroundContext
+                    context.perform {
+                        if let accountMO = self.persistentContainer.account(for: account.id, in: context) {
                             accountMO.updateFrom(apiAccount: account, container: self.persistentContainer)
+                            accountMO.active = true
                         } else {
-                            // the first time the user's account is added to the store,
-                            // increment its reference count so that it's never removed
-                            self.persistentContainer.addOrUpdate(account: account)
+                            let account = self.persistentContainer.addOrUpdateSynchronously(account: account, in: context)
+                            account.active = true
                         }
                         completion?(.success(account))
                     }
@@ -367,16 +374,22 @@ class MastodonController: ObservableObject {
         }
     }
     
+    @MainActor
+    private func fetchActiveAccountID() {
+        let req = AccountMO.fetchRequest()
+        req.predicate = NSPredicate(format: "active = YES")
+        if let activeAccount = try? persistentContainer.viewContext.fetch(req).first {
+            accountID = activeAccount.id
+        }
+    }
+    
+    @MainActor
     private func fetchActiveInstance() {
-        persistentContainer.performBackgroundTask { context in
-            if let activeInstance = try? context.fetch(ActiveInstance.fetchRequest()).first {
+        if let activeInstance = try? persistentContainer.viewContext.fetch(ActiveInstance.fetchRequest()).first {
             let info = InstanceInfo(activeInstance: activeInstance)
-                DispatchQueue.main.async {
             self.instanceInfo = info
         }
     }
-        }
-    }
     
     func getCustomEmojis(completion: @escaping ([Emoji]) -> Void) {
         if let emojis = self.customEmojis {

Tusker/CoreData/AccountMO.swift

@@ -25,6 +25,8 @@ public final class AccountMO: NSManagedObject, AccountProtocol {
     }
     
     @NSManaged public var acct: String
+    /// Whether this AccountMO is the active (logged-in) account.
+    @NSManaged public var active: Bool
     @NSManaged public var avatar: URL?
     @NSManaged public var botCD: Bool
     @NSManaged public var createdAt: Date

Tusker/CoreData/MastodonCachePersistentStore.swift

@@ -311,6 +311,14 @@ class MastodonCachePersistentStore: NSPersistentCloudKitContainer {
         }
     }
     
+    /// The caller is responsible for calling this on a queue appropriate for `context`.
+    func addOrUpdateSynchronously(account: Account, in context: NSManagedObjectContext) -> AccountMO {
+        let accountMO = self.upsert(account: account, in: context)
+        self.save(context: context)
+        self.accountSubject.send(account.id)
+        return accountMO
+    }
+    
     func relationship(forAccount id: String, in context: NSManagedObjectContext? = nil) -> RelationshipMO? {
         let context = context ?? viewContext
         let request: NSFetchRequest<RelationshipMO> = RelationshipMO.fetchRequest()

Tusker/CoreData/Tusker.xcdatamodeld/Tusker.xcdatamodel/contents

@@ -2,6 +2,7 @@
 <model type="com.apple.IDECoreDataModeler.DataModel" documentVersion="1.0" lastSavedToolsVersion="21754" systemVersion="22D49" minimumToolsVersion="Automatic" sourceLanguage="Swift" userDefinedModelVersionIdentifier="">
     <entity name="Account" representedClassName="AccountMO" syncable="YES">
         <attribute name="acct" attributeType="String"/>
+        <attribute name="active" attributeType="Boolean" defaultValueString="NO" usesScalarValueType="YES"/>
         <attribute name="avatar" optional="YES" attributeType="URI"/>
         <attribute name="botCD" optional="YES" attributeType="Boolean" usesScalarValueType="YES"/>
         <attribute name="createdAt" attributeType="Date" usesScalarValueType="NO"/>