[AltStore] Basic Account tab

AltStore/Model/DatabaseManager.swift

@@ -38,6 +38,35 @@ public extension DatabaseManager
             completionHandler(error)
         }
     }
+    
+    func signOut(completionHandler: @escaping (Error?) -> Void)
+    {
+        self.persistentContainer.performBackgroundTask { (context) in
+            if let account = self.activeAccount(in: context)
+            {
+                account.isActiveAccount = false
+            }
+            
+            if let team = self.activeTeam(in: context)
+            {
+                team.isActiveTeam = false
+            }
+            
+            do
+            {
+                try context.save()
+                
+                Keychain.shared.reset()
+                
+                completionHandler(nil)
+            }
+            catch
+            {
+                print("Failed to save when signing out.", error)
+                completionHandler(error)
+            }
+        }
+    }
 }
 
 public extension DatabaseManager
@@ -46,3 +75,22 @@ public extension DatabaseManager
         return self.persistentContainer.viewContext
     }
 }
+
+extension DatabaseManager
+{
+    func activeAccount(in context: NSManagedObjectContext = DatabaseManager.shared.viewContext) -> Account?
+    {
+        let predicate = NSPredicate(format: "%K == YES", #keyPath(Account.isActiveAccount))
+        
+        let activeAccount = Account.first(satisfying: predicate, in: context)
+        return activeAccount
+    }
+    
+    func activeTeam(in context: NSManagedObjectContext = DatabaseManager.shared.viewContext) -> Team?
+    {
+        let predicate = NSPredicate(format: "%K == YES", #keyPath(Team.isActiveTeam))
+        
+        let activeTeam = Team.first(satisfying: predicate, in: context)
+        return activeTeam
+    }
+}