added function to persistentdataprovider

enzevalos_iphone/SwiftUI/Contact/SimpleMailRowView.swift

@@ -53,8 +53,9 @@ struct SimpleMailRowView <M: DisplayMail>: View {
     }
 }
 
+/*
 struct SimpleMailRow_Previews: PreviewProvider {
     static var previews: some View {
         SimpleMailRowView(mail: ProxyData.PlainMail)
     }
-}
+}*/

enzevalos_iphone/persistentData/PersistentDataProvider.swift

@@ -420,6 +420,53 @@ class PersistentDataProvider {
         }
     }
     
+    
+    func setCategoryOpenability(category:CategoryIDType,filter: @escaping MailFilter) throws{
+        var performError: Error? = nil
+        let queue = DispatchQueue(label: "AddCategoryEntriesToDatabase", qos: .userInitiated)
+        queue.async {
+            
+            let predicate = NSPredicate(format:
+                                            
+                //filter for mails not categorized by this category (no entry in inCategory for this category)
+                "SUBQUERY(inCategory, $category, $category.categoryName == %@ AND $category.openability > -1).@count == 0"
+                                        
+            ,category)
+            
+            let taskContext = self.newTaskContext()
+            let sortDescriptors = [NSSortDescriptor(key: "date", ascending: true)]
+            if let unclassifiedMailRecords = self.generateFetchResultController(
+                enitityName: MailRecord.entityName,
+                sortDescriptors: sortDescriptors,
+                predicate: predicate,
+                propertiesToFetch: nil,
+                fetchLimit: PersistentDataProvider.FETCHLIMIT,
+                inViewContext: false,
+                context: taskContext
+            ).fetchedObjects as? [MailRecord]{
+                taskContext.performAndWait {
+                    
+                    for mail in unclassifiedMailRecords {
+                        let categoryRec = CategoryRecord(context: taskContext)
+                        categoryRec.categoryName = category
+                        categoryRec.openability = filter(mail).rawValue
+                        mail.addToInCategory(categoryRec)
+                    }
+                    
+                    //save
+                    do {try self.save(taskContext: taskContext)}
+                    catch {performError = error}
+                }
+            }else{
+                performError = PersistentDataError.missingData
+            }
+            
+        }
+        if let error = performError {
+            throw error
+        }
+    }
+    
     func save(taskContext: NSManagedObjectContext) throws -> () {
         // Save all insertions and deletions from the context to the store.
         if taskContext.hasChanges {
@@ -681,6 +728,45 @@ class PersistentDataProvider {
         return controller
     }
     
+    
+    
+    func generateNoMailsController()->NSFetchedResultsController<MailRecord> {
+        let sortDescriptors = [NSSortDescriptor(key: "date", ascending: true)]
+        return generateFetchResultController(enitityName: MailRecord.entityName, sortDescriptors: sortDescriptors, predicate: nil, propertiesToFetch: nil, fetchLimit: PersistentDataProvider.FETCHLIMIT, inViewContext: true, context: nil)
+    }
+    
+    func generateFetchedMailsInFolderAndCategoryResultsController(folderpath: String, category:String, andPredicate:NSPredicate=NSPredicate(value: true), important:Bool = false) -> NSFetchedResultsController<MailRecord> {
+        let sortDescriptors = [NSSortDescriptor(key: "date", ascending: false)]
+        
+        let mustOpenPredicate = NSPredicate(format:
+                                                
+            //filter for mails that must be opened by this category
+            "SUBQUERY(inCategory, $category, $category.categoryName == %@ AND $category.openability == 3).@count > 0"
+                                    
+        ,category)
+        
+        let openablePredicate = NSPredicate(format:
+                                        
+            //filter for mails beeing openable by this category (at least .canOpen (= 1))
+            "SUBQUERY(inCategory, $category, $category.categoryName == %@ AND $category.openability > \(important ? 1 : 0)).@count > 0 " +
+            //where no other categories have a .mustOpen (= 3)
+            "AND SUBQUERY(inCategory, $category, $category.categoryName != %@ AND $category.openability == 3).@count == 0"
+                                    
+        ,category)
+        
+        //an eMail is in this category if it must open it OR it can open it and no other kategory mustOPen
+        let inCategoryPredicate = NSCompoundPredicate(type: .or, subpredicates: [mustOpenPredicate,openablePredicate])
+        
+        let inFolderPredicate = NSPredicate(format: "inFolder.path == %@", folderpath)
+        
+        //it also has to be in this folder (folders have higher rank than categories)
+        let predicate = NSCompoundPredicate(type: .and, subpredicates: [inCategoryPredicate,inFolderPredicate,andPredicate])
+        
+        return generateFetchResultController(enitityName: MailRecord.entityName, sortDescriptors: sortDescriptors, predicate: predicate, propertiesToFetch: nil, fetchLimit: PersistentDataProvider.FETCHLIMIT, inViewContext: true, context: nil)
+    }
+    
+    
+    
     func generateFetchedMailsInFolderResultsController(folderpath: String) -> NSFetchedResultsController<MailRecord> {
         let sortDescriptors = [NSSortDescriptor(key: "date", ascending: true)]
         let predicate = NSPredicate(format: "inFolder.path == %@", folderpath)