From bce40f328850f41da5265f7a69e4d8d976b7e9e2 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Micha=C5=82=20Buczek?= <michal.buczek@protonmail.com>
Date: Fri, 7 Dec 2018 17:19:02 +0100
Subject: [PATCH] Fix #593: Bookmark order migration (#602)

---
 Client/Application/Migration.swift |  5 +++++
 Data/models/Bookmark.swift         | 34 ++++++++++++++++++++++++++++++
 2 files changed, 39 insertions(+)

diff --git a/Client/Application/Migration.swift b/Client/Application/Migration.swift
index 0e5b7720906..4861a265525 100644
--- a/Client/Application/Migration.swift
+++ b/Client/Application/Migration.swift
@@ -97,9 +97,14 @@ extension Preferences {
         // This needs to be translated to our new preference.
         Preferences.General.isFirstLaunch.value = Preferences.DAU.lastLaunchInfo.value == nil
         
+        // Core Data
+        
         // Migrate the shield overrides
         migrateShieldOverrides()
         
+        Bookmark.migrateOrder(forFavorites: true)
+        Bookmark.migrateOrder(forFavorites: false)
+        
         Preferences.Migration.completed.value = true
     }
     
diff --git a/Data/models/Bookmark.swift b/Data/models/Bookmark.swift
index 95b8c232c34..7f4bd0fc2e5 100644
--- a/Data/models/Bookmark.swift
+++ b/Data/models/Bookmark.swift
@@ -309,6 +309,40 @@ public final class Bookmark: NSManagedObject, WebsitePresentable, Syncable, CRUD
         DataController.save(context: frc.managedObjectContext)
     }
     
+    /// Takes all Bookmarks and Favorites from 1.6 and sets correct order for them.
+    /// 1.6 had few bugs with reordering which we want to avoid, in particular non-reordered bookmarks on 1.6
+    /// all have order set to 0 which makes sorting confusing.
+    /// In migration we take all bookmarks using the same sorting method as on 1.6 and add a proper `order`
+    /// attribute to them. The goal is to have all bookmarks with a proper unique order number set.
+    public class func migrateOrder(parentFolder: Bookmark? = nil,
+                                   forFavorites: Bool,
+                                   context: NSManagedObjectContext = DataController.newBackgroundContext()) {
+        
+        let predicate = forFavorites ?
+            NSPredicate(format: "isFavorite == true") : allBookmarksOfAGivenLevelPredicate(parent: parentFolder)
+        
+        let orderSort = NSSortDescriptor(key: #keyPath(Bookmark.order), ascending: true)
+        let folderSort = NSSortDescriptor(key: #keyPath(Bookmark.isFolder), ascending: false)
+        let createdSort = NSSortDescriptor(key: #keyPath(Bookmark.created), ascending: true)
+        
+        let sort = [orderSort, folderSort, createdSort]
+        
+        guard let allBookmarks = all(where: predicate, sortDescriptors: sort, context: context),
+              !allBookmarks.isEmpty else {
+            return
+        }
+        
+        for (i, bookmark) in allBookmarks.enumerated() {
+            bookmark.order = Int16(i)
+            // Calling this method recursively to get ordering for nested bookmarks
+            if !forFavorites && bookmark.isFolder {
+                migrateOrder(parentFolder: bookmark, forFavorites: forFavorites, context: context)
+            }
+        }
+        
+        DataController.save(context: context)
+    }
+    
     // TODO: Migration syncUUIDS still needs to be solved
     // Should only ever be used for migration from old db
     // Always uses worker context