From 3a8c32d41b83cf980eb778ab8a9162c32586ae0c Mon Sep 17 00:00:00 2001
From: Dean Herbert <pe@ppy.sh>
Date: Mon, 11 Mar 2019 17:03:01 +0900
Subject: [PATCH] Add the ability for ArchiveModelManager to re-import even
 when existing entry is present

---
 osu.Game/Beatmaps/BeatmapManager.cs      | 12 ++++++
 osu.Game/Database/ArchiveModelManager.cs | 51 ++++++++++++++++++------
 2 files changed, 51 insertions(+), 12 deletions(-)

diff --git a/osu.Game/Beatmaps/BeatmapManager.cs b/osu.Game/Beatmaps/BeatmapManager.cs
index 88f5e777e3..974c023a20 100644
--- a/osu.Game/Beatmaps/BeatmapManager.cs
+++ b/osu.Game/Beatmaps/BeatmapManager.cs
@@ -106,7 +106,10 @@ namespace osu.Game.Beatmaps
 
             foreach (BeatmapInfo b in beatmapSet.Beatmaps)
                 fetchAndPopulateOnlineValues(b, beatmapSet.Beatmaps);
+        }
 
+        protected override void PreImport(BeatmapSetInfo beatmapSet)
+        {
             // check if a set already exists with the same online id, delete if it does.
             if (beatmapSet.OnlineBeatmapSetID != null)
             {
@@ -254,6 +257,15 @@ namespace osu.Game.Beatmaps
         /// <returns>The first result for the provided query, or null if no results were found.</returns>
         public BeatmapSetInfo QueryBeatmapSet(Expression<Func<BeatmapSetInfo, bool>> query) => beatmaps.ConsumableItems.AsNoTracking().FirstOrDefault(query);
 
+        protected override bool CanUndelete(BeatmapSetInfo existing, BeatmapSetInfo import)
+        {
+            if (!base.CanUndelete(existing, import))
+                return false;
+
+            // force re-import if we are not in a sane state.
+            return existing.OnlineBeatmapSetID == import.OnlineBeatmapSetID;
+        }
+
         /// <summary>
         /// Returns a list of all usable <see cref="BeatmapSetInfo"/>s.
         /// </summary>
diff --git a/osu.Game/Database/ArchiveModelManager.cs b/osu.Game/Database/ArchiveModelManager.cs
index 9ec184abd7..3805921ac2 100644
--- a/osu.Game/Database/ArchiveModelManager.cs
+++ b/osu.Game/Database/ArchiveModelManager.cs
@@ -300,21 +300,31 @@ namespace osu.Game.Database
                     {
                         if (!write.IsTransactionLeader) throw new InvalidOperationException($"Ensure there is no parent transaction so errors can correctly be handled by {this}");
 
-                        var existing = CheckForExisting(item);
-
-                        if (existing != null)
-                        {
-                            Undelete(existing);
-                            Logger.Log($"Found existing {typeof(TModel)} for {item} (ID {existing.ID}). Skipping import.", LoggingTarget.Database);
-                            handleEvent(() => ItemAdded?.Invoke(existing, true));
-                            return existing;
-                        }
-
                         if (archive != null)
                             item.Files = createFileInfos(archive, Files);
 
                         Populate(item, archive);
 
+                        var existing = CheckForExisting(item);
+
+                        if (existing != null)
+                        {
+                            if (CanUndelete(existing, item))
+                            {
+                                Undelete(existing);
+                                Logger.Log($"Found existing {typeof(TModel)} for {item} (ID {existing.ID}). Skipping import.", LoggingTarget.Database);
+                                handleEvent(() => ItemAdded?.Invoke(existing, true));
+                                return existing;
+                            }
+                            else
+                            {
+                                Delete(existing);
+                                ModelStore.PurgeDeletable(s => s.ID == existing.ID);
+                            }
+                        }
+
+                        PreImport(item);
+
                         // import to store
                         ModelStore.Add(item);
                     }
@@ -542,12 +552,29 @@ namespace osu.Game.Database
         {
         }
 
+        /// <summary>
+        /// Perform any final actions before the import to database executes.
+        /// </summary>
+        /// <param name="model">The model prepared for import.</param>
+        protected virtual void PreImport(TModel model)
+        {
+        }
+
         /// <summary>
         /// Check whether an existing model already exists for a new import item.
         /// </summary>
-        /// <param name="model">The new model proposed for import. Note that <see cref="Populate"/> has not yet been run on this model.</param>
+        /// <param name="model">The new model proposed for import.
         /// <returns>An existing model which matches the criteria to skip importing, else null.</returns>
-        protected virtual TModel CheckForExisting(TModel model) => model.Hash == null ? null : ModelStore.ConsumableItems.FirstOrDefault(b => b.Hash == model.Hash);
+        protected TModel CheckForExisting(TModel model) => model.Hash == null ? null : ModelStore.ConsumableItems.FirstOrDefault(b => b.Hash == model.Hash);
+
+        /// <summary>
+        /// After an existing <see cref="TModel"/> is found during an import process, the default behaviour is to restore the existing
+        /// item and skip the import. This method allows changing that behaviour.
+        /// </summary>
+        /// <param name="existing">The existing model.</param>
+        /// <param name="import">The newly imported model.</param>
+        /// <returns>Whether the existing model should be restored and used. Returning false will delete the existing a force a re-import.</returns>
+        protected virtual bool CanUndelete(TModel existing, TModel import) => true;
 
         private DbSet<TModel> queryModel() => ContextFactory.Get().Set<TModel>();