auto-fix save data when a custom NPC mod is removed

1 files changed, 94 insertions, 0 deletions

diff --git a/src/SMAPI/Patches/LoadErrorPatch.cs b/src/SMAPI/Patches/LoadErrorPatch.cs
new file mode 100644
index 00000000..87e8ee14
--- /dev/null
+++ b/src/SMAPI/Patches/LoadErrorPatch.cs
@@ -0,0 +1,94 @@
+using System.Collections.Generic;
+using System.Diagnostics.CodeAnalysis;
+using System.Linq;
+using Harmony;
+using StardewModdingAPI.Framework.Patching;
+using StardewValley;
+using StardewValley.Locations;
+
+namespace StardewModdingAPI.Patches
+{
+    /// <summary>A Harmony patch for <see cref="SaveGame"/> which prevents some errors due to broken save data.</summary>
+    /// <remarks>Patch methods must be static for Harmony to work correctly. See the Harmony documentation before renaming patch arguments.</remarks>
+    [SuppressMessage("ReSharper", "InconsistentNaming", Justification = "Argument names are defined by Harmony and methods are named for clarity.")]
+    [SuppressMessage("ReSharper", "IdentifierTypo", Justification = "Argument names are defined by Harmony and methods are named for clarity.")]
+    internal class LoadErrorPatch : IHarmonyPatch
+    {
+        /*********
+        ** Fields
+        *********/
+        /// <summary>Writes messages to the console and log file.</summary>
+        private static IMonitor Monitor;
+
+
+        /*********
+        ** Accessors
+        *********/
+        /// <summary>A unique name for this patch.</summary>
+        public string Name => nameof(LoadErrorPatch);
+
+
+        /*********
+        ** Public methods
+        *********/
+        /// <summary>Construct an instance.</summary>
+        /// <param name="monitor">Writes messages to the console and log file.</param>
+        public LoadErrorPatch(IMonitor monitor)
+        {
+            LoadErrorPatch.Monitor = monitor;
+        }
+
+
+        /// <summary>Apply the Harmony patch.</summary>
+        /// <param name="harmony">The Harmony instance.</param>
+        public void Apply(HarmonyInstance harmony)
+        {
+            harmony.Patch(
+                original: AccessTools.Method(typeof(SaveGame), nameof(SaveGame.loadDataToLocations)),
+                prefix: new HarmonyMethod(this.GetType(), nameof(LoadErrorPatch.Before_SaveGame_LoadDataToLocations))
+            );
+        }
+
+
+        /*********
+        ** Private methods
+        *********/
+        /// <summary>The method to call instead of <see cref="SaveGame.loadDataToLocations"/>.</summary>
+        /// <param name="gamelocations">The game locations being loaded.</param>
+        /// <returns>Returns whether to execute the original method.</returns>
+        private static bool Before_SaveGame_LoadDataToLocations(List<GameLocation> gamelocations)
+        {
+            // get building interiors
+            var interiors =
+                (
+                    from location in gamelocations.OfType<BuildableGameLocation>()
+                    from building in location.buildings
+                    where building.indoors.Value != null
+                    select building.indoors.Value
+                );
+
+            // remove custom NPCs which no longer exist
+            IDictionary<string, string> data = Game1.content.Load<Dictionary<string, string>>("Data\\NPCDispositions");
+            foreach (GameLocation location in gamelocations.Concat(interiors))
+            {
+                foreach (NPC npc in location.characters.ToArray())
+                {
+                    if (npc.isVillager() && !data.ContainsKey(npc.Name))
+                    {
+                        try
+                        {
+                            npc.reloadSprite(); // this won't crash for special villagers like Bouncer
+                        }
+                        catch
+                        {
+                            LoadErrorPatch.Monitor.Log($"Removed invalid villager '{npc.Name}' to avoid a crash when loading save '{Constants.SaveFolderName}'. (Did you remove a custom NPC mod?)", LogLevel.Warn);
+                            location.characters.Remove(npc);
+                        }
+                    }
+                }
+            }
+
+            return true;
+        }
+    }
+}