Add persistent storage for party inventories

gradle.properties

@@ -36,7 +36,7 @@ mod_name=Stalinium
 # The license of the mod. Review your options at https://choosealicense.com/. All Rights Reserved is the default.
 mod_license=MIT
 # The mod version. See https://semver.org/
-mod_version=0.2.1
+mod_version=0.2.2
 # The group ID for the mod. It is only important when publishing as an artifact to a Maven repository.
 # This should match the base package used for the mod sources.
 # See https://maven.apache.org/guides/mini/guide-naming-conventions.html

src/main/java/net/krituximon/stalinium/block/entity/StaliniumCacheBlockEntity.java

@@ -3,6 +3,7 @@
 package net.krituximon.stalinium.block.entity;
 
 import net.krituximon.stalinium.event.ComradeHandler;
+import net.krituximon.stalinium.util.StaliniumPartyCacheData;
 import net.minecraft.core.BlockPos;
 import net.minecraft.core.HolderLookup;
 import net.minecraft.core.registries.Registries;
@@ -29,22 +30,39 @@ import java.util.concurrent.ConcurrentHashMap;
 
 public class StaliniumCacheBlockEntity extends BlockEntity {
     private static final int SIZE = 27;
-    private static final Map<UUID, SimpleContainer> PARTY_INVENTORIES = new ConcurrentHashMap<>();
 
     public StaliniumCacheBlockEntity(BlockPos pos, BlockState state) {
         super(ModBlockEntities.STALINIUM_CACHE_BE.get(), pos, state);
     }
-    
+
+    /**
+     * Obtain – and create if necessary – the inventory that belongs to the player’s party.
+     */
     public static SimpleContainer getPartyInventory(@Nullable Player who) {
+        UUID key;
         if (who == null) {
-            UUID defaultKey = UUID.randomUUID(); 
-            return PARTY_INVENTORIES.computeIfAbsent(defaultKey, __ -> new SimpleContainer(SIZE));
+            key = new UUID(0L, 0L);                // world-wide default dump
+        } else {
+            Optional<ComradeHandler.Party> opt = ComradeHandler.findPartyOf(who.getUUID());
+            key = opt.map(p -> p.leader).orElse(who.getUUID());
         }
-        Optional<ComradeHandler.Party> opt = ComradeHandler.findPartyOf(who.getUUID());
-        UUID key = opt.map(p -> p.leader).orElse(who.getUUID());
-        return PARTY_INVENTORIES.computeIfAbsent(key, __ -> new SimpleContainer(SIZE));
+
+        // We keep the containers in the world-persistent SavedData
+        Level lvl = who != null ? who.level() : null;
+        if (lvl == null || lvl.isClientSide)           // should never happen on the server
+            return new SimpleContainer(SIZE);
+
+        StaliniumPartyCacheData data = StaliniumPartyCacheData.get(lvl);
+        return data.getOrCreate(key);
     }
 
+    /* ---------- helper to mark the SavedData dirty whenever the container changes ---------- */
+    public static void markDirty(Level level, UUID key) {
+        if (level.isClientSide) return;
+        StaliniumPartyCacheData.get(level).setDirty();
+    }
+
+    // drop-logic unchanged …
     public void drops() {
         SimpleContainer inv = getPartyInventory(null);
         SimpleContainer tmp = new SimpleContainer(SIZE);

src/main/java/net/krituximon/stalinium/util/StaliniumPartyCacheData.java

@@ -0,0 +1,101 @@
+package net.krituximon.stalinium.util;
+
+import net.minecraft.core.HolderLookup;
+import net.minecraft.core.NonNullList;
+import net.minecraft.nbt.*;
+import net.minecraft.server.level.ServerLevel;
+import net.minecraft.world.ContainerHelper;
+import net.minecraft.world.SimpleContainer;
+import net.minecraft.world.item.ItemStack;
+import net.minecraft.world.level.Level;
+import net.minecraft.world.level.saveddata.SavedData;
+
+import java.util.HashMap;
+import java.util.Map;
+import java.util.UUID;
+
+/**
+ * World-persistent store for every party’s cache inventory.
+ * Saved/loaded automatically by the game.
+ */
+public class StaliniumPartyCacheData extends SavedData {
+    private static final String DATA_NAME = "stalinium_party_caches";
+    private static final int SIZE = 27;
+
+    private final Map<UUID, SimpleContainer> inventories = new HashMap<>();
+
+    /* ------------------------------------------------- */
+    /* helper that produces an inventory wired to setDirty */
+    /* ------------------------------------------------- */
+
+    private SimpleContainer newContainer() {
+        /* Every time the container changes, flag the data object. */
+        return new SimpleContainer(SIZE) {
+            @Override
+            public void setChanged() {
+                super.setChanged();
+                StaliniumPartyCacheData.this.setDirty();
+            }
+        };
+    }
+
+    /* ---------------- public API ---------------- */
+
+    /** Get (or lazily create) the inventory for the given party / player. */
+    public SimpleContainer getOrCreate(UUID id) {
+        return inventories.computeIfAbsent(id, __ -> newContainer());
+    }
+
+    /* ---------------- persistence ---------------- */
+
+    @Override
+    public CompoundTag save(CompoundTag tag, HolderLookup.Provider provider) {
+        ListTag list = new ListTag();
+
+        inventories.forEach((uuid, container) -> {
+            CompoundTag entry = new CompoundTag();
+            entry.putUUID("Id", uuid);
+
+            NonNullList<ItemStack> tmp =
+                    NonNullList.withSize(container.getContainerSize(), ItemStack.EMPTY);
+            for (int i = 0; i < container.getContainerSize(); ++i) {
+                tmp.set(i, container.getItem(i));
+            }
+            ContainerHelper.saveAllItems(entry, tmp, provider);
+            list.add(entry);
+        });
+
+        tag.put("Inventories", list);
+        return tag;
+    }
+
+    /** Deserializer – now also uses {@link #newContainer()} so the hook survives loading. */
+    public static StaliniumPartyCacheData load(CompoundTag tag, HolderLookup.Provider provider) {
+        StaliniumPartyCacheData data = new StaliniumPartyCacheData();
+        ListTag list = tag.getList("Inventories", Tag.TAG_COMPOUND);
+
+        list.forEach(t -> {
+            CompoundTag entry = (CompoundTag) t;
+            UUID id = entry.getUUID("Id");
+
+            SimpleContainer cont = data.newContainer();
+            NonNullList<ItemStack> tmp = NonNullList.withSize(SIZE, ItemStack.EMPTY);
+            ContainerHelper.loadAllItems(entry, tmp, provider);
+            for (int i = 0; i < SIZE; ++i) cont.setItem(i, tmp.get(i));
+
+            data.inventories.put(id, cont);
+        });
+
+        return data;
+    }
+
+    /* ---------------- factory / access ---------------- */
+
+    private static final SavedData.Factory<StaliniumPartyCacheData> FACTORY =
+            new SavedData.Factory<>(StaliniumPartyCacheData::new, StaliniumPartyCacheData::load);
+
+    public static StaliniumPartyCacheData get(Level lvl) {
+        if (lvl.isClientSide) throw new IllegalStateException("Called on client");
+        return ((ServerLevel) lvl).getDataStorage().computeIfAbsent(FACTORY, DATA_NAME);
+    }
+}