Treat shelves as containers in pipes

src/main/java/com/sk89q/craftbook/mechanics/pipe/Pipes.java

@@ -351,16 +351,7 @@ private void startPipe(Block block, List<ItemStack> items, boolean request) {
             Block fac = block.getRelative(p.getFacing());
             Material facType = fac.getType();
 
-            if (facType == Material.CHEST
-                    || facType == Material.TRAPPED_CHEST
-                    || facType == Material.DROPPER
-                    || facType == Material.DISPENSER
-                    || facType == Material.HOPPER
-                    || facType == Material.BARREL
-                    || facType == Material.CHISELED_BOOKSHELF
-                    || facType == Material.CRAFTER
-                    || facType == Material.DECORATED_POT
-                    || Tag.SHULKER_BOXES.isTagged(facType)) {
+            if (InventoryUtil.hasGenericInventory(facType)) {
                 for (ItemStack stack : ((InventoryHolder) fac.getState()).getInventory().getContents()) {
 
                     if (!ItemUtil.isStackValid(stack))
@@ -369,12 +360,18 @@ private void startPipe(Block block, List<ItemStack> items, boolean request) {
                     if(!ItemUtil.doesItemPassFilters(stack, filters, exceptions))
                         continue;
 
-                    items.add(stack);
+                    items.add(stack.clone());
                     ((InventoryHolder) fac.getState()).getInventory().removeItem(stack);
                     if (pipeStackPerPull)
                         break;
                 }
 
+                // syncDisplayedContainer captures its state AFTER the removals;
+                // updating a state from before them writes the old contents
+                // back into the world.
+                if (!items.isEmpty())
+                    InventoryUtil.syncDisplayedContainer(fac);
+
                 PipeSuckEvent event = new PipeSuckEvent(block, new ArrayList<>(items), fac);
                 Bukkit.getPluginManager().callEvent(event);
                 items.clear();

src/main/java/com/sk89q/craftbook/util/InventoryUtil.java

@@ -1,6 +1,7 @@
 package com.sk89q.craftbook.util;
 
 import org.bukkit.Material;
+import org.bukkit.Tag;
 import org.bukkit.block.Block;
 import org.bukkit.block.BrewingStand;
 import org.bukkit.block.Chest;
@@ -67,6 +68,8 @@ public static List<ItemStack> addItemsToInventory(InventoryHolder container, boo
                 ((Chest) ((DoubleChestInventory) container.getInventory()).getLeftSide().getHolder()).update(true);
                 ((Chest) ((DoubleChestInventory) container.getInventory()).getRightSide().getHolder()).update(true);
             }
+            if (container instanceof org.bukkit.block.BlockState)
+                syncDisplayedContainer(((org.bukkit.block.BlockState) container).getBlock());
             //if(container instanceof BlockState && update)
             //    ((BlockState) container).update();
             return leftovers;
@@ -211,6 +214,7 @@ public static List<ItemStack> addItemsToChiseledBookshelf(ChiseledBookshelf chis
         stacks = Arrays.stream(stacks).filter(item -> ItemUtil.isAStorableBook(item)).toArray(ItemStack[]::new);
 
         leftovers.addAll(chiseledBookshelf.getInventory().addItem(stacks).values());
+        syncDisplayedContainer(chiseledBookshelf.getBlock());
 
         return leftovers;
     }
@@ -339,13 +343,67 @@ public static boolean fitsInSlot(ItemStack stack, ItemStack slot) {
     public static boolean doesBlockHaveInventory(Block block) {
 
         switch(block.getType()) {
+            case FURNACE:
+            case BLAST_FURNACE:
+            case SMOKER:
+            case BREWING_STAND:
+                return true;
+            default:
+                return hasGenericInventory(block.getType());
+        }
+    }
+
+    /**
+     * Publishes a display container's contents after a plugin-side mutation.
+     * Player interaction is the only thing vanilla syncs on, so a pipe edit
+     * otherwise leaves clients rendering stale contents. The two mechanisms
+     * differ: chiseled bookshelves render and emit comparator signal from
+     * their slot_X_occupied blockstate properties, while shelves render
+     * straight from block-entity data, which a fresh post-mutation state
+     * update rebroadcasts. Every other container is a no-op here.
+     *
+     * @param block The container block that was mutated.
+     */
+    public static void syncDisplayedContainer(Block block) {
+        Material type = block.getType();
+        if (type == Material.CHISELED_BOOKSHELF) {
+            org.bukkit.block.BlockState state = block.getState();
+            if (!(state instanceof ChiseledBookshelf))
+                return;
+            Inventory inv = ((ChiseledBookshelf) state).getInventory();
+            org.bukkit.block.data.BlockData data = block.getBlockData();
+            if (!(data instanceof org.bukkit.block.data.type.ChiseledBookshelf))
+                return;
+            org.bukkit.block.data.type.ChiseledBookshelf occupancy = (org.bukkit.block.data.type.ChiseledBookshelf) data;
+            for (int i = 0; i < inv.getSize(); i++)
+                occupancy.setSlotOccupied(i, ItemUtil.isStackValid(inv.getItem(i)));
+            block.setBlockData(occupancy, false);
+        } else if (Tag.WOODEN_SHELVES.isTagged(type)) {
+            block.getState().update(true, false);
+        }
+    }
+
+    /**
+     * Checks whether a material is a container whose whole inventory is plain
+     * item slots, safe to insert into or pull from generically. Furnaces,
+     * smokers, blast furnaces and brewing stands are containers too but have
+     * role-specific slots (fuel, ingredient, result), so their callers route
+     * them through dedicated branches instead of this family.
+     *
+     * @param type The material to check.
+     * @return If the material is a generic container.
+     */
+    public static boolean hasGenericInventory(Material type) {
+        switch(type) {
             case CHEST:
             case TRAPPED_CHEST:
             case DROPPER:
             case DISPENSER:
-            case FURNACE:
-            case BREWING_STAND:
             case HOPPER:
+            case BARREL:
+            case CHISELED_BOOKSHELF:
+            case DECORATED_POT:
+            case CRAFTER:
             case WHITE_SHULKER_BOX:
             case ORANGE_SHULKER_BOX:
             case MAGENTA_SHULKER_BOX:
@@ -363,15 +421,12 @@ public static boolean doesBlockHaveInventory(Block block) {
             case BLACK_SHULKER_BOX:
             case RED_SHULKER_BOX:
             case SHULKER_BOX:
-            case BLAST_FURNACE:
-            case SMOKER:
-            case BARREL:
-            case CHISELED_BOOKSHELF:
-            case DECORATED_POT:
-            case CRAFTER:
                 return true;
             default:
-                return false;
+                // Only the open-ended family stays a tag lookup: shelf materials
+                // grow with each new wood type, while the shulker colour set has
+                // been fixed since 1.11.
+                return Tag.WOODEN_SHELVES.isTagged(type);
         }
     }