Let pocket computer on lecterns wrap the peripheral below

- Shuffle some of the accessors in PocketComputerItem around, to make them easier to use in the lectern code. I still don't think we've got a good interface here. We could possibly move more of the update code into PocketBrain, and just have PocketComputerItem responsible for syncing brain<->stack state. Something to fiddle with, but not sure it would be any cleaner. - Set the bottom peripheral when the pocket computer is placed in the lectern (and on block updates, etc...), and clear it when removed. Again, the code here is uglier than I would like (particularly with all the instanceofs). I did wonder about having some LecternBehaviour class, which holds the printout/pocket-specific state, but there's so many places we need to hook in (and they're so different between the two), I'm not sure it's worth it right now. Fixes #2126, closes #2223.
2026-09-16 14:21:24 +00:00 · 2025-12-15 19:22:40 +00:00
parent 5f704b2c58
commit 9ad3b03946
3 changed files with 91 additions and 41 deletions
@@ -4,10 +4,14 @@

 package dan200.computercraft.shared.lectern;

+import dan200.computercraft.core.computer.ComputerSide;
 import dan200.computercraft.shared.ModRegistry;
 import dan200.computercraft.shared.media.items.PrintoutItem;
+import dan200.computercraft.shared.pocket.core.PocketHolder;
+import dan200.computercraft.shared.pocket.items.PocketComputerItem;
 import dan200.computercraft.shared.util.BlockEntityHelpers;
 import net.minecraft.core.BlockPos;
+import net.minecraft.core.Direction;
 import net.minecraft.server.level.ServerLevel;
 import net.minecraft.stats.Stats;
 import net.minecraft.util.RandomSource;
@@ -21,6 +25,7 @@ import net.minecraft.world.item.Items;
 import net.minecraft.world.item.context.UseOnContext;
 import net.minecraft.world.level.BlockGetter;
 import net.minecraft.world.level.Level;
+import net.minecraft.world.level.block.Block;
 import net.minecraft.world.level.block.Blocks;
 import net.minecraft.world.level.block.LecternBlock;
 import net.minecraft.world.level.block.entity.BlockEntity;
@@ -102,6 +107,16 @@ public class CustomLecternBlock extends LecternBlock {
        return new ItemStack(Items.LECTERN);
    }

+    @Override
+    @Deprecated
+    public final void neighborChanged(BlockState state, Level level, BlockPos pos, Block neighbourBlock, BlockPos neighbourPos, boolean isMoving) {
+        if (!level.isClientSide() && pos.relative(Direction.DOWN).equals(neighbourPos)
+            && level.getBlockEntity(pos) instanceof CustomLecternBlockEntity lectern && lectern.getItem().getItem() instanceof PocketComputerItem
+        ) {
+            lectern.markRefreshPeripheral();
+        }
+    }
+
    @Override
    public void tick(BlockState state, ServerLevel level, BlockPos pos, RandomSource random) {
        // If we've no lectern, remove it.
@@ -133,6 +148,12 @@ public class CustomLecternBlock extends LecternBlock {
        var entity = new ItemEntity(level, pos.getX() + 0.5 + dx, pos.getY() + 1, pos.getZ() + 0.5 + dz, stack);
        entity.setDefaultPickUpDelay();
        level.addFreshEntity(entity);
+
+        // If we're a pocket computer, update the holder and clear the peripheral.
+        if (stack.getItem() instanceof PocketComputerItem pocket) {
+            var brain = pocket.getBrain(new PocketHolder.ItemEntityHolder(entity), stack);
+            if (brain != null) brain.computer().setPeripheral(ComputerSide.BOTTOM, null);
+        }
    }

    @Override
@@ -4,17 +4,22 @@

 package dan200.computercraft.shared.lectern;

+import dan200.computercraft.api.peripheral.IPeripheral;
+import dan200.computercraft.core.computer.ComputerSide;
 import dan200.computercraft.shared.ModRegistry;
 import dan200.computercraft.shared.container.BasicContainer;
 import dan200.computercraft.shared.container.SingleContainerData;
 import dan200.computercraft.shared.media.PrintoutMenu;
 import dan200.computercraft.shared.media.items.PrintoutItem;
 import dan200.computercraft.shared.network.container.ComputerContainerData;
+import dan200.computercraft.shared.platform.ComponentAccess;
 import dan200.computercraft.shared.platform.PlatformHelper;
+import dan200.computercraft.shared.pocket.core.PocketBrain;
 import dan200.computercraft.shared.pocket.core.PocketHolder;
 import dan200.computercraft.shared.pocket.items.PocketComputerItem;
 import dan200.computercraft.shared.util.BlockEntityHelpers;
 import net.minecraft.core.BlockPos;
+import net.minecraft.core.Direction;
 import net.minecraft.nbt.CompoundTag;
 import net.minecraft.nbt.Tag;
 import net.minecraft.network.protocol.Packet;
@@ -30,6 +35,7 @@ import net.minecraft.world.level.block.LecternBlock;
 import net.minecraft.world.level.block.entity.BlockEntity;
 import net.minecraft.world.level.block.entity.LecternBlockEntity;
 import net.minecraft.world.level.block.state.BlockState;
+import org.jspecify.annotations.Nullable;

 import java.util.AbstractList;
 import java.util.List;
@@ -46,10 +52,21 @@ public final class CustomLecternBlockEntity extends BlockEntity {
    private ItemStack item = ItemStack.EMPTY;
    private int page, pageCount;

+    private final PocketHolder.LecternHolder pocketHolder = new PocketHolder.LecternHolder(this);
+    private @Nullable PocketBrain activePocketBrain;
+    private final ComponentAccess<IPeripheral> peripherals = PlatformHelper.get().createPeripheralAccess(this, d -> markRefreshPeripheral());
+    private boolean refreshPeripheral;
+
    public CustomLecternBlockEntity(BlockPos pos, BlockState blockState) {
        super(ModRegistry.BlockEntities.LECTERN.get(), pos, blockState);
    }

+    @Override
+    public void clearRemoved() {
+        refreshPeripheral = true;
+        super.clearRemoved();
+    }
+
    public ItemStack getItem() {
        return item;
    }
@@ -79,11 +96,27 @@ public final class CustomLecternBlockEntity extends BlockEntity {
        } else {
            pageCount = page = 0;
        }
+
+        activePocketBrain = null;
+    }
+
+    void markRefreshPeripheral() {
+        refreshPeripheral = true;
    }

    void tick() {
        if (item.getItem() instanceof PocketComputerItem pocket) {
-            pocket.tick(item, new PocketHolder.LecternHolder(this), false);
+            // Get our pocket computer, and tick it.
+            var brain = pocket.getOrCreateBrain(pocketHolder, item);
+            brain.computer().keepAlive();
+            pocket.tick(item, pocketHolder, brain);
+
+            // Update the peripheral if the peripheral or brain has changed.
+            if (refreshPeripheral || brain != activePocketBrain) {
+                refreshPeripheral = false;
+                activePocketBrain = brain;
+                brain.computer().setPeripheral(ComputerSide.BOTTOM, peripherals.get(Direction.DOWN));
+            }
        }
    }

@@ -138,11 +171,11 @@ public final class CustomLecternBlockEntity extends BlockEntity {
                new PrintoutContainerData()
            ), getItem().getDisplayName()));
        } else if (item.getItem() instanceof PocketComputerItem pocket) {
-            var holder = new PocketHolder.LecternHolder(this);
-            var computer = pocket.getAndTurnOnServerComputer(item, holder);
+            var computer = pocket.getOrCreateBrain(pocketHolder, item).computer();
+            computer.turnOn();
            PlatformHelper.get().openMenu(
                player, item.getHoverName(),
-                (id, inv, entity) -> new PocketComputerLecternMenu(id, inv, holder, computer),
+                (id, inv, entity) -> new PocketComputerLecternMenu(id, inv, pocketHolder, computer),
                new PocketComputerLecternMenu.Data(new ComputerContainerData(computer, item), getBlockPos())
            );
        }
@@ -31,7 +31,6 @@ import net.minecraft.ChatFormatting;
 import net.minecraft.nbt.CompoundTag;
 import net.minecraft.network.chat.Component;
 import net.minecraft.server.MinecraftServer;
-import net.minecraft.server.level.ServerLevel;
 import net.minecraft.server.level.ServerPlayer;
 import net.minecraft.world.InteractionHand;
 import net.minecraft.world.InteractionResult;
@@ -80,25 +79,16 @@ public class PocketComputerItem extends Item implements IComputerItem, IColoured
    /**
     * Tick a pocket computer.
     *
-     * @param stack   The current pocket computer stack.
-     * @param holder  The entity holding the pocket item.
-     * @param passive If set, the pocket computer will not be created if it doesn't exist, and will not be kept alive.
+     * @param stack  The current pocket computer stack.
+     * @param holder The entity holding the pocket item.
+     * @param brain  The pocket brain.
     */
-    public void tick(ItemStack stack, PocketHolder holder, boolean passive) {
-        PocketBrain brain;
-        if (passive) {
-            var computer = getServerComputer(holder.level().getServer(), stack);
-            if (computer == null) return;
-            brain = computer.getBrain();
-        } else {
-            brain = getOrCreateBrain(holder.level(), holder, stack);
-            brain.computer().keepAlive();
-        }
-
+    public void tick(ItemStack stack, PocketHolder holder, PocketBrain brain) {
        // Update pocket upgrade
        var upgrade = brain.getUpgrade();
        if (upgrade != null) upgrade.upgrade().update(brain, brain.computer().getPeripheral(ComputerSide.BACK));

+        // Sync pocket state back to the item
        if (updateItem(stack, brain)) holder.setChanged();
    }

@@ -150,7 +140,10 @@ public class PocketComputerItem extends Item implements IComputerItem, IColoured
        if (slot < 0) return;

        // If we're in the inventory, create a computer and keep it alive.
-        tick(stack, new PocketHolder.PlayerHolder(player, slot), false);
+        var holder = new PocketHolder.PlayerHolder(player, slot);
+        var brain = getOrCreateBrain(holder, stack);
+        brain.computer().keepAlive();
+        tick(stack, holder, brain);
    }

    @ForgeOverride
@@ -160,7 +153,9 @@ public class PocketComputerItem extends Item implements IComputerItem, IColoured

        // If we're an item entity, tick an already existing computer (as to update the position), but do not keep the
        // computer alive.
-        tick(stack, new PocketHolder.ItemEntityHolder(entity), true);
+        var holder = new PocketHolder.ItemEntityHolder(entity);
+        var brain = getBrain(holder, stack);
+        if (brain != null) tick(stack, holder, brain);

        return false;
    }
@@ -175,7 +170,7 @@ public class PocketComputerItem extends Item implements IComputerItem, IColoured
        var stack = player.getItemInHand(hand);
        if (!world.isClientSide) {
            var holder = new PocketHolder.PlayerHolder((ServerPlayer) player, InventoryUtil.getHandSlot(player, hand));
-            var brain = getOrCreateBrain((ServerLevel) world, holder, stack);
+            var brain = getOrCreateBrain(holder, stack);
            var computer = brain.computer();
            computer.turnOn();

@@ -239,8 +234,16 @@ public class PocketComputerItem extends Item implements IComputerItem, IColoured
        return ComputerCraftAPI.MOD_ID;
    }

-    private PocketBrain getOrCreateBrain(ServerLevel level, PocketHolder holder, ItemStack stack) {
-        var registry = ServerContext.get(level.getServer()).registry();
+    /**
+     * Get (or create) the pocket brain and turn it on, ready for the player to interact with.
+     *
+     * @param stack  The pocket computer stack.
+     * @param holder The holder of the pocket computer.
+     * @return The pocket brain.
+     */
+    public PocketBrain getOrCreateBrain(PocketHolder holder, ItemStack stack) {
+        var server = holder.level().getServer();
+        var registry = ServerContext.get(server).registry();
        {
            var computer = getServerComputer(registry, stack);
            if (computer != null) {
@@ -252,7 +255,7 @@ public class PocketComputerItem extends Item implements IComputerItem, IColoured

        var computerID = getComputerID(stack);
        if (computerID < 0) {
-            computerID = ComputerCraftAPI.createUniqueNumberedSaveDir(level.getServer(), IDAssigner.COMPUTER);
+            computerID = ComputerCraftAPI.createUniqueNumberedSaveDir(server, IDAssigner.COMPUTER);
            setComputerID(stack, computerID);
        }

@@ -275,18 +278,13 @@ public class PocketComputerItem extends Item implements IComputerItem, IColoured
        return brain;
    }

-    /**
-     * Get (or create) the pocket server computer and turn it on, ready for the player to interact with.
-     *
-     * @param stack  The pocket computer stack.
-     * @param holder The holder of the pocket computer.
-     * @return The pocket server computer.
-     */
-    public ServerComputer getAndTurnOnServerComputer(ItemStack stack, PocketHolder holder) {
-        var brain = getOrCreateBrain(holder.level(), holder, stack);
-        var computer = brain.computer();
-        computer.turnOn();
-        return computer;
+    public @Nullable PocketBrain getBrain(PocketHolder holder, ItemStack stack) {
+        var computer = getServerComputer(holder.level().getServer(), stack);
+        if (computer == null) return null;
+
+        var brain = computer.getBrain();
+        brain.updateHolder(holder);
+        return brain;
    }

    public static boolean isServerComputer(ServerComputer computer, ItemStack stack) {
@@ -294,13 +292,11 @@ public class PocketComputerItem extends Item implements IComputerItem, IColoured
            && getServerComputer(computer.getLevel().getServer(), stack) == computer;
    }

-    @Nullable
-    public static PocketServerComputer getServerComputer(ServerComputerRegistry registry, ItemStack stack) {
+    private static @Nullable PocketServerComputer getServerComputer(ServerComputerRegistry registry, ItemStack stack) {
        return (PocketServerComputer) registry.get(getSessionID(stack), getInstanceID(stack));
    }

-    @Nullable
-    public static PocketServerComputer getServerComputer(MinecraftServer server, ItemStack stack) {
+    private static @Nullable PocketServerComputer getServerComputer(MinecraftServer server, ItemStack stack) {
        return getServerComputer(ServerContext.get(server).registry(), stack);
    }