don't look at this code, it's truly terrible

src/main/java/de/ellpeck/prettypipes/Registry.java

@@ -3,6 +3,7 @@ package de.ellpeck.prettypipes;
 import com.mojang.datafixers.types.Func;
 import de.ellpeck.prettypipes.blocks.pipe.*;
 import de.ellpeck.prettypipes.items.ExtractionModuleItem;
+import de.ellpeck.prettypipes.items.IModule;
 import de.ellpeck.prettypipes.items.ModuleTier;
 import de.ellpeck.prettypipes.items.WrenchItem;
 import de.ellpeck.prettypipes.network.PipeNetwork;
@@ -91,7 +92,9 @@ public final class Registry {
         event.getRegistry().registerAll(
                 pipeContainer = (ContainerType<PipeContainer>) IForgeContainerType.create((windowId, inv, data) -> {
                     PipeTileEntity tile = Utility.getTileEntity(PipeTileEntity.class, inv.player.world, data.readBlockPos());
-                    return tile != null ? new PipeContainer(pipeContainer, windowId, inv.player, tile) : null;
+                    int openModule = data.readInt();
+                    IModule module = openModule < 0 ? null : (IModule) tile.modules.getStackInSlot(openModule).getItem();
+                    return tile != null ? new PipeContainer(pipeContainer, windowId, inv.player, tile, module) : null;
                 }).setRegistryName("pipe")
         );
     }

src/main/java/de/ellpeck/prettypipes/blocks/pipe/PipeBlock.java

@@ -70,7 +70,10 @@ public class PipeBlock extends ContainerBlock {
         if (!tile.isConnectedInventory())
             return ActionResultType.PASS;
         if (!worldIn.isRemote)
-            NetworkHooks.openGui((ServerPlayerEntity) player, tile, pos);
+            NetworkHooks.openGui((ServerPlayerEntity) player, tile.createContainer(-1), buf -> {
+                buf.writeBlockPos(pos);
+                buf.writeInt(-1);
+            });
         return ActionResultType.SUCCESS;
     }
 

src/main/java/de/ellpeck/prettypipes/blocks/pipe/PipeContainer.java

@@ -7,21 +7,33 @@ import net.minecraft.inventory.container.ContainerType;
 import net.minecraft.inventory.container.Slot;
 import net.minecraft.item.ItemStack;
 import net.minecraftforge.items.SlotItemHandler;
+import org.apache.commons.lang3.Range;
 
 import javax.annotation.Nullable;
 
 public class PipeContainer extends Container {
-    public PipeContainer(@Nullable ContainerType<?> type, int id, PlayerEntity player, PipeTileEntity tile) {
-        super(type, id);
 
+    public final PipeTileEntity tile;
+    public final IModule openModule;
+
+    public PipeContainer(@Nullable ContainerType<?> type, int id, PlayerEntity player, PipeTileEntity tile, IModule openModule) {
+        super(type, id);
+        this.tile = tile;
+        this.openModule = openModule;
+
+        if (openModule == null) {
             for (int i = 0; i < 3; i++)
-            this.addSlot(new SlotItemHandler(tile.modules, i, 62 + i * 18, 17));
+                this.addSlot(new SlotItemHandler(tile.modules, i, 62 + i * 18, 17 + 32));
+        } else {
+            for (Slot slot : openModule.getContainerSlots(tile, this))
+                this.addSlot(slot);
+        }
 
         for (int l = 0; l < 3; ++l)
             for (int j1 = 0; j1 < 9; ++j1)
-                this.addSlot(new Slot(player.inventory, j1 + l * 9 + 9, 8 + j1 * 18, 89 + l * 18));
+                this.addSlot(new Slot(player.inventory, j1 + l * 9 + 9, 8 + j1 * 18, 89 + l * 18 + 32));
         for (int i1 = 0; i1 < 9; ++i1)
-            this.addSlot(new Slot(player.inventory, i1, 8 + i1 * 18, 147));
+            this.addSlot(new Slot(player.inventory, i1, 8 + i1 * 18, 147 + 32));
     }
 
     @Override
@@ -31,8 +43,7 @@ public class PipeContainer extends Container {
 
     @Override
     public ItemStack transferStackInSlot(PlayerEntity player, int slotIndex) {
-        // change this to the amount of slots that we have
+        int inventoryStart = (int) this.inventorySlots.stream().filter(slot -> slot.inventory != player.inventory).count();
-        int inventoryStart = 3;
         int inventoryEnd = inventoryStart + 26;
         int hotbarStart = inventoryEnd + 1;
         int hotbarEnd = hotbarStart + 8;
@@ -42,17 +53,29 @@ public class PipeContainer extends Container {
             ItemStack newStack = slot.getStack();
             ItemStack currentStack = newStack.copy();
 
+            inv:
             if (slotIndex >= inventoryStart) {
                 // shift into this container here
                 // mergeItemStack with the slots that newStack should go into
                 // return an empty stack if mergeItemStack fails
+                if (this.openModule == null) {
                     if (newStack.getItem() instanceof IModule) {
                         if (!this.mergeItemStack(newStack, 0, 3, false))
                             return ItemStack.EMPTY;
+                        break inv;
+                    }
+                } else {
+                    // bleh
+                    Range<Integer> range = this.openModule.getShiftClickSlots(this.tile, this, newStack);
+                    if (range != null) {
+                        if (!this.mergeItemStack(newStack, range.getMinimum(), range.getMaximum(), false))
+                            return ItemStack.EMPTY;
+                        break inv;
+                    }
                 }
                 // end custom code
 
-                else if (slotIndex >= inventoryStart && slotIndex <= inventoryEnd) {
+                if (slotIndex >= inventoryStart && slotIndex <= inventoryEnd) {
                     if (!this.mergeItemStack(newStack, hotbarStart, hotbarEnd + 1, false))
                         return ItemStack.EMPTY;
                 } else if (slotIndex >= inventoryEnd + 1 && slotIndex < hotbarEnd + 1 && !this.mergeItemStack(newStack, inventoryStart, inventoryEnd + 1, false)) {
@@ -73,5 +96,4 @@ public class PipeContainer extends Container {
         }
         return ItemStack.EMPTY;
     }
-
 }

src/main/java/de/ellpeck/prettypipes/blocks/pipe/PipeGui.java

@@ -1,21 +1,43 @@
 package de.ellpeck.prettypipes.blocks.pipe;
 
-import com.mojang.blaze3d.platform.GlStateManager;
+import com.mojang.blaze3d.systems.RenderSystem;
 import de.ellpeck.prettypipes.PrettyPipes;
+import de.ellpeck.prettypipes.Registry;
+import de.ellpeck.prettypipes.items.IModule;
+import de.ellpeck.prettypipes.packets.PacketButton;
+import de.ellpeck.prettypipes.packets.PacketHandler;
+import net.minecraft.client.audio.SimpleSound;
 import net.minecraft.client.gui.AbstractGui;
 import net.minecraft.client.gui.screen.inventory.ContainerScreen;
 import net.minecraft.entity.player.PlayerInventory;
+import net.minecraft.inventory.container.ClickType;
+import net.minecraft.inventory.container.Slot;
+import net.minecraft.item.Item;
+import net.minecraft.item.ItemStack;
 import net.minecraft.util.ResourceLocation;
+import net.minecraft.util.SoundEvents;
 import net.minecraft.util.text.ITextComponent;
 
+import java.util.ArrayList;
+import java.util.Iterator;
+import java.util.List;
+
 public class PipeGui extends ContainerScreen<PipeContainer> {
 
     private static final ResourceLocation TEXTURE = new ResourceLocation(PrettyPipes.ID, "textures/gui/pipe.png");
+    private final List<Tab> tabs = new ArrayList<>();
+    private int lastTabAmount;
 
     public PipeGui(PipeContainer screenContainer, PlayerInventory inv, ITextComponent titleIn) {
         super(screenContainer, inv, titleIn);
         this.xSize = 176;
-        this.ySize = 171;
+        this.ySize = 171 + 32;
+    }
+
+    @Override
+    protected void init() {
+        super.init();
+        this.initTabs();
     }
 
     @Override
@@ -27,16 +49,110 @@ public class PipeGui extends ContainerScreen<PipeContainer> {
 
     @Override
     protected void drawGuiContainerForegroundLayer(int mouseX, int mouseY) {
-        this.font.drawString(this.title.getFormattedText(), 8, 6, 4210752);
         this.font.drawString(this.playerInventory.getDisplayName().getFormattedText(), 8, this.ySize - 96 + 2, 4210752);
+        this.font.drawString(this.title.getFormattedText(), 8, 6 + 32, 4210752);
+        if (this.container.openModule != null)
+            this.container.openModule.drawContainerGuiForeground(this.container.tile, this.container, this, mouseX, mouseY);
+
+        for (Tab tab : this.tabs)
+            tab.drawForeground(mouseX, mouseY);
     }
 
     @Override
     protected void drawGuiContainerBackgroundLayer(float partialTicks, int mouseX, int mouseY) {
         this.getMinecraft().getTextureManager().bindTexture(TEXTURE);
-        this.blit(this.guiLeft, this.guiTop, 0, 0, 176, 171);
+        this.blit(this.guiLeft, this.guiTop + 32, 0, 0, 176, 171);
 
+        for (Tab tab : this.tabs)
+            tab.draw();
+
+        if (this.container.openModule == null) {
             for (int i = 0; i < 3; i++)
-            this.blit(this.guiLeft + 61 + i * 18, this.guiTop + 16, 176, 62, 18, 18);
+                this.blit(this.guiLeft + 61 + i * 18, this.guiTop + 32 + 16, 176, 62, 18, 18);
+        } else {
+            this.container.openModule.drawContainerGuiBackground(this.container.tile, this.container, this, mouseX, mouseY);
+        }
+    }
+
+    @Override
+    protected void handleMouseClick(Slot slotIn, int slotId, int mouseButton, ClickType type) {
+        super.handleMouseClick(slotIn, slotId, mouseButton, type);
+        // this might cause unnecessary tab initializations, but
+        // it's a pretty cheap operation so it should be fine
+        if (slotIn != null)
+            this.initTabs();
+    }
+
+    @Override
+    public boolean mouseClicked(double x, double y, int button) {
+        for (Tab tab : this.tabs) {
+            if (tab.onClicked(x, y, button))
+                return true;
+        }
+        return super.mouseClicked(x, y, button);
+    }
+
+    private void initTabs() {
+        this.tabs.clear();
+        this.tabs.add(new Tab(new ItemStack(Registry.pipeBlock), null, 0, -1));
+        for (int i = 0; i < this.container.tile.modules.getSlots(); i++) {
+            ItemStack stack = this.container.tile.modules.getStackInSlot(i);
+            if (stack.isEmpty())
+                continue;
+            IModule module = (IModule) stack.getItem();
+            if (module.hasContainerTab(this.container.tile, this.container))
+                this.tabs.add(new Tab(stack, module, this.tabs.size(), i));
+        }
+    }
+
+    private class Tab {
+        private final ItemStack moduleStack;
+        private final IModule module;
+        private final int index;
+        private final int x;
+        private final int y;
+
+        public Tab(ItemStack moduleStack, IModule module, int tabIndex, int index) {
+            this.moduleStack = moduleStack;
+            this.module = module;
+            this.index = index;
+            this.x = PipeGui.this.guiLeft + 5 + tabIndex * 28;
+            this.y = PipeGui.this.guiTop;
+        }
+
+        private void draw() {
+            int y = 2;
+            int v = 0;
+            int height = 30;
+            int itemOffset = 9;
+            if (this.module == PipeGui.this.container.openModule) {
+                y = 0;
+                v = 30;
+                height = 32;
+                itemOffset = 7;
+            }
+            PipeGui.this.blit(this.x, this.y + y, 176, v, 28, height);
+
+            PipeGui.this.itemRenderer.renderItemIntoGUI(this.moduleStack, this.x + 6, this.y + itemOffset);
+            PipeGui.this.getMinecraft().getTextureManager().bindTexture(TEXTURE);
+        }
+
+        private void drawForeground(int mouseX, int mouseY) {
+            if (mouseX < this.x || mouseY < this.y || mouseX >= this.x + 28 || mouseY >= this.y + 32)
+                return;
+            PipeGui.this.renderTooltip(this.moduleStack.getDisplayName().getFormattedText(), mouseX - PipeGui.this.guiLeft, mouseY - PipeGui.this.guiTop);
+        }
+
+        private boolean onClicked(double mouseX, double mouseY, int button) {
+            if (this.module == PipeGui.this.container.openModule)
+                return false;
+            if (button != 0)
+                return false;
+            if (mouseX < this.x || mouseY < this.y || mouseX >= this.x + 28 || mouseY >= this.y + 32)
+                return false;
+            PacketHandler.sendToServer(new PacketButton(PipeGui.this.container.tile.getPos(), PacketButton.ButtonResult.PIPE_TAB, this.index));
+            PipeGui.this.getMinecraft().getSoundHandler().play(SimpleSound.master(SoundEvents.UI_BUTTON_CLICK, 1));
+            return true;
+        }
     }
 }

src/main/java/de/ellpeck/prettypipes/blocks/pipe/PipeTileEntity.java

@@ -32,12 +32,21 @@ import java.util.Arrays;
 import java.util.List;
 import java.util.stream.Stream;
 
-public class PipeTileEntity extends TileEntity implements INamedContainerProvider, ITickableTileEntity {
+public class PipeTileEntity extends TileEntity implements ITickableTileEntity {
 
     public final ItemStackHandler modules = new ItemStackHandler(3) {
         @Override
         public boolean isItemValid(int slot, @Nonnull ItemStack stack) {
-            return stack.getItem() instanceof IModule;
+            Item item = stack.getItem();
+            if (!(item instanceof IModule))
+                return false;
+            IModule module = (IModule) item;
+            return PipeTileEntity.this.streamModules().allMatch(m -> module.isCompatible(PipeTileEntity.this, m) && m.isCompatible(PipeTileEntity.this, module));
+        }
+
+        @Override
+        public int getSlotLimit(int slot) {
+            return 1;
         }
     };
     public final List<PipeItem> items = new ArrayList<>();
@@ -46,17 +55,6 @@ public class PipeTileEntity extends TileEntity implements INamedContainerProvide
         super(Registry.pipeTileEntity);
     }
 
-    @Override
-    public ITextComponent getDisplayName() {
-        return new TranslationTextComponent("container." + PrettyPipes.ID + ".pipe");
-    }
-
-    @Nullable
-    @Override
-    public Container createMenu(int window, PlayerInventory inv, PlayerEntity player) {
-        return new PipeContainer(Registry.pipeContainer, window, player, this);
-    }
-
     @Override
     public CompoundNBT write(CompoundNBT compound) {
         compound.put("modules", this.modules.serializeNBT());
@@ -141,16 +139,35 @@ public class PipeTileEntity extends TileEntity implements INamedContainerProvide
         return Arrays.stream(Direction.values()).anyMatch(this::isConnectedInventory);
     }
 
-    private Stream<IModule> streamModules() {
+    public Stream<IModule> streamModules() {
         Stream.Builder<IModule> builder = Stream.builder();
         for (int i = 0; i < this.modules.getSlots(); i++) {
             ItemStack stack = this.modules.getStackInSlot(i);
             if (stack.isEmpty())
                 continue;
-            Item item = stack.getItem();
+            builder.accept((IModule) stack.getItem());
-            if (item instanceof IModule)
-                builder.accept((IModule) item);
         }
         return builder.build();
     }
+
+    public INamedContainerProvider createContainer(int openModule) {
+        ItemStack moduleStack = openModule < 0 ? null : this.modules.getStackInSlot(openModule);
+        return new INamedContainerProvider() {
+
+            @Override
+            public ITextComponent getDisplayName() {
+                if (moduleStack != null)
+                    return moduleStack.getDisplayName();
+                return new TranslationTextComponent("container." + PrettyPipes.ID + ".pipe");
+            }
+
+            @Nullable
+            @Override
+            public Container createMenu(int window, PlayerInventory inv, PlayerEntity player) {
+                IModule module = moduleStack == null ? null : (IModule) moduleStack.getItem();
+                return new PipeContainer(Registry.pipeContainer, window, player, PipeTileEntity.this, module);
+            }
+
+        };
+    }
 }

src/main/java/de/ellpeck/prettypipes/items/ExtractionModuleItem.java

@@ -1,5 +1,6 @@
 package de.ellpeck.prettypipes.items;
 
+import de.ellpeck.prettypipes.blocks.pipe.PipeContainer;
 import de.ellpeck.prettypipes.blocks.pipe.PipeTileEntity;
 import de.ellpeck.prettypipes.network.PipeNetwork;
 import net.minecraft.item.ItemStack;
@@ -39,4 +40,14 @@ public class ExtractionModuleItem extends ModuleItem {
     public boolean canAcceptItem(PipeTileEntity tile, ItemStack stack) {
         return false;
     }
+
+    @Override
+    public boolean isCompatible(PipeTileEntity tile, IModule other) {
+        return !(other instanceof ExtractionModuleItem);
+    }
+
+    @Override
+    public boolean hasContainerTab(PipeTileEntity tile, PipeContainer container) {
+        return true;
+    }
 }

src/main/java/de/ellpeck/prettypipes/items/IModule.java

@@ -1,9 +1,18 @@
 package de.ellpeck.prettypipes.items;
 
+import de.ellpeck.prettypipes.blocks.pipe.PipeContainer;
+import de.ellpeck.prettypipes.blocks.pipe.PipeGui;
 import de.ellpeck.prettypipes.blocks.pipe.PipeTileEntity;
+import net.minecraft.inventory.container.Slot;
 import net.minecraft.item.ItemStack;
 import net.minecraft.tileentity.TileEntity;
+import net.minecraftforge.api.distmarker.Dist;
+import net.minecraftforge.api.distmarker.OnlyIn;
 import net.minecraftforge.items.IItemHandler;
+import org.apache.commons.lang3.Range;
+
+import java.util.Collections;
+import java.util.List;
 
 public interface IModule {
 
@@ -14,4 +23,24 @@ public interface IModule {
     boolean isAvailableDestination(PipeTileEntity tile, ItemStack stack, IItemHandler destination);
 
     int getPriority(PipeTileEntity tile);
+
+    boolean hasContainerTab(PipeTileEntity tile, PipeContainer container);
+
+    boolean isCompatible(PipeTileEntity tile, IModule other);
+
+    default List<Slot> getContainerSlots(PipeTileEntity tile, PipeContainer container) {
+        return Collections.emptyList();
+    }
+
+    default Range<Integer> getShiftClickSlots(PipeTileEntity tile, PipeContainer container, ItemStack newStack) {
+        return null;
+    }
+
+    @OnlyIn(Dist.CLIENT)
+    default void drawContainerGuiBackground(PipeTileEntity tile, PipeContainer container, PipeGui gui, int mouseX, int mouseY) {
+    }
+
+    @OnlyIn(Dist.CLIENT)
+    default void drawContainerGuiForeground(PipeTileEntity tile, PipeContainer container, PipeGui gui, int mouseX, int mouseY) {
+    }
 }

src/main/java/de/ellpeck/prettypipes/items/ModuleItem.java

@@ -1,12 +1,13 @@
 package de.ellpeck.prettypipes.items;
 
 import de.ellpeck.prettypipes.Registry;
+import de.ellpeck.prettypipes.blocks.pipe.PipeContainer;
 import de.ellpeck.prettypipes.blocks.pipe.PipeTileEntity;
 import net.minecraft.item.Item;
 import net.minecraft.item.ItemStack;
 import net.minecraftforge.items.IItemHandler;
 
-public class ModuleItem extends Item implements IModule {
+public abstract class ModuleItem extends Item implements IModule {
     public ModuleItem() {
         super(new Properties().group(Registry.GROUP).maxStackSize(16));
     }
@@ -30,4 +31,9 @@ public class ModuleItem extends Item implements IModule {
     public int getPriority(PipeTileEntity tile) {
         return 0;
     }
+
+    @Override
+    public boolean hasContainerTab(PipeTileEntity tile, PipeContainer container) {
+        return false;
+    }
 }

src/main/java/de/ellpeck/prettypipes/packets/PacketButton.java

@@ -0,0 +1,75 @@
+package de.ellpeck.prettypipes.packets;
+
+import de.ellpeck.prettypipes.Utility;
+import de.ellpeck.prettypipes.blocks.pipe.PipeTileEntity;
+import de.ellpeck.prettypipes.items.IModule;
+import net.minecraft.entity.player.PlayerEntity;
+import net.minecraft.entity.player.ServerPlayerEntity;
+import net.minecraft.network.PacketBuffer;
+import net.minecraft.tileentity.TileEntity;
+import net.minecraft.util.math.BlockPos;
+import net.minecraftforge.fml.network.NetworkEvent;
+import net.minecraftforge.fml.network.NetworkHooks;
+import org.apache.logging.log4j.util.TriConsumer;
+
+import java.util.function.BiConsumer;
+import java.util.function.Supplier;
+
+public class PacketButton {
+
+    private BlockPos pos;
+    private ButtonResult result;
+    private int[] data;
+
+    public PacketButton(BlockPos pos, ButtonResult result, int... data) {
+        this.pos = pos;
+        this.result = result;
+        this.data = data;
+    }
+
+    private PacketButton() {
+
+    }
+
+    public static PacketButton fromBytes(PacketBuffer buf) {
+        PacketButton packet = new PacketButton();
+        packet.pos = buf.readBlockPos();
+        packet.result = ButtonResult.values()[buf.readByte()];
+        packet.data = buf.readVarIntArray();
+        return packet;
+    }
+
+    public static void toBytes(PacketButton packet, PacketBuffer buf) {
+        buf.writeBlockPos(packet.pos);
+        buf.writeByte(packet.result.ordinal());
+        buf.writeVarIntArray(packet.data);
+    }
+
+    @SuppressWarnings("Convert2Lambda")
+    public static void onMessage(PacketButton message, Supplier<NetworkEvent.Context> ctx) {
+        ctx.get().enqueueWork(new Runnable() {
+            @Override
+            public void run() {
+                PlayerEntity player = ctx.get().getSender();
+                message.result.action.accept(message.pos, message.data, player);
+            }
+        });
+        ctx.get().setPacketHandled(true);
+    }
+
+    public enum ButtonResult {
+        PIPE_TAB((pos, data, player) -> {
+            PipeTileEntity tile = Utility.getTileEntity(PipeTileEntity.class, player.world, pos);
+            NetworkHooks.openGui((ServerPlayerEntity) player, tile.createContainer(data[0]), buf -> {
+                buf.writeBlockPos(pos);
+                buf.writeInt(data[0]);
+            });
+        });
+
+        public final TriConsumer<BlockPos, int[], PlayerEntity> action;
+
+        ButtonResult(TriConsumer<BlockPos, int[], PlayerEntity> action) {
+            this.action = action;
+        }
+    }
+}

src/main/java/de/ellpeck/prettypipes/packets/PacketHandler.java

@@ -19,6 +19,7 @@ public final class PacketHandler {
     public static void setup() {
         network = NetworkRegistry.newSimpleChannel(new ResourceLocation(PrettyPipes.ID, "network"), () -> VERSION, VERSION::equals, VERSION::equals);
         network.registerMessage(0, PacketItemEnterPipe.class, PacketItemEnterPipe::toBytes, PacketItemEnterPipe::fromBytes, PacketItemEnterPipe::onMessage);
+        network.registerMessage(1, PacketButton.class, PacketButton::toBytes, PacketButton::fromBytes, PacketButton::onMessage);
     }
 
     public static void sendToAllLoaded(World world, BlockPos pos, Object message) {
@@ -29,7 +30,7 @@ public final class PacketHandler {
         network.send(PacketDistributor.NEAR.with(() -> new PacketDistributor.TargetPoint(pos.getX(), pos.getY(), pos.getZ(), range, world.getDimension().getType())), message);
     }
 
-    public static void sendTo(PlayerEntity player, Object message) {
+    public static void sendToServer(Object message) {
-        network.send(PacketDistributor.PLAYER.with(() -> (ServerPlayerEntity) player), message);
+        network.send(PacketDistributor.SERVER.noArg(), message);
     }
 }