Add exchange block and trading system with price manager

src/main/java/fr/jachou/cryptoworld/CryptoWorld.java

@@ -1,9 +1,12 @@
 package fr.jachou.cryptoworld;
 
 import fr.jachou.cryptoworld.block.ModBlocks;
+import fr.jachou.cryptoworld.blockentity.ModBlockEntities;
 import fr.jachou.cryptoworld.datagen.DataGenerators;
 import fr.jachou.cryptoworld.item.ModCreativeModTabs;
 import fr.jachou.cryptoworld.item.ModItems;
+import fr.jachou.cryptoworld.menu.ModMenus;
+import fr.jachou.cryptoworld.util.PriceManager;
 import net.minecraft.world.item.CreativeModeTabs;
 import net.minecraftforge.common.MinecraftForge;
 import net.minecraftforge.data.event.GatherDataEvent;
@@ -24,11 +27,15 @@ public CryptoWorld() {
         ModCreativeModTabs.register(bus);
         ModItems.register(bus);
         ModBlocks.register(bus);
+        ModBlockEntities.register(bus);
+        ModMenus.register(bus);
 
         bus.addListener(this::setup);
         MinecraftForge.EVENT_BUS.register(this);
         bus.addListener(this::doClientStuff);
         bus.addListener(this::addCreative);
+
+        PriceManager.init();
     }
 
     private void addCreative(BuildCreativeModeTabContentsEvent event) {

src/main/java/fr/jachou/cryptoworld/block/ExchangeBlock.java

@@ -0,0 +1,45 @@
+package fr.jachou.cryptoworld.block;
+
+import fr.jachou.cryptoworld.blockentity.ExchangeBlockEntity;
+import net.minecraft.core.BlockPos;
+import net.minecraft.world.InteractionHand;
+import net.minecraft.world.InteractionResult;
+import net.minecraft.world.entity.player.Player;
+import net.minecraft.world.level.Level;
+import net.minecraft.world.level.block.Block;
+import net.minecraft.world.level.block.EntityBlock;
+import net.minecraft.world.level.block.state.BlockState;
+import net.minecraft.world.level.block.entity.BlockEntity;
+import net.minecraft.world.level.block.entity.BlockEntityTicker;
+import net.minecraft.world.level.block.entity.BlockEntityType;
+import net.minecraft.world.phys.BlockHitResult;
+import org.jetbrains.annotations.Nullable;
+
+public class ExchangeBlock extends Block implements EntityBlock {
+    public ExchangeBlock(Properties properties) {
+        super(properties);
+    }
+
+    @Override
+    public InteractionResult use(BlockState state, Level level, BlockPos pos, Player player, InteractionHand hand, BlockHitResult hit) {
+        if (!level.isClientSide) {
+            BlockEntity blockEntity = level.getBlockEntity(pos);
+            if (blockEntity instanceof ExchangeBlockEntity exchange) {
+                player.openMenu(exchange);
+            }
+        }
+        return InteractionResult.SUCCESS;
+    }
+
+    @Nullable
+    @Override
+    public BlockEntity newBlockEntity(BlockPos pos, BlockState state) {
+        return new ExchangeBlockEntity(pos, state);
+    }
+
+    @Nullable
+    @Override
+    public <T extends BlockEntity> BlockEntityTicker<T> getTicker(Level level, BlockState state, BlockEntityType<T> type) {
+        return null; // No ticking required for this block entity
+    }
+}

src/main/java/fr/jachou/cryptoworld/block/ModBlocks.java

@@ -36,6 +36,9 @@ public class ModBlocks {
     public static final RegistryObject<Block> CRYPTONIUM_BLOCK = registerBlock("cryptonium_block",
             () -> new Block((BlockBehaviour.Properties.ofFullCopy(Blocks.DIAMOND_BLOCK))));
 
+    public static final RegistryObject<Block> EXCHANGE_BLOCK = registerBlock("exchange_block",
+            () -> new ExchangeBlock(BlockBehaviour.Properties.ofFullCopy(Blocks.IRON_BLOCK)));
+
 
 
     private static <T extends Block>RegistryObject<T> registerBlock(String name, Supplier<T> block) {

src/main/java/fr/jachou/cryptoworld/blockentity/ExchangeBlockEntity.java

@@ -0,0 +1,91 @@
+package fr.jachou.cryptoworld.blockentity;
+
+import fr.jachou.cryptoworld.item.ModItems;
+import fr.jachou.cryptoworld.menu.ExchangeMenu;
+import fr.jachou.cryptoworld.util.PriceManager;
+import net.minecraft.core.BlockPos;
+import net.minecraft.nbt.CompoundTag;
+import net.minecraft.network.chat.Component;
+import net.minecraft.world.MenuProvider;
+import net.minecraft.world.entity.player.Inventory;
+import net.minecraft.world.entity.player.Player;
+import net.minecraft.world.inventory.AbstractContainerMenu;
+import net.minecraft.world.item.ItemStack;
+import net.minecraft.world.level.block.entity.BlockEntity;
+import net.minecraft.world.level.block.state.BlockState;
+import net.minecraftforge.items.ItemStackHandler;
+import org.jetbrains.annotations.NotNull;
+
+public class ExchangeBlockEntity extends BlockEntity implements MenuProvider {
+    private final ItemStackHandler itemHandler = new ItemStackHandler(2) {
+        @Override
+        protected void onContentsChanged(int slot) {
+            super.onContentsChanged(slot);
+            setChanged();
+            if (slot == 0) {
+                updateDemand();
+            }
+        }
+
+        @Override
+        public boolean isItemValid(int slot, @NotNull ItemStack stack) {
+            return slot == 0;
+        }
+    };
+
+    public ExchangeBlockEntity(BlockPos pos, BlockState state) {
+        super(ModBlockEntities.EXCHANGE_BLOCK_ENTITY.get(), pos, state);
+    }
+
+    public void updateDemand() {
+        ItemStack offer = itemHandler.getStackInSlot(0);
+        if (offer.isEmpty()) {
+            itemHandler.setStackInSlot(1, ItemStack.EMPTY);
+            return;
+        }
+        if (offer.getItem() == ModItems.BITCOIN.get()) {
+            int rate = PriceManager.getBitcoinToEthereumRate();
+            itemHandler.setStackInSlot(1, new ItemStack(ModItems.ETHEREUM.get(), offer.getCount() * rate));
+        } else if (offer.getItem() == ModItems.ETHEREUM.get()) {
+            int rate = PriceManager.getEthereumToBitcoinRate();
+            int amount = offer.getCount() / rate;
+            if (amount > 0) {
+                itemHandler.setStackInSlot(1, new ItemStack(ModItems.BITCOIN.get(), amount));
+            } else {
+                itemHandler.setStackInSlot(1, ItemStack.EMPTY);
+            }
+        } else {
+            itemHandler.setStackInSlot(1, ItemStack.EMPTY);
+        }
+    }
+
+    public ItemStackHandler getItemHandler() {
+        return itemHandler;
+    }
+
+    public void removeOffer() {
+        itemHandler.setStackInSlot(0, ItemStack.EMPTY);
+    }
+
+    @Override
+    public Component getDisplayName() {
+        return Component.literal("Exchange");
+    }
+
+    @Override
+    public AbstractContainerMenu createMenu(int id, Inventory inventory, Player player) {
+        return new ExchangeMenu(id, inventory, this);
+    }
+
+    @Override
+    protected void saveAdditional(CompoundTag tag) {
+        tag.put("inventory", itemHandler.serializeNBT());
+        super.saveAdditional(tag);
+    }
+
+    @Override
+    public void load(CompoundTag tag) {
+        super.load(tag);
+        itemHandler.deserializeNBT(tag.getCompound("inventory"));
+    }
+}

src/main/java/fr/jachou/cryptoworld/blockentity/ModBlockEntities.java

@@ -0,0 +1,22 @@
+package fr.jachou.cryptoworld.blockentity;
+
+import fr.jachou.cryptoworld.CryptoWorld;
+import fr.jachou.cryptoworld.block.ModBlocks;
+import net.minecraft.world.level.block.entity.BlockEntityType;
+import net.minecraftforge.eventbus.api.IEventBus;
+import net.minecraftforge.registries.DeferredRegister;
+import net.minecraftforge.registries.ForgeRegistries;
+import net.minecraftforge.registries.RegistryObject;
+
+public class ModBlockEntities {
+    public static final DeferredRegister<BlockEntityType<?>> BLOCK_ENTITIES =
+            DeferredRegister.create(ForgeRegistries.BLOCK_ENTITY_TYPES, CryptoWorld.MODID);
+
+    public static final RegistryObject<BlockEntityType<ExchangeBlockEntity>> EXCHANGE_BLOCK_ENTITY =
+            BLOCK_ENTITIES.register("exchange_block_entity",
+                    () -> BlockEntityType.Builder.of(ExchangeBlockEntity::new, ModBlocks.EXCHANGE_BLOCK.get()).build(null));
+
+    public static void register(IEventBus eventBus) {
+        BLOCK_ENTITIES.register(eventBus);
+    }
+}

src/main/java/fr/jachou/cryptoworld/datagen/ModBlockStateProvider.java

@@ -24,6 +24,7 @@ protected void registerStatesAndModels() {
         blockWithItem(ModBlocks.SILICIUM_ORE);
         blockWithItem(ModBlocks.SILICIUM_BLOCK);
         blockWithItem(ModBlocks.SERVER_BLOCK);
+        blockWithItem(ModBlocks.EXCHANGE_BLOCK);
     }
 
     private void blockWithItem(RegistryObject<Block> blockRegistryObject) {

src/main/java/fr/jachou/cryptoworld/datagen/loot/ModBlockLootTables.java

@@ -23,6 +23,7 @@ protected void generate() {
         this.dropSelf(ModBlocks.CRYPTONIUM_ORE.get());
         this.dropSelf(ModBlocks.SERVER_BLOCK.get());
         this.dropSelf(ModBlocks.SILICIUM_ORE.get());
+        this.dropSelf(ModBlocks.EXCHANGE_BLOCK.get());
     }
 
     @Override

src/main/java/fr/jachou/cryptoworld/item/ModCreativeModTabs.java

@@ -36,6 +36,7 @@ public class ModCreativeModTabs {
                         pOutput.accept(ModBlocks.SILICIUM_ORE.get());
                         pOutput.accept(ModBlocks.CRYPTONIUM_BLOCK.get());
                         pOutput.accept(ModBlocks.SILICIUM_BLOCK.get());
+                        pOutput.accept(ModBlocks.EXCHANGE_BLOCK.get());
                     })
                     .build());
 

src/main/java/fr/jachou/cryptoworld/menu/ExchangeMenu.java

@@ -0,0 +1,67 @@
+package fr.jachou.cryptoworld.menu;
+
+import fr.jachou.cryptoworld.block.ModBlocks;
+import fr.jachou.cryptoworld.blockentity.ExchangeBlockEntity;
+import net.minecraft.network.FriendlyByteBuf;
+import net.minecraft.world.entity.player.Inventory;
+import net.minecraft.world.entity.player.Player;
+import net.minecraft.world.inventory.AbstractContainerMenu;
+import net.minecraft.world.inventory.ContainerLevelAccess;
+import net.minecraft.world.inventory.Slot;
+import net.minecraft.world.item.ItemStack;
+import net.minecraftforge.items.SlotItemHandler;
+
+public class ExchangeMenu extends AbstractContainerMenu {
+    private final ExchangeBlockEntity blockEntity;
+    private final ContainerLevelAccess access;
+
+    public ExchangeMenu(int id, Inventory playerInv, FriendlyByteBuf buf) {
+        this(id, playerInv, (ExchangeBlockEntity) playerInv.player.level().getBlockEntity(buf.readBlockPos()));
+    }
+
+    public ExchangeMenu(int id, Inventory playerInv, ExchangeBlockEntity blockEntity) {
+        super(ModMenus.EXCHANGE_MENU.get(), id);
+        this.blockEntity = blockEntity;
+        this.access = ContainerLevelAccess.create(blockEntity.getLevel(), blockEntity.getBlockPos());
+
+        var handler = blockEntity.getItemHandler();
+        // Offer slot
+        this.addSlot(new SlotItemHandler(handler, 0, 44, 35));
+        // Demand slot (output)
+        this.addSlot(new SlotItemHandler(handler, 1, 116, 35) {
+            @Override
+            public boolean mayPlace(ItemStack stack) {
+                return false;
+            }
+
+            @Override
+            public void onTake(Player player, ItemStack stack) {
+                super.onTake(player, stack);
+                blockEntity.removeOffer();
+            }
+        });
+
+        addPlayerInventory(playerInv);
+    }
+
+    private void addPlayerInventory(Inventory inventory) {
+        for (int row = 0; row < 3; ++row) {
+            for (int col = 0; col < 9; ++col) {
+                this.addSlot(new Slot(inventory, col + row * 9 + 9, 8 + col * 18, 84 + row * 18));
+            }
+        }
+        for (int col = 0; col < 9; ++col) {
+            this.addSlot(new Slot(inventory, col, 8 + col * 18, 142));
+        }
+    }
+
+    @Override
+    public boolean stillValid(Player player) {
+        return stillValid(access, player, ModBlocks.EXCHANGE_BLOCK.get());
+    }
+
+    @Override
+    public ItemStack quickMoveStack(Player player, int index) {
+        return ItemStack.EMPTY;
+    }
+}

src/main/java/fr/jachou/cryptoworld/menu/ModMenus.java

@@ -0,0 +1,21 @@
+package fr.jachou.cryptoworld.menu;
+
+import fr.jachou.cryptoworld.CryptoWorld;
+import net.minecraft.world.inventory.MenuType;
+import net.minecraftforge.common.extensions.IForgeMenuType;
+import net.minecraftforge.eventbus.api.IEventBus;
+import net.minecraftforge.registries.DeferredRegister;
+import net.minecraftforge.registries.ForgeRegistries;
+import net.minecraftforge.registries.RegistryObject;
+
+public class ModMenus {
+    public static final DeferredRegister<MenuType<?>> MENUS =
+            DeferredRegister.create(ForgeRegistries.MENU_TYPES, CryptoWorld.MODID);
+
+    public static final RegistryObject<MenuType<ExchangeMenu>> EXCHANGE_MENU =
+            MENUS.register("exchange_menu", () -> IForgeMenuType.create(ExchangeMenu::new));
+
+    public static void register(IEventBus eventBus) {
+        MENUS.register(eventBus);
+    }
+}

src/main/java/fr/jachou/cryptoworld/util/PriceManager.java

@@ -0,0 +1,31 @@
+package fr.jachou.cryptoworld.util;
+
+import fr.jachou.cryptoworld.item.ModItems;
+import net.minecraft.world.item.Item;
+
+import java.util.HashMap;
+import java.util.Map;
+import java.util.Random;
+
+public class PriceManager {
+    private static final Map<Item, Integer> PRICES = new HashMap<>();
+    private static final Random RANDOM = new Random();
+
+    public static void init() {
+        PRICES.put(ModItems.BITCOIN.get(), 2); // 1 BTC -> 2 ETH
+        PRICES.put(ModItems.ETHEREUM.get(), 2); // 2 ETH -> 1 BTC
+    }
+
+    public static void updateRandom() {
+        // Randomly vary BTC to ETH rate between 1 and 4
+        PRICES.put(ModItems.BITCOIN.get(), 1 + RANDOM.nextInt(4));
+    }
+
+    public static int getBitcoinToEthereumRate() {
+        return PRICES.getOrDefault(ModItems.BITCOIN.get(), 1);
+    }
+
+    public static int getEthereumToBitcoinRate() {
+        return PRICES.getOrDefault(ModItems.ETHEREUM.get(), 2);
+    }
+}