Basic villager trades

src/main/java/cn/nukkit/Player.java

@@ -143,6 +143,8 @@ public class Player extends EntityHuman implements CommandSender, InventoryHolde
     protected final Set<Integer> permanentWindows = new IntOpenHashSet();
     private boolean inventoryOpen;
     protected int closingWindowId = Integer.MIN_VALUE;
+
+    public boolean isTrading = false;
 
     protected int messageCounter = 2;
 
@@ -4690,6 +4692,15 @@ public PlayerCursorInventory getCursorInventory() {
     public CraftingGrid getCraftingGrid() {
         return this.craftingGrid;
     }
+
+    public TradeInventory getTradeInventory() {
+        for(Inventory inv : this.windows.keySet()) {
+            if(inv instanceof TradeInventory) {
+                return (TradeInventory) inv;
+            }
+        }
+        return null;
+    }
 
     public void setCraftingGrid(CraftingGrid grid) {
         this.craftingGrid = grid;

src/main/java/cn/nukkit/entity/passive/EntityVillager.java

@@ -1,13 +1,27 @@
 package cn.nukkit.entity.passive;
 
+import java.util.ArrayList;
+import java.util.List;
+
+import cn.nukkit.Player;
+import cn.nukkit.entity.Entity;
 import cn.nukkit.entity.EntityAgeable;
 import cn.nukkit.entity.EntityCreature;
+import cn.nukkit.inventory.Inventory;
+import cn.nukkit.inventory.InventoryHolder;
+import cn.nukkit.inventory.TradeInventory;
+import cn.nukkit.inventory.TradeInventoryRecipe;
+import cn.nukkit.item.Item;
 import cn.nukkit.level.format.FullChunk;
 import cn.nukkit.nbt.tag.CompoundTag;
+import cn.nukkit.nbt.tag.ListTag;
+import cn.nukkit.utils.ServerException;
 
-public class EntityVillager extends EntityCreature implements EntityNPC, EntityAgeable {
+public class EntityVillager extends EntityCreature implements InventoryHolder, EntityNPC, EntityAgeable {
 
     public static final int NETWORK_ID = 115;
+    private TradeInventory inventory;
+    private List<TradeInventoryRecipe> recipes;
 
     public EntityVillager(FullChunk chunk, CompoundTag nbt) {
         super(chunk, nbt);
@@ -43,6 +57,134 @@ public String getName() {
     public void initEntity() {
         super.initEntity();
         this.setMaxHealth(20);
+        this.inventory = new TradeInventory(this);
+        this.recipes = new ArrayList<TradeInventoryRecipe>();
+        this.dataProperties.putLong(DATA_TRADING_PLAYER_EID, 0L);
+        if(this.namedTag.contains("Offers")) {
+            ListTag<CompoundTag> nbtRecipes = getListRecipes();
+            for(CompoundTag nbt : nbtRecipes.getAll()) {
+                recipes.add(TradeInventoryRecipe.toNBT(nbt));
+            }
+        } else {
+            CompoundTag nbt = new CompoundTag("Offers");
+            nbt.putList(new ListTag<CompoundTag>("Recipes"));
+            nbt.putList(getDefaultTierExpRequirements());
+            this.namedTag.putCompound("Offers", nbt);
+        }
+    }
+
+    public void setTraderName(String name) {
+        this.namedTag.putString("TraderName", name);
+    }
+
+    public String getTraderName() {
+        if(!this.namedTag.contains("TraderName")) {
+            this.namedTag.putString("TraderName", getNameTag());
+        }
+        return this.namedTag.getString("TraderName");
+    }
+
+    public void setTradeTier(int tier) {
+    	if(tier > 4){
+    	    throw new ServerException("Maximal tier is 4, but your tier is higher than 4");
+    	}
+        this.namedTag.putInt("TradeTier", tier);
+        this.dataProperties.putInt(DATA_TRADE_TIER, tier);
+    }
+
+    public void setMaxTradeTier(int maxTier) {
+    	if(maxTier > 4) maxTier = 4;
+        this.dataProperties.putInt(DATA_MAX_TRADE_TIER, maxTier);
+    }
+
+    public int getMaxTradeTier() {
+        if(!this.dataProperties.exists(DATA_MAX_TRADE_TIER)) {
+            this.setMaxTradeTier(4);
+        }
+        return this.dataProperties.getInt(DATA_MAX_TRADE_TIER);
+    }
+
+    public void setExperience(int experience) {
+        this.dataProperties.putInt(DATA_TRADE_EXPERIENCE, experience);
+    }
+
+    public int getExperience() {
+        if(!this.dataProperties.exists(DATA_TRADE_EXPERIENCE)) {
+            setExperience(0);
+        }
+        return this.dataProperties.getInt(DATA_TRADE_EXPERIENCE);
+    }
+
+    public int getTradeTier() {
+        if(!this.namedTag.contains("TradeTier")) {
+            this.namedTag.putInt("TradeTier", 0);
+        }
+        return this.namedTag.getInt("TradeTier");
+    }
+
+    public void setWilling(boolean value) {
+        this.namedTag.putBoolean("Willing", value);
+    }
+
+    public boolean isWilling() {
+        if(!this.namedTag.contains("Willing")) {
+            this.namedTag.putBoolean("Willing", true);
+        }
+        return this.namedTag.getBoolean("Willing");
+    }
+
+    public void cancelTradingWithPlayer() {
+    	this.setTradingWith(0L);
+    }
+
+    public void setTradingWith(long eid) {
+        this.dataProperties.putLong(DATA_TRADING_PLAYER_EID, eid);
+    }
+
+    public boolean isTrading() {
+        return this.dataProperties.getLong(DATA_TRADING_PLAYER_EID) != 0L;
+    }
+
+    @Override
+    public boolean onInteract(Player player, Item item) {
+        if(this.namedTag.contains("Offers") && !isTrading()) {
+            player.addWindow(this.getInventory());
+            return true;
+        }
+        return false;
+    }
+
+    public void addTradeRecipe(TradeInventoryRecipe recipe) {
+        this.recipes.add(recipe);
+        getListRecipes().add(recipe.toNBT());
+    }
+
+    public List<TradeInventoryRecipe> getRecipes(){
+        return this.recipes;
+    }
+
+    public ListTag<CompoundTag> getListRecipes(){
+        if(!this.getOffers().contains("Recipes")) {
+            this.getOffers().putList(new ListTag<CompoundTag>("Recipes"));
+        }
+        return this.getOffers().getList("Recipes", CompoundTag.class);
+    }
+
+    public CompoundTag getOffers() {
+        if(!this.namedTag.contains("Offers")) {
+            this.namedTag.putCompound("Offers", new CompoundTag("Offers"));
+        }
+        return this.namedTag.getCompound("Offers");
+	}
+
+	public ListTag<CompoundTag> getDefaultTierExpRequirements() {
+	    ListTag<CompoundTag> tag = new ListTag<CompoundTag>("TierExpRequirements");
+	    tag.add(new CompoundTag().putInt("0", 0));
+	    tag.add(new CompoundTag().putInt("1", 10));
+	    tag.add(new CompoundTag().putInt("2", 70));
+	    tag.add(new CompoundTag().putInt("3", 150));
+	    tag.add(new CompoundTag().putInt("4", 250));
+	    return tag;
     }
 
     public boolean isBaby() {
@@ -53,4 +195,9 @@ public void setBaby(boolean baby) {
         this.setDataFlag(DATA_FLAGS, DATA_FLAG_BABY, baby);
         this.setScale(baby ? 0.5f : 1);
     }
+
+	@Override
+	public Inventory getInventory() {
+		return this.inventory;
+	}
 }

src/main/java/cn/nukkit/inventory/InventoryType.java

@@ -23,7 +23,8 @@ public enum InventoryType {
     BEACON(1, "Beacon", 13),
     OFFHAND(1, "Offhand", -1),
     MINECART_CHEST(27, "Minecart with Chest", 0),
-    MINECART_HOPPER(5, "Minecart with Hopper", 8);
+    MINECART_HOPPER(5, "Minecart with Hopper", 8),
+    TRADING(3, "Villager Trade", 15);
 
     private final int size;
     private final String title;

src/main/java/cn/nukkit/inventory/TradeInventory.java

@@ -0,0 +1,71 @@
+package cn.nukkit.inventory;
+
+import java.io.IOException;
+import java.nio.ByteOrder;
+
+import cn.nukkit.Player;
+import cn.nukkit.entity.passive.EntityVillager;
+import cn.nukkit.item.Item;
+import cn.nukkit.nbt.NBTIO;
+import cn.nukkit.nbt.tag.CompoundTag;
+import cn.nukkit.network.protocol.UpdateTradePacket;
+
+public class TradeInventory extends BaseInventory {
+
+	public static final int TRADE_INPUT_A = 4;
+	public static final int TRADE_INPUT_B = 5;
+	public static final int TRADE_OUTPUT = 51;
+
+	// mojang, what the heck??
+	public static final int FAKE_TRADE_INPUT = -30; // moves from fake ui (villager inventory) to player inventory
+	public static final int FAKE_TRADE_OUTPUT = -31; // item is sent from player inventory to villager fake inv
+
+	public TradeInventory(InventoryHolder holder) {
+		super(holder, InventoryType.TRADING);
+	}
+
+	public void onOpen(Player who) {
+		super.onOpen(who);
+
+		UpdateTradePacket pk = new UpdateTradePacket();
+		pk.windowId = (byte) who.getWindowId(this);
+		pk.windowType = (byte) InventoryType.TRADING.getNetworkType();
+		pk.isWilling = this.getHolder().isWilling();
+		pk.screen2 = true;
+		pk.trader = this.getHolder().getId();
+		pk.tradeTier = this.getHolder().getTradeTier();
+		pk.displayName = this.getHolder().getTraderName();
+		pk.player = who.getId();
+		pk.unknownVarInt1 = 0;
+		try {
+			pk.offers = NBTIO.write(this.getHolder().getOffers(),ByteOrder.LITTLE_ENDIAN, true);
+		} catch(IOException ex) {}
+
+		this.getHolder().setTradingWith(who.getId());
+		who.isTrading = true;
+
+		who.dataPacket(pk);
+	}
+
+	public void onClose(Player who) {
+		for(int i = 0; i <= 1; i++) {
+			Item item = getItem(i);
+			if(who.getInventory().canAddItem(item)) {
+				who.getInventory().addItem(item);
+			} else {
+				who.dropItem(item);
+			}
+			this.clear(i);
+		}
+
+		this.getHolder().cancelTradingWithPlayer();
+		who.isTrading = false;
+
+		super.onClose(who);
+	}
+
+	public EntityVillager getHolder() {
+		return (EntityVillager) this.holder;
+	}
+
+}