SPIGOT-2272: Add API for virtual Merchants

nms-patches/InventoryMerchant.patch

@@ -43,12 +43,12 @@
 +    }
 +
 +    public org.bukkit.inventory.InventoryHolder getOwner() {
-+        return (CraftVillager) ((EntityVillager) this.merchant).getBukkitEntity();
++        return (merchant instanceof EntityVillager) ? (CraftVillager) ((EntityVillager) this.merchant).getBukkitEntity() : null;
 +    }
 +
 +    @Override
 +    public Location getLocation() {
-+        return ((EntityVillager) this.merchant).getBukkitEntity().getLocation();
++        return (merchant instanceof EntityVillager) ? ((EntityVillager) this.merchant).getBukkitEntity().getLocation() : null;
 +    }
 +    // CraftBukkit end
 +

src/main/java/org/bukkit/craftbukkit/CraftServer.java

@@ -59,6 +59,7 @@ import org.bukkit.craftbukkit.help.SimpleHelpMap;
 import org.bukkit.craftbukkit.inventory.CraftFurnaceRecipe;
 import org.bukkit.craftbukkit.inventory.CraftInventoryCustom;
 import org.bukkit.craftbukkit.inventory.CraftItemFactory;
+import org.bukkit.craftbukkit.inventory.CraftMerchantCustom;
 import org.bukkit.craftbukkit.inventory.CraftRecipe;
 import org.bukkit.craftbukkit.inventory.CraftShapedRecipe;
 import org.bukkit.craftbukkit.inventory.CraftShapelessRecipe;
@@ -85,6 +86,7 @@ import org.bukkit.generator.ChunkGenerator;
 import org.bukkit.help.HelpMap;
 import org.bukkit.inventory.FurnaceRecipe;
 import org.bukkit.inventory.ItemStack;
+import org.bukkit.inventory.Merchant;
 import org.bukkit.inventory.Inventory;
 import org.bukkit.inventory.InventoryHolder;
 import org.bukkit.inventory.Recipe;
@@ -1480,6 +1482,11 @@ public final class CraftServer implements Server {
         return new CraftInventoryCustom(owner, size, title);
     }
 
+    @Override
+    public Merchant createMerchant(String title) {
+        return new CraftMerchantCustom(title);
+    }
+
     @Override
     public HelpMap getHelpMap() {
         return helpMap;

src/main/java/org/bukkit/craftbukkit/entity/CraftHumanEntity.java

@@ -8,8 +8,10 @@ import net.minecraft.server.*;
 import org.bukkit.GameMode;
 import org.bukkit.Location;
 import org.bukkit.inventory.MainHand;
+import org.bukkit.inventory.Merchant;
 import org.bukkit.Material;
 import org.bukkit.entity.HumanEntity;
+import org.bukkit.entity.Villager;
 import org.bukkit.event.inventory.InventoryType;
 import org.bukkit.inventory.Inventory;
 import org.bukkit.inventory.InventoryView;
@@ -22,8 +24,8 @@ import org.bukkit.craftbukkit.inventory.CraftInventory;
 import org.bukkit.craftbukkit.inventory.CraftInventoryPlayer;
 import org.bukkit.craftbukkit.inventory.CraftInventoryView;
 import org.bukkit.craftbukkit.inventory.CraftItemStack;
+import org.bukkit.craftbukkit.inventory.CraftMerchant;
 import org.bukkit.craftbukkit.CraftServer;
-import org.bukkit.entity.Villager;
 import org.bukkit.inventory.EntityEquipment;
 import org.bukkit.permissions.PermissibleBase;
 import org.bukkit.permissions.Permission;
@@ -357,16 +359,32 @@ public class CraftHumanEntity extends CraftLivingEntity implements HumanEntity {
     @Override
     public InventoryView openMerchant(Villager villager, boolean force) {
         Preconditions.checkNotNull(villager, "villager cannot be null");
-        if (!force && villager.isTrading()) {
+
+        return this.openMerchant(villager, force);
+    }
+
+    @Override
+    public InventoryView openMerchant(Merchant merchant, boolean force) {
+        Preconditions.checkNotNull(merchant, "merchant cannot be null");
+
+        if (!force && merchant.isTrading()) {
             return null;
-        } else if (villager.isTrading()) {
-            // we're not supposed to have multiple people using the same villager, so we have to close it.
-            villager.getTrader().closeInventory();
+        } else if (merchant.isTrading()) {
+            // we're not supposed to have multiple people using the same merchant, so we have to close it.
+            merchant.getTrader().closeInventory();
         }
 
-        EntityVillager ev = ((CraftVillager) villager).getHandle();
-        ev.setTradingPlayer(this.getHandle());
-        this.getHandle().openTrade(ev);
+        IMerchant mcMerchant;
+        if (merchant instanceof CraftVillager) {
+            mcMerchant = ((CraftVillager) merchant).getHandle();
+        } else if (merchant instanceof CraftMerchant) {
+            mcMerchant = ((CraftMerchant) merchant).getMerchant();
+        } else {
+            throw new IllegalArgumentException("Can't open merchant " + merchant.toString());
+        }
+
+        mcMerchant.setTradingPlayer(this.getHandle());
+        this.getHandle().openTrade(mcMerchant);
 
         return this.getHandle().activeContainer.getBukkitView();
     }

src/main/java/org/bukkit/craftbukkit/entity/CraftVillager.java

@@ -1,16 +1,11 @@
 package org.bukkit.craftbukkit.entity;
 
-import com.google.common.base.Function;
-import com.google.common.collect.Lists;
-import java.util.Collections;
 import java.util.List;
-import net.minecraft.server.EntityHuman;
 import net.minecraft.server.EntityVillager;
-import net.minecraft.server.MerchantRecipeList;
 import org.apache.commons.lang.Validate;
 import org.bukkit.craftbukkit.CraftServer;
 import org.bukkit.craftbukkit.inventory.CraftInventory;
-import org.bukkit.craftbukkit.inventory.CraftMerchantRecipe;
+import org.bukkit.craftbukkit.inventory.CraftMerchant;
 import org.bukkit.entity.EntityType;
 import org.bukkit.entity.HumanEntity;
 import org.bukkit.entity.Villager;
@@ -20,6 +15,8 @@ import org.bukkit.inventory.MerchantRecipe;
 
 public class CraftVillager extends CraftAgeable implements Villager, InventoryHolder {
 
+    private CraftMerchant merchant;
+
     public CraftVillager(CraftServer server, EntityVillager entity) {
         super(server, entity);
     }
@@ -53,38 +50,33 @@ public class CraftVillager extends CraftAgeable implements Villager, InventoryHo
         return new CraftInventory(getHandle().inventory);
     }
 
-    @Override
-    public List<MerchantRecipe> getRecipes() {
-        return Collections.unmodifiableList(Lists.transform(getHandle().getOffers(null), new Function<net.minecraft.server.MerchantRecipe, MerchantRecipe>() {
-            @Override
-            public MerchantRecipe apply(net.minecraft.server.MerchantRecipe recipe) {
-                return recipe.asBukkit();
-            }
-        }));
+    private CraftMerchant getMerchant() {
+        return (merchant == null) ? merchant = new CraftMerchant(getHandle()) : merchant;
     }
 
     @Override
-    public void setRecipes(List<MerchantRecipe> list) {
-        MerchantRecipeList recipes = getHandle().getOffers(null);
-        recipes.clear();
-        for (MerchantRecipe m : list) {
-            recipes.add(CraftMerchantRecipe.fromBukkit(m).toMinecraft());
-        }
+    public List<MerchantRecipe> getRecipes() {
+        return getMerchant().getRecipes();
+    }
+
+    @Override
+    public void setRecipes(List<MerchantRecipe> recipes) {
+        this.getMerchant().setRecipes(recipes);
     }
 
     @Override
     public MerchantRecipe getRecipe(int i) {
-        return getHandle().getOffers(null).get(i).asBukkit();
+        return getMerchant().getRecipe(i);
     }
 
     @Override
     public void setRecipe(int i, MerchantRecipe merchantRecipe) {
-        getHandle().getOffers(null).set(i, CraftMerchantRecipe.fromBukkit(merchantRecipe).toMinecraft());
+        getMerchant().setRecipe(i, merchantRecipe);
     }
 
     @Override
     public int getRecipeCount() {
-        return getHandle().getOffers(null).size();
+        return getMerchant().getRecipeCount();
     }
 
     @Override
@@ -94,8 +86,7 @@ public class CraftVillager extends CraftAgeable implements Villager, InventoryHo
 
     @Override
     public HumanEntity getTrader() {
-        EntityHuman eh = getHandle().getTrader();
-        return eh == null ? null : eh.getBukkitEntity();
+        return getMerchant().getTrader();
     }
 
     @Override

src/main/java/org/bukkit/craftbukkit/inventory/CraftMerchant.java

@@ -0,0 +1,80 @@
+package org.bukkit.craftbukkit.inventory;
+
+import com.google.common.base.Function;
+import com.google.common.collect.Lists;
+import java.util.Collections;
+import java.util.List;
+import net.minecraft.server.EntityHuman;
+import net.minecraft.server.IMerchant;
+import net.minecraft.server.MerchantRecipeList;
+import org.bukkit.entity.HumanEntity;
+import org.bukkit.inventory.Merchant;
+import org.bukkit.inventory.MerchantRecipe;
+
+public class CraftMerchant implements Merchant {
+
+    protected final IMerchant merchant;
+
+    public CraftMerchant(IMerchant merchant) {
+        this.merchant = merchant;
+    }
+
+    public IMerchant getMerchant() {
+        return merchant;
+    }
+
+    @Override
+    public List<MerchantRecipe> getRecipes() {
+        return Collections.unmodifiableList(Lists.transform(merchant.getOffers(null), new Function<net.minecraft.server.MerchantRecipe, MerchantRecipe>() {
+            @Override
+            public MerchantRecipe apply(net.minecraft.server.MerchantRecipe recipe) {
+                return recipe.asBukkit();
+            }
+        }));
+    }
+
+    @Override
+    public void setRecipes(List<MerchantRecipe> recipes) {
+        MerchantRecipeList recipesList = merchant.getOffers(null);
+        recipesList.clear();
+        for (MerchantRecipe recipe : recipes) {
+            recipesList.add(CraftMerchantRecipe.fromBukkit(recipe).toMinecraft());
+        }
+    }
+
+    @Override
+    public MerchantRecipe getRecipe(int i) {
+        return merchant.getOffers(null).get(i).asBukkit();
+    }
+
+    @Override
+    public void setRecipe(int i, MerchantRecipe merchantRecipe) {
+        merchant.getOffers(null).set(i, CraftMerchantRecipe.fromBukkit(merchantRecipe).toMinecraft());
+    }
+
+    @Override
+    public int getRecipeCount() {
+        return merchant.getOffers(null).size();
+    }
+
+    @Override
+    public boolean isTrading() {
+        return getTrader() != null;
+    }
+
+    @Override
+    public HumanEntity getTrader() {
+        EntityHuman eh = merchant.getTrader();
+        return eh == null ? null : eh.getBukkitEntity();
+    }
+
+    @Override
+    public int hashCode() {
+        return merchant.hashCode();
+    }
+
+    @Override
+    public boolean equals(final Object obj) {
+        return obj instanceof CraftMerchant && ((CraftMerchant) obj).merchant.equals(this.merchant);
+    }
+}

src/main/java/org/bukkit/craftbukkit/inventory/CraftMerchantCustom.java

@@ -0,0 +1,74 @@
+package org.bukkit.craftbukkit.inventory;
+
+import net.minecraft.server.BlockPosition;
+import net.minecraft.server.EntityHuman;
+import net.minecraft.server.IChatBaseComponent;
+import net.minecraft.server.IMerchant;
+import net.minecraft.server.ItemStack;
+import net.minecraft.server.MerchantRecipe;
+import net.minecraft.server.MerchantRecipeList;
+import net.minecraft.server.World;
+import org.bukkit.craftbukkit.util.CraftChatMessage;
+
+public class CraftMerchantCustom extends CraftMerchant {
+
+    public CraftMerchantCustom(String title) {
+        super(new MinecraftMerchant(title));
+    }
+
+    @Override
+    public String toString() {
+        return "CraftMerchantCustom";
+    }
+
+    private static class MinecraftMerchant implements IMerchant {
+
+        private final String title;
+        private final MerchantRecipeList trades = new MerchantRecipeList();
+        private EntityHuman tradingPlayer;
+
+        public MinecraftMerchant(String title) {
+            this.title = title;
+        }
+
+        @Override
+        public void setTradingPlayer(EntityHuman entityhuman) {
+            this.tradingPlayer = entityhuman;
+        }
+
+        @Override
+        public EntityHuman getTrader() {
+            return this.tradingPlayer;
+        }
+
+        @Override
+        public MerchantRecipeList getOffers(EntityHuman entityhuman) {
+            return this.trades;
+        }
+
+        @Override
+        public void a(MerchantRecipe merchantrecipe) {
+            // increase recipe's uses
+            merchantrecipe.g(); // PAIL: rename
+        }
+
+        @Override
+        public void a(ItemStack itemstack) {
+        }
+
+        @Override
+        public IChatBaseComponent getScoreboardDisplayName() {
+            return CraftChatMessage.fromString(title)[0];
+        }
+
+        @Override
+        public World t_() {
+            return null;
+        }
+
+        @Override
+        public BlockPosition u_() {
+            return null;
+        }
+    }
+}

src/main/java/org/bukkit/craftbukkit/inventory/CraftMerchantRecipe.java

@@ -19,8 +19,8 @@ public class CraftMerchantRecipe extends MerchantRecipe {
     public CraftMerchantRecipe(ItemStack result, int uses, int maxUses, boolean experienceReward) {
         super(result, uses, maxUses, experienceReward);
         this.handle = new net.minecraft.server.MerchantRecipe(
-                null,
-                null,
+                net.minecraft.server.ItemStack.a,
+                net.minecraft.server.ItemStack.a,
                 CraftItemStack.asNMSCopy(result),
                 uses,
                 maxUses,