added gui factory for entity gui holder

src/main/java/com/cleanroommc/modularui/factory/EntityGuiData.java

@@ -0,0 +1,18 @@
+package com.cleanroommc.modularui.factory;
+
+import net.minecraft.entity.Entity;
+import net.minecraft.entity.player.EntityPlayer;
+
+public class EntityGuiData extends GuiData {
+
+    private final Entity guiHolder;
+
+    public EntityGuiData(EntityPlayer player, Entity guiHolder) {
+        super(player);
+        this.guiHolder = guiHolder;
+    }
+
+    public Entity getGuiHolder() {
+        return guiHolder;
+    }
+}

src/main/java/com/cleanroommc/modularui/factory/EntityGuiFactory.java

@@ -0,0 +1,61 @@
+package com.cleanroommc.modularui.factory;
+
+import com.cleanroommc.modularui.api.IGuiHolder;
+
+import net.minecraft.entity.Entity;
+import net.minecraft.entity.player.EntityPlayer;
+import net.minecraft.entity.player.EntityPlayerMP;
+import net.minecraft.network.PacketBuffer;
+
+import org.jetbrains.annotations.NotNull;
+
+import java.util.Objects;
+
+public class EntityGuiFactory extends AbstractUIFactory<EntityGuiData> {
+
+    public static EntityGuiFactory INSTANCE = new EntityGuiFactory();
+
+    protected EntityGuiFactory() {
+        super("mui:entity");
+    }
+
+    public <E extends Entity & IGuiHolder<EntityGuiData>> void open(EntityPlayer player, E entity) {
+        Objects.requireNonNull(player);
+        verifyEntity(player, entity);
+        GuiManager.open(this, new EntityGuiData(player, entity), (EntityPlayerMP) player);
+    }
+
+    private static <E extends Entity & IGuiHolder<EntityGuiData>> void verifyEntity(EntityPlayer player, E entity) {
+        Objects.requireNonNull(entity);
+        if (!entity.isEntityAlive()) {
+            throw new IllegalArgumentException("Can't open dead Entity GUI!");
+        } else if (player.world != entity.world) {
+            throw new IllegalArgumentException("Entity must be in same dimension as the player!");
+        }
+    }
+
+    @Override
+    public @NotNull IGuiHolder<EntityGuiData> getGuiHolder(EntityGuiData guiData) {
+        return Objects.requireNonNull(castGuiHolder(guiData.getGuiHolder()), "Found Entity is not a gui holder!");
+    }
+
+    @Override
+    public void writeGuiData(EntityGuiData guiData, PacketBuffer packetBuffer) {
+        packetBuffer.writeInt(guiData.getGuiHolder().getEntityId());
+    }
+
+    @Override
+    public @NotNull EntityGuiData readGuiData(EntityPlayer entityPlayer, PacketBuffer packetBuffer) {
+        return new EntityGuiData(entityPlayer, entityPlayer.world.getEntityByID(packetBuffer.readInt()));
+    }
+
+    @Override
+    public boolean canInteractWith(EntityPlayer player, EntityGuiData guiData) {
+        Entity guiHolder = guiData.getGuiHolder();
+        return super.canInteractWith(player, guiData) &&
+                guiHolder != null &&
+                player.getDistanceSq(guiHolder.posX, guiHolder.posY, guiHolder.posZ) <= 64 &&
+                player.world == guiHolder.world &&
+                guiHolder.isEntityAlive();
+    }
+}

src/main/java/com/cleanroommc/modularui/factory/GuiFactories.java

@@ -16,6 +16,10 @@ public static SidedTileEntityGuiFactory sidedTileEntity() {
         return SidedTileEntityGuiFactory.INSTANCE;
     }
 
+    public static EntityGuiFactory entity() {
+        return EntityGuiFactory.INSTANCE;
+    }
+
     @Deprecated
     public static ItemGuiFactory item() {
         return ItemGuiFactory.INSTANCE;
@@ -37,6 +41,7 @@ public static SimpleGuiFactory createSimple(String name, Supplier<IGuiHolder<Gui
     public static void init() {
         GuiManager.registerFactory(tileEntity());
         GuiManager.registerFactory(sidedTileEntity());
+        GuiManager.registerFactory(entity());
         GuiManager.registerFactory(item());
         GuiManager.registerFactory(playerInventory());
     }