Unsafe_InspectVillagerTrades

import java.lang.reflect.Field;
import java.lang.reflect.Method;
import java.util.ArrayList;
import java.util.List;

import org.bukkit.entity.Villager;
import org.bukkit.inventory.ItemStack;

import com.google.common.collect.Lists;

/**
 * FIXME https://github.com/Bukkit/Bukkit/pull/921
 *
 * @author riking
 */
class Unsafe_InspectVillagerTrades
{
    public static List<ItemStack> getTradeResults(Villager vil) throws Exception, Error
    {
        Object internalVillager = vil.getClass().getDeclaredMethod("getHandle", (Class<?>) null).invoke(vil, (Object[]) null);
        Class<?> internalEntityHumanClass = Class.forName("net.minecraft.server.v1_6_R2.EntityHuman");
        ArrayList<?> merchantRecipeList = (ArrayList<?>) internalVillager.getClass().getDeclaredMethod("getOffers", internalEntityHumanClass).invoke(internalVillager, new Object[] {null});

        if (merchantRecipeList.size() == 0) return Lists.newArrayList();
        List<ItemStack> ret = Lists.newArrayListWithCapacity(merchantRecipeList.size());

        Field itemField = merchantRecipeList.get(0).getClass().getField("sellingItem");
        Class<?> internalItemClass = Class.forName("net.minecraft.server.v1_6_R2.ItemStack");
        Method getStackMethod = Class.forName("org.bukkit.craftbukkit.v1_6_R2.inventory.CraftItemStack").getDeclaredMethod("asBukkitCopy", internalItemClass);
        for (Object o : merchantRecipeList)
        {
            Object internalItemStack = itemField.get(o);
            if (!internalItemStack.getClass().equals(internalItemClass)) continue;
            Object bukkitItemStack = getStackMethod.invoke(null, internalItemStack);
            if (!ItemStack.class.isAssignableFrom(bukkitItemStack.getClass()))
            {
                new RuntimeException("asBukkitCopy() did not return a Bukkit ItemStack..? Investigate.").printStackTrace();
                continue;
            }
            ret.add((ItemStack) bukkitItemStack);
        }
        return ret;
    }
}