package net.minecraft.world.entity.ai.behavior;

import com.google.common.collect.ImmutableMap;
import com.google.common.collect.ImmutableSet;
import java.util.Set;
import java.util.stream.Collectors;
import net.minecraft.server.level.ServerLevel;
import net.minecraft.world.SimpleContainer;
import net.minecraft.world.entity.EntityTypes;
import net.minecraft.world.entity.LivingEntity;
import net.minecraft.world.entity.ai.memory.MemoryModuleType;
import net.minecraft.world.entity.ai.memory.MemoryStatus;
import net.minecraft.world.entity.npc.villager.Villager;
import net.minecraft.world.entity.npc.villager.VillagerProfession;
import net.minecraft.world.item.Item;
import net.minecraft.world.item.ItemStack;
import net.minecraft.world.item.Items;

public class TradeWithVillager extends Behavior<Villager> {
	private Set<Item> trades = ImmutableSet.of();

	public TradeWithVillager() {
		super(
			ImmutableMap.of(
				MemoryModuleType.INTERACTION_TARGET, MemoryStatus.VALUE_PRESENT, MemoryModuleType.NEAREST_VISIBLE_LIVING_ENTITIES, MemoryStatus.VALUE_PRESENT
			)
		);
	}

	protected boolean checkExtraStartConditions(final ServerLevel level, final Villager body) {
		return BehaviorUtils.targetIsValid(body.getBrain(), MemoryModuleType.INTERACTION_TARGET, EntityTypes.VILLAGER);
	}

	protected boolean canStillUse(final ServerLevel level, final Villager body, final long timestamp) {
		return this.checkExtraStartConditions(level, body);
	}

	protected void start(final ServerLevel level, final Villager myBody, final long timestamp) {
		Villager target = (Villager)myBody.getBrain().getMemory(MemoryModuleType.INTERACTION_TARGET).get();
		BehaviorUtils.lockGazeAndWalkToEachOther(myBody, target, 0.5F, 2);
		this.trades = figureOutWhatIAmWillingToTrade(myBody, target);
	}

	protected void tick(final ServerLevel level, final Villager body, final long timestamp) {
		Villager target = (Villager)body.getBrain().getMemory(MemoryModuleType.INTERACTION_TARGET).get();
		if (!(body.distanceToSqr(target) > 5.0)) {
			BehaviorUtils.lockGazeAndWalkToEachOther(body, target, 0.5F, 2);
			body.gossip(level, target, timestamp);
			boolean isFarmer = body.getVillagerData().profession().is(VillagerProfession.FARMER);
			if (body.hasExcessFood() && (isFarmer || target.wantsMoreFood())) {
				throwHalfStack(body, Villager.FOOD_POINTS.keySet(), target);
			}

			if (isFarmer && body.getInventory().countItem(Items.WHEAT) > Items.WHEAT.getDefaultMaxStackSize() / 2) {
				throwHalfStack(body, ImmutableSet.of(Items.WHEAT), target);
			}

			if (!this.trades.isEmpty() && body.getInventory().hasAnyOf(this.trades)) {
				throwHalfStack(body, this.trades, target);
			}
		}
	}

	protected void stop(final ServerLevel level, final Villager body, final long timestamp) {
		body.getBrain().eraseMemory(MemoryModuleType.INTERACTION_TARGET);
	}

	private static Set<Item> figureOutWhatIAmWillingToTrade(final Villager myBody, final Villager target) {
		ImmutableSet<Item> targetItems = target.getVillagerData().profession().value().requestedItems();
		ImmutableSet<Item> selfItems = myBody.getVillagerData().profession().value().requestedItems();
		return (Set<Item>)targetItems.stream().filter(entry -> !selfItems.contains(entry)).collect(Collectors.toSet());
	}

	private static void throwHalfStack(final Villager villager, final Set<Item> items, final LivingEntity target) {
		SimpleContainer inventory = villager.getInventory();
		ItemStack toThrow = ItemStack.EMPTY;
		int i = 0;

		while (i < inventory.getContainerSize()) {
			ItemStack itemStack;
			Item item;
			int count;
			label28: {
				itemStack = inventory.getItem(i);
				if (!itemStack.isEmpty()) {
					item = itemStack.getItem();
					if (items.contains(item)) {
						if (itemStack.getCount() > itemStack.getMaxStackSize() / 2) {
							count = itemStack.getCount() / 2;
							break label28;
						}

						if (itemStack.getCount() > 24) {
							count = itemStack.getCount() - 24;
							break label28;
						}
					}
				}

				i++;
				continue;
			}

			itemStack.shrink(count);
			toThrow = new ItemStack(item, count);
			break;
		}

		if (!toThrow.isEmpty()) {
			BehaviorUtils.throwItem(villager, toThrow, target.position());
		}
	}
}