package autodig.client.service;

import autodig.client.config.DigConfig;
import autodig.client.config.MineTask;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;
import net.minecraft.client.MinecraftClient;
import net.minecraft.entity.player.PlayerEntity;
import net.minecraft.item.BlockItem;
import net.minecraft.item.ItemStack;
import net.minecraft.registry.Registries;
import net.minecraft.screen.ScreenHandler;
import net.minecraft.screen.slot.SlotActionType;

/**
 * 背包垃圾自动清理服务。
 *
 * <p>背包接近满（已用格数达到阈值）时就主动把 {@code trashItems} 清单里的
 * 垃圾物品丢出背包（圆石、凝灰岩、深板岩等挖掘副产物），为挖到的矿物提前
 * 腾出空间，避免背包彻底满后触发"背包已满需返回"而中断挖矿。方块类垃圾
 * 保留 {@code trashReserve} 个供 Baritone 搭路/垫脚使用。丢弃通过
 * {@code clickSlot(THROW)} 走正规网络包，单人/多人均可用。</p>
 */
public final class AutoTrash {

    /** 每 tick 最多丢弃的物品组数，避免一次产生过多数据包 */
    private static final int MAX_DROPS_PER_TICK = 4;
    /** 背包已用格数达到该值（共 36 格）即开始丢垃圾，留出余量防误判满包 */
    private static final int NEARLY_FULL_SLOTS = 30;

    /** 每帧调用：背包接近满时提前丢弃垃圾物品。 */
    public void tick(DigConfig config) {
        MinecraftClient client = MinecraftClient.getInstance();
        if (client.player == null || client.world == null || client.interactionManager == null) {
            return;
        }
        if (!config.autoTrash || config.task == MineTask.NONE) {
            return;
        }
        if (client.currentScreen != null) {
            return; // 有界面（箱子/死亡界面等）打开时不操作背包
        }
        PlayerEntity player = client.player;
        ScreenHandler handler = player.currentScreenHandler;
        if (handler != player.playerScreenHandler) {
            return;
        }
        if (!handler.getCursorStack().isEmpty()) {
            return;
        }
        // 背包接近满才开始丢，避免背包还没满就误丢
        if (this.usedSlots(player) < NEARLY_FULL_SLOTS) {
            return;
        }
        Set<String> trash = new HashSet<>(config.getTrashItemList());
        if (trash.isEmpty()) {
            return;
        }

        // 收集背包里的垃圾，按物品 id 分组（并记录是否为可放置的方块）
        Map<String, List<ItemStack>> groups = new HashMap<>();
        Map<String, Boolean> blockLike = new HashMap<>();
        for (int i = 0; i < 36; i++) {
            ItemStack s = player.getInventory().main.get(i);
            if (s.isEmpty()) {
                continue;
            }
            String id = this.itemId(s);
            if (!trash.contains(id)) {
                continue;
            }
            groups.computeIfAbsent(id, k -> new ArrayList<>()).add(s);
            blockLike.putIfAbsent(id, s.getItem() instanceof BlockItem);
        }
        if (groups.isEmpty()) {
            return;
        }

        // 决定丢弃哪些：方块类垃圾保留 trashReserve 个（搭路用），非方块全丢
        List<ItemStack> drops = new ArrayList<>();
        for (Map.Entry<String, List<ItemStack>> e : groups.entrySet()) {
            int keep = Boolean.TRUE.equals(blockLike.get(e.getKey())) ? config.trashReserve : 0;
            for (ItemStack s : e.getValue()) {
                if (keep > 0) {
                    keep -= s.getCount();
                    continue; // 还在保留额度内
                }
                drops.add(s);
            }
        }
        if (drops.isEmpty()) {
            // 满背但垃圾全在保留额度内：只丢一组腾出空间，尽量保住搭路方块
            for (List<ItemStack> list : groups.values()) {
                if (!list.isEmpty()) {
                    drops.add(list.get(0));
                    break;
                }
            }
        }

        // 执行丢弃（每 tick 限量，剩余下 tick 继续）
        int dropped = 0;
        for (ItemStack s : drops) {
            if (dropped >= MAX_DROPS_PER_TICK) {
                break;
            }
            int slot = this.screenSlotOf(handler, s);
            if (slot < 0) {
                continue;
            }
            // THROW + 按钮 1 = 丢出整组
            client.interactionManager.clickSlot(handler.syncId, slot, 1, SlotActionType.THROW, player);
            dropped++;
        }
    }

    /** 统计背包已用格数（快捷栏 + 主背包 0-35，共 36 格）。 */
    private int usedSlots(PlayerEntity player) {
        int used = 0;
        for (int i = 0; i < 36; i++) {
            if (!player.getInventory().main.get(i).isEmpty()) {
                used++;
            }
        }
        return used;
    }

    /** 按对象引用在 ScreenHandler 里找槽位下标。 */
    private int screenSlotOf(ScreenHandler handler, ItemStack stack) {
        for (int i = 0; i < handler.slots.size(); i++) {
            if (handler.getSlot(i).getStack() == stack) {
                return i;
            }
        }
        return -1;
    }

    private String itemId(ItemStack stack) {
        return Registries.ITEM.getId(stack.getItem()).toString();
    }
}