# belt_system.gd —— Metin2 40250 腰带系统与专属药水背包 1:1
# 对照 40250 服务端 belt.cpp, char_item.cpp, uiinventory.py
class_name BeltSystem
extends RefCounted

signal belt_equipped(belt_name: String, slots_unlocked: int)
signal belt_unequipped()
signal belt_item_stored(slot: int, item_name: String)
signal belt_item_removed(slot: int)

const MAX_BELT_SLOTS := 16 # 最大 4x4 空间

# 允许存入腰带的消耗品/药水类型
const ALLOWED_CONSUMABLE_TYPES: Array = ["potion", "consumable", "dew", "elixir"]

# 已装备的腰带
var equipped_belt: Dictionary = {}
var belt_inventory: Array = [] # 16 个格子

func _init() -> void:
	belt_inventory.resize(MAX_BELT_SLOTS)
	for i in range(MAX_BELT_SLOTS):
		belt_inventory[i] = null

# 根据腰带强化等级计算开放的药水槽位数量
static func calculate_unlocked_slots(refine_level: int) -> int:
	if refine_level >= 9:
		return 16 # 4x4
	elif refine_level >= 7:
		return 12 # 3x4
	elif refine_level >= 5:
		return 10
	elif refine_level >= 3:
		return 8  # 2x4
	elif refine_level >= 1:
		return 6
	else:
		return 4  # 1x4

# 获取当前开放的药水格子数
func get_unlocked_slot_count() -> int:
	if equipped_belt.is_empty():
		return 0
	var refine: int = int(equipped_belt.get("refine_level", 0))
	return calculate_unlocked_slots(refine)

# 佩戴腰带
func equip_belt(belt_item: Dictionary) -> Dictionary:
	if belt_item.is_empty():
		return {"ok": false, "reason": "EMPTY_BELT", "msg": "腰带数据为空！"}

	equipped_belt = belt_item.duplicate(true)
	var unlocked := get_unlocked_slot_count()
	var bname: String = equipped_belt.get("name", "腰带")

	belt_equipped.emit(bname, unlocked)

	return {
		"ok": true,
		"belt": equipped_belt,
		"unlocked_slots": unlocked,
		"msg": "已佩戴【%s】，解锁了 %d 格专属药水空间！" % [bname, unlocked]
	}

# 卸下腰带 (需确保腰带内物品能够全部安全移出或为空)
func unequip_belt(main_inventory: Array) -> Dictionary:
	if equipped_belt.is_empty():
		return {"ok": false, "reason": "NO_BELT_EQUIPPED", "msg": "当前未佩戴腰带！"}

	# 检查腰带内是否有物品
	var items_in_belt: Array = []
	for i in range(MAX_BELT_SLOTS):
		if belt_inventory[i] != null:
			items_in_belt.append({"belt_slot": i, "item": belt_inventory[i]})

	if not items_in_belt.is_empty():
		# 统计主背包空位
		var empty_slots: Array = []
		for j in range(main_inventory.size()):
			if main_inventory[j] == null:
				empty_slots.append(j)

		if empty_slots.size() < items_in_belt.size():
			return {
				"ok": false,
				"reason": "BELT_NOT_EMPTY",
				"items_count": items_in_belt.size(),
				"empty_slots": empty_slots.size(),
				"msg": "主背包空间不足以容纳腰带内的药水，无法卸下腰带！"
			}

		# 移入主背包
		for k in range(items_in_belt.size()):
			var m_slot: int = empty_slots[k]
			var it = items_in_belt[k]["item"]
			var b_slot: int = items_in_belt[k]["belt_slot"]
			main_inventory[m_slot] = it
			belt_inventory[b_slot] = null

	var old_belt := equipped_belt.duplicate(true)
	equipped_belt.clear()
	belt_unequipped.emit()

	return {
		"ok": true,
		"belt": old_belt,
		"msg": "腰带已卸下！内部药水已全部归还至主背包。"
	}

# 存放药水至腰带专属背包
func store_item_in_belt(slot_idx: int, item: Dictionary) -> Dictionary:
	if equipped_belt.is_empty():
		return {"ok": false, "reason": "NO_BELT_EQUIPPED", "msg": "未佩戴腰带，无法使用专属药水栏！"}

	var unlocked := get_unlocked_slot_count()
	if slot_idx < 0 or slot_idx >= unlocked:
		return {
			"ok": false,
			"reason": "SLOT_LOCKED_OR_INVALID",
			"unlocked_slots": unlocked,
			"msg": "该腰带槽位尚未解锁或无效！当前腰带只开放了前 %d 格。" % unlocked
		}

	# 药品类型校验
	var it_type: String = item.get("item_type", "")
	var is_potion: bool = ALLOWED_CONSUMABLE_TYPES.has(it_type) or item.get("is_potion", false)
	if not is_potion:
		return {
			"ok": false,
			"reason": "NOT_A_POTION",
			"msg": "腰带栏位专用于补给品，只能存放药水、灵药与神圣露水！"
		}

	belt_inventory[slot_idx] = item.duplicate(true)
	var iname: String = item.get("name", "药水")
	belt_item_stored.emit(slot_idx, iname)

	return {
		"ok": true,
		"slot_idx": slot_idx,
		"item": belt_inventory[slot_idx],
		"msg": "已将【%s】置入腰带快捷栏！" % iname
	}

# 从腰带栏取出药水
func take_item_from_belt(slot_idx: int) -> Dictionary:
	if slot_idx < 0 or slot_idx >= MAX_BELT_SLOTS:
		return {"ok": false, "reason": "INVALID_SLOT"}

	var item = belt_inventory[slot_idx]
	if item == null:
		return {"ok": false, "reason": "EMPTY_SLOT"}

	belt_inventory[slot_idx] = null
	belt_item_removed.emit(slot_idx)

	return {
		"ok": true,
		"slot_idx": slot_idx,
		"item": item
	}