アップグレード

using UnityEngine;
using UnityEngine.InputSystem;
using UnityEngine.UI;
using TMPro;

public class BuildManager : MonoBehaviour
{
    [SerializeField] private GameManager game;
    [SerializeField] private Tower[] shop;
    [SerializeField] private Button[] shopButtons;
    [SerializeField] private Color chosenColor = new Color(1f, 0.85f, 0.3f);
    [SerializeField] private GameObject towerPanel;
    [SerializeField] private TMP_Text towerNameText;
    [SerializeField] private TMP_Text towerStatsText;
    [SerializeField] private TMP_Text upgradeLabel;

    private Tower chosen;
    private Tower selected;

    void Start()
    {
        for (int i = 0; i < shop.Length; i++)
        {
            Tower prefab = shop[i];
            shopButtons[i].GetComponentInChildren<TMP_Text>().text = prefab.data.towerName + "\n" + prefab.data.cost;
            shopButtons[i].onClick.AddListener(() => Choose(prefab));
        }
        Choose(shop[0]);
        Select(null);
    }

    void Choose(Tower prefab)
    {
        chosen = prefab;
        for (int i = 0; i < shop.Length; i++)
        {
            shopButtons[i].image.color = shop[i] == chosen ? chosenColor : Color.white;
        }
    }

    void Update()
    {
        if (!Mouse.current.leftButton.wasPressedThisFrame)
        {
            return;
        }

        Ray ray = Camera.main.ScreenPointToRay(Mouse.current.position.ReadValue());
        if (!Physics.Raycast(ray, out RaycastHit hit))
        {
            Select(null);
            return;
        }

        Tower tower = hit.collider.GetComponentInParent<Tower>();
        if (tower != null)
        {
            Select(tower);
            return;
        }

        Select(null);
        if (hit.collider.TryGetComponent(out BuildPad pad))
        {
            Build(pad);
        }
    }

    void Build(BuildPad pad)
    {
        if (pad.tower != null)
        {
            return;
        }

        if (!game.TrySpend(chosen.data.cost))
        {
            Debug.Log("Not enough money");
            return;
        }

        pad.tower = Instantiate(chosen, pad.transform.position, Quaternion.identity);
    }

    void Select(Tower tower)
    {
        selected = tower;
        towerPanel.SetActive(tower != null);
        if (tower != null)
        {
            ShowPanel();
        }
    }

    void ShowPanel()
    {
        TowerData data = selected.data;
        int level = selected.Level;
        towerNameText.text = data.towerName + " level " + level;
        towerStatsText.text = "Damage " + data.DamageAt(level) + " > " + data.DamageAt(level + 1)
            + "\nRange " + data.RangeAt(level) + " > " + data.RangeAt(level + 1);
        upgradeLabel.text = "Upgrade " + data.UpgradeCost(level);
    }
}