gather-and-defend/Assets/Scripts/ResourceMaker.cs

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class ResourceMaker : MonoBehaviour
{
    [SerializeField] 
    private int _resourceMakingAmount;
    [SerializeField] 
    private ResourceChoice _resourceChoice;

    private ResourceManager _resourceManager;
    private enum ResourceChoice
    {
        Rock,
        Wood,
        Food
    };

    public void GenerateResource()
    {
        _resourceManager = ResourceManager.Instance;
        StartCoroutine(Make());
    }

    private IEnumerator Make()
    {
        switch (_resourceChoice)
        {
            case ResourceChoice.Rock:
                _resourceManager.RockAmount = _resourceMakingAmount;
                break;
            case ResourceChoice.Wood:
                _resourceManager.WoodAmount = _resourceMakingAmount;
                break;
            case ResourceChoice.Food:
                _resourceManager.FoodAmount = _resourceMakingAmount;
                break;
            default:
                break;
        }
        Debug.Log("Generating...");

        yield return new WaitForSeconds(3f);
    }

    public void StopGenerate()
    {
        StopCoroutine(Make());
    }
}