ScavengerStateMachine.cs

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

public class ScavengerStateMachine : MonoBehaviour
{
    public float Speed;

    delegate void ScavengerState();

    ScavengerState currentState;

    Mineral bestMineral;

    public Transform Home;

    // Use this for initialization
    void Start()
    {
        currentState = SearchNearestMineral;
    }

    // Update is called once per frame
    void Update()
    {
        currentState();
    }

    void SearchNearestMineral()
    {
        bestMineral = null;
        Mineral[] minerals = GameObject.FindObjectsOfType<Mineral>();
        float currentDist = float.MaxValue;

        for (int i = 0; i < minerals.Length; i++)
        {
            if (minerals[i].transform.parent != null)
                continue;
            float distance = (minerals[i].transform.position - this.transform.position).magnitude;

            if (distance < currentDist)
            {
                bestMineral = minerals[i];
                currentDist = distance;
            }
        }

        if (bestMineral != null)
        {
            currentState = GoToMineral;
        }
    }

    void GoToMineral()
    {
        Vector3 direction = (bestMineral.transform.position - transform.position).normalized;
        direction.y = 0;

        if (direction != Vector3.zero)
        {
            transform.position += direction * Time.deltaTime * Speed;
            transform.forward = direction;
        }

        float distance = (transform.position - bestMineral.transform.position).magnitude;
        if (distance < 0.5f)
        {
            bestMineral.transform.SetParent(transform);
            currentState = BringMineralToBase;
        }
    }

    void BringMineralToBase()
    {
        Vector3 direction = (Home.position - transform.position).normalized;
        direction.y = 0;

        if (direction != Vector3.zero)
        {
            transform.position += direction * Speed * Time.deltaTime;

            transform.forward = direction;
        }

        float distance = (transform.position - Home.position).magnitude;
        if (distance < 1.5f)
        {
            bestMineral.transform.SetParent(Home);
            currentState = SearchNearestMineral;
        }
    }
}