CastleDefence/Assets/Scripts/EnemyController.cs

using UnityEngine;
using UnityEngine.AI;

public class EnemyController : MonoBehaviour
{
    public float moveSpeed;
    public float targetRange;
    public float attackRange;
    public float attackSpeed;
    public float attackDamage;
    public float health;
    public Transform defaultTarget;
    public Transform target;
    private NavMeshAgent navMeshAgent;
    private Animator animator;
    private SphereCollider targetCollider;
    private float attackCooldown;

    void Awake()
    {
        navMeshAgent = GetComponent<NavMeshAgent>();
        animator = GetComponentInChildren<Animator>();
        targetCollider = GetComponentInChildren<SphereCollider>();
        navMeshAgent.speed = moveSpeed;
        targetCollider.radius = targetRange;
    }

    void Start()
    {
        MoveToDefault();
    }

    void Update()
    {
        if(target != null && !target.gameObject.activeInHierarchy)
        {
            target = null;
            MoveToDefault();
        }

        if(target != null)
            Attack();

        animator.SetFloat("Speed", navMeshAgent.velocity.magnitude);
    }

    private void OnTriggerEnter(Collider other)
    {
        if(target != null) return;
        if(!other.CompareTag("Gate")) return;

        AttackPoint attackPoint = other.GetComponentInChildren<AttackPoint>();
        if(attackPoint != null)
        {
            target = attackPoint.transform;
            navMeshAgent.stoppingDistance = attackRange;
            navMeshAgent.destination = attackPoint.transform.position;
        }
    }

    private void MoveToDefault()
    {
        navMeshAgent.stoppingDistance = 0f;
        if(defaultTarget != null)
            navMeshAgent.destination = defaultTarget.position;
    }

    private void Attack()
    {
        attackCooldown -= Time.deltaTime;
        if(Vector3.Distance(target.position, transform.position) < attackRange && attackCooldown <= 0f)
        {
            transform.LookAt(target.position);
            animator.SetTrigger("Attack");
            attackCooldown = 1f / attackSpeed;
            target.GetComponent<AttackPoint>().AddAttacker();
            target.GetComponentInParent<Building>().TakeDamage(attackDamage);
        }
    }

    private void OnDrawGizmosSelected()
    {
        // Target range — green if priority target is assigned, red if not
        Gizmos.color = target != null ? Color.green : Color.red;
        Gizmos.DrawWireSphere(transform.position, targetRange);

        // Attack range — green if target is within attack range, red if not
        bool inAttackRange = target != null && Vector3.Distance(target.position, transform.position) < attackRange;
        Gizmos.color = inAttackRange ? Color.green : Color.red;
        Gizmos.DrawWireSphere(transform.position, attackRange);
    }
}