using UnityEngine;

public class Enemy : MonoBehaviour, IMovementDirection
{
    [Header("Movement")]
    [SerializeField]
    private float moveSpeed = 0.5f;

    [SerializeField]
    private float targetReachedDistance = 0.1f;

    private EnemyTargetManager targetManager;
    private Transform currentTarget;

    // Wird von CharacterRotation verwendet.
    public Vector2 MovementDirection { get; private set; }

    private void Awake()
    {
        targetManager =
            FindFirstObjectByType<EnemyTargetManager>();

        if (targetManager == null)
        {
            Debug.LogError(
                "Enemy: Kein EnemyTargetManager gefunden!",
                this
            );
        }
    }

    private void OnEnable()
    {
        if (targetManager != null)
        {
            targetManager.OnTargetsChanged +=
                SelectClosestTarget;
        }
    }

    private void OnDisable()
    {
        if (targetManager != null)
        {
            targetManager.OnTargetsChanged -=
                SelectClosestTarget;
        }
    }

    private void Start()
    {
        if (targetManager == null)
            return;

        SelectClosestTarget();
    }

    private void Update()
    {
        if (targetManager == null)
            return;

        // Kein aktuelles Ziel vorhanden.
        if (currentTarget == null)
        {
            MovementDirection = Vector2.zero;

            SelectClosestTarget();

            return;
        }

        // Das aktuelle Ziel wurde deaktiviert.
        if (!currentTarget.gameObject.activeInHierarchy)
        {
            SelectClosestTarget();

            return;
        }

        MoveTowardsTarget();

        // Ziel erreicht.
        if (HasReachedTarget())
        {
            SelectClosestTarget();
        }
    }

    private void SelectClosestTarget()
    {
        if (targetManager == null)
            return;

        currentTarget =
            targetManager.GetClosestActiveTarget(
                transform.position
            );

        if (currentTarget == null)
        {
            MovementDirection = Vector2.zero;
        }
    }

    private void MoveTowardsTarget()
    {
        if (currentTarget == null)
            return;

        Vector3 direction =
            currentTarget.position - transform.position;

        MovementDirection = new Vector2(
            direction.x,
            direction.y
        ).normalized;

        transform.position = Vector3.MoveTowards(
            transform.position,
            currentTarget.position,
            moveSpeed * Time.deltaTime
        );
    }

    private bool HasReachedTarget()
    {
        if (currentTarget == null)
            return false;

        return Vector3.Distance(
            transform.position,
            currentTarget.position
        ) <= targetReachedDistance;
    }
}