using UnityEngine;
using UnityEngine.AI;
[RequireComponent(typeof(NavMeshAgent))]
public sealed class NavPathProbe : MonoBehaviour
{
    [SerializeField] private Transform destination;
    private NavMeshAgent agent;
    private bool submitted;
    private string lastState;
    private int requestFrame;
    private void Awake() { agent = GetComponent<NavMeshAgent>(); }
    private void Start() { RequestPath(); }
    [ContextMenu("Request Path (Play Mode)")]
    public void RequestPath()
    {
        if (!Application.isPlaying || !isActiveAndEnabled || agent == null) return;
        submitted = false;
        if (destination == null || !agent.enabled || !agent.isOnNavMesh)
        { Publish("assign destination and place enabled agent on a compatible NavMesh"); return; }
        submitted = agent.SetDestination(destination.position);
        requestFrame = Time.frameCount;
        Publish(submitted ? "requested" : "request rejected");
    }
    private void Update()
    {
        if (!submitted || Time.frameCount <= requestFrame) return;
        if (!agent.enabled || !agent.isOnNavMesh) { Publish("not on NavMesh"); return; }
        if (agent.pathPending) { Publish("pending"); return; }
        if (agent.pathStatus != NavMeshPathStatus.PathComplete) { Publish(agent.pathStatus.ToString()); return; }
        if (!agent.hasPath) { Publish("no active path"); return; }
        float distance = agent.remainingDistance;
        if (float.IsInfinity(distance) || float.IsNaN(distance)) { Publish("unknown distance"); return; }
        if (distance > agent.stoppingDistance) { Publish("travelling"); return; }
        Publish(agent.velocity.sqrMagnitude > 0.01f ? "braking" : "arrived");
    }
    private void Publish(string state)
    {
        if (state == lastState) return;
        lastState = state;
        Debug.Log("Navigation: " + state, this);
    }
}