using UnityEngine;
using System.Collections.Generic;

public class EnemyAI : MonoBehaviour
{
    public enum EnemyState { Patrol, Chase, Returning }
    public EnemyState currentState = EnemyState.Patrol;

    [Header("Movement Settings")]
    public float patrolSpeed = 3f;
    public float chaseSpeed = 6f;
    public float detectionRadius = 12f;
    public float maxChaseDistance = 30f; // The "Leash" length

    private Vector3 spawnPosition;
    public List<Vector3> patrolPoints = new List<Vector3>();
    private int currentPointIndex = 0;
    private Transform player;
    private LayerMask terrainLayer;

    void Start()
    {
        player = GameObject.FindGameObjectWithTag("Player").transform;
        // Looking for the "Terrain" layer specifically as per your Spawner
        terrainLayer = LayerMask.GetMask("Terrain");
        spawnPosition = transform.position; // Remember where it was born

        // Generate 3 patrol points around spawn
        for (int i = 0; i < 3; i++)
        {
            Vector3 randomPos = spawnPosition + new Vector3(Random.Range(-15f, 15f), 10f, Random.Range(-15f, 15f));
            if (Physics.Raycast(randomPos, Vector3.down, out RaycastHit hit, 20f, terrainLayer))
            {
                patrolPoints.Add(hit.point + Vector3.up * 1f);
            }
        }
    }

    void Update()
    {
        float distToPlayer = Vector3.Distance(transform.position, player.position);
        float distFromHome = Vector3.Distance(transform.position, spawnPosition);

        // State Logic
        if (currentState == EnemyState.Chase && distFromHome > maxChaseDistance)
        {
            currentState = EnemyState.Returning;
        }
        else if (distToPlayer < detectionRadius && currentState != EnemyState.Returning)
        {
            currentState = EnemyState.Chase;
        }
        else if (currentState == EnemyState.Returning && distFromHome < 2f)
        {
            currentState = EnemyState.Patrol;
        }

        ExecuteState();
    }

    void ExecuteState()
    {
        switch (currentState)
        {
            case EnemyState.Patrol:
                Patrol();
                break;
            case EnemyState.Chase:
                MoveTowards(player.position, chaseSpeed);
                break;
            case EnemyState.Returning:
                MoveTowards(spawnPosition, patrolSpeed);
                break;
        }
    }

    void Patrol()
    {
        if (patrolPoints.Count == 0) return;
        Vector3 target = patrolPoints[currentPointIndex];
        MoveTowards(target, patrolSpeed);

        if (Vector3.Distance(transform.position, target) < 1.5f)
            currentPointIndex = (currentPointIndex + 1) % patrolPoints.Count;
    }

    void MoveTowards(Vector3 target, float speed)
    {
        Vector3 dir = (target - transform.position).normalized;
        dir.y = 0;

        // 1. Check for obstacles directly in front
        // We fire a ray from the "chest" of the enemy forward
        RaycastHit wallHit;
        if (Physics.Raycast(transform.position + Vector3.up * 1f, dir, out wallHit, 1.5f, terrainLayer))
        {
            // If the hill is too steep, we try to "step up" or slide along it
            dir += wallHit.normal * 0.5f;
        }

        // 2. Apply movement
        transform.position += dir * speed * Time.deltaTime;

        // 3. Ground Hugging (Smooth height adjustment)
        // We use a longer ray and a SmoothDamp or Lerp to prevent snapping
        if (Physics.Raycast(transform.position + Vector3.up * 10f, Vector3.down, out RaycastHit groundHit, 20f, terrainLayer))
        {
            float targetHeight = groundHit.point.y + 0.5f;
            // Smoothly transition the Y position so they don't "teleport" up hills
            float newY = Mathf.MoveTowards(transform.position.y, targetHeight, speed * Time.deltaTime);
            transform.position = new Vector3(transform.position.x, newY, transform.position.z);
        }

        // 4. Rotation (Make them face where they are going)
        if (dir != Vector3.zero)
        {
            Quaternion targetRotation = Quaternion.LookRotation(dir);
            transform.rotation = Quaternion.Slerp(transform.rotation, targetRotation, Time.deltaTime * 5f);
        }
    }
}