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

namespace Samkwang
{
    public class ObjectTourController : MonoBehaviour
    {
        public Transform controlObject;
        public ObjectTourPoint[] tourPoints;

        public float moveSpeed = 2f;         // 이동 속도 (SmoothDamp의 maxSpeed 대신 이동속도로 사용)
        public float turnSpeedDegrees = 120f; // 초당 최대 회전 각도 (degree/sec)
        public float arrivalThreshold = 0.05f;

        // look-ahead: 목표에 가까워질때 다음 포인트 방향으로 미리 보도록 하는 거리
        public float lookAheadDistance = 1.0f;

        private int currentIndex = 0;

        private void Start()
        {
            controlObject = transform.Find("Walking_cart").transform;
            tourPoints = transform.GetComponentsInChildren<ObjectTourPoint>().OrderBy(p => p.transform.GetSiblingIndex()).ToArray();

            if (tourPoints.Length > 0)
                StartCoroutine(MoveTour());
        }

        private IEnumerator MoveTour()
        {
            while (true)
            {
                yield return StartCoroutine(MoveToTarget(currentIndex));

                currentIndex = (currentIndex + 1) % tourPoints.Length;
            }
        }

        private IEnumerator MoveToTarget(int index)
        {
            Transform target = tourPoints[index].transform;
            Transform nextTarget = tourPoints[(index + 1) % tourPoints.Length].transform;

            while (Vector3.Distance(controlObject.position, target.position) > arrivalThreshold)
            {
                // --- 위치 이동 (SmoothDamp style)
                // SmoothDamp의 maxSpeed 파라미터 대신 단순 MoveTowards 기반으로 안정적 제어
                float step = moveSpeed * Time.deltaTime;
                controlObject.position = Vector3.MoveTowards(controlObject.position, target.position, step);

                // --- 회전: look-ahead 처리
                float distToTarget = Vector3.Distance(controlObject.position, target.position);

                // 가까워질수록 다음 포인트를 더 바라보게 보간
                Vector3 desiredLookPos;
                if (distToTarget <= lookAheadDistance)
                {
                    // 보간 비율: 0(멀때) -> 1(가까울때)
                    float t = Mathf.InverseLerp(lookAheadDistance, 0f, distToTarget);
                    Vector3 dirToCurrent = (target.position - controlObject.position).normalized;
                    Vector3 dirToNext = (nextTarget.position - controlObject.position).normalized;
                    Vector3 blendedDir = Vector3.Slerp(dirToCurrent, dirToNext, t).normalized;
                    desiredLookPos = controlObject.position + blendedDir;
                }
                else
                {
                    desiredLookPos = target.position;
                }

                Vector3 dir = (desiredLookPos - controlObject.position);
                if (dir.sqrMagnitude > 0.0001f)
                {
                    Quaternion targetRot = Quaternion.LookRotation(dir.normalized);

                    // 초당 회전 한계를 적용 (더 자연스러운 회전)
                    float maxDeg = turnSpeedDegrees * Time.deltaTime;
                    controlObject.rotation = Quaternion.RotateTowards(controlObject.rotation, targetRot, maxDeg);
                }

                yield return null;
            }

            // 도착 후 정확히 위치/회전 정렬 (선택)
            controlObject.position = target.position;
        }
    }
}