using System.Collections;
using System.Collections.Generic;
using BaseGames.Core.Events;
using UnityEngine;

namespace BaseGames.World
{
    /// <summary>
    /// 移动平台。Kinematic Rigidbody2D，支持三种移动模式。
    /// 乘客跟随：OnTriggerEnter2D 时 SetParent，离开时还原并附加速度。
    /// </summary>
    [RequireComponent(typeof(Rigidbody2D))]
    public class MovingPlatform : MonoBehaviour
    {
        public enum MoveType { LinearAB, WayPoints, TriggeredLinear }

        [Header("移动配置")]
        [SerializeField] private MoveType    _moveType        = MoveType.LinearAB;
        [SerializeField] private Transform[] _wayPoints;
        [SerializeField] private float       _speed           = 3f;
        [SerializeField] private float       _waitAtEndpoint  = 0.5f;

        [Header("TriggeredLinear 模式")]
        [SerializeField] private VoidEventChannelSO _activationChannel;

        [Header("乘客检测")]
        [SerializeField] private BoxCollider2D _passengerSensor;  // IsTrigger，用于乘客 SetParent

        private Rigidbody2D        _rb;
        private List<Transform>    _passengers    = new();
        private int                _waypointIndex;
        private bool               _movingForward = true;
        private bool               _triggered;
        private bool               _waiting;
        private WaitForSeconds     _waitForEndpoint;
        private readonly CompositeDisposable _subs = new();

        private void Awake()
        {
            _rb = GetComponent<Rigidbody2D>();
            _rb.bodyType      = RigidbodyType2D.Kinematic;
            _rb.interpolation = RigidbodyInterpolation2D.Interpolate;
            _waitForEndpoint  = new WaitForSeconds(_waitAtEndpoint);
        }

        private void OnEnable()
        {
            _activationChannel?.Subscribe(OnTriggered).AddTo(_subs);
        }

        private void OnDisable()
        {
            _subs.Clear();
        }

        private void FixedUpdate()
        {
            if (_wayPoints == null || _wayPoints.Length == 0) return;
            if (_moveType == MoveType.TriggeredLinear && !_triggered) return;
            if (_waiting) return;

            MoveTowardsNextWaypoint();
        }

        private void MoveTowardsNextWaypoint()
        {
            var target = (Vector2)_wayPoints[_waypointIndex].position;
            var next   = Vector2.MoveTowards(_rb.position, target, _speed * Time.fixedDeltaTime);
            _rb.MovePosition(next);

            if (Vector2.Distance(_rb.position, target) < 0.02f)
                StartCoroutine(WaitAndAdvance());
        }

        private IEnumerator WaitAndAdvance()
        {
            _waiting = true;
            yield return _waitForEndpoint;
            AdvanceWaypoint();
            _waiting = false;
        }

        private void AdvanceWaypoint()
        {
            if (_moveType == MoveType.TriggeredLinear)
            {
                _waypointIndex = Mathf.Min(_waypointIndex + 1, _wayPoints.Length - 1);
                if (_waypointIndex == _wayPoints.Length - 1)
                    _triggered = false;
                return;
            }

            if (_moveType == MoveType.LinearAB)
            {
                _movingForward = !_movingForward;
                _waypointIndex = _movingForward ? 1 : 0;
            }
            else // WayPoints
            {
                _waypointIndex = (_waypointIndex + 1) % _wayPoints.Length;
            }
        }

        private void OnTriggered() => _triggered = true;

        // ── Passenger Pattern ─────────────────────────────────────────────────

        private void OnTriggerEnter2D(Collider2D other)
        {
            if (!IsPassenger(other.gameObject)) return;
            other.transform.SetParent(transform);
            _passengers.Add(other.transform);
        }

        private void OnTriggerExit2D(Collider2D other)
        {
            if (!_passengers.Contains(other.transform)) return;

            other.transform.SetParent(null);
            _passengers.Remove(other.transform);

            // 离开时附加平台速度，避免卡顿
            var passengerRb = other.GetComponentInParent<Rigidbody2D>();
            if (passengerRb != null)
                passengerRb.AddForce(_rb.velocity, ForceMode2D.Impulse);
        }

        private static bool IsPassenger(GameObject go)
        {
            return go.CompareTag("Player") || go.CompareTag("Enemy");
        }

#if UNITY_EDITOR
        private void OnDrawGizmos()
        {
            if (_wayPoints == null || _wayPoints.Length < 2) return;
            Gizmos.color = new Color(1f, 0.8f, 0f, 0.8f);
            for (int i = 0; i < _wayPoints.Length - 1; i++)
            {
                if (_wayPoints[i] != null && _wayPoints[i + 1] != null)
                    Gizmos.DrawLine(_wayPoints[i].position, _wayPoints[i + 1].position);
            }
        }
#endif
    }
}