using UnityEngine;
using Unheimlich.Gameplay.Portals;

namespace Unheimlich.Managers
{
    /// <summary>
    /// Dynamically adjusts Unity's shadow rendering distance based on proximity to active portals.
    /// When the player is near a portal with a loaded room, shadow distance is extended to ensure
    /// shadows from the remote room are visible through the portal. This improves visual quality
    /// while maintaining performance when far from portals.
    /// </summary>
    public class DynamicShadowDistance : MonoBehaviour
    {
        private const float PORTAL_CHECK_DISTANCE = 100f;
        
        [Header("Shadow Distance Settings")]
        [SerializeField] private float _baseShadowDistance = 50f;
        [SerializeField] private float _extendedShadowDistance = 250f;
        [SerializeField] private float _transitionSpeed = 2f;
        
        [Header("Detection")]
        [SerializeField] private float _checkInterval = 0.5f;
        
        private float _targetShadowDistance;
        private float _currentShadowDistance;
        private float _nextCheckTime;
        private Transform _playerTransform;

        private void Start()
        {
            _playerTransform = Camera.main.transform;
            _currentShadowDistance = _baseShadowDistance;
            _targetShadowDistance = _baseShadowDistance;
            QualitySettings.shadowDistance = _baseShadowDistance;
        }

        private void Update()
        {
            if (Time.time >= _nextCheckTime)
            {
                _nextCheckTime = Time.time + _checkInterval;
                UpdateTargetShadowDistance();
            }

            if (!Mathf.Approximately(_currentShadowDistance, _targetShadowDistance))
            {
                _currentShadowDistance = Mathf.Lerp(_currentShadowDistance, _targetShadowDistance, Time.deltaTime * _transitionSpeed);
                QualitySettings.shadowDistance = _currentShadowDistance;
            }
        }

        /// <summary>
        /// Checks if any active portal with a loaded room is within range.
        /// If found, extends shadow distance to cover the remote room.
        /// </summary>
        private void UpdateTargetShadowDistance()
        {
            bool needsExtendedDistance = false;

            foreach (var portal in Portal.AllPortals)
            {
                if (portal == null || !portal.isActiveAndEnabled)
                    continue;

                if (portal.LoadedRoomInstance != null)
                {
                    float distanceToPortal = Vector3.Distance(_playerTransform.position, portal.transform.position);
                    
                    if (distanceToPortal < PORTAL_CHECK_DISTANCE)
                    {
                        needsExtendedDistance = true;
                        break;
                    }
                }
            }

            _targetShadowDistance = needsExtendedDistance ? _extendedShadowDistance : _baseShadowDistance;
        }

        private void OnValidate()
        {
            if (_baseShadowDistance < 0)
                _baseShadowDistance = 0;
            if (_extendedShadowDistance < _baseShadowDistance)
                _extendedShadowDistance = _baseShadowDistance;
        }

#if UNITY_EDITOR
        private void OnDrawGizmosSelected()
        {
            if (_playerTransform == null)
                return;

            Gizmos.color = new Color(1f, 1f, 0f, 0.2f);
            Gizmos.DrawWireSphere(_playerTransform.position, QualitySettings.shadowDistance);
            
            UnityEditor.Handles.Label(_playerTransform.position + Vector3.up * 2, 
                $"Shadow Distance: {QualitySettings.shadowDistance:F0}");
        }
#endif
    }
}