using UnityEngine;
using Unheimlich.Managers;

namespace Unheimlich.Interactions.Core
{
    /// <summary>
    /// Detects interactable objects in front of the player camera using raycasts.
    /// Triggers interaction when player presses interact button while looking at an interactable.
    /// </summary>
    public class InteractionHandler : MonoBehaviour
{
    public static InteractionHandler Instance { get; private set; }

    [Header("Settings")]
    [SerializeField] private float _interactionRange = 1f;
    [SerializeField] private LayerMask _interactableLayers;
    [SerializeField] private float _raycastInterval = 0.1f;

    private InteractableBase _currentInteractable;
    private Camera _playerCamera;
    private float _raycastTimer;
    
    private static readonly Vector3 ViewportCenter = new Vector3(0.5f, 0.5f, 0f);

    private void Awake()
    {
        if (Instance != null && Instance != this)
        {
            Destroy(this);
            return;
        }
        Instance = this;
        _playerCamera = GetComponent<Camera>();
    }

    private void Update()
    {
        _raycastTimer += Time.deltaTime;
        
        if (_raycastTimer >= _raycastInterval)
        {
            CheckForInteractable();
            _raycastTimer = 0f;
        }
        
        HandleInteractionInput();
    }
    
    /// <summary>
    /// Performs raycast from camera center to detect interactable objects within range.
    /// Updates the current interactable reference for input handling.
    /// </summary>
    private void CheckForInteractable()
    {
        Ray ray = _playerCamera.ViewportPointToRay(ViewportCenter);
        
        if (Physics.Raycast(ray, out RaycastHit hit, _interactionRange, _interactableLayers))
        {
            InteractableBase hitInteractable = hit.collider.GetComponent<InteractableBase>();
            _currentInteractable = hitInteractable;
        }
        else
            _currentInteractable = null;
    }
    
    private void HandleInteractionInput()
    {
        if (PlayerInputManager.Instance != null && 
            PlayerInputManager.Instance.InteractAction.action.WasPressedThisFrame())
        {
            if (_currentInteractable != null)
                _currentInteractable.Interact(transform.parent.gameObject);
        }
    }

    private void OnDrawGizmosSelected()
    {
        if (_playerCamera != null)
        {
            Gizmos.color = _currentInteractable != null ? Color.green : Color.red;
            
            Ray ray = _playerCamera.ViewportPointToRay(ViewportCenter);
            Gizmos.DrawRay(ray.origin, ray.direction * _interactionRange);
        }
    }
}
}