using UnityEngine;
using Ashwild.Interaction;

namespace Ashwild.Player
{
    /// <summary>
    /// Raycasts forward on interact input and triggers the first IInteractable hit.
    /// Draws a selection gizmo that turns its "can interact" colour and shortens to
    /// the hit point when the aim is currently pointing at an interactable target.
    /// </summary>
    [DisallowMultipleComponent]
    public class PlayerInteractor : MonoBehaviour
    {
        #region Serialized Fields

        [Header("Raycast")]
        /// <summary>
        /// Maximum distance, in metres, at which an interactable can be triggered.
        /// </summary>
        [SerializeField] private float interactRange = 3f;

        /// <summary>
        /// Layers the interaction ray is allowed to hit.
        /// </summary>
        [SerializeField] private LayerMask interactMask = ~0;

        /// <summary>
        /// Origin and forward direction of the interaction ray (usually the camera).
        /// </summary>
        [SerializeField] private Transform raycastOrigin;

        /// <summary>
        /// How long, in seconds, a new target must stay under the ray before the
        /// hover change is committed. Debounces fast view sweeps so the crosshair
        /// animation never flickers on objects only glanced at for a few frames.
        /// </summary>
        [SerializeField] private float hoverStabilityTime = 0.08f;

        [Header("Gizmo")]
        /// <summary>
        /// Gizmo colour when the ray is not aiming at any interactable.
        /// </summary>
        [SerializeField] private Color idleGizmoColor = Color.green;

        /// <summary>
        /// Gizmo colour when the ray is aiming at a valid interactable.
        /// </summary>
        [SerializeField] private Color interactableGizmoColor = Color.cyan;

        #endregion

        #region State

        /// <summary>
        /// The committed hover target broadcast on the bus, reused by interact.
        /// </summary>
        private IInteractable currentHover;

        /// <summary>
        /// The target the ray currently sees, pending stability before it is
        /// committed as the hover (debounce against fast view sweeps).
        /// </summary>
        private IInteractable candidateHover;

        /// <summary>
        /// How long the candidate has stayed unchanged, in seconds.
        /// </summary>
        private float candidateTimer;

        #endregion

        #region Unity Lifecycle

        /// <summary>
        /// Subscribes to the interact input event.
        /// </summary>
        private void OnEnable()  { PlayerEvents.InteractPressed += OnInteractPressed; }

        /// <summary>
        /// Unsubscribes — must mirror OnEnable exactly — and clears any hover so
        /// consumers (crosshair) reset when this component is disabled.
        /// </summary>
        private void OnDisable()
        {
            PlayerEvents.InteractPressed -= OnInteractPressed;
            CommitHover(null);
        }

        /// <summary>
        /// Detects the interactable under the aim ray each frame and commits hover
        /// changes only once a new target has stayed stable for hoverStabilityTime,
        /// so quick view sweeps never spam the bus. One raycast per frame.
        /// </summary>
        private void Update()
        {
            // While input is locked, drop the hover immediately (no debounce).
            if (PlayerEvents.InputLocked)
            {
                candidateHover = null;
                candidateTimer = 0f;
                CommitHover(null);
                return;
            }

            IInteractable raw = null;
            if (raycastOrigin != null
                && Physics.Raycast(raycastOrigin.position, raycastOrigin.forward, out RaycastHit hit,
                    interactRange, interactMask, QueryTriggerInteraction.Collide))
            {
                hit.collider.TryGetComponent(out raw);
            }

            // Restart the stability timer whenever the seen target changes.
            if (!ReferenceEquals(raw, candidateHover))
            {
                candidateHover = raw;
                candidateTimer = 0f;
            }
            else
            {
                candidateTimer += Time.deltaTime;
            }

            // Commit only once the candidate has been stable long enough.
            if (!ReferenceEquals(candidateHover, currentHover) && candidateTimer >= hoverStabilityTime)
                CommitHover(candidateHover);
        }

        #endregion

        #region Hover Detection

        /// <summary>
        /// Stores the committed hover target and raises the bus event when it
        /// differs from the previous one.
        /// </summary>
        private void CommitHover(IInteractable hover)
        {
            if (ReferenceEquals(hover, currentHover)) return;

            currentHover = hover;
            PlayerEvents.RaiseInteractableHoverChanged(hover);
        }

        #endregion

        #region Event Handlers

        /// <summary>
        /// Interacts with whatever the ray points at right now. Uses a fresh raycast
        /// rather than the debounced hover so a quick aim-and-click never misses.
        /// </summary>
        private void OnInteractPressed()
        {
            if (PlayerEvents.InputLocked || raycastOrigin == null) return;

            if (Physics.Raycast(raycastOrigin.position, raycastOrigin.forward, out RaycastHit hit,
                    interactRange, interactMask, QueryTriggerInteraction.Collide)
                && hit.collider.TryGetComponent(out IInteractable interactable))
            {
                interactable.Interact();
            }
        }

        #endregion

        #region Gizmos

        /// <summary>
        /// Draws the interaction ray when selected. The ray turns the "interactable"
        /// colour and stops at the hit point whenever it is aiming at an IInteractable;
        /// otherwise it stays the idle colour and spans the full range.
        /// </summary>
        private void OnDrawGizmosSelected()
        {
            Transform o = raycastOrigin != null ? raycastOrigin : transform;

            bool hitInteractable = Physics.Raycast(o.position, o.forward, out RaycastHit hit,
                    interactRange, interactMask, QueryTriggerInteraction.Collide)
                && hit.collider.TryGetComponent(out IInteractable _);

            float length = hitInteractable ? hit.distance : interactRange;
            Vector3 endPoint = o.position + o.forward * length;

            Gizmos.color = hitInteractable ? interactableGizmoColor : idleGizmoColor;
            Gizmos.DrawRay(o.position, o.forward * length);
            Gizmos.DrawWireSphere(endPoint, 0.1f);
        }

        #endregion
    }
}