using UnityEngine;
using UnityEngine.Rendering;

namespace Unheimlich.Features.Hallucination
{
    /// <summary>
    /// Drives a persistent post-process weight targeting either a URP/HDRP <see cref="Volume"/>
    /// and/or a <see cref="Material"/> exposing a <c>_Weight</c> property, based on an
    /// internal sanity value [0, 1].
    /// Wire the Wrapper methods to any UnityEvent with no arguments.
    /// </summary>
    public class HallucinationPostProcess : MonoBehaviour
    {
        [Header("Targets")]
        [Tooltip("URP/HDRP Volume driven by the sanity weight.")]
        [SerializeField] private Volume   _volume;
        [Tooltip("Optional material exposing a _Weight property.")]
        [SerializeField] private Material _shaderMaterial;

        [Header("Sanity")]
        [SerializeField, Range(0f, 1f)] private float _initialSanity  = 0f;
        [Tooltip("Sanity lost per second after each tween completes. 0 = no decay.")]
        [SerializeField, Min(0f)]        private float _autoDecayRate  = 0f;

        [Header("Wrappers")]
        [Tooltip("Amount added when calling AddSanityWrapper().")]
        [SerializeField, Range(0f, 1f)] private float _wrapperAddAmount    = 0.2f;
        [Tooltip("Amount removed when calling RemoveSanityWrapper().")]
        [SerializeField, Range(0f, 1f)] private float _wrapperRemoveAmount = 0.2f;
        [Tooltip("Transition duration used by all wrappers (seconds).")]
        [SerializeField, Min(0f)]        private float _wrapperDuration     = 1f;

        // ─── State ─────────────────────────────────────────────────────────────

        private float _sanity;
        private int   _tweenId   = -1;
        private bool  _decaying  = false;

        // ─── Lifecycle ─────────────────────────────────────────────────────────

        private void Awake()
        {
            _sanity = Mathf.Clamp01(_initialSanity);
            Apply(_sanity);
        }

        private void Update()
        {
            if (!_decaying || _autoDecayRate <= 0f || _sanity <= 0f) return;

            _sanity = Mathf.Max(0f, _sanity - _autoDecayRate * Time.deltaTime);
            Apply(_sanity);

            if (_sanity <= 0f) _decaying = false;
        }

        // ─── Wrappers ──────────────────────────────────────────────────────────

        /// <summary>Adds <see cref="_wrapperAddAmount"/> sanity over <see cref="_wrapperDuration"/> seconds.
        /// Auto-decay starts when the tween completes, if <see cref="_autoDecayRate"/> is greater than 0.</summary>
        public void AddSanityWrapper()    => TweenSanity(_sanity + _wrapperAddAmount,    _wrapperDuration);

        /// <summary>Removes <see cref="_wrapperRemoveAmount"/> sanity over <see cref="_wrapperDuration"/> seconds.</summary>
        public void RemoveSanityWrapper() => TweenSanity(_sanity - _wrapperRemoveAmount, _wrapperDuration);

        /// <summary>Snaps sanity to 0 instantly and stops decay.</summary>
        public void ResetSanityWrapper()
        {
            CancelCurrent();
            _decaying = false;
            _sanity   = 0f;
            Apply(0f);
        }

        // ─── Private ───────────────────────────────────────────────────────────

        private void TweenSanity(float target, float duration)
        {
            target   = Mathf.Clamp01(target);
            _decaying = false;

            if (duration <= 0f)
            {
                CancelCurrent();
                _sanity = target;
                Apply(target);
                if (_autoDecayRate > 0f) _decaying = true;
                return;
            }

            CancelCurrent();

            float from = _sanity;
            _tweenId = LeanTween.value(gameObject, from, target, duration)
                .setEase(LeanTweenType.easeInOutQuad)
                .setOnUpdate((float w) =>
                {
                    _sanity = w;
                    Apply(w);
                })
                .setOnComplete(() =>
                {
                    // Start decay only after the tween has fully completed.
                    if (_autoDecayRate > 0f) _decaying = true;
                }).id;
        }

        private void Apply(float weight)
        {
            if (_volume         != null) _volume.weight = weight;
            if (_shaderMaterial != null) _shaderMaterial.SetFloat("_Weight", weight);
        }

        private void CancelCurrent()
        {
            if (_tweenId == -1) return;
            LeanTween.cancel(_tweenId);
            _tweenId = -1;
        }
    }
}