using System.Collections;
using UnityEngine;
using UnityEngine.Rendering;

namespace MonoLimboStudio
{
    public class LightFlicker : MonoBehaviour
    {
        [Header("Light Settings")]
        public Light targetLight;

        [Tooltip("Base intensity set externally (e.g. by ScarecrowFire). Flicker oscillates around this value.")]
        public float baseIntensity = 1f;

        [Tooltip("Flicker range applied relative to baseIntensity (e.g. 0.3 = ±30%).")]
        [Range(0f, 1f)]
        public float flickerRange = 0.3f;

        [Header("Perlin Flicker (smooth)")]
        public float flickerSpeed = 5f;

        [Header("Glitch Flicker (bursts)")]
        [Range(0f, 1f)] public float glitchChance        = 0.15f;
        public float                 glitchMinDuration   = 0.02f;
        public float                 glitchMaxDuration   = 0.12f;

        [Header("Material Settings")]
        public Renderer targetRenderer;
        public string   opacityProperty = "_Opacity";
        [Range(0f, 1f)] public float minOpacity = 0.2f;
        [Range(0f, 1f)] public float maxOpacity = 1.0f;

        private Material _materialInstance;
        private float    _randomOffset;

        // ─────────────────────────────────────────────────────────────────────

        void Start()
        {
            _randomOffset = Random.Range(0f, 1000f);

            if (targetRenderer != null)
            {
                _materialInstance = targetRenderer.material;

                if (!_materialInstance.HasProperty(opacityProperty))
                    Debug.LogWarning($"Property '{opacityProperty}' not found on material.");
            }

            StartCoroutine(FlickerRoutine());
        }

        // ─────────────────────────────────────────────────────────────────────

        /// <summary>
        /// Sets the base intensity that the flicker oscillates around.
        /// Called each frame by ScarecrowFire as the fire grows.
        /// </summary>
        public void SetBaseIntensity(float value)
        {
            baseIntensity = value;
        }

        // ─────────────────────────────────────────────────────────────────────

        private IEnumerator FlickerRoutine()
        {
            while (true)
            {
                float perlinValue = Mathf.PerlinNoise(Time.time * flickerSpeed + _randomOffset, 0f);
                ApplyFlicker(perlinValue);

                if (Random.value < glitchChance)
                    yield return StartCoroutine(GlitchBurst());

                yield return null;
            }
        }

        private IEnumerator GlitchBurst()
        {
            float duration = Random.Range(glitchMinDuration, glitchMaxDuration);
            float elapsed  = 0f;

            while (elapsed < duration)
            {
                ApplyFlicker(Random.value);
                elapsed += Time.deltaTime;
                yield return null;
            }
        }

        /// <summary>
        /// Applies flicker as an offset around baseIntensity rather than
        /// absolute min/max, so external intensity control stays intact.
        /// </summary>
        private void ApplyFlicker(float t)
        {
            if (targetLight != null)
            {
                float offset = Mathf.Lerp(-flickerRange, flickerRange, t);
                targetLight.intensity = Mathf.Max(0f, baseIntensity + offset);
            }

            if (_materialInstance != null && _materialInstance.HasProperty(opacityProperty))
                _materialInstance.SetFloat(opacityProperty, Mathf.Lerp(minOpacity, maxOpacity, t));
        }

        void OnDestroy()
        {
            if (_materialInstance != null)
                Destroy(_materialInstance);
        }
    }
}