using System.Collections;
using UnityEngine;

namespace Unheimlich.VFX
{
    public class LightFlicker : MonoBehaviour
    {
        public Light targetLight;

        [Tooltip("Flicker oscillates around this value. Driven each frame by ScarecrowFire.")]
        public float baseIntensity = 0f;

        [Range(0f, 1f)] public float flickerRange = 0.3f;
        public float flickerSpeed = 5f;

        [Range(0f, 1f)] public float glitchChance      = 0.15f;
        public float                 glitchMinDuration = 0.02f;
        public float                 glitchMaxDuration = 0.12f;

        private float _randomOffset;

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

        /// <summary>Called each frame by ScarecrowFire to update the base the flicker oscillates around.</summary>
        public void SetBaseIntensity(float value) => baseIntensity = value;

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

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

                yield return null;
            }
        }

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

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

        private void ApplyFlicker(float t)
        {
            if (targetLight == null) return;
            float offset = Mathf.Lerp(-baseIntensity * flickerRange,
                                       baseIntensity * flickerRange, t);
            targetLight.intensity = Mathf.Max(0f, baseIntensity + offset);
        }
    }
}