using System;
using UnityEngine;
using UnityEngine.Rendering;
using UnityEngine.Rendering.HighDefinition;

namespace Misaki.HdrpToon
{
    internal class UTSPass : CustomPass
    {
        private const int Adjustment_Curve_Precision = 128;

        private const string Compensation_Prop_Name = "_ToonEvAdjustmentCompensation";
        private const string Exposure_Adjustment_Prop_Name = "_ToonEvAdjustmentCurve";
        private const string Exposure_Array_Prop_Name = "_ToonEvAdjustmentValueArray";
        private const string Exposure_Min_Prop_Name = "_ToonEvAdjustmentValueMin";
        private const string Exposure_Max_Prop_Name = "_ToonEvAdjustmentValueMax";
        private const string Toon_Light_Filter_Prop_Name = "_ToonLightHiCutFilter";
        private const string Ignore_Volume_Exposure_Prop_Name = "_ToonIgnoreExposureMultiplier";

        private float _max;
        private float _min;
        private float[] _exposureArray;

        protected override void Setup(ScriptableRenderContext renderContext, CommandBuffer cmd)
        {
            _exposureArray = new float[Adjustment_Curve_Precision];
        }

        protected override void Execute(CustomPassContext ctx)
        {
            var utsRenderer = ctx.hdCamera.volumeStack.GetComponent<UTSRenderer>();
            if (utsRenderer == null)
            {
                return;
            }

            var toonEVAdjustment = utsRenderer.toonEVAdjustment.value ? 1 : 0;
            var lightIntensityLimiter = utsRenderer.lightIntensityLimiter.value ? 1 : 0;
            var ignoreVolumeExposure = utsRenderer.ignoreVolumeExposure.value ? 1 : 0;
            var compensation = utsRenderer.compensation.value;

            if (!utsRenderer.state.value)
            {
                _min = 0;
                _max = 0;
                _exposureArray.AsSpan().Fill(0);

                toonEVAdjustment = 0;
                lightIntensityLimiter = 0;
                ignoreVolumeExposure = 0;
                compensation = 0;
            }
            else
            {
                // Fail safe in case the curve is deleted / has 0 point
                var curve = utsRenderer.adjustmentCurve.value;

                if (curve == null || curve.length == 0)
                {
                    _min = 0f;
                    _max = 0f;
                    _exposureArray.AsSpan().Fill(0);
                }
                else
                {
                    _min = curve[0].time;
                    _max = curve[curve.length - 1].time;
                    var step = (_max - _min) / (Adjustment_Curve_Precision - 1f);

                    for (var i = 0; i < Adjustment_Curve_Precision; i++)
                    {
                        _exposureArray[i] = curve.Evaluate(_min + step * i);
                    }
                }
            }

            Shader.SetGlobalFloatArray(Exposure_Array_Prop_Name, _exposureArray);
            Shader.SetGlobalFloat(Exposure_Min_Prop_Name, _min);
            Shader.SetGlobalFloat(Exposure_Max_Prop_Name, _max);
            Shader.SetGlobalInt(Exposure_Adjustment_Prop_Name, toonEVAdjustment);
            Shader.SetGlobalInt(Toon_Light_Filter_Prop_Name, lightIntensityLimiter);
            Shader.SetGlobalInt(Ignore_Volume_Exposure_Prop_Name, ignoreVolumeExposure);
            Shader.SetGlobalFloat(Compensation_Prop_Name, compensation);
        }

        protected override void Cleanup()
        {
            _exposureArray = null;
        }
    }
}