using System;
using UnityEditor;
using UnityEngine;
using UnityEngine.Experimental.Rendering;
using UnityEngine.Rendering;
using UnityEngine.Rendering.HighDefinition;
using UnityEngine.Rendering.RendererUtils;

namespace Misaki.HdrpToon
{
    [HideInInspector]
    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 const string _HAIR_SHADOW_DISTANCE_PROP_NAME = "_HairShadowDistance";
        private const string _HAIR_SHADOW_DISTANCE_SCALE_PROP_NAME = "_HairShadowDistanceScaleFactor";
        private const string _HAIR_SHADOW_DEPTH_BIAS_PROP_NAME = "_HairShadowDepthBias";
        private const string _HAIR_SHADOW_FADEIN_PROP_NAME = "_HairShadowFadeInDistance";
        private const string _HAIR_SHADOW_FADE_OUT_PROP_NAME = "_HairShadowFadeOutDistance";

        private const string _HAIR_SHADOW_RT_PROP_NAME = "_HairShadowTex";
        private const string _HAIR_BLENDING_PROP_NAME = "_HairBlendingTex";

        private static readonly ProfilingSampler _hairShadowProfilingSampler = new("UTS Hair Shadow");
        private static readonly ProfilingSampler _hairBlendingProfilingSampler = new("UTS Hair Blending Target");

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

        private RTHandle _hairShadowRTHandle;
        private bool _needReallocateHairShadow;

        // TODO: Possible to avoid another RTHandle for depth?
        private RTHandle _hairBlendingRTHandle;
        private RTHandle _hairBlendingDepthRTHandle;
        private bool _needReallocateHairBlending;

        private bool _enableHairShadow;
        public bool EnableHairShadow
        {
            get => _enableHairShadow;
            set
            {
                if (_enableHairShadow == value)
                {
                    return;
                }

                _enableHairShadow = value;

                if (_enableHairShadow)
                {
                    Shader.EnableKeyword("ENABLE_UTS_HAIR_SHAOW");
                }
                else
                {
                    Shader.DisableKeyword("ENABLE_UTS_HAIR_SHAOW");
                    _hairShadowRTHandle?.Release();
                }
            }
        }

        private bool _enableHairBlending;
        public bool EnableHairBlending
        {
            get => _enableHairBlending;
            set
            {
                if (_enableHairBlending == value)
                {
                    return;
                }

                _enableHairBlending = value;

                if (_enableHairBlending)
                {
                    Shader.EnableKeyword("ENABLE_UTS_HAIR_BLENDING");
                }
                else
                {
                    Shader.DisableKeyword("ENABLE_UTS_HAIR_BLENDING");
                    _hairBlendingRTHandle?.Release();
                }
            }
        }

        private BufferQuality _hairShadowQuality = BufferQuality.High;
        internal BufferQuality HairShadowQuality
        {
            get => _hairShadowQuality;
            set
            {
                if (_hairShadowQuality == value)
                {
                    return;
                }

                _hairShadowQuality = value;
                _needReallocateHairShadow = true;
            }
        }

        private BufferQuality _hairBlendingQuality = BufferQuality.High;
        internal BufferQuality HairBlendingQuality
        {
            get => _hairBlendingQuality;
            set
            {
                if (_hairBlendingQuality == value)
                {
                    return;
                }

                _hairBlendingQuality = value;
                _needReallocateHairBlending = true;
            }
        }

        private bool ShouldReallocateHairShadowBuffer()
        {
            return _hairShadowRTHandle == null || _hairShadowRTHandle.rt == null || !_hairShadowRTHandle.rt.IsCreated() || _needReallocateHairShadow;
        }

        private void ReallocateHairShadowBuffer()
        {
#if UNITY_EDITOR
            if (EditorApplication.isCompiling)
            {
                return;
            }
#endif

            // Use R8 or R16 directly?
            var format = _hairShadowQuality switch
            {
                BufferQuality.Low => GraphicsFormat.D16_UNorm,
                BufferQuality.High => GraphicsFormat.D32_SFloat,
                _ => GraphicsFormat.R16G16B16A16_SFloat
            };

            _hairShadowRTHandle?.Release();
            _hairShadowRTHandle = RTHandles.Alloc(Vector2.one, useDynamicScale: true, format: format, isShadowMap: true, name: _HAIR_SHADOW_RT_PROP_NAME);
            Shader.SetGlobalTexture(_HAIR_SHADOW_RT_PROP_NAME, _hairShadowRTHandle);

            _needReallocateHairShadow = false;
        }

        private bool ShouldReallocateHairBlendingBuffer()
        {
            return _hairBlendingRTHandle == null || _hairBlendingRTHandle.rt == null || !_hairBlendingRTHandle.rt.IsCreated() || _needReallocateHairBlending;
        }

        private void ReallocateHairBlendingBuffer()
        {
#if UNITY_EDITOR
            if (EditorApplication.isCompiling)
            {
                return;
            }
#endif

            var format = _hairBlendingQuality switch
            {
                BufferQuality.Low => GraphicsFormat.A2B10G10R10_UNormPack32,
                BufferQuality.High => GraphicsFormat.R16G16B16A16_UNorm,
                _ => GraphicsFormat.A2B10G10R10_UNormPack32
            };

            _hairBlendingRTHandle?.Release();
            _hairBlendingRTHandle = RTHandles.Alloc(Vector2.one, useDynamicScale: true, dimension: TextureXR.dimension, colorFormat: format, name: _HAIR_BLENDING_PROP_NAME);

            if (_hairBlendingDepthRTHandle == null || _hairBlendingDepthRTHandle.rt == null || !_hairBlendingDepthRTHandle.rt.IsCreated())
            {
                _hairBlendingDepthRTHandle?.Release();
                _hairBlendingDepthRTHandle = RTHandles.Alloc(Vector2.one, useDynamicScale: true, dimension: TextureXR.dimension, colorFormat: GraphicsFormat.D16_UNorm, name: _HAIR_BLENDING_PROP_NAME + "_depth");
            }

            Shader.SetGlobalTexture(_HAIR_BLENDING_PROP_NAME, _hairBlendingRTHandle);

            _needReallocateHairBlending = false;
        }

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

        private void UpdateSceneEV(UTSRenderer 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);
        }

        private void RenderHairShadow(ref CustomPassContext ctx, UTSRenderer utsRenderer)
        {
            if (!_enableHairShadow
                || utsRenderer == null
                || !utsRenderer.state.value
                || !utsRenderer.enableHairShadow.value)
            {
                return;
            }

            if (ShouldReallocateHairShadowBuffer())
            {
                ReallocateHairShadowBuffer();
                return;
            }

            using (new ProfilingScope(ctx.cmd, _hairShadowProfilingSampler))
            {
                CoreUtils.SetRenderTarget(ctx.cmd, _hairShadowRTHandle, ClearFlag.Depth);

                var result = new RendererListDesc(UtsShaderPassName.hairShadowCasterPassId, ctx.cullingResults, ctx.hdCamera.camera)
                {
                    renderQueueRange = GetRenderQueueRange(RenderQueueType.AllOpaque),
                    sortingCriteria = SortingCriteria.CommonOpaque,
                    excludeObjectMotionVectors = false,
                };

                CoreUtils.DrawRendererList(ctx.renderContext, ctx.cmd, ctx.renderContext.CreateRendererList(result));

                Shader.SetGlobalFloat(_HAIR_SHADOW_DISTANCE_PROP_NAME, utsRenderer.shadowDistance.value);
                Shader.SetGlobalFloat(_HAIR_SHADOW_DISTANCE_SCALE_PROP_NAME, utsRenderer.shadowDistanceScale.value);
                Shader.SetGlobalFloat(_HAIR_SHADOW_DEPTH_BIAS_PROP_NAME, utsRenderer.shadowDepthBias.value);
                Shader.SetGlobalFloat(_HAIR_SHADOW_FADEIN_PROP_NAME, utsRenderer.shadowFadeIn.value);
                Shader.SetGlobalFloat(_HAIR_SHADOW_FADE_OUT_PROP_NAME, utsRenderer.shadowFadeOut.value);
            }
        }

        private void RenderHairBlending(ref CustomPassContext ctx)
        {
            if (!_enableHairBlending)
            {
                return;
            }

            if (ShouldReallocateHairBlendingBuffer())
            {
                ReallocateHairBlendingBuffer();
                return;
            }

            using (new ProfilingScope(ctx.cmd, _hairBlendingProfilingSampler))
            {
                CoreUtils.SetRenderTarget(ctx.cmd, _hairBlendingRTHandle, _hairBlendingDepthRTHandle, ClearFlag.Color | ClearFlag.Depth);

                var result = new RendererListDesc(UtsShaderPassName.hairBlendingTargetPassId, ctx.cullingResults, ctx.hdCamera.camera)
                {
                    renderQueueRange = GetRenderQueueRange(RenderQueueType.AllOpaque),
                    sortingCriteria = SortingCriteria.CommonOpaque,
                    excludeObjectMotionVectors = false,
                };

                CoreUtils.DrawRendererList(ctx.renderContext, ctx.cmd, ctx.renderContext.CreateRendererList(result));
            }
        }

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

            UpdateSceneEV(utsRenderer);
            RenderHairShadow(ref ctx, utsRenderer);
            RenderHairBlending(ref ctx);
        }

        protected override void Cleanup()
        {
            _exposureArray = null;
            _hairShadowRTHandle?.Release();
            _hairBlendingRTHandle?.Release();
            _hairBlendingDepthRTHandle?.Release();
        }
    }
}