using System;
using UnityEngine.Serialization;

namespace UnityEngine.Rendering.HighDefinition
{
    /// <summary>
    /// A volume component that holds settings for the global illumination (screen space and ray traced).
    /// </summary>
    [Serializable, VolumeComponentMenu("Lighting/Screen Space Global Illumination")]
    [SupportedOnRenderPipeline(typeof(HDRenderPipelineAsset))]
    [HDRPHelpURL("Override-Screen-Space-GI")]
    public sealed class GlobalIllumination : VolumeComponentWithQuality
    {
        bool UsesQualityMode()
        {
            // The default value is set to quality. So we should be in quality if not overriden or we have an override set to quality
            return (tracing.overrideState && tracing == RayCastingMode.RayTracing && (!mode.overrideState || (mode.overrideState && mode == RayTracingMode.Quality)));
        }

        #region General
        /// <summary>
        /// Enable screen space global illumination.
        /// </summary>
        [Tooltip("Enable screen space global illumination.")]
        public BoolParameter enable = new BoolParameter(false, BoolParameter.DisplayType.EnumPopup);

        /// <summary>
        /// </summary>
        [Tooltip("Controls the casting technique used to evaluate the effect. Ray marching uses a ray-marched screen-space solution, Ray tracing uses a hardware accelerated world-space solution. Mixed uses first Ray marching, then Ray tracing if it fails to intersect on-screen geometry.")]
        public RayCastingModeParameter tracing = new RayCastingModeParameter(RayCastingMode.RayMarching);

        /// <summary>
        /// Controls the fallback hierarchy for indirect diffuse in case the ray misses.
        /// </summary>
        [Tooltip("Controls the fallback hierarchy for indirect diffuse in case the ray misses.")]
        [FormerlySerializedAs("fallbackHierarchy")]
        [AdditionalProperty]
        public RayMarchingFallbackHierarchyParameter rayMiss = new RayMarchingFallbackHierarchyParameter(RayMarchingFallbackHierarchy.ReflectionProbesAndSky);

        /// <summary>
        /// Controls the fallback hierarchy for indirect diffuse in case the ray misses.
        /// </summary>
        [Tooltip("Controls which APV rendering layer mask to sample from. If no probes in proximity are from the specified layer or the feature is disabled for the Baking Set, any surrounding probes will be sampled.")]
        [AdditionalProperty]
        public RenderingLayerMaskParameter adaptiveProbeVolumesLayerMask = new RenderingLayerMaskParameter(UnityEngine.RenderingLayerMask.defaultRenderingLayerMask);
        #endregion

        #region RayMarching
        /// <summary>
        /// The thickness of the depth buffer value used for the ray marching step
        /// </summary>
        [Tooltip("Controls the thickness of the depth buffer used for ray marching.")]
        public ClampedFloatParameter depthBufferThickness = new ClampedFloatParameter(0.1f, 0.0f, 0.5f);

        GlobalIllumination()
        {
            displayName = "Screen Space Global Illumination";
        }

        /// <summary>
        /// Defines if the screen space global illumination should be evaluated at full resolution.
        /// </summary>
        public BoolParameter fullResolutionSS = new BoolParameter(true);

        /// <summary>
        /// The number of steps that should be used during the ray marching pass.
        /// </summary>
        public int maxRaySteps
        {
            get
            {
                if (!UsesQualitySettings())
                    return m_MaxRaySteps.value;
                else
                    return GetLightingQualitySettings().SSGIRaySteps[(int)quality.value];
            }
            set { m_MaxRaySteps.value = value; }
        }
        [SerializeField]
        [Tooltip("Controls the number of steps used for ray marching.")]
        private MinIntParameter m_MaxRaySteps = new MinIntParameter(32, 0);

        // Filtering
        /// <summary>
        /// Defines if the screen space global illumination should be denoised.
        /// </summary>
        public bool denoiseSS
        {
            get
            {
                if (!UsesQualitySettings())
                    return m_DenoiseSS.value;
                else
                    return GetLightingQualitySettings().SSGIDenoise[(int)quality.value];
            }
            set { m_DenoiseSS.value = value; }
        }
        [SerializeField, FormerlySerializedAs("denoise")]
        private BoolParameter m_DenoiseSS = new BoolParameter(true);

        /// <summary>
        /// Defines if the denoiser should be evaluated at half resolution.
        /// </summary>
        public bool halfResolutionDenoiserSS
        {
            get
            {
                if (!UsesQualitySettings() || UsesQualityMode())
                    return m_HalfResolutionDenoiserSS.value;
                else
                    return GetLightingQualitySettings().SSGIHalfResDenoise[(int)quality.value];
            }
            set { m_HalfResolutionDenoiserSS.value = value; }
        }
        [SerializeField]
        [Tooltip("Use a half resolution denoiser.")]
        private BoolParameter m_HalfResolutionDenoiserSS = new BoolParameter(false);

        /// <summary>
        /// Controls the radius of the global illumination denoiser (First Pass).
        /// </summary>
        public float denoiserRadiusSS
        {
            get
            {
                if (!UsesQualitySettings())
                    return m_DenoiserRadiusSS.value;
                else
                    return GetLightingQualitySettings().SSGIDenoiserRadius[(int)quality.value];
            }
            set { m_DenoiserRadiusSS.value = value; }
        }
        [SerializeField]
        [Tooltip("Controls the radius of the GI denoiser (First Pass).")]
        private ClampedFloatParameter m_DenoiserRadiusSS = new ClampedFloatParameter(0.6f, 0.001f, 1.0f);

        /// <summary>
        /// Defines if the second denoising pass should be enabled.
        /// </summary>
        public bool secondDenoiserPassSS
        {
            get
            {
                if (!UsesQualitySettings())
                    return m_SecondDenoiserPassSS.value;
                else
                    return GetLightingQualitySettings().SSGISecondDenoise[(int)quality.value];
            }
            set { m_SecondDenoiserPassSS.value = value; }
        }
        [SerializeField]
        [Tooltip("Enable second denoising pass.")]
        private BoolParameter m_SecondDenoiserPassSS = new BoolParameter(true);

        #endregion

        #region RayTracing
        /// <summary>
        /// Controls the fallback hierarchy for lighting the last bounce.
        /// </summary>
        [Tooltip("Controls the fallback hierarchy for lighting the last bounce.")]
        [AdditionalProperty]
        public RayMarchingFallbackHierarchyParameter lastBounceFallbackHierarchy = new RayMarchingFallbackHierarchyParameter(RayMarchingFallbackHierarchy.ReflectionProbesAndSky);

        /// <summary>
        /// Controls the dimmer applied to the ambient and legacy light probes.
        /// </summary>
        [Tooltip("Controls the dimmer applied to the ambient and legacy light probes.")]
        [AdditionalProperty]
        public ClampedFloatParameter ambientProbeDimmer = new ClampedFloatParameter(0.0f, 0.0f, 1.0f);

        /// <summary>
        /// Defines the layers that GI should include.
        /// </summary>
        [Tooltip("Defines the layers that GI should include.")]
        public LayerMaskParameter layerMask = new LayerMaskParameter(-1);

        /// <summary>
        /// The LOD Bias that HDRP adds to texture sampling in the global illumination.
        /// </summary>
        [Tooltip("The LOD Bias that HDRP adds to texture sampling in the global illumination. A higher value increases performance and makes denoising easier, but it might reduce visual fidelity.")]
        public ClampedFloatParameter textureLodBias = new ClampedFloatParameter(7.0f, 0.0f, 7.0f);

        /// <summary>
        /// Controls the length of GI rays in meters.
        /// </summary>
        public float rayLength
        {
            get
            {
                if (!UsesQualitySettings() || UsesQualityMode())
                    return m_RayLength.value;
                else
                    return GetLightingQualitySettings().RTGIRayLength[(int)quality.value];
            }
            set { m_RayLength.value = value; }
        }
        [SerializeField, FormerlySerializedAs("rayLength")]
        private MinFloatParameter m_RayLength = new MinFloatParameter(50.0f, 0.01f);

        /// <summary>
        /// Controls the clamp of intensity.
        /// </summary>
        public float clampValue
        {
            get
            {
                return m_ClampValue.value;
            }
            set { m_ClampValue.value = value; }
        }
        [SerializeField, FormerlySerializedAs("clampValue")]
        [Tooltip("Controls the clamp of intensity.")]
        private MinFloatParameter m_ClampValue = new MinFloatParameter(100.0f, 0.001f);

        /// <summary>
        /// Controls which version of the effect should be used.
        /// </summary>
        [Tooltip("Controls which version of the effect should be used.")]
        public RayTracingModeParameter mode = new RayTracingModeParameter(RayTracingMode.Quality);

        // Performance
        /// <summary>
        /// Defines if the effect should be evaluated at full resolution.
        /// </summary>
        public bool fullResolution
        {
            get
            {
                if (!UsesQualitySettings())
                    return m_FullResolution.value;
                else
                    return GetLightingQualitySettings().RTGIFullResolution[(int)quality.value];
            }
            set { m_FullResolution.value = value; }
        }
        [SerializeField, FormerlySerializedAs("fullResolution")]
        [Tooltip("Full Resolution")]
        private BoolParameter m_FullResolution = new BoolParameter(false);

        // Quality
        /// <summary>
        /// Number of samples for evaluating the effect.
        /// </summary>
        [Tooltip("Number of samples for GI.")]
        public ClampedIntParameter sampleCount = new ClampedIntParameter(2, 1, 32);

        /// <summary>
        /// Number of bounces for evaluating the effect.
        /// </summary>
        [Tooltip("Number of bounces for GI.")]
        public ClampedIntParameter bounceCount = new ClampedIntParameter(1, 1, 8);

        // Filtering
        /// <summary>
        /// Defines if the ray traced global illumination should be denoised.
        /// </summary>
        public bool denoise
        {
            get
            {
                if (!UsesQualitySettings() || UsesQualityMode())
                    return m_Denoise.value;
                else
                    return GetLightingQualitySettings().RTGIDenoise[(int)quality.value];
            }
            set { m_Denoise.value = value; }
        }
        [SerializeField, FormerlySerializedAs("denoise")]
        [Tooltip("Denoise the ray-traced GI.")]
        private BoolParameter m_Denoise = new BoolParameter(true);

        /// <summary>
        /// Defines if the denoiser should be evaluated at half resolution.
        /// </summary>
        public bool halfResolutionDenoiser
        {
            get
            {
                if (!UsesQualitySettings() || UsesQualityMode())
                    return m_HalfResolutionDenoiser.value;
                else
                    return GetLightingQualitySettings().RTGIHalfResDenoise[(int)quality.value];
            }
            set { m_HalfResolutionDenoiser.value = value; }
        }
        [SerializeField, FormerlySerializedAs("halfResolutionDenoiser")]
        [Tooltip("Use a half resolution denoiser.")]
        private BoolParameter m_HalfResolutionDenoiser = new BoolParameter(false);

        /// <summary>
        /// Controls the radius of the global illumination denoiser (First Pass).
        /// </summary>
        public float denoiserRadius
        {
            get
            {
                if (!UsesQualitySettings() || UsesQualityMode())
                    return m_DenoiserRadius.value;
                else
                    return GetLightingQualitySettings().RTGIDenoiserRadius[(int)quality.value];
            }
            set { m_DenoiserRadius.value = value; }
        }
        [SerializeField, FormerlySerializedAs("denoiserRadius")]
        [Tooltip("Controls the radius of the GI denoiser (First Pass).")]
        private ClampedFloatParameter m_DenoiserRadius = new ClampedFloatParameter(0.6f, 0.001f, 1.0f);

        /// <summary>
        /// Defines if the second denoising pass should be enabled.
        /// </summary>
        public bool secondDenoiserPass
        {
            get
            {
                if (!UsesQualitySettings() || UsesQualityMode())
                    return m_SecondDenoiserPass.value;
                else
                    return GetLightingQualitySettings().RTGISecondDenoise[(int)quality.value];
            }
            set { m_SecondDenoiserPass.value = value; }
        }
        [SerializeField, FormerlySerializedAs("secondDenoiserPass")]
        [Tooltip("Enable second denoising pass.")]
        private BoolParameter m_SecondDenoiserPass = new BoolParameter(true);

        /// <summary>
        /// Controls the number of steps used for the mixed tracing
        /// </summary>
        public int maxMixedRaySteps
        {
            get
            {
                if (!UsesQualitySettings() || UsesQualityMode())
                    return m_MaxMixedRaySteps.value;
                else
                    return GetLightingQualitySettings().RTGIRaySteps[(int)quality.value];
            }
            set { m_MaxMixedRaySteps.value = value; }
        }
        [SerializeField]
        [Tooltip("Controls the number of steps HDRP uses for mixed tracing.")]
        private MinIntParameter m_MaxMixedRaySteps = new MinIntParameter(48, 0);

        /// <summary>
        /// When enabled, global illumination generated by moving objects will not be accumulated, generating less ghosting but introducing additional noise.
        /// </summary>
        [AdditionalProperty]
        [Tooltip("When enabled, global illumination generated by moving objects will not be accumulated, generating less ghosting but introducing additional noise.")]
        public BoolParameter receiverMotionRejection = new BoolParameter(true);

        #endregion

        internal static bool RayTracingActive(GlobalIllumination volume)
        {
            return volume.tracing.value != RayCastingMode.RayMarching;
        }
    }
}