using System;
using System.Runtime.InteropServices;

namespace XCEngine.Rendering
{
    [StructLayout(LayoutKind.Sequential)]
    public struct DirectionalShadowSamplingSettings
        : IEquatable<DirectionalShadowSamplingSettings>
    {
        public float receiverDepthBias;
        public float normalBiasScale;
        public float shadowStrength;

        public static DirectionalShadowSamplingSettings CreateDefault()
        {
            return new DirectionalShadowSamplingSettings
            {
                receiverDepthBias = 0.0010f,
                normalBiasScale = 2.0f,
                shadowStrength = 0.85f
            };
        }

        public bool Equals(
            DirectionalShadowSamplingSettings other)
        {
            return receiverDepthBias == other.receiverDepthBias &&
                   normalBiasScale == other.normalBiasScale &&
                   shadowStrength == other.shadowStrength;
        }

        public override bool Equals(object obj)
        {
            return obj is DirectionalShadowSamplingSettings other &&
                   Equals(other);
        }

        public override int GetHashCode()
        {
            unchecked
            {
                int hash = receiverDepthBias.GetHashCode();
                hash = (hash * 397) ^ normalBiasScale.GetHashCode();
                hash = (hash * 397) ^ shadowStrength.GetHashCode();
                return hash;
            }
        }
    }

    [StructLayout(LayoutKind.Sequential)]
    public struct DirectionalShadowCasterBiasSettings
        : IEquatable<DirectionalShadowCasterBiasSettings>
    {
        public float depthBiasFactor;
        public int depthBiasUnits;

        public static DirectionalShadowCasterBiasSettings CreateDefault()
        {
            return new DirectionalShadowCasterBiasSettings
            {
                depthBiasFactor = 2.5f,
                depthBiasUnits = 4
            };
        }

        public bool Equals(
            DirectionalShadowCasterBiasSettings other)
        {
            return depthBiasFactor == other.depthBiasFactor &&
                   depthBiasUnits == other.depthBiasUnits;
        }

        public override bool Equals(object obj)
        {
            return obj is DirectionalShadowCasterBiasSettings other &&
                   Equals(other);
        }

        public override int GetHashCode()
        {
            unchecked
            {
                return (depthBiasFactor.GetHashCode() * 397) ^
                       depthBiasUnits;
            }
        }
    }

    [StructLayout(LayoutKind.Sequential)]
    public struct DirectionalShadowPlanningSettings
        : IEquatable<DirectionalShadowPlanningSettings>
    {
        public uint mapDimension;
        public float minFocusDistance;
        public float maxFocusDistance;
        public float perspectiveFocusFactor;
        public float orthographicFocusFactor;
        public float minDepthRange;
        public float boundsPadding;
        public float minDepthPadding;
        public DirectionalShadowSamplingSettings sampling;
        public DirectionalShadowCasterBiasSettings casterBias;

        public static DirectionalShadowPlanningSettings CreateDefault()
        {
            return new DirectionalShadowPlanningSettings
            {
                mapDimension = 2048u,
                minFocusDistance = 5.0f,
                maxFocusDistance = 32.0f,
                perspectiveFocusFactor = 1.0f,
                orthographicFocusFactor = 2.0f,
                minDepthRange = 20.0f,
                boundsPadding = 0.5f,
                minDepthPadding = 2.0f,
                sampling =
                    DirectionalShadowSamplingSettings.CreateDefault(),
                casterBias =
                    DirectionalShadowCasterBiasSettings.CreateDefault()
            };
        }

        public bool Equals(
            DirectionalShadowPlanningSettings other)
        {
            return mapDimension == other.mapDimension &&
                   minFocusDistance == other.minFocusDistance &&
                   maxFocusDistance == other.maxFocusDistance &&
                   perspectiveFocusFactor ==
                       other.perspectiveFocusFactor &&
                   orthographicFocusFactor ==
                       other.orthographicFocusFactor &&
                   minDepthRange == other.minDepthRange &&
                   boundsPadding == other.boundsPadding &&
                   minDepthPadding == other.minDepthPadding &&
                   sampling.Equals(other.sampling) &&
                   casterBias.Equals(other.casterBias);
        }

        public override bool Equals(object obj)
        {
            return obj is DirectionalShadowPlanningSettings other &&
                   Equals(other);
        }

        public override int GetHashCode()
        {
            unchecked
            {
                int hash = (int)mapDimension;
                hash = (hash * 397) ^ minFocusDistance.GetHashCode();
                hash = (hash * 397) ^ maxFocusDistance.GetHashCode();
                hash = (hash * 397) ^
                    perspectiveFocusFactor.GetHashCode();
                hash = (hash * 397) ^
                    orthographicFocusFactor.GetHashCode();
                hash = (hash * 397) ^ minDepthRange.GetHashCode();
                hash = (hash * 397) ^ boundsPadding.GetHashCode();
                hash = (hash * 397) ^ minDepthPadding.GetHashCode();
                hash = (hash * 397) ^ sampling.GetHashCode();
                hash = (hash * 397) ^ casterBias.GetHashCode();
                return hash;
            }
        }
    }
}