using UnityEngine;
using UnityEngine.Rendering;
using static Misaki.HdrpToon.UTSPropertyName;

namespace Misaki.HdrpToon
{
    internal class UTSAPI
    {
        private enum RenderPriority
        {
            Opaque = RenderQueue.Geometry,
            OpaqueDecal = RenderQueue.Geometry + 225, // Opaque Decal mean Opaque that can receive decal
            OpaqueAlphaTest = RenderQueue.AlphaTest,
            OpaqueDecalAlphaTest = RenderQueue.AlphaTest + 25,
            // Warning: we must not change Geometry last value to stay compatible with occlusion
            OpaqueLast = RenderQueue.GeometryLast,

            AfterPostprocessOpaque = RenderQueue.GeometryLast + 1,
            AfterPostprocessOpaqueAlphaTest = RenderQueue.GeometryLast + 10,

            TransparentFirst = RenderQueue.Transparent - 100,
            Transparent = RenderQueue.Transparent,
            TransparentLast = RenderQueue.Transparent + 100,
        }

        public static void SetupPass(Material material)
        {
            material.SetShaderPassEnabled(UTSPassName.HAIR_SHADOW_CASTER_PASS_NAME, (MaterialType)material.GetInteger(SurfaceOptions.MATERIAL_TYPE) == MaterialType.FrontHair);
            material.SetShaderPassEnabled(UTSPassName.HAIR_BLENDING_TARGET_PASS_NAME, material.GetInteger(SurfaceOptions.HAIR_BLENDING_TARGET) == 1);
        }

        public static void SetupKeywords(Material material)
        {
            var surfaceType = (SurfaceType)material.GetInteger(SurfaceOptions.SURFACE_TYPE);
            var cullMode = (CullMode)material.GetInteger(SurfaceOptions.CULL_MODE);
            var doubleSidedEnable = cullMode == CullMode.Off;

            CoreUtils.SetKeyword(material, "_SURFACE_TYPE_TRANSPARENT", surfaceType == SurfaceType.Transparent);
            CoreUtils.SetKeyword(material, "_DOUBLESIDED_ON", doubleSidedEnable);
        }

        public static void SetupProperties(Material material)
        {
            var surfaceType = (SurfaceType)material.GetInteger(SurfaceOptions.SURFACE_TYPE);
            var cullMode = (CullMode)material.GetInteger(SurfaceOptions.CULL_MODE);

            // Surface type
            var isTransparent = surfaceType == SurfaceType.Transparent;
            var isAlphaClip = material.GetInteger(SurfaceOptions.ALPHA_CLIP_ENABLE) == 1;

            var renderQueue = isTransparent ? RenderPriority.Transparent : (isAlphaClip ? RenderPriority.OpaqueAlphaTest : RenderPriority.Opaque);
            material.SetInteger(InternalProperties.SURFACE_TYPE, isTransparent ? 1 : 0);
            material.renderQueue = (int)renderQueue;

            // We only do clip for alpha clip in depth pre-pass once. Z test for GBuffer and forward pass need to set to equal to make sure alpha clip works correctly.
            if (isAlphaClip)
            {
                material.SetInteger(InternalProperties.ZTEST_GBUFFER, (int)CompareFunction.Equal);
            }
            else
            {
                material.SetInteger(InternalProperties.ZTEST_GBUFFER, (int)CompareFunction.LessEqual);
            }

            if (isTransparent)
            {
                material.SetInteger(InternalProperties.ZTEST_DEPTH_EQUAL_FOR_OPAQUE, material.GetInteger(InternalProperties.ZTEST_TRANSPARENT));

                material.SetOverrideTag("RenderType", "Transparent");
                // TODO: Z write for transparent.
                material.SetInteger(InternalProperties.ZWRITE, 0);
                material.SetInteger(InternalProperties.DEST_BLEND2, (int)BlendMode.OneMinusSrcAlpha);

                //TODO: Implement additive and pre-multiply mode.
                material.SetInteger(InternalProperties.SRC_BLEND, (int)BlendMode.One);
                material.SetInteger(InternalProperties.DEST_BLEND, (int)BlendMode.OneMinusSrcAlpha);
                material.SetInteger(InternalProperties.ALPHA_SRC_BLEND, (int)BlendMode.One);
                material.SetInteger(InternalProperties.ALPHA_DEST_BLEND, (int)BlendMode.OneMinusSrcAlpha);
            }
            else
            {
                material.SetInteger(InternalProperties.ZTEST_DEPTH_EQUAL_FOR_OPAQUE, (int)CompareFunction.Equal);

                material.SetOverrideTag("RenderType", isAlphaClip ? "TransparentCutout" : "");

                material.SetInteger(InternalProperties.SRC_BLEND, (int)BlendMode.One);
                material.SetInteger(InternalProperties.DEST_BLEND, (int)BlendMode.Zero);
                material.SetInteger(InternalProperties.DEST_BLEND2, (int)BlendMode.Zero);
                // Caution:  we need to setup One for src and Zero for Dst for all element as users could switch from transparent to Opaque and keep remaining value.
                // Unity will disable Blending based on these default value.
                // Note that for after postprocess we setup 0 in opacity inside the shaders, so we correctly end with 0 in opacity for the compositing pass
                material.SetInteger(InternalProperties.ALPHA_SRC_BLEND, (int)BlendMode.One);
                material.SetInteger(InternalProperties.ALPHA_DEST_BLEND, (int)BlendMode.Zero);
                material.SetInteger(InternalProperties.ZWRITE, 1);
            }

            // Double sided
            var isBackFaceEnable = material.GetInteger(InternalProperties.TRANSPARENT_BACKFACE_ENABLE) == 1 && surfaceType == SurfaceType.Transparent;
            var doubleSidedEnable = cullMode == CullMode.Off;

            if (doubleSidedEnable)
            {
                var doubleSidedNormalMode = (DoubleSidedMode)material.GetInteger(SurfaceOptions.DOUBLE_SIDED_NORMAL_MODE);
                switch (doubleSidedNormalMode)
                {
                    case DoubleSidedMode.None:
                        material.SetVector(InternalProperties.DOUBLE_SIDED_CONSTANTS, new Vector4(1.0f, 1.0f, 1.0f, 0.0f));
                        break;

                    case DoubleSidedMode.Mirror:
                        material.SetVector(InternalProperties.DOUBLE_SIDED_CONSTANTS, new Vector4(1.0f, 1.0f, -1.0f, 0.0f));
                        break;

                    case DoubleSidedMode.Flip:
                        material.SetVector(InternalProperties.DOUBLE_SIDED_CONSTANTS, new Vector4(-1.0f, -1.0f, -1.0f, 0.0f));
                        break;
                }
            }

            if (isBackFaceEnable)
            {
                material.SetInt(InternalProperties.CULL_MODE_FORWARD, (int)CullMode.Back);
            }
            else
            {
                material.SetInteger(InternalProperties.CULL_MODE_FORWARD, (int)(doubleSidedEnable ? CullMode.Off : cullMode));
            }

            // TODO: Setup stencil value. Currently it produce noticeable jittering when surface type is transparent.
            // This is caused by taa, _StencilWriteMask need to include StencilUsage.ExcludeFromTUAndAA when surface type is transparent.
        }
    }
}