using Unity.Toonshader;
using UnityEngine;
using UnityEngine.Experimental.Rendering;
using UnityEngine.Rendering;
using UnityEngine.Rendering.HighDefinition;
using UnityEngine.Rendering.RendererUtils;

[HideInInspector]
public class UTSHairShadowPass : DrawRenderersCustomPass
{
    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 Output_RT_Name = "_HairShadowTex";

    private RTHandle _outputRTHandle;
    private bool _isEnable = false;

    protected override void Setup(ScriptableRenderContext renderContext, CommandBuffer cmd)
    {
        _outputRTHandle?.Release();
        _outputRTHandle = RTHandles.Alloc(Screen.width, Screen.height, colorFormat: GraphicsFormat.D32_SFloat, filterMode: FilterMode.Bilinear, wrapMode: TextureWrapMode.Clamp, name: Output_RT_Name);

        SetEnable(true);
    }

    protected override void Execute(CustomPassContext ctx)
    {
        var utsRenderer = ctx.hdCamera.volumeStack.GetComponent<UTSRenderer>();
        if (utsRenderer == null || !utsRenderer.enableHairShadow.value || !utsRenderer.enable.value)
        {
            SetEnable(false);
            return;
        }

        if (!_isEnable)
        {
            return;
        }

        SetShadowProperty(utsRenderer);

        if (_outputRTHandle != null)
        {
            Shader.SetGlobalTexture(Output_RT_Name, _outputRTHandle);
            CoreUtils.SetRenderTarget(ctx.cmd, _outputRTHandle, ClearFlag.DepthStencil);
        }

        var mask = RenderStateMask.Nothing;
        var stateBlock = new RenderStateBlock(mask)
        {
            depthState = new DepthState(depthWrite, depthCompareFunction),
        };

        var result = new RendererListDesc(HDShaderPassNames.s_DepthForwardOnlyName, ctx.cullingResults, ctx.hdCamera.camera)
        {
            renderQueueRange = GetRenderQueueRange(renderQueueType),
            sortingCriteria = sortingCriteria,
            excludeObjectMotionVectors = false,
            stateBlock = stateBlock,
            layerMask = layerMask,
        };

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

    private static void SetShadowProperty(UTSRenderer utsRenderer)
    {
        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);
    }

    protected override void Cleanup()
    {
        Release();
    }

    public void Release()
    {
        SetEnable(false);
        _outputRTHandle?.Release();
    }

    public void SetEnable(bool isEnable)
    {
        if (_isEnable != isEnable)
        {
            if (isEnable)
            {
                Shader.EnableKeyword("_HAIR_SHADOWS");
            }
            else
            {
                Shader.DisableKeyword("_HAIR_SHADOWS");
            }

            _isEnable = isEnable;
        }
    }
}