using XCEngine;
using XCEngine.Rendering;

namespace XCEngine.Rendering.Universal
{
    internal sealed class UniversalPostProcessBlock
    {
        public void ConfigureCameraFramePlan(
            ScriptableRenderPipelinePlanningContext context,
            CameraFrameColorSource sourceColor)
        {
            if (context == null)
            {
                return;
            }

            bool needsGraphManagedOutputColor =
                context.HasFinalColorProcessing() ||
                context.IsStageRequested(
                    CameraFrameStage.FinalOutput);
            EnsurePostProcessStage(
                context,
                sourceColor,
                needsGraphManagedOutputColor);
        }

        public CameraFrameColorSource ResolveFinalOutputSource(
            ScriptableRenderPipelinePlanningContext context)
        {
            if (context == null ||
                !context.IsStageRequested(
                    CameraFrameStage.PostProcess))
            {
                return CameraFrameColorSource.MainSceneColor;
            }

            CameraFrameColorSource postProcessSource =
                context.GetStageColorSource(
                    CameraFrameStage.PostProcess);
            if (postProcessSource ==
                CameraFrameColorSource.ExplicitSurface)
            {
                return CameraFrameColorSource.MainSceneColor;
            }

            PromoteToGraphManagedOutputColor(
                context);
            return CameraFrameColorSource.PostProcessColor;
        }

        public void EnqueueRenderPass(
            ScriptableRenderer renderer,
            RenderingData renderingData,
            ScriptableRenderPass renderPass)
        {
            if (renderer == null ||
                renderingData == null ||
                renderPass == null ||
                !renderingData.isPostProcessStage)
            {
                return;
            }

            renderer.EnqueuePass(renderPass);
        }

        private static void EnsurePostProcessStage(
            ScriptableRenderPipelinePlanningContext context,
            CameraFrameColorSource sourceColor,
            bool needsGraphManagedOutputColor)
        {
            if (!context.IsStageRequested(
                    CameraFrameStage.PostProcess))
            {
                context.RequestFullscreenStage(
                    CameraFrameStage.PostProcess,
                    sourceColor,
                    needsGraphManagedOutputColor);
                return;
            }

            if (!needsGraphManagedOutputColor)
            {
                return;
            }

            PromoteToGraphManagedOutputColor(
                context);
        }

        private static void PromoteToGraphManagedOutputColor(
            ScriptableRenderPipelinePlanningContext context)
        {
            if (context == null)
            {
                return;
            }

            CameraFrameColorSource source =
                context.GetStageColorSource(
                    CameraFrameStage.PostProcess);
            if (source ==
                    CameraFrameColorSource.ExplicitSurface ||
                context.UsesGraphManagedOutputColor(
                    CameraFrameStage.PostProcess))
            {
                return;
            }

            context.ClearFullscreenStage(
                CameraFrameStage.PostProcess);
            context.RequestFullscreenStage(
                CameraFrameStage.PostProcess,
                source,
                true);
        }
    }
}