using System.Collections.Generic;
using XCEngine;
using XCEngine.Rendering;
using XCEngine.Rendering.RenderGraphModule;

namespace XCEngine.Rendering.Universal
{
    public abstract class ScriptableRenderer
    {
        private struct PassQueueStageManifest
        {
            public bool shadowCaster;
            public bool depthOnly;
            public bool postProcess;
            public bool finalOutput;
        }

        private readonly List<ScriptableRendererFeature> m_features =
            new List<ScriptableRendererFeature>();
        private readonly List<ScriptableRenderPass> m_activePassQueue =
            new List<ScriptableRenderPass>();
        private readonly RendererBlocks m_rendererBlocks =
            new RendererBlocks();
        private readonly CommandBuffer m_finishCameraStackCommandBuffer =
            new CommandBuffer("ScriptableRenderer.FinishCameraStack");
        private bool m_isBuildingPassQueue;
        private CameraFrameStage m_passQueueStage =
            CameraFrameStage.MainScene;
        private bool m_disposed;

        protected ScriptableRenderer()
        {
        }

        internal void ReleaseRuntimeResourcesInstance()
        {
            if (m_disposed)
            {
                return;
            }

            ReleaseRuntimeResources();

            for (int i = 0; i < m_features.Count; ++i)
            {
                ScriptableRendererFeature feature = m_features[i];
                if (feature != null)
                {
                    feature.ReleaseRuntimeResourcesInstance();
                }
            }

            m_features.Clear();
            m_activePassQueue.Clear();
            m_rendererBlocks.Clear();
            m_disposed = true;
        }

        public void EnqueuePass(
            ScriptableRenderPass renderPass)
        {
            if (renderPass == null)
            {
                return;
            }

            if (m_isBuildingPassQueue &&
                !renderPass.SupportsStage(m_passQueueStage))
            {
                return;
            }

            InsertActivePass(
                renderPass);
        }

        private void InsertActivePass(
            ScriptableRenderPass renderPass)
        {
            int insertIndex = m_activePassQueue.Count;
            while (insertIndex > 0 &&
                   m_activePassQueue[insertIndex - 1].renderPassEvent >
                       renderPass.renderPassEvent)
            {
                insertIndex--;
            }

            m_activePassQueue.Insert(
                insertIndex,
                renderPass);
        }

        protected void AddFeature(
            ScriptableRendererFeature feature)
        {
            if (feature == null)
            {
                return;
            }

            m_features.Add(feature);
            feature.CreateInstance();
        }

        protected virtual void AddRenderPasses(
            RenderingData renderingData)
        {
        }

        internal void AddFeatureInstance(
            ScriptableRendererFeature feature)
        {
            AddFeature(feature);
        }

        internal bool SupportsRendererRecordingInstance(
            RendererRecordingContext context)
        {
            return SupportsRendererRecording(context);
        }

        internal void ConfigureCameraFramePlanInstance(
            ScriptableRenderPipelinePlanningContext context)
        {
            ConfigureCameraFramePlan(context);
            ConfigureRendererFeaturesCameraFramePlan(context);
        }

        internal void ConfigurePassQueueCameraFramePlanInstance(
            ScriptableRenderPipelinePlanningContext context)
        {
            if (context == null)
            {
                return;
            }

            PassQueueStageManifest manifest =
                BuildPassQueueStageManifest(context);
            ApplyPassQueueStageManifest(context, manifest);
            ClearPassQueue();
        }

        internal void FinalizeCameraFramePlanInstance(
            ScriptableRenderPipelinePlanningContext context)
        {
            FinalizeCameraFramePlan(context);
        }

        internal void ConfigureRenderSceneSetupInstance(
            RenderSceneSetupContext context)
        {
            ConfigureRenderSceneSetup(context);
            ConfigureRendererFeaturesRenderSceneSetup(context);
        }

        internal void ConfigureDirectionalShadowExecutionStateInstance(
            DirectionalShadowExecutionContext context)
        {
            ConfigureDirectionalShadowExecutionState(context);
            ConfigureRendererFeaturesDirectionalShadowExecutionState(
                context);
        }

        internal bool RecordRendererInstance(
            RendererRecordingContext context)
        {
            return RecordRenderer(context);
        }

        protected virtual bool SupportsRendererRecording(
            RendererRecordingContext context)
        {
            if (context == null)
            {
                return false;
            }

            RenderingData renderingData =
                context.renderingData;
            BuildPassQueue(renderingData);
            return SupportsRendererStage(context);
        }

        protected virtual bool RecordRenderer(
            RendererRecordingContext context)
        {
            if (context == null ||
                context.renderContext == null)
            {
                return false;
            }

            RenderingData renderingData =
                context.renderingData;
            BuildPassQueue(renderingData);
            bool recorded;
            using (ContextContainer frameData =
                   ScriptableRenderPass.BuildRenderGraphFrameData(
                       renderingData))
            {
                recorded =
                    RecordRendererStage(
                        context,
                        new RenderGraph(context.renderContext),
                        frameData);
            }
            if (recorded)
            {
                FinishCameraStackRendering();
            }

            return recorded;
        }

        protected internal virtual bool SupportsStageRenderGraph(
            CameraFrameStage stage)
        {
            return SupportsRendererRecording(
                new RendererRecordingContext(stage));
        }

        protected internal virtual bool RecordStageRenderGraph(
            ScriptableRenderContext context)
        {
            return context != null &&
                   RecordRenderer(
                       new RendererRecordingContext(context));
        }

        protected virtual void ConfigureCameraFramePlan(
            ScriptableRenderPipelinePlanningContext context)
        {
        }

        protected virtual void FinalizeCameraFramePlan(
            ScriptableRenderPipelinePlanningContext context)
        {
        }

        protected virtual void ConfigureRenderSceneSetup(
            RenderSceneSetupContext context)
        {
        }

        protected virtual void ConfigureDirectionalShadowExecutionState(
            DirectionalShadowExecutionContext context)
        {
        }

        private void ConfigureRendererFeaturesCameraFramePlan(
            ScriptableRenderPipelinePlanningContext context)
        {
            for (int i = 0; i < m_features.Count; ++i)
            {
                ScriptableRendererFeature feature = m_features[i];
                if (feature != null &&
                    feature.isActive)
                {
                    feature.ConfigureCameraFramePlan(context);
                }
            }
        }

        private void ConfigureRendererFeaturesRenderSceneSetup(
            RenderSceneSetupContext context)
        {
            for (int i = 0; i < m_features.Count; ++i)
            {
                ScriptableRendererFeature feature = m_features[i];
                if (feature != null &&
                    feature.isActive)
                {
                    feature.ConfigureRenderSceneSetup(context);
                }
            }
        }

        private void ConfigureRendererFeaturesDirectionalShadowExecutionState(
            DirectionalShadowExecutionContext context)
        {
            for (int i = 0; i < m_features.Count; ++i)
            {
                ScriptableRendererFeature feature = m_features[i];
                if (feature != null &&
                    feature.isActive)
                {
                    feature.ConfigureDirectionalShadowExecutionState(
                        context);
                }
            }
        }

        private bool HasRendererBlock(
            RendererBlock block)
        {
            return m_rendererBlocks.HasPasses(block);
        }

        protected virtual bool SupportsRendererStage(
            RendererRecordingContext context)
        {
            if (context == null)
            {
                return false;
            }

            return HasRendererStageBlocks(context.stage);
        }

        private bool HasRendererStageBlocks(
            CameraFrameStage stage)
        {
            switch (stage)
            {
                case CameraFrameStage.ShadowCaster:
                    return HasRendererBlock(
                        RendererBlock.ShadowCaster);
                case CameraFrameStage.DepthOnly:
                    return HasRendererBlock(
                        RendererBlock.DepthPrepass);
                case CameraFrameStage.MainScene:
                    return HasRendererBlock(
                               RendererBlock.MainOpaque) ||
                           HasRendererBlock(
                               RendererBlock.MainSkybox) ||
                           HasRendererBlock(
                               RendererBlock.MainTransparent);
                case CameraFrameStage.PostProcess:
                    return HasRendererBlock(
                        RendererBlock.PostProcess);
                case CameraFrameStage.FinalOutput:
                    return HasRendererBlock(
                        RendererBlock.FinalOutput);
                default:
                    return false;
            }
        }

        private PassQueueStageManifest BuildPassQueueStageManifest(
            ScriptableRenderPipelinePlanningContext context)
        {
            bool finalColorRequiresProcessing =
                context.HasFinalColorProcessing();
            int rendererIndex = context.rendererIndex;

            return new PassQueueStageManifest
            {
                shadowCaster =
                    HasPassQueueStage(
                        CameraFrameStage.ShadowCaster,
                        rendererIndex,
                        finalColorRequiresProcessing),
                depthOnly =
                    HasPassQueueStage(
                        CameraFrameStage.DepthOnly,
                        rendererIndex,
                        finalColorRequiresProcessing),
                postProcess =
                    HasPassQueueStage(
                        CameraFrameStage.PostProcess,
                        rendererIndex,
                        finalColorRequiresProcessing),
                finalOutput =
                    HasPassQueueStage(
                        CameraFrameStage.FinalOutput,
                        rendererIndex,
                        finalColorRequiresProcessing)
            };
        }

        private bool HasPassQueueStage(
            CameraFrameStage stage,
            int rendererIndex,
            bool finalColorRequiresProcessing)
        {
            BuildPassQueue(
                RenderingData.CreatePlanning(
                    stage,
                    rendererIndex,
                    finalColorRequiresProcessing));
            return HasRendererStageBlocks(stage);
        }

        private static void ApplyPassQueueStageManifest(
            ScriptableRenderPipelinePlanningContext context,
            PassQueueStageManifest manifest)
        {
            if (manifest.shadowCaster)
            {
                context.RequestShadowCasterStage();
            }
            else
            {
                context.ClearShadowCasterStage();
            }

            if (manifest.depthOnly)
            {
                context.RequestCameraDepthOnlyStage();
            }
            else
            {
                context.ClearDepthOnlyStage();
            }

            ApplyPostProcessStageManifest(context, manifest);
            ApplyFinalOutputStageManifest(context, manifest);
        }

        private static void ApplyPostProcessStageManifest(
            ScriptableRenderPipelinePlanningContext context,
            PassQueueStageManifest manifest)
        {
            if (!manifest.postProcess)
            {
                context.ClearFullscreenStage(
                    CameraFrameStage.PostProcess);
                return;
            }

            bool finalOutputReadsPostProcess =
                ShouldFinalOutputReadPostProcess(
                    context,
                    manifest);

            if (!context.IsStageRequested(
                    CameraFrameStage.PostProcess))
            {
                context.RequestFullscreenStage(
                    CameraFrameStage.PostProcess,
                    CameraFrameColorSource.MainSceneColor,
                    finalOutputReadsPostProcess);
                return;
            }

            if (finalOutputReadsPostProcess &&
                !context.UsesGraphManagedOutputColor(
                    CameraFrameStage.PostProcess))
            {
                CameraFrameColorSource source =
                    context.GetStageColorSource(
                        CameraFrameStage.PostProcess);
                context.ClearFullscreenStage(
                    CameraFrameStage.PostProcess);
                context.RequestFullscreenStage(
                    CameraFrameStage.PostProcess,
                    source,
                    true);
            }
        }

        private static bool ShouldFinalOutputReadPostProcess(
            ScriptableRenderPipelinePlanningContext context,
            PassQueueStageManifest manifest)
        {
            if (!manifest.finalOutput ||
                !manifest.postProcess)
            {
                return false;
            }

            return !context.IsStageRequested(
                       CameraFrameStage.PostProcess) ||
                   context.GetStageColorSource(
                       CameraFrameStage.PostProcess) !=
                       CameraFrameColorSource.ExplicitSurface;
        }

        private static void ApplyFinalOutputStageManifest(
            ScriptableRenderPipelinePlanningContext context,
            PassQueueStageManifest manifest)
        {
            if (!manifest.finalOutput)
            {
                context.ClearFullscreenStage(
                    CameraFrameStage.FinalOutput);
                return;
            }

            if (context.IsStageRequested(
                    CameraFrameStage.FinalOutput) &&
                context.GetStageColorSource(
                    CameraFrameStage.FinalOutput) ==
                    CameraFrameColorSource.ExplicitSurface)
            {
                return;
            }

            context.ClearFullscreenStage(
                CameraFrameStage.FinalOutput);
            context.RequestFullscreenStage(
                CameraFrameStage.FinalOutput,
                ResolveFinalOutputSource(context));
        }

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

            return context.GetStageColorSource(
                       CameraFrameStage.PostProcess) ==
                   CameraFrameColorSource.ExplicitSurface
                ? CameraFrameColorSource.MainSceneColor
                : CameraFrameColorSource.PostProcessColor;
        }

        protected virtual bool RecordRendererStage(
            RendererRecordingContext context,
            RenderGraph renderGraph,
            ContextContainer frameData)
        {
            if (context == null ||
                context.renderContext == null)
            {
                return false;
            }

            bool recordedAnyPass = false;
            switch (context.stage)
            {
                case CameraFrameStage.ShadowCaster:
                    return RecordRendererBlock(
                               RendererBlock.ShadowCaster,
                               context,
                               renderGraph,
                               frameData,
                               ref recordedAnyPass) &&
                           recordedAnyPass;
                case CameraFrameStage.DepthOnly:
                    return RecordRendererBlock(
                               RendererBlock.DepthPrepass,
                               context,
                               renderGraph,
                               frameData,
                               ref recordedAnyPass) &&
                           recordedAnyPass;
                case CameraFrameStage.MainScene:
                    return RecordRendererBlock(
                               RendererBlock.MainOpaque,
                               context,
                               renderGraph,
                               frameData,
                               ref recordedAnyPass) &&
                           RecordRendererBlock(
                               RendererBlock.MainSkybox,
                               context,
                               renderGraph,
                               frameData,
                               ref recordedAnyPass) &&
                           RecordRendererBlock(
                               RendererBlock.MainTransparent,
                               context,
                               renderGraph,
                               frameData,
                               ref recordedAnyPass) &&
                           recordedAnyPass;
                case CameraFrameStage.PostProcess:
                    return RecordRendererBlock(
                               RendererBlock.PostProcess,
                               context,
                               renderGraph,
                               frameData,
                               ref recordedAnyPass) &&
                           recordedAnyPass;
                case CameraFrameStage.FinalOutput:
                    return RecordRendererBlock(
                               RendererBlock.FinalOutput,
                               context,
                               renderGraph,
                               frameData,
                               ref recordedAnyPass) &&
                           recordedAnyPass;
                default:
                    return false;
            }
        }

        private bool RecordRendererBlock(
            RendererBlock block,
            RendererRecordingContext context,
            RenderGraph renderGraph,
            ContextContainer frameData,
            ref bool recordedAnyPass)
        {
            if (context == null ||
                context.renderContext == null)
            {
                return false;
            }

            int firstPassIndex;
            int lastPassIndex;
            if (!m_rendererBlocks.TryGetPassRange(
                    block,
                    out firstPassIndex,
                    out lastPassIndex))
            {
                return true;
            }

            for (int i = firstPassIndex;
                 i <= lastPassIndex;
                 ++i)
            {
                ScriptableRenderPass renderPass =
                    m_activePassQueue[i];
                if (renderPass == null ||
                    !renderPass.SupportsRendererBlock(block))
                {
                    continue;
                }

                if (!renderPass.Record(
                        context.renderContext,
                        context.renderingData,
                        renderGraph,
                        frameData))
                {
                    return false;
                }

                recordedAnyPass = true;
            }

            return true;
        }

        private void BuildPassQueue(
            RenderingData renderingData)
        {
            ClearPassQueue();
            m_isBuildingPassQueue = true;
            m_passQueueStage =
                renderingData != null
                    ? renderingData.stage
                    : CameraFrameStage.MainScene;

            try
            {
                for (int i = 0; i < m_features.Count; ++i)
                {
                    ScriptableRendererFeature feature = m_features[i];
                    if (feature == null || !feature.isActive)
                    {
                        continue;
                    }

                    feature.SetupRenderPasses(
                        this,
                        in renderingData);
                    feature.AddRenderPasses(
                        this,
                        ref renderingData);
                }

                AddRenderPasses(renderingData);
                m_rendererBlocks.Build(m_activePassQueue);
            }
            finally
            {
                m_isBuildingPassQueue = false;
                m_passQueueStage =
                    CameraFrameStage.MainScene;
            }
        }

        private void ClearPassQueue()
        {
            m_activePassQueue.Clear();
            m_rendererBlocks.Clear();
        }

        private void FinishCameraStackRendering()
        {
            for (int i = 0; i < m_activePassQueue.Count; ++i)
            {
                ScriptableRenderPass renderPass =
                    m_activePassQueue[i];
                if (renderPass == null)
                {
                    continue;
                }

                renderPass.OnFinishCameraStackRendering(
                    m_finishCameraStackCommandBuffer);
            }
        }

        protected virtual void ReleaseRuntimeResources()
        {
        }
    }
}