using System;
using XCEngine;
using XCEngine.Rendering;

namespace XCEngine.Rendering.Universal
{
    public abstract class ScriptableRenderPass
    {
        private enum RecordedScenePhase
        {
            Opaque = 0,
            Skybox = 1,
            Transparent = 3
        }

        private enum RecordedSceneInjectionPoint
        {
            BeforeOpaque = 0,
            AfterOpaque = 1,
            BeforeSkybox = 2,
            AfterSkybox = 3,
            BeforeTransparent = 4,
            AfterTransparent = 5
        }

        private enum RecordedFullscreenPassType
        {
            ColorScale = 0,
            ShaderVector = 1
        }

        protected ScriptableRenderPass()
        {
        }

        public RenderPassEvent renderPassEvent { get; protected set; } =
            RenderPassEvent.BeforeRenderingOpaques;

        public virtual bool SupportsStage(
            CameraFrameStage stage)
        {
            CameraFrameStage resolvedStage;
            return TryResolveStage(
                renderPassEvent,
                out resolvedStage) &&
                resolvedStage == stage;
        }

        internal bool Record(
            ScriptableRenderContext context,
            RenderingData renderingData)
        {
            return RecordRenderGraph(
                context,
                renderingData);
        }

        protected abstract bool RecordRenderGraph(
            ScriptableRenderContext context,
            RenderingData renderingData);

        protected bool RecordScene(
            ScriptableRenderContext context)
        {
            return context != null &&
                   InternalCalls
                       .Rendering_ScriptableRenderContext_RecordScene(
                           context.nativeHandle);
        }

        protected bool RecordOpaqueScenePhase(
            ScriptableRenderContext context)
        {
            return RecordScenePhaseInternal(
                context,
                RecordedScenePhase.Opaque);
        }

        protected bool RecordSkyboxScenePhase(
            ScriptableRenderContext context)
        {
            return RecordScenePhaseInternal(
                context,
                RecordedScenePhase.Skybox);
        }

        protected bool RecordTransparentScenePhase(
            ScriptableRenderContext context)
        {
            return RecordScenePhaseInternal(
                context,
                RecordedScenePhase.Transparent);
        }

        protected bool RecordBeforeOpaqueInjection(
            ScriptableRenderContext context)
        {
            return RecordSceneInjectionPointInternal(
                context,
                RecordedSceneInjectionPoint.BeforeOpaque);
        }

        protected bool RecordAfterOpaqueInjection(
            ScriptableRenderContext context)
        {
            return RecordSceneInjectionPointInternal(
                context,
                RecordedSceneInjectionPoint.AfterOpaque);
        }

        protected bool RecordBeforeSkyboxInjection(
            ScriptableRenderContext context)
        {
            return RecordSceneInjectionPointInternal(
                context,
                RecordedSceneInjectionPoint.BeforeSkybox);
        }

        protected bool RecordAfterSkyboxInjection(
            ScriptableRenderContext context)
        {
            return RecordSceneInjectionPointInternal(
                context,
                RecordedSceneInjectionPoint.AfterSkybox);
        }

        protected bool RecordBeforeTransparentInjection(
            ScriptableRenderContext context)
        {
            return RecordSceneInjectionPointInternal(
                context,
                RecordedSceneInjectionPoint.BeforeTransparent);
        }

        protected bool RecordAfterTransparentInjection(
            ScriptableRenderContext context)
        {
            return RecordSceneInjectionPointInternal(
                context,
                RecordedSceneInjectionPoint.AfterTransparent);
        }

        protected bool RecordColorScaleFullscreenPass(
            ScriptableRenderContext context,
            Vector4 colorScale)
        {
            return RecordFullscreenPassInternal(
                context,
                RecordedFullscreenPassType.ColorScale,
                string.Empty,
                string.Empty,
                colorScale);
        }

        protected bool RecordShaderVectorFullscreenPass(
            ScriptableRenderContext context,
            string shaderPath,
            Vector4 vectorPayload,
            string passName = null)
        {
            if (string.IsNullOrEmpty(shaderPath))
            {
                throw new ArgumentException(
                    "Fullscreen shader path cannot be null or empty.",
                    nameof(shaderPath));
            }

            return RecordFullscreenPassInternal(
                context,
                RecordedFullscreenPassType.ShaderVector,
                shaderPath,
                passName ?? string.Empty,
                vectorPayload);
        }

        internal static bool TryResolveStage(
            RenderPassEvent passEvent,
            out CameraFrameStage stage)
        {
            switch (passEvent)
            {
                case RenderPassEvent.BeforeRenderingOpaques:
                case RenderPassEvent.RenderOpaques:
                case RenderPassEvent.AfterRenderingOpaques:
                case RenderPassEvent.BeforeRenderingSkybox:
                case RenderPassEvent.RenderSkybox:
                case RenderPassEvent.AfterRenderingSkybox:
                case RenderPassEvent.BeforeRenderingTransparents:
                case RenderPassEvent.RenderTransparents:
                case RenderPassEvent.AfterRenderingTransparents:
                    stage = CameraFrameStage.MainScene;
                    return true;
                case RenderPassEvent.BeforeRenderingPostProcessing:
                case RenderPassEvent.AfterRenderingPostProcessing:
                    stage = CameraFrameStage.PostProcess;
                    return true;
                case RenderPassEvent.BeforeRenderingFinalOutput:
                case RenderPassEvent.AfterRenderingFinalOutput:
                    stage = CameraFrameStage.FinalOutput;
                    return true;
                default:
                    stage = CameraFrameStage.MainScene;
                    return false;
            }
        }

        private bool RecordScenePhaseInternal(
            ScriptableRenderContext context,
            RecordedScenePhase scenePhase)
        {
            return context != null &&
                   InternalCalls
                       .Rendering_ScriptableRenderContext_RecordScenePhase(
                           context.nativeHandle,
                           (int)scenePhase);
        }

        private bool RecordSceneInjectionPointInternal(
            ScriptableRenderContext context,
            RecordedSceneInjectionPoint injectionPoint)
        {
            return context != null &&
                   InternalCalls
                       .Rendering_ScriptableRenderContext_RecordSceneInjectionPoint(
                           context.nativeHandle,
                           (int)injectionPoint);
        }

        private bool RecordFullscreenPassInternal(
            ScriptableRenderContext context,
            RecordedFullscreenPassType passType,
            string shaderPath,
            string passName,
            Vector4 vectorPayload)
        {
            return context != null &&
                   InternalCalls
                       .Rendering_ScriptableRenderContext_RecordFullscreenPass(
                           context.nativeHandle,
                           (int)passType,
                           shaderPath,
                           passName,
                           ref vectorPayload);
        }
    }
}