using System.Collections;
using System.Collections.Generic;
using System.Diagnostics;
using UnityEngine.Experimental.Rendering;
using UnityEngine.Experimental.Rendering.RenderGraphModule;

namespace UnityEngine.Rendering.Universal
{
    class DebugHandler : IDebugDisplaySettingsQuery
    {
        #region Property Id Constants

        static readonly int k_DebugColorInvalidModePropertyId = Shader.PropertyToID("_DebugColorInvalidMode");

        static readonly int k_DebugColorPropertyId = Shader.PropertyToID("_DebugColor");
        static readonly int k_DebugTexturePropertyId = Shader.PropertyToID("_DebugTexture");
        static readonly int k_DebugTextureNoStereoPropertyId = Shader.PropertyToID("_DebugTextureNoStereo");
        static readonly int k_DebugTextureDisplayRect = Shader.PropertyToID("_DebugTextureDisplayRect");
        static readonly int k_DebugRenderTargetSupportsStereo = Shader.PropertyToID("_DebugRenderTargetSupportsStereo");

        // Material settings...
        static readonly int k_DebugMaterialModeId = Shader.PropertyToID("_DebugMaterialMode");
        static readonly int k_DebugVertexAttributeModeId = Shader.PropertyToID("_DebugVertexAttributeMode");
        static readonly int k_DebugMaterialValidationModeId = Shader.PropertyToID("_DebugMaterialValidationMode");

        // Rendering settings...
        static readonly int k_DebugMipInfoModeId = Shader.PropertyToID("_DebugMipInfoMode");
        static readonly int k_DebugSceneOverrideModeId = Shader.PropertyToID("_DebugSceneOverrideMode");
        static readonly int k_DebugFullScreenModeId = Shader.PropertyToID("_DebugFullScreenMode");
        static readonly int k_DebugValidationModeId = Shader.PropertyToID("_DebugValidationMode");
        static readonly int k_DebugValidateBelowMinThresholdColorPropertyId = Shader.PropertyToID("_DebugValidateBelowMinThresholdColor");
        static readonly int k_DebugValidateAboveMaxThresholdColorPropertyId = Shader.PropertyToID("_DebugValidateAboveMaxThresholdColor");
        static readonly int k_DebugMaxPixelCost = Shader.PropertyToID("_DebugMaxPixelCost");


        // Lighting settings...
        static readonly int k_DebugLightingModeId = Shader.PropertyToID("_DebugLightingMode");
        static readonly int k_DebugLightingFeatureFlagsId = Shader.PropertyToID("_DebugLightingFeatureFlags");

        static readonly int k_DebugValidateAlbedoMinLuminanceId = Shader.PropertyToID("_DebugValidateAlbedoMinLuminance");
        static readonly int k_DebugValidateAlbedoMaxLuminanceId = Shader.PropertyToID("_DebugValidateAlbedoMaxLuminance");
        static readonly int k_DebugValidateAlbedoSaturationToleranceId = Shader.PropertyToID("_DebugValidateAlbedoSaturationTolerance");
        static readonly int k_DebugValidateAlbedoHueToleranceId = Shader.PropertyToID("_DebugValidateAlbedoHueTolerance");
        static readonly int k_DebugValidateAlbedoCompareColorId = Shader.PropertyToID("_DebugValidateAlbedoCompareColor");

        static readonly int k_DebugValidateMetallicMinValueId = Shader.PropertyToID("_DebugValidateMetallicMinValue");
        static readonly int k_DebugValidateMetallicMaxValueId = Shader.PropertyToID("_DebugValidateMetallicMaxValue");

        static readonly int k_ValidationChannelsId = Shader.PropertyToID("_ValidationChannels");
        static readonly int k_RangeMinimumId = Shader.PropertyToID("_RangeMinimum");
        static readonly int k_RangeMaximumId = Shader.PropertyToID("_RangeMaximum");

        #endregion

        readonly Material m_ReplacementMaterial;
        readonly Material m_HDRDebugViewMaterial;

        HDRDebugViewPass m_HDRDebugViewPass;
        internal RTHandle m_DebugScreenTextureHandle;

        bool m_HasDebugRenderTarget;
        bool m_DebugRenderTargetSupportsStereo;
        Vector4 m_DebugRenderTargetPixelRect;
        RenderTargetIdentifier m_DebugRenderTargetIdentifier;

        readonly UniversalRenderPipelineDebugDisplaySettings m_DebugDisplaySettings;

        DebugDisplaySettingsLighting LightingSettings => m_DebugDisplaySettings.lightingSettings;
        DebugDisplaySettingsMaterial MaterialSettings => m_DebugDisplaySettings.materialSettings;
        DebugDisplaySettingsRendering RenderingSettings => m_DebugDisplaySettings.renderingSettings;

        #region IDebugDisplaySettingsQuery

        /// <inheritdoc/>
        public bool AreAnySettingsActive => m_DebugDisplaySettings.AreAnySettingsActive;

        /// <inheritdoc/>
        public bool IsPostProcessingAllowed => m_DebugDisplaySettings.IsPostProcessingAllowed;

        /// <inheritdoc/>
        public bool IsLightingActive => m_DebugDisplaySettings.IsLightingActive;

        // These modes would require putting custom data into gbuffer, so instead we just disable deferred mode.
        internal bool IsActiveModeUnsupportedForDeferred =>
            m_DebugDisplaySettings.lightingSettings.lightingDebugMode != DebugLightingMode.None ||
            m_DebugDisplaySettings.lightingSettings.lightingFeatureFlags != DebugLightingFeatureFlags.None ||
            m_DebugDisplaySettings.renderingSettings.sceneOverrideMode != DebugSceneOverrideMode.None ||
            m_DebugDisplaySettings.materialSettings.materialDebugMode != DebugMaterialMode.None ||
            m_DebugDisplaySettings.materialSettings.vertexAttributeDebugMode != DebugVertexAttributeMode.None ||
            m_DebugDisplaySettings.materialSettings.materialValidationMode != DebugMaterialValidationMode.None;

        /// <inheritdoc/>
        public bool TryGetScreenClearColor(ref Color color)
        {
            return m_DebugDisplaySettings.TryGetScreenClearColor(ref color);
        }

        #endregion

        internal Material ReplacementMaterial => m_ReplacementMaterial;
        internal UniversalRenderPipelineDebugDisplaySettings DebugDisplaySettings => m_DebugDisplaySettings;
        internal RTHandle DebugScreenTextureHandle => m_DebugScreenTextureHandle;
        internal HDRDebugViewPass hdrDebugViewPass => m_HDRDebugViewPass;

        internal bool HDRDebugViewIsActive(ref CameraData cameraData)
        {
            // HDR debug views should only apply to the last camera in the stack
            return DebugDisplaySettings.lightingSettings.hdrDebugMode != HDRDebugMode.None && cameraData.resolveFinalTarget;
        }

        internal bool WriteToDebugScreenTexture(ref CameraData cameraData)
        {
            return HDRDebugViewIsActive(ref cameraData);
        }

        internal bool IsScreenClearNeeded
        {
            get
            {
                Color color = Color.black;

                return TryGetScreenClearColor(ref color);
            }
        }

        internal bool IsRenderPassSupported
        {
            get
            {
                return RenderingSettings.sceneOverrideMode == DebugSceneOverrideMode.None || RenderingSettings.sceneOverrideMode == DebugSceneOverrideMode.Overdraw;
            }
        }

        internal DebugHandler(ScriptableRendererData scriptableRendererData)
        {
            Shader debugReplacementShader = scriptableRendererData.debugShaders.debugReplacementPS;
            Shader hdrDebugViewShader = scriptableRendererData.debugShaders.hdrDebugViewPS;

            m_DebugDisplaySettings = UniversalRenderPipelineDebugDisplaySettings.Instance;

            m_ReplacementMaterial = (debugReplacementShader == null) ? null : CoreUtils.CreateEngineMaterial(debugReplacementShader);
            m_HDRDebugViewMaterial = (hdrDebugViewShader == null) ? null : CoreUtils.CreateEngineMaterial(hdrDebugViewShader);

            m_HDRDebugViewPass = new HDRDebugViewPass(m_HDRDebugViewMaterial);
        }

        public void Dispose()
        {
            m_HDRDebugViewPass.Dispose();
            m_DebugScreenTextureHandle?.Release();
            CoreUtils.Destroy(m_HDRDebugViewMaterial);
            CoreUtils.Destroy(m_ReplacementMaterial);
        }

        internal bool IsActiveForCamera(ref CameraData cameraData)
        {
            return !cameraData.isPreviewCamera && AreAnySettingsActive;
        }

        internal bool TryGetFullscreenDebugMode(out DebugFullScreenMode debugFullScreenMode)
        {
            return TryGetFullscreenDebugMode(out debugFullScreenMode, out _);
        }

        internal bool TryGetFullscreenDebugMode(out DebugFullScreenMode debugFullScreenMode, out int textureHeightPercent)
        {
            debugFullScreenMode = RenderingSettings.fullScreenDebugMode;
            textureHeightPercent = RenderingSettings.fullScreenDebugModeOutputSizeScreenPercent;
            return debugFullScreenMode != DebugFullScreenMode.None;
        }

        internal void BlitTextureToDebugScreenTexture(CommandBuffer cmd, RTHandle sourceTexture, Material material, int passId)
        {
            Vector2 viewportScale = sourceTexture.useScaling ? new Vector2(sourceTexture.rtHandleProperties.rtHandleScale.x, sourceTexture.rtHandleProperties.rtHandleScale.y) : Vector2.one;

            CoreUtils.SetRenderTarget(cmd, m_DebugScreenTextureHandle, RenderBufferLoadAction.Load, RenderBufferStoreAction.Store);
            Blitter.BlitTexture(cmd, sourceTexture, viewportScale, material, passId);
        }

        [Conditional("DEVELOPMENT_BUILD"), Conditional("UNITY_EDITOR")]
        internal void SetupShaderProperties(RasterCommandBuffer cmd, int passIndex = 0)
        {
            if (LightingSettings.lightingDebugMode == DebugLightingMode.ShadowCascades)
            {
                // we disable cubemap reflections, too distracting (in TemplateLWRP for ex.)
                cmd.EnableShaderKeyword("_DEBUG_ENVIRONMENTREFLECTIONS_OFF");
            }
            else
            {
                cmd.DisableShaderKeyword("_DEBUG_ENVIRONMENTREFLECTIONS_OFF");
            }

            switch (RenderingSettings.sceneOverrideMode)
            {
                case DebugSceneOverrideMode.Overdraw:
                {
                    // Target texture can contains only a value between 0 and 1
                    // So we encode the number of overdraw in the range (0, max displayed overdaw count)
                    // The value will be clamped by the GPU driver
                    var value = 1 / (float)RenderingSettings.maxOverdrawCount;
                    cmd.SetGlobalColor(k_DebugColorPropertyId, new Color(value, value, value, 1));
                    break;
                }

                case DebugSceneOverrideMode.Wireframe:
                {
                    cmd.SetGlobalColor(k_DebugColorPropertyId, Color.black);
                    break;
                }

                case DebugSceneOverrideMode.SolidWireframe:
                {
                    cmd.SetGlobalColor(k_DebugColorPropertyId, (passIndex == 0) ? Color.white : Color.black);
                    break;
                }

                case DebugSceneOverrideMode.ShadedWireframe:
                {
                    if (passIndex == 0)
                    {
                        cmd.DisableShaderKeyword(ShaderKeywordStrings.DEBUG_DISPLAY);
                    }
                    else if (passIndex == 1)
                    {
                        cmd.SetGlobalColor(k_DebugColorPropertyId, Color.black);
                        cmd.EnableShaderKeyword(ShaderKeywordStrings.DEBUG_DISPLAY);
                    }

                    break;
                }
            }

            switch (MaterialSettings.materialValidationMode)
            {
                case DebugMaterialValidationMode.Albedo:
                    cmd.SetGlobalFloat(k_DebugValidateAlbedoMinLuminanceId, MaterialSettings.albedoMinLuminance);
                    cmd.SetGlobalFloat(k_DebugValidateAlbedoMaxLuminanceId, MaterialSettings.albedoMaxLuminance);
                    cmd.SetGlobalFloat(k_DebugValidateAlbedoSaturationToleranceId, MaterialSettings.albedoSaturationTolerance);
                    cmd.SetGlobalFloat(k_DebugValidateAlbedoHueToleranceId, MaterialSettings.albedoHueTolerance);
                    cmd.SetGlobalColor(k_DebugValidateAlbedoCompareColorId, MaterialSettings.albedoCompareColor.linear);
                    break;

                case DebugMaterialValidationMode.Metallic:
                    cmd.SetGlobalFloat(k_DebugValidateMetallicMinValueId, MaterialSettings.metallicMinValue);
                    cmd.SetGlobalFloat(k_DebugValidateMetallicMaxValueId, MaterialSettings.metallicMaxValue);
                    break;
            }
        }

        internal void SetDebugRenderTarget(RenderTargetIdentifier renderTargetIdentifier, Rect displayRect, bool supportsStereo)
        {
            m_HasDebugRenderTarget = true;
            m_DebugRenderTargetSupportsStereo = supportsStereo;
            m_DebugRenderTargetIdentifier = renderTargetIdentifier;
            m_DebugRenderTargetPixelRect = new Vector4(displayRect.x, displayRect.y, displayRect.width, displayRect.height);
        }

        internal void ResetDebugRenderTarget()
        {
            m_HasDebugRenderTarget = false;
        }

        [Conditional("DEVELOPMENT_BUILD"), Conditional("UNITY_EDITOR")]
        internal void UpdateShaderGlobalPropertiesForFinalValidationPass(CommandBuffer cmd, ref CameraData cameraData, bool isFinalPass)
        {
            // Ensure final validation & fullscreen debug modes are only done once in the very final pass, for the last camera on the stack.
            bool isFinal = isFinalPass && cameraData.resolveFinalTarget;
            if (!isFinal)
            {
                cmd.DisableShaderKeyword(ShaderKeywordStrings.DEBUG_DISPLAY);
                return;
            }

            if (IsActiveForCamera(ref cameraData))
            {
                cmd.EnableShaderKeyword(ShaderKeywordStrings.DEBUG_DISPLAY);
            }
            else
            {
                cmd.DisableShaderKeyword(ShaderKeywordStrings.DEBUG_DISPLAY);
            }

            if (m_HasDebugRenderTarget)
            {
                cmd.SetGlobalTexture(m_DebugRenderTargetSupportsStereo ? k_DebugTexturePropertyId : k_DebugTextureNoStereoPropertyId, m_DebugRenderTargetIdentifier);
                cmd.SetGlobalVector(k_DebugTextureDisplayRect, m_DebugRenderTargetPixelRect);
                cmd.SetGlobalInteger(k_DebugRenderTargetSupportsStereo, m_DebugRenderTargetSupportsStereo ? 1 : 0);
            }

            var renderingSettings = m_DebugDisplaySettings.renderingSettings;
            if (renderingSettings.validationMode == DebugValidationMode.HighlightOutsideOfRange)
            {
                cmd.SetGlobalInteger(k_ValidationChannelsId, (int)renderingSettings.validationChannels);
                cmd.SetGlobalFloat(k_RangeMinimumId, renderingSettings.validationRangeMin);
                cmd.SetGlobalFloat(k_RangeMaximumId, renderingSettings.validationRangeMax);
            }
        }

        [Conditional("DEVELOPMENT_BUILD"), Conditional("UNITY_EDITOR")]
        internal void Setup(ref RenderingData renderingData)
        {
            var cmd = renderingData.commandBuffer;
            ref var cameraData = ref renderingData.cameraData;

            if (IsActiveForCamera(ref cameraData))
            {
                cmd.EnableShaderKeyword(ShaderKeywordStrings.DEBUG_DISPLAY);

                // Material settings...
                cmd.SetGlobalFloat(k_DebugMaterialModeId, (int)MaterialSettings.materialDebugMode);
                cmd.SetGlobalFloat(k_DebugVertexAttributeModeId, (int)MaterialSettings.vertexAttributeDebugMode);

                cmd.SetGlobalInteger(k_DebugMaterialValidationModeId, (int)MaterialSettings.materialValidationMode);

                // Rendering settings...
                cmd.SetGlobalInteger(k_DebugMipInfoModeId, (int)RenderingSettings.mipInfoMode);
                cmd.SetGlobalInteger(k_DebugSceneOverrideModeId, (int)RenderingSettings.sceneOverrideMode);
                cmd.SetGlobalInteger(k_DebugFullScreenModeId, (int)RenderingSettings.fullScreenDebugMode);
                cmd.SetGlobalInteger(k_DebugMaxPixelCost, (int)RenderingSettings.maxOverdrawCount);
                cmd.SetGlobalInteger(k_DebugValidationModeId, (int)RenderingSettings.validationMode);
                cmd.SetGlobalColor(k_DebugValidateBelowMinThresholdColorPropertyId, Color.red);
                cmd.SetGlobalColor(k_DebugValidateAboveMaxThresholdColorPropertyId, Color.blue);

                // Lighting settings...
                cmd.SetGlobalFloat(k_DebugLightingModeId, (int)LightingSettings.lightingDebugMode);
                cmd.SetGlobalInteger(k_DebugLightingFeatureFlagsId, (int)LightingSettings.lightingFeatureFlags);

                // Set-up any other persistent properties...
                cmd.SetGlobalColor(k_DebugColorInvalidModePropertyId, Color.red);

                if (HDRDebugViewIsActive(ref cameraData))
                    m_HDRDebugViewPass.Setup(LightingSettings.hdrDebugMode);
            }
            else
            {
                cmd.DisableShaderKeyword(ShaderKeywordStrings.DEBUG_DISPLAY);
            }
        }

        [Conditional("DEVELOPMENT_BUILD"), Conditional("UNITY_EDITOR")]
        internal void Render(RenderGraph renderGraph, ref RenderingData renderingData, TextureHandle srcColor, TextureHandle overlayTexture, TextureHandle dstColor)
        {
            ref var cameraData = ref renderingData.cameraData;
            if (IsActiveForCamera(ref cameraData) && HDRDebugViewIsActive(ref cameraData))
            {
                m_HDRDebugViewPass.RenderHDRDebug(renderGraph, ref renderingData, srcColor, overlayTexture, dstColor, LightingSettings.hdrDebugMode);
            }
        }

        #region DebugRendererLists

        internal DebugRendererLists CreateRendererListsWithDebugRenderState(
             ScriptableRenderContext context,
             ref RenderingData renderingData,
             ref DrawingSettings drawingSettings,
             ref FilteringSettings filteringSettings,
             ref RenderStateBlock renderStateBlock)
        {
            DebugRendererLists debug = new DebugRendererLists(this, filteringSettings);
            debug.CreateRendererListsWithDebugRenderState(context, ref renderingData, ref drawingSettings, ref filteringSettings, ref renderStateBlock);
            return debug;
        }

        internal DebugRendererLists CreateRendererListsWithDebugRenderState(
            RenderGraph renderGraph,
            ref RenderingData renderingData,
            ref DrawingSettings drawingSettings,
            ref FilteringSettings filteringSettings,
            ref RenderStateBlock renderStateBlock)
        {
            DebugRendererLists debug = new DebugRendererLists(this, filteringSettings);
            debug.CreateRendererListsWithDebugRenderState(renderGraph, ref renderingData, ref drawingSettings, ref filteringSettings, ref renderStateBlock);
            return debug;
        }
        #endregion
    }

    internal class DebugRendererLists
    {
        private readonly DebugHandler m_DebugHandler;
        readonly FilteringSettings m_FilteringSettings;
        List<DebugRenderSetup> m_DebugRenderSetups = new List<DebugRenderSetup>(2);
        List<RendererList> m_ActiveDebugRendererList = new List<RendererList>(2);
        List<RendererListHandle> m_ActiveDebugRendererListHdl = new List<RendererListHandle>(2);

        public DebugRendererLists(DebugHandler debugHandler,
            FilteringSettings filteringSettings)
        {
            m_DebugHandler = debugHandler;
            m_FilteringSettings = filteringSettings;
        }

        private void CreateDebugRenderSetups(FilteringSettings filteringSettings)
        {
            var sceneOverrideMode = m_DebugHandler.DebugDisplaySettings.renderingSettings.sceneOverrideMode;
            var numIterations = ((sceneOverrideMode == DebugSceneOverrideMode.SolidWireframe) || (sceneOverrideMode == DebugSceneOverrideMode.ShadedWireframe)) ? 2 : 1;
            for (var i = 0; i < numIterations; i++)
                m_DebugRenderSetups.Add(new DebugRenderSetup(m_DebugHandler, i, filteringSettings));
        }

        void DisposeDebugRenderLists()
        {
            foreach (var debugRenderSetup in m_DebugRenderSetups)
            {
                debugRenderSetup.Dispose();
            }
            m_DebugRenderSetups.Clear();
            m_ActiveDebugRendererList.Clear();
            m_ActiveDebugRendererListHdl.Clear();
        }

        internal void CreateRendererListsWithDebugRenderState(
             ScriptableRenderContext context,
             ref RenderingData renderingData,
             ref DrawingSettings drawingSettings,
             ref FilteringSettings filteringSettings,
             ref RenderStateBlock renderStateBlock)
        {
            CreateDebugRenderSetups(filteringSettings);
            foreach (DebugRenderSetup debugRenderSetup in m_DebugRenderSetups)
            {
                DrawingSettings debugDrawingSettings = debugRenderSetup.CreateDrawingSettings(drawingSettings);
                RenderStateBlock debugRenderStateBlock = debugRenderSetup.GetRenderStateBlock(renderStateBlock);
                RendererList rendererList = new RendererList();
                RenderingUtils.CreateRendererListWithRenderStateBlock(context, renderingData, debugDrawingSettings, filteringSettings, debugRenderStateBlock, ref rendererList);
                m_ActiveDebugRendererList.Add((rendererList));
            }
        }

        internal void CreateRendererListsWithDebugRenderState(
            RenderGraph renderGraph,
            ref RenderingData renderingData,
            ref DrawingSettings drawingSettings,
            ref FilteringSettings filteringSettings,
            ref RenderStateBlock renderStateBlock)
        {
            CreateDebugRenderSetups(filteringSettings);
            foreach (DebugRenderSetup debugRenderSetup in m_DebugRenderSetups)
            {
                DrawingSettings debugDrawingSettings = debugRenderSetup.CreateDrawingSettings(drawingSettings);
                RenderStateBlock debugRenderStateBlock = debugRenderSetup.GetRenderStateBlock(renderStateBlock);
                RendererListHandle rendererListHdl = new RendererListHandle();
                RenderingUtils.CreateRendererListWithRenderStateBlock(renderGraph, renderingData, debugDrawingSettings, filteringSettings, debugRenderStateBlock, ref rendererListHdl);
                m_ActiveDebugRendererListHdl.Add((rendererListHdl));
            }
        }

        internal void PrepareRendererListForRasterPass(IRasterRenderGraphBuilder builder)
        {
            foreach (RendererListHandle rendererListHdl in m_ActiveDebugRendererListHdl)
            {
                builder.UseRendererList(rendererListHdl);
            }
        }

        internal void DrawWithRendererList(RasterCommandBuffer cmd)
        {
            foreach (DebugRenderSetup debugRenderSetup in m_DebugRenderSetups)
            {
                debugRenderSetup.Begin(cmd);
                RendererList rendererList = new RendererList();
                if (m_ActiveDebugRendererList.Count > 0)
                {
                    rendererList = m_ActiveDebugRendererList[debugRenderSetup.GetIndex()];
                }
                else if(m_ActiveDebugRendererListHdl.Count > 0)
                {
                    rendererList = m_ActiveDebugRendererListHdl[debugRenderSetup.GetIndex()];
                }

                debugRenderSetup.DrawWithRendererList(cmd, ref rendererList);
                debugRenderSetup.End(cmd);
            }

            DisposeDebugRenderLists();
        }
    }
}