using System.Collections.Generic;
using UnityEngine;
using UnityEngine.Rendering;
using UnityEngine.Rendering.Universal;

#if ENABLE_VR 
using UnityEngine.XR;
#endif

namespace Golems
{
    public class OutlineScriptableRenderFeature : ScriptableRendererFeature
    {
        
        [SerializeField] private bool m_IsEnabled = true;
        
        [SerializeField]
        private Material m_SolidUnlitMaterial = default;
        
        [SerializeField]
        private Material m_BlurMaterial = default;
        
        private OutlineScriptableRenderPass m_Pass = default;

        [SerializeField] private RenderPassEvent m_RenderPassEvent = RenderPassEvent.AfterRenderingOpaques;
        
        /// <summary>
        /// The number of Blur passes performed.
        /// This effects ALL objects rendered
        /// </summary>
        [Tooltip("How many times we Blur all the objects. Note, the bigger the number, the bigger the performance hit")]
        [Range(1, 10)][SerializeField] private int m_BlurPasses = 1;

        /// <summary>
        /// Effects how far off centre each Blur sample becomes
        /// </summary>
        [Tooltip("Effects how far off centre each Blur sample becomes. Note, the bigger the number, the bigger the pixelation")]
        [Range(0.0f, 10.0f)] [SerializeField] private float m_BlurRadius = .5f;

        /// <summary>
        /// Index into the m_BlurTextureSizes
        /// </summary>
        [Range(0,4)] [SerializeField] private int m_BlurTextureSize = 3;

        /// <summary>
        /// Texture size of the blur textures
        /// </summary>
        private int[] m_BlurTextureSizes = new int[5] { 128, 256, 512, 1024, 2048 };

        [Header("Outlines Occluders")]
        /// <summary>
        /// Material used to render the occluders
        /// </summary>
        [Tooltip("Material used to render the occluders")]
        [SerializeField] Material m_OutlinesOccludersMat;

        /// <summary>
        /// Used to set the objects that will be part of the outlines occluders
        /// </summary>
        [Tooltip("Used to set the objects that will be part of the outlines occluders")]
        [SerializeField] LayerMask m_OccludersMask;

        /// <summary>
        /// Initializes this feature's resources.
        /// </summary>
        public override void Create()
        {
            m_Pass = new OutlineScriptableRenderPass(m_SolidUnlitMaterial, m_BlurMaterial, m_OutlinesOccludersMat, m_OccludersMask);
            
        }
        
        private void DebugSetEnabledState(bool state)
        {
            m_IsEnabled = state;
        }
        private bool DebugGetEnabledState()
        {
            return m_IsEnabled;
        }

        /// <summary>
        /// Injects the outline ScriptableRenderPass into the renderer.
        /// </summary>
        public override void AddRenderPasses(ScriptableRenderer renderer, ref RenderingData renderingData)
        {
            if (!m_IsEnabled)
            {
                return;
            }
            
            //
            // Zeroing this here in case the pass is not added
            //
            OutlineCollection.NumberOfObjectsRendered = 0;
            var outlineRenderers = OutlineCollection.RendererBundles;
            if (outlineRenderers == null || outlineRenderers.Count <= 0) return;

            m_Pass.Setup(
                m_RenderPassEvent, 
                renderingData.cameraData.camera, 
                outlineRenderers, 
                m_BlurPasses,
                m_BlurRadius,
                m_BlurTextureSizes[Mathf.Max(0, Mathf.Min(m_BlurTextureSize, m_BlurTextureSizes.Length-1))]);
            renderer.EnqueuePass(m_Pass);
        }
    }

    public class OutlineScriptableRenderPass : ScriptableRenderPass
    {
        private const string k_ProfilerIdent = "Outline";

        #region Texture Consts
        private const string k_DefaultDrawObjectsTex = "_DefaultDrawObjects";
        private const string k_SolidDrawObjectsTex = "_SolidDrawObjects";
        private const string k_BlurTex = "_BlurTex";
        private const string k_MainText = "_MainTex";
        private const string k_TempTex = "_TempTex";
        #endregion Texture Consts

        #region Shader Fields
        private readonly int m_ColourID = Shader.PropertyToID("_Color");
        private readonly int m_AlphaID = Shader.PropertyToID("_Alpha");

        private readonly int m_BlurResolution = Shader.PropertyToID("_BlurResolution");
        private readonly int m_BlurRadius = Shader.PropertyToID("_BlurRadius");
        private readonly int m_BlurDirectionX = Shader.PropertyToID("_BlurDirectionX");
        private readonly int m_BlurDirectionY = Shader.PropertyToID("_BlurDirectionY");
        #endregion Shader Fields

        #region Render Texture IDs
        private readonly int m_DefaultDrawObjects = Shader.PropertyToID(k_DefaultDrawObjectsTex);
        private readonly int m_SolidDrawObjects = Shader.PropertyToID(k_SolidDrawObjectsTex);
        private readonly int m_BlurPassRenderTexID = Shader.PropertyToID(k_BlurTex);
        private readonly int m_TempRenderTexID = Shader.PropertyToID(k_TempTex);
        #endregion

        private Camera m_Camera;
        private IList<Outline2> m_Renderers;
        private Material m_SolidUnlitMaterial;
        private Material m_BlurMaterial;
        
        /// <summary>
        /// The uniform Blur texture size, calculated from the current screen size
        /// </summary>
        private int m_BlurRes;
        
        /// <summary>
        /// Effects how far off centre each Blur sample becomes
        /// </summary>
        private float m_BlurRad = 1.0f;

        /// <summary>
        /// The number of Blur passes performed.
        /// This effects ALL objects rendered
        /// </summary>
        private int m_BlurPasses = 1;

        /// <summary>
        /// Used in DrawObjectsXYZ. We use this in conjunction with GetSharedMaterials.
        /// Avoids GC alloc from .sharedMaterials
        /// </summary>
        private readonly List<Material> m_SharedMaterials = new List<Material>();

        /// <summary>
        /// Used to Get and Store the each Outline instances Color
        /// </summary>
        private Color m_OutlineColour = new Color(1,1,1,1);


        /// <summary>
        /// Occluders shader tags list
        /// </summary>
        private List<ShaderTagId> m_ShaderTagsList = new List<ShaderTagId>();

        /// <summary>
        /// Filter settings for occluders rendering 
        /// </summary>
        private FilteringSettings m_FilteringSettings;

        /// <summary>
        /// Material used to render the occluders
        /// </summary>
        private Material m_OccludersOverrideMaterial;

#if UNITY_EDITOR
        private readonly HashSet<Outline2> m_EditorLoggedNullMaterialOutlines = new HashSet<Outline2>();
        private readonly HashSet<Renderer> m_EditorLoggedNullMaterialRenderers = new HashSet<Renderer>();
#endif

        public OutlineScriptableRenderPass(Material solidUnlitMaterial, Material blurMaterial, Material occludersOverrideMaterial, LayerMask occludersMask)
        {
            m_BlurMaterial = blurMaterial;
            m_SolidUnlitMaterial = solidUnlitMaterial;
            m_OccludersOverrideMaterial = occludersOverrideMaterial;

            // Initialise occluders related properties
            m_ShaderTagsList.Add(new ShaderTagId("SRPDefaultUnlit"));
            m_ShaderTagsList.Add(new ShaderTagId("UniversalForward"));
            m_ShaderTagsList.Add(new ShaderTagId("UniversalForwardOnly"));
            m_ShaderTagsList.Add(new ShaderTagId("ForwardLit"));

            m_FilteringSettings = new FilteringSettings(RenderQueueRange.opaque, occludersMask);
        }

        public void Setup(RenderPassEvent whenToRender, Camera camera, IList<Outline2> renderers, int blurPasses,
            float blurRadius, int blurTextureSize)
        {
            renderPassEvent = whenToRender;
            m_Renderers = renderers;
            m_Camera = camera;
            m_BlurPasses = blurPasses;
            m_BlurRad = blurRadius;
            m_BlurRes = blurTextureSize;
        }

        public override void Configure(CommandBuffer cmd, RenderTextureDescriptor cameraTextureDescriptor)
        {
            //
            // Attempt to make RTs for XR, otherwise use Default Settings
            //
            if (!ConfigureTemporaryRenderTexturesForXR(in cmd)) ConfigureTemporaryRenderTextures(in cmd);
        }

        public override void OnCameraSetup(CommandBuffer cmd, ref RenderingData renderingData)
        {
            ConfigureTarget(m_SolidDrawObjects);
            ConfigureClear(ClearFlag.All, Color.clear);
        }

        /// <summary>
        /// Execute the pass. This is where custom rendering occurs. Specific details are left to the implementation
        /// </summary>
        public override void Execute(ScriptableRenderContext context, ref RenderingData renderingData)
        {
            //
            // Always make sure we reset, this is the begining of a new Outline process
            //
            OutlineCollection.NumberOfObjectsRendered = 0;

            var cmd = CommandBufferPool.Get(k_ProfilerIdent);
            cmd.Clear();

            //
            // First render objects using their default materials
            //
            DrawObjectsDefault(cmd);

            //
            // OutlineCollection.NumberOfObjectsRendered is incremented 
            // inside DrawObjectsDefault. If it's 0 we rendered nothing. 
            //
            if (OutlineCollection.NumberOfObjectsRendered > 0)
            {
                DrawOccluders(context, ref renderingData);
                DrawObjectsSolid(cmd);
                cmd.SetGlobalFloat(m_BlurResolution, m_BlurRes);
                cmd.SetGlobalFloat(m_BlurRadius, m_BlurRad);
                DrawBlur(in cmd);
                context.ExecuteCommandBuffer(cmd);
            }

            cmd.Clear();
            CommandBufferPool.Release(cmd);
        }

        /// <summary>
        /// Draw outlines occluders
        /// </summary>
        private void DrawOccluders(ScriptableRenderContext context, ref RenderingData renderingData)
        {
            // Draw the occluders into m_SolidDrawObjects
            // This pass will fill in the depth buffer so that the outlines could get occluded by the soldiers or other occluders as needed
            DrawingSettings drawingSettings = CreateDrawingSettings(m_ShaderTagsList, ref renderingData, renderingData.cameraData.defaultOpaqueSortFlags);

            drawingSettings.overrideMaterial = m_OccludersOverrideMaterial;
            context.DrawRenderers(renderingData.cullResults, ref drawingSettings, ref m_FilteringSettings);
        }

        /// <summary>
        /// Draw all objects using their default material/s
        /// </summary>
        private void DrawObjectsDefault(in CommandBuffer commandBuffer)
        {
            CoreUtils.SetRenderTarget(commandBuffer, m_DefaultDrawObjects, ClearFlag.All, Color.clear);
            commandBuffer.ClearRenderTarget(true, true, Color.clear);

            for (int i = 0, counti = m_Renderers.Count; i < counti; ++i)
            {
                var outline = m_Renderers[i];

                // 
                // Don't waste time drawing objects which are currently invisible
                //
                if (outline.Alpha <= 0) continue;

                ++OutlineCollection.NumberOfObjectsRendered;
                
                var outlineRenderers = outline.Renderers;
                for (int j = 0; j < outlineRenderers.Length; j++)
                {
                    var renderer = outlineRenderers[j];
                    if (renderer == null) continue;
                    m_SharedMaterials.Clear();
                    renderer.GetSharedMaterials(m_SharedMaterials);

                    if (m_SharedMaterials.Count > 0)
                    {
                        for (int m = 0, countm = m_SharedMaterials.Count; m < countm; ++m)
                        {
                            if (m_SharedMaterials[m] == null)
                            {
#if UNITY_EDITOR
                                if (!m_EditorLoggedNullMaterialOutlines.Contains(outline))
                                {
                                    Debug.LogErrorFormat(outline, "Outline {0} has a renderer {1} with null material", outline.name, renderer.name);
                                    m_EditorLoggedNullMaterialOutlines.Add(outline);
                                }
                                if (!m_EditorLoggedNullMaterialRenderers.Contains(renderer))
                                {
                                    Debug.LogErrorFormat(outline, "Outline {0} has a renderer {1} with null material", outline.name, renderer.name);
                                    m_EditorLoggedNullMaterialRenderers.Add(renderer);
                                }
#endif
                                continue;
                            }
                            commandBuffer.DrawRenderer(renderer, m_SharedMaterials[m], m, 0);
                        }
                    }
                    else
                    {
                        commandBuffer.DrawRenderer(renderer, renderer.material);
                    }

                }
            }
        }

        /// <summary>
        /// Draw all objects using the special Solid Unlit shader
        /// </summary>
        private void DrawObjectsSolid(in CommandBuffer commandBuffer)
        {
            CoreUtils.SetRenderTarget(commandBuffer, m_SolidDrawObjects, ClearFlag.None, Color.clear);
            //commandBuffer.ClearRenderTarget(true, true, Color.clear);

            for (int i = 0, counti = m_Renderers.Count; i < counti; ++i)
            {
                var outline = m_Renderers[i];
                if (outline.Alpha <= 0) continue;
                
                outline.GetColour(out m_OutlineColour);
                commandBuffer.SetGlobalColor(m_ColourID, m_OutlineColour);
                commandBuffer.SetGlobalFloat(m_AlphaID, outline.Alpha);
                
                var outlineRenderers = outline.Renderers;
                for (int j = 0; j < outlineRenderers.Length; ++j)
                {
                    var renderer = outlineRenderers[j];
                    if (renderer == null) continue;
                    m_SharedMaterials.Clear();
                    renderer.GetSharedMaterials(m_SharedMaterials);
                    
                    if (m_SharedMaterials.Count > 0)
                    {
                        for (int m = 0, countm = m_SharedMaterials.Count; m < countm; ++m)
                        {
                            commandBuffer.DrawRenderer(renderer, m_SolidUnlitMaterial, m, 0);
                        }
                    }
                    else
                    {
                        commandBuffer.DrawRenderer(renderer, m_SolidUnlitMaterial);
                    }
                }
            }
        }

        /// <summary>
        /// Creates the Blur mask RT. Blur the Outline objects
        /// </summary>
        private void DrawBlur(in CommandBuffer commandBuffer)
        {
            commandBuffer.Blit(m_SolidDrawObjects, m_BlurPassRenderTexID);

            for (int i = 0, counti = m_BlurPasses; i < counti; ++i)
            {
                commandBuffer.SetGlobalFloat(m_BlurDirectionX, 0);
                commandBuffer.SetGlobalFloat(m_BlurDirectionY, 1);

                commandBuffer.SetGlobalTexture(k_MainText, m_BlurPassRenderTexID);
                commandBuffer.Blit(m_BlurPassRenderTexID, m_TempRenderTexID,
                    m_BlurMaterial, 0);

                commandBuffer.SetGlobalFloat(m_BlurDirectionX, 1);
                commandBuffer.SetGlobalFloat(m_BlurDirectionY, 0);

                commandBuffer.SetGlobalTexture(k_MainText, m_TempRenderTexID);
                commandBuffer.Blit(m_TempRenderTexID, m_BlurPassRenderTexID,
                    m_BlurMaterial, 0);
            }
        }

        /// <summary>
        /// Configure Temporary RTs for XR
        /// Relies on ENABLE_VR 
        /// </summary>
        /// <param name="cmd">SRF CommandBuffer</param>
        /// <returns>True if RTs were setup using XRSettings, Otherwise False.</returns>
        private bool ConfigureTemporaryRenderTexturesForXR(in CommandBuffer cmd)
        {
            #if ENABLE_VR 
            if (!XRSettings.enabled) return false;
            var renderTextureDescriptor = XRSettings.eyeTextureDesc;
            cmd.GetTemporaryRT(m_DefaultDrawObjects, renderTextureDescriptor, FilterMode.Bilinear);
            cmd.GetTemporaryRT(m_SolidDrawObjects, renderTextureDescriptor, FilterMode.Bilinear);

            renderTextureDescriptor.depthBufferBits = 0;

            renderTextureDescriptor.width = renderTextureDescriptor.height = m_BlurRes;

            cmd.GetTemporaryRT(m_BlurPassRenderTexID, renderTextureDescriptor, FilterMode.Bilinear);
            cmd.GetTemporaryRT(m_TempRenderTexID, renderTextureDescriptor, FilterMode.Bilinear);
            return true;
            #endif
            return false;
        }

        /// <summary>
        /// Configure Temporary RTs for SRF.
        /// </summary>
        /// <param name="cmd">SRF CommandBuffer</param>
        private void ConfigureTemporaryRenderTextures(in CommandBuffer cmd)
        {
            var width = m_Camera.scaledPixelWidth;
            var height = m_Camera.scaledPixelHeight;
            
            var aa = Mathf.Max(1, QualitySettings.antiAliasing);

            //
            // We can't really down sample the Solid Render. This is the render of the 
            //
            cmd.GetTemporaryRT(m_DefaultDrawObjects, width, height, 24, FilterMode.Bilinear,
                RenderTextureFormat.ARGB32, RenderTextureReadWrite.Default, aa);

            cmd.GetTemporaryRT(m_SolidDrawObjects, width >> 1, height >> 1, 24,
            FilterMode.Bilinear, RenderTextureFormat.ARGB32, RenderTextureReadWrite.Default,aa);
                
            cmd.GetTemporaryRT(m_BlurPassRenderTexID, m_BlurRes, m_BlurRes, 0, FilterMode.Bilinear);
            cmd.GetTemporaryRT(m_TempRenderTexID, m_BlurRes, m_BlurRes, 0, FilterMode.Bilinear);
        }
    }
}