using System;
using XCEngine;
using XCEngine.Rendering;

namespace XCEngine.Rendering.Universal
{
    public abstract class RendererBackedRenderPipelineAsset
        : ScriptableRenderPipelineAsset
    {
        public ScriptableRendererData[] rendererDataList =
            Array.Empty<ScriptableRendererData>();
        public int defaultRendererIndex = 0;
        private int m_rendererDataRuntimeStateHash;
        private bool m_rendererDataRuntimeStateHashResolved;

        protected RendererBackedRenderPipelineAsset()
        {
        }

        protected override ScriptableRenderPipeline CreatePipeline()
        {
            return CreateRendererBackedPipeline();
        }

        protected override void ConfigureCameraRenderRequest(
            CameraRenderRequestContext context)
        {
            ConfigureRendererCameraRequest(
                new RendererCameraRequestContext(context));

            ScriptableRendererData resolvedRendererData =
                ResolveSelectedRendererData();
            if (resolvedRendererData != null)
            {
                resolvedRendererData
                    .ConfigureCameraRenderRequestInstance(
                        context);
            }
        }

        protected override void ConfigureCameraFramePlan(
            ScriptableRenderPipelinePlanningContext context)
        {
            ScriptableRendererData resolvedRendererData =
                ResolveSelectedRendererData();
            if (resolvedRendererData != null)
            {
                resolvedRendererData
                    .ConfigureCameraFramePlanInstance(
                        context);
            }
        }

        protected override string GetPipelineRendererAssetKey()
        {
            ScriptableRendererData resolvedRendererData =
                ResolveSelectedRendererData();
            return resolvedRendererData != null
                ? resolvedRendererData
                    .GetPipelineRendererAssetKeyInstance()
                : string.Empty;
        }

        protected override void ReleaseRuntimeResources()
        {
            ReleaseRendererDataRuntimeResources();
        }

        protected override void SynchronizeRuntimeResourceVersion()
        {
            int runtimeStateHash =
                ComputeRendererDataRuntimeStateHash();
            if (!m_rendererDataRuntimeStateHashResolved)
            {
                m_rendererDataRuntimeStateHash =
                    runtimeStateHash;
                m_rendererDataRuntimeStateHashResolved = true;
                return;
            }

            if (runtimeStateHash ==
                m_rendererDataRuntimeStateHash)
            {
                return;
            }

            m_rendererDataRuntimeStateHash =
                runtimeStateHash;
            SetDirty();
        }

        protected virtual ScriptableRenderPipeline
        CreateRendererBackedPipeline()
        {
            return new RendererBackedRenderPipeline(this);
        }

        protected virtual void ConfigureRendererCameraRequest(
            RendererCameraRequestContext context)
        {
        }

        protected virtual ScriptableRendererData
        CreateDefaultRendererData()
        {
            return null;
        }

        internal ScriptableRendererData GetDefaultRendererData()
        {
            return ResolveSelectedRendererData();
        }

        internal ScriptableRenderer GetDefaultRenderer()
        {
            return ResolveSelectedRenderer();
        }

        internal ScriptableRendererData ResolveSelectedRendererData()
        {
            return ResolveRendererDataByResolvedIndex(
                ResolveSelectedRendererIndex());
        }

        internal ScriptableRenderer ResolveSelectedRenderer()
        {
            ScriptableRendererData rendererData =
                ResolveSelectedRendererData();
            return rendererData != null
                ? rendererData.GetRendererInstance()
                : null;
        }

        internal ScriptableRendererData GetRendererData(
            int rendererIndex)
        {
            return ResolveRendererDataByResolvedIndex(
                ResolveRendererIndex(rendererIndex));
        }

        internal ScriptableRenderer GetRenderer(
            int rendererIndex)
        {
            ScriptableRendererData rendererData =
                GetRendererData(rendererIndex);
            return rendererData != null
                ? rendererData.GetRendererInstance()
                : null;
        }

        protected internal void ReleaseRendererDataRuntimeResources()
        {
            EnsureRendererDataList();

            for (int i = 0; i < rendererDataList.Length; ++i)
            {
                ScriptableRendererData rendererData =
                    rendererDataList[i];
                if (rendererData == null ||
                    WasRendererDataReleasedEarlier(i))
                {
                    continue;
                }

                rendererData.ReleaseRuntimeResourcesInstance();
            }
        }

        private void EnsureRendererDataList()
        {
            if (rendererDataList != null &&
                rendererDataList.Length > 0)
            {
                return;
            }

            ScriptableRendererData defaultRendererData =
                CreateDefaultRendererData();
            rendererDataList =
                defaultRendererData != null
                    ? new ScriptableRendererData[]
                    {
                        defaultRendererData
                    }
                    : Array.Empty<ScriptableRendererData>();
            defaultRendererIndex = 0;
        }

        private bool WasRendererDataReleasedEarlier(
            int rendererDataIndex)
        {
            ScriptableRendererData rendererData =
                rendererDataList[rendererDataIndex];
            for (int i = 0; i < rendererDataIndex; ++i)
            {
                if (object.ReferenceEquals(
                        rendererDataList[i],
                        rendererData))
                {
                    return true;
                }
            }

            return false;
        }

        private int ComputeRendererDataRuntimeStateHash()
        {
            unchecked
            {
                int hash = 17;
                hash =
                    (hash * 31) +
                    ResolveSelectedRendererIndex();
                if (rendererDataList == null)
                {
                    return hash;
                }

                hash = (hash * 31) + rendererDataList.Length;
                for (int i = 0; i < rendererDataList.Length; ++i)
                {
                    ScriptableRendererData rendererData =
                        rendererDataList[i];
                    if (rendererData != null)
                    {
                        hash =
                            (hash * 31) +
                            rendererData
                                .GetRuntimeStateVersionInstance();
                    }
                }

                return hash;
            }
        }

        private ScriptableRendererData ResolveRendererDataByResolvedIndex(
            int resolvedRendererIndex)
        {
            EnsureRendererDataList();
            if (resolvedRendererIndex < 0)
            {
                return null;
            }

            if (rendererDataList[resolvedRendererIndex] == null)
            {
                rendererDataList[resolvedRendererIndex] =
                    CreateDefaultRendererData();
            }

            return rendererDataList[resolvedRendererIndex];
        }

        private int ResolveSelectedRendererIndex()
        {
            return ResolveRendererIndex(defaultRendererIndex);
        }

        private int ResolveRendererIndex(
            int rendererIndex)
        {
            EnsureRendererDataList();
            if (rendererDataList.Length == 0)
            {
                return -1;
            }

            if (rendererIndex < 0 ||
                rendererIndex >= rendererDataList.Length)
            {
                return ResolveDefaultRendererIndex();
            }

            return rendererIndex;
        }

        private int ResolveDefaultRendererIndex()
        {
            EnsureRendererDataList();
            if (rendererDataList.Length == 0)
            {
                return -1;
            }

            if (defaultRendererIndex < 0 ||
                defaultRendererIndex >= rendererDataList.Length)
            {
                defaultRendererIndex = 0;
            }

            return defaultRendererIndex;
        }
    }
}