using System;
using System.Runtime.CompilerServices;
using XCEngine;
using XCEngine.Rendering;

namespace XCEngine.Rendering.Universal
{
    internal sealed class ScriptableRendererFeatureCollection
    {
        private readonly ScriptableRendererData m_owner;
        private ScriptableRendererFeature[] m_features;

        public ScriptableRendererFeatureCollection(
            ScriptableRendererData owner)
        {
            m_owner = owner;
            m_features = Array.Empty<ScriptableRendererFeature>();
        }

        public ScriptableRendererFeature[] GetFeatures(
            ref ScriptableRendererFeature[] configuredFeatures)
        {
            if (m_features == null)
            {
                ScriptableRendererFeature[] resolvedFeatures =
                    configuredFeatures ??
                    Array.Empty<ScriptableRendererFeature>();
                configuredFeatures = resolvedFeatures;
                m_features = resolvedFeatures;
            }

            BindOwners(m_features);
            return m_features;
        }

        public void Reset(
            ref ScriptableRendererFeature[] configuredFeatures,
            ScriptableRendererFeature[] features)
        {
            configuredFeatures =
                features ??
                Array.Empty<ScriptableRendererFeature>();
            m_features = configuredFeatures;
            BindOwners(m_features);
        }

        public void Invalidate(
            ref ScriptableRendererFeature[] configuredFeatures,
            ref int collectionHash,
            ref bool collectionHashResolved)
        {
            ScriptableRendererFeature[] features =
                ResolveConfiguredFeatures(
                    ref configuredFeatures);
            collectionHash =
                ComputeCollectionHash(features);
            collectionHashResolved = true;
        }

        public void Synchronize(
            ref ScriptableRendererFeature[] configuredFeatures,
            ref int collectionHash,
            ref bool collectionHashResolved,
            Action onChanged)
        {
            ScriptableRendererFeature[] features =
                ResolveConfiguredFeatures(
                    ref configuredFeatures);
            int resolvedHash =
                ComputeCollectionHash(features);
            if (!collectionHashResolved)
            {
                collectionHash = resolvedHash;
                collectionHashResolved = true;
                return;
            }

            if (resolvedHash == collectionHash)
            {
                return;
            }

            collectionHash = resolvedHash;
            onChanged?.Invoke();
        }

        public void ConfigureCameraRenderRequest(
            ref ScriptableRendererFeature[] configuredFeatures,
            CameraRenderRequestContext context)
        {
            ScriptableRendererFeature[] features =
                GetFeatures(ref configuredFeatures);
            for (int i = 0; i < features.Length; ++i)
            {
                ScriptableRendererFeature feature =
                    features[i];
                if (feature == null ||
                    !feature.isActive)
                {
                    continue;
                }

                feature.ConfigureCameraRenderRequest(
                    context);
            }
        }

        public void ConfigureCameraFramePlan(
            ref ScriptableRendererFeature[] configuredFeatures,
            ScriptableRenderPipelinePlanningContext context)
        {
            ScriptableRendererFeature[] features =
                GetFeatures(ref configuredFeatures);
            for (int i = 0; i < features.Length; ++i)
            {
                ScriptableRendererFeature feature =
                    features[i];
                if (feature == null ||
                    !feature.isActive)
                {
                    continue;
                }

                feature.ConfigureCameraFramePlan(
                    context);
            }
        }

        public void ConfigureRenderSceneSetup(
            ref ScriptableRendererFeature[] configuredFeatures,
            RenderSceneSetupContext context)
        {
            ScriptableRendererFeature[] features =
                GetFeatures(ref configuredFeatures);
            for (int i = 0; i < features.Length; ++i)
            {
                ScriptableRendererFeature feature =
                    features[i];
                if (feature == null ||
                    !feature.isActive)
                {
                    continue;
                }

                feature.ConfigureRenderSceneSetup(
                    context);
            }
        }

        public void ConfigureDirectionalShadowExecutionState(
            ref ScriptableRendererFeature[] configuredFeatures,
            DirectionalShadowExecutionContext context)
        {
            ScriptableRendererFeature[] features =
                GetFeatures(ref configuredFeatures);
            for (int i = 0; i < features.Length; ++i)
            {
                ScriptableRendererFeature feature =
                    features[i];
                if (feature == null ||
                    !feature.isActive)
                {
                    continue;
                }

                feature
                    .ConfigureDirectionalShadowExecutionState(
                        context);
            }
        }

        public void ReleaseRuntimeResources()
        {
            if (m_features == null)
            {
                return;
            }

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

            m_features = null;
        }

        public void ResetResolvedCache()
        {
            m_features = null;
        }

        private ScriptableRendererFeature[] ResolveConfiguredFeatures(
            ref ScriptableRendererFeature[] configuredFeatures)
        {
            ScriptableRendererFeature[] features =
                configuredFeatures ??
                Array.Empty<ScriptableRendererFeature>();
            configuredFeatures = features;
            m_features = features;
            BindOwners(features);
            return features;
        }

        private void BindOwners(
            ScriptableRendererFeature[] features)
        {
            if (features == null)
            {
                return;
            }

            for (int i = 0; i < features.Length; ++i)
            {
                ScriptableRendererFeature feature =
                    features[i];
                if (feature != null)
                {
                    feature.BindOwnerInstance(m_owner);
                }
            }
        }

        private static int ComputeCollectionHash(
            ScriptableRendererFeature[] features)
        {
            unchecked
            {
                int hash = 17;
                if (features == null)
                {
                    return hash;
                }

                hash = (hash * 31) + features.Length;
                for (int i = 0; i < features.Length; ++i)
                {
                    ScriptableRendererFeature feature =
                        features[i];
                    if (feature == null)
                    {
                        hash = (hash * 31) + 1;
                        continue;
                    }

                    hash =
                        (hash * 31) +
                        RuntimeHelpers.GetHashCode(feature);
                    hash =
                        (hash * 31) +
                        feature.GetRuntimeStateVersionInstance();
                }

                return hash;
            }
        }
    }
}