using System;
using UnityEngine.Rendering.RenderGraphModule;

// cleanup code
// listMinDepth and maxDepth should be stored in a different uniform block?
// Point lights stored as vec4
// RelLightIndices should be stored in ushort instead of uint.
// TODO use Unity.Mathematics
// TODO Check if there is a bitarray structure (with dynamic size) available in Unity

namespace UnityEngine.Rendering.Universal.Internal
{
    // Render all tiled-based deferred lights.
    internal class DeferredPass : ScriptableRenderPass
    {
        DeferredLights m_DeferredLights;

        public DeferredPass(RenderPassEvent evt, DeferredLights deferredLights)
        {
            profilingSampler = new ProfilingSampler("Render Deferred Lighting");
            base.renderPassEvent = evt;
            m_DeferredLights = deferredLights;
        }

        private class PassData
        {
            internal UniversalCameraData cameraData;
            internal UniversalLightData lightData;
            internal UniversalShadowData shadowData;

            internal TextureHandle[] gbuffer;
            internal DeferredLights deferredLights;
        }

        public override void RecordRenderGraph(RenderGraph renderGraph, ContextContainer frameData)
        {
            var cameraData = frameData.Get<UniversalCameraData>();
            var resourceData = frameData.Get<UniversalResourceData>();
            var lightData = frameData.Get<UniversalLightData>();
            var shadowData = frameData.Get<UniversalShadowData>();

            var color = resourceData.activeColorTexture;
            var depth = resourceData.activeDepthTexture;
            var gbuffer = resourceData.gBuffer;

            using (var builder = renderGraph.AddRasterRenderPass<PassData>(passName, out var passData, profilingSampler))
            {
                passData.cameraData = cameraData;
                passData.lightData = lightData;
                passData.shadowData = shadowData;

                builder.SetRenderAttachment(color, 0, AccessFlags.Write);
                builder.SetRenderAttachmentDepth(depth, AccessFlags.ReadWrite);
                passData.deferredLights = m_DeferredLights;

                for (int i = 0, idx = 0; i < gbuffer.Length; ++i)
                {
                    if (i == m_DeferredLights.GBufferLightingIndex)
                        continue;

                    builder.SetInputAttachment(gbuffer[i], idx++); 
                }

                builder.AllowGlobalStateModification(true);

                builder.SetRenderFunc(static (PassData data, RasterGraphContext context) =>
                {
                    data.deferredLights.ExecuteDeferredPass(context.cmd, data.cameraData, data.lightData, data.shadowData, data.gbuffer);
                });
            }
        }

        // ScriptableRenderPass
        public override void OnCameraCleanup(CommandBuffer cmd)
        {
            m_DeferredLights.OnCameraCleanup(cmd);
        }
    }
}