using UnityEngine.Rendering;

namespace UnityEngine.Experimental.Rendering.LightweightPipeline
{
    public class RenderTransparentForwardPass : ScriptableRenderPass
    {
        const string k_RenderTransparentsTag = "Render Transparents";

        FilterRenderersSettings m_TransparentFilterSettings;

        RenderTargetHandle colorAttachmentHandle { get; set; }
        RenderTargetHandle depthAttachmentHandle { get; set; }
        RenderTextureDescriptor descriptor { get; set; }
        RendererConfiguration rendererConfiguration;

        public RenderTransparentForwardPass()
        {
            RegisterShaderPassName("LightweightForward");
            RegisterShaderPassName("SRPDefaultUnlit");

            m_TransparentFilterSettings = new FilterRenderersSettings(true)
            {
                renderQueueRange = RenderQueueRange.transparent,
            };
        }

        public void Setup(
            RenderTextureDescriptor baseDescriptor,
            RenderTargetHandle colorAttachmentHandle,
            RenderTargetHandle depthAttachmentHandle,
            RendererConfiguration configuration)
        {
            this.colorAttachmentHandle = colorAttachmentHandle;
            this.depthAttachmentHandle = depthAttachmentHandle;
            descriptor = baseDescriptor;
            rendererConfiguration = configuration;
        }

        public override void Execute(ScriptableRenderer renderer, ScriptableRenderContext context, ref RenderingData renderingData)
        {
            CommandBuffer cmd = CommandBufferPool.Get(k_RenderTransparentsTag);
            using (new ProfilingSample(cmd, k_RenderTransparentsTag))
            {
                RenderBufferLoadAction loadOp = RenderBufferLoadAction.Load;
                RenderBufferStoreAction storeOp = RenderBufferStoreAction.Store;
                SetRenderTarget(cmd, colorAttachmentHandle.Identifier(), loadOp, storeOp,
                    depthAttachmentHandle.Identifier(), loadOp, storeOp, ClearFlag.None, Color.black, descriptor.dimension);

                context.ExecuteCommandBuffer(cmd);
                cmd.Clear();

                Camera camera = renderingData.cameraData.camera;
                var drawSettings = CreateDrawRendererSettings(camera, SortFlags.CommonTransparent, rendererConfiguration, renderingData.supportsDynamicBatching);
                context.DrawRenderers(renderingData.cullResults.visibleRenderers, ref drawSettings, m_TransparentFilterSettings);

                // Render objects that did not match any shader pass with error shader
                renderer.RenderObjectsWithError(context, ref renderingData.cullResults, camera, m_TransparentFilterSettings, SortFlags.None);
            }

            context.ExecuteCommandBuffer(cmd);
            CommandBufferPool.Release(cmd);
        }
    }
}