/*
Crafter®.Graphics
Copyright (C) 2026 Catcrafts®
catcrafts.net

This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License version 3.0 as published by the Free Software Foundation;

This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.

You should have received a copy of the GNU Lesser General Public
License along with this library; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301 USA
*/
module;
#ifndef CRAFTER_GRAPHICS_WINDOW_DOM
#include "vulkan/vulkan.h"
#endif // !CRAFTER_GRAPHICS_WINDOW_DOM
export module Crafter.Graphics:ComputeShader;
#ifndef CRAFTER_GRAPHICS_WINDOW_DOM
import std;
import :Device;

export namespace Crafter {
    // Tier 1: thin compute-pipeline wrapper. Owns one VkPipeline created with
    // VK_PIPELINE_CREATE_2_DESCRIPTOR_HEAP_BIT_EXT (no pipeline layout — the
    // bindless heap supplies all bindings, push constants travel via
    // vkCmdPushDataEXT). Use this to dispatch the four standard UI shaders
    // and any user-authored compute shader that follows the ui-shared.glsl
    // contract.
    class ComputeShader {
    public:
        VkPipeline pipeline = VK_NULL_HANDLE;

        // NVIDIA descriptor-heap AS-read workaround (issue #15 / #7): set by
        // Load when this shader ray-queries the TLAS through the descriptor
        // heap and was rewritten to read its device address from a push
        // constant. `workaroundTlasPushOffset` is the byte offset of that member
        // (after the caller's own push payload, or 0 if the shader had none).
        // Tracked per-shader — a global is clobbered by whichever shader was
        // patched last. Both inert (false/0) on every other driver.
        bool workaroundNeedsTlas = false;
        std::uint32_t workaroundTlasPushOffset = 0;

        ComputeShader() = default;
        ComputeShader(const ComputeShader&) = delete;
        ComputeShader& operator=(const ComputeShader&) = delete;
        ComputeShader(ComputeShader&& other) noexcept;
        ComputeShader& operator=(ComputeShader&& other) noexcept;
        ~ComputeShader();

        // Loads a SPIR-V compute shader from disk and creates a pipeline that
        // uses the bindless descriptor-heap binding model.
        void Load(const std::filesystem::path& spvPath);

        // Bind, push constants (if any), dispatch. Caller computes group counts
        // and is responsible for any inter-dispatch barriers (UIRenderer::Dispatch
        // wraps this with the standard write-after-write barrier).
        //
        // tlasAddress is the NVIDIA descriptor-heap AS-read workaround hook
        // (issue #15 / #7): a shader that ray-queries the TLAS through the
        // descriptor heap is rewritten to read its device address from a push
        // constant, so the caller must supply the active frame's TLAS address
        // (RenderingElement3D::tlases[frameIdx].address) here. It is pushed at
        // the shader's workaroundTlasPushOffset only when the shader was
        // rewritten (workaroundNeedsTlas) — ignored otherwise and on every
        // other driver, so shaders that don't touch an AS pass nothing.
        void Dispatch(VkCommandBuffer cmd,
                      const void* push, std::uint32_t pushBytes,
                      std::uint32_t gx,
                      std::uint32_t gy = 1,
                      std::uint32_t gz = 1,
                      VkDeviceAddress tlasAddress = 0) const;
    };
}
#endif // !CRAFTER_GRAPHICS_WINDOW_DOM
