/*
Crafter®.Graphics
Copyright (C) 2025 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 as published by the Free Software Foundation; either
version 3.0 of the License, or (at your option) any later version.

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;

#include <cstdint>
#include <vulkan/vulkan.h>
#include <cstring>
#include <iostream>
#include <cmath>
#include "../../lib/VulkanInitializers.hpp"

export module Crafter.Graphics:MeshShader;
import :Mesh;
import :Camera;
import :VulkanPipeline;
import :DescriptorSet;
import Crafter.Math;

namespace Crafter {
    /**
    * @brief Shader for rendering indexed meshes
    * @tparam VertexType The vertex type to use that is internally stored, this must match the type the glsl shader expects.
    */
    export template <typename VertexType>
    class MeshShader {
    public:
        MatrixRowMajor<float, 4, 4, 1> transform;
        Mesh<VertexType>* mesh;
        Camera* camera;
        Buffer<MatrixRowMajor<float, 4, 4, 1>> mvp;
        std::uint32_t threadCount;
    private:
        EventListener<void> cameraUpdate;
    public:
        /**
        * @brief Constructs the MeshShader with a mesh. 
        * The Model-View-Projection (MVP) matrix and the transform matrix are initialized to the identity matrix.
        * 
        * @param mesh Pointer to the mesh to use. The mesh must remain valid for the lifetime of this object.
        */
        MeshShader(Mesh<VertexType>* mesh) : threadCount(std::ceil(static_cast<double>(mesh->indexCount)/64/3)), mvp(VK_BUFFER_USAGE_UNIFORM_BUFFER_BIT, VK_MEMORY_PROPERTY_HOST_VISIBLE_BIT | VK_MEMORY_PROPERTY_HOST_COHERENT_BIT), mesh(mesh), camera(nullptr) {
            transform = MatrixRowMajor<float, 4, 4, 1>::Identity();
            *mvp.value = MatrixRowMajor<float, 4, 4, 1>::Identity();
        }
        /**
        * @brief Constructs the MeshShader with a mesh. 
        * The transform is initialized to identity, the transform is initialized to identity and the mvp to the camera's projectionView.
        * 
        * @param mesh Pointer to the mesh to use. The mesh must remain valid for the lifetime of this object.
        * @param mesh Pointer to the camera to use. The camera must remain valid for the lifetime of this object.
        */
        MeshShader(Mesh<VertexType>* mesh, Camera* camera) : threadCount(std::ceil(static_cast<double>(mesh->indexCount)/64/3)), mvp(VK_BUFFER_USAGE_UNIFORM_BUFFER_BIT, VK_MEMORY_PROPERTY_HOST_VISIBLE_BIT | VK_MEMORY_PROPERTY_HOST_COHERENT_BIT), mesh(mesh), camera(camera), cameraUpdate(
            &camera->onUpdate, [this](){
                Update();
            }
        ) {
            transform = MatrixRowMajor<float, 4, 4, 1>::Identity();
            *mvp.value = camera->projectionView;
        }
        /**
        * @brief Writes this class's 3 descriptors to the set, this method must be called before rendering with this shader.
        * Slot 0 mvp: VK_DESCRIPTOR_TYPE_UNIFORM_BUFFER.
        * Slot 1 vertex: VK_DESCRIPTOR_TYPE_UNIFORM_BUFFER.
        * Slot 2 index: VK_DESCRIPTOR_TYPE_UNIFORM_BUFFER.
        */
        void WriteDescriptors(VkDescriptorSet set) {
            VkWriteDescriptorSet write[3] = {
                vks::initializers::writeDescriptorSet(set, VK_DESCRIPTOR_TYPE_UNIFORM_BUFFER, 0, &mvp.descriptor),
                vks::initializers::writeDescriptorSet(set, VK_DESCRIPTOR_TYPE_STORAGE_BUFFER, 1, &mesh->verticies.descriptor),
                vks::initializers::writeDescriptorSet(set, VK_DESCRIPTOR_TYPE_STORAGE_BUFFER, 2, &mesh->indicies.descriptor)
            };
            vkUpdateDescriptorSets(VulkanDevice::device, 3, &write[0], 0, nullptr);
        }
        /**
        * @brief Must be called after every update to the camera or this transform
        */
        void Update() {
            *mvp.value = camera->projectionView*transform;
        }
    };
}