#include "hk_model.hpp"

#include <cassert>
#include <cstring>

namespace hk{
    Model::Model(Device &device, const Builder &builder)
        : m_device{device}
    {
        createVertexBuffers(builder.vertices);
        createIndexBuffers(builder.indices);
    }

    Model::~Model()
    {
        vkDestroyBuffer(m_device.device(), m_vertexBuffer, nullptr);
        vkFreeMemory(m_device.device(), m_vertexBufferMemory, nullptr);
        vkDestroyBuffer(m_device.device(), m_indexBuffer, nullptr);
        vkFreeMemory(m_device.device(), m_indexBufferMemory, nullptr);
    }

    void Model::createVertexBuffers(const std::vector<Vertex> &vertices)
    {
        m_vertexCount = static_cast<uint32_t>(vertices.size());
        assert(m_vertexCount >= 3 && "Vertex count must be at least 3");
        VkDeviceSize bufferSize = sizeof(vertices[0]) * m_vertexCount;

        VkBuffer stagingBuffer;
        VkDeviceMemory stagingBufferMemory;
        m_device.createBuffer(
            bufferSize,
            VK_BUFFER_USAGE_TRANSFER_SRC_BIT,
            VK_MEMORY_PROPERTY_HOST_VISIBLE_BIT | VK_MEMORY_PROPERTY_HOST_COHERENT_BIT,
            stagingBuffer,
            stagingBufferMemory
        );
        void *data;
        vkMapMemory(m_device.device(), stagingBufferMemory, 0, bufferSize, 0, &data);
        memcpy(data, vertices.data(), static_cast<size_t>(bufferSize));
        vkUnmapMemory(m_device.device(), stagingBufferMemory);

        m_device.createBuffer(
            bufferSize,
            VK_BUFFER_USAGE_VERTEX_BUFFER_BIT | VK_BUFFER_USAGE_TRANSFER_DST_BIT,
            VK_MEMORY_PROPERTY_DEVICE_LOCAL_BIT,
            m_vertexBuffer,
            m_vertexBufferMemory
        );
        m_device.copyBuffer(stagingBuffer, m_vertexBuffer, bufferSize);

        vkDestroyBuffer(m_device.device(), stagingBuffer, nullptr);
        vkFreeMemory(m_device.device(), stagingBufferMemory, nullptr);
    }

    void Model::createIndexBuffers(const std::vector<uint32_t> &indices)
    {
        m_indexCount = static_cast<uint32_t>(indices.size());
        m_hasIndexBuffer = m_indexCount > 0;
        
        if (!m_hasIndexBuffer)
            return;

        VkDeviceSize bufferSize = sizeof(indices[0]) * m_indexCount;

        VkBuffer stagingBuffer;
        VkDeviceMemory stagingBufferMemory;
        m_device.createBuffer(
            bufferSize,
            VK_BUFFER_USAGE_TRANSFER_SRC_BIT,
            VK_MEMORY_PROPERTY_HOST_VISIBLE_BIT | VK_MEMORY_PROPERTY_HOST_COHERENT_BIT,
            stagingBuffer,
            stagingBufferMemory
        );
        void *data;
        vkMapMemory(m_device.device(), stagingBufferMemory, 0, bufferSize, 0, &data);
        memcpy(data, indices.data(), static_cast<size_t>(bufferSize));
        vkUnmapMemory(m_device.device(), stagingBufferMemory);

        m_device.createBuffer(
            bufferSize,
            VK_BUFFER_USAGE_INDEX_BUFFER_BIT | VK_BUFFER_USAGE_TRANSFER_DST_BIT,
            VK_MEMORY_PROPERTY_DEVICE_LOCAL_BIT,
            m_indexBuffer,
            m_indexBufferMemory
        );
        m_device.copyBuffer(stagingBuffer, m_indexBuffer, bufferSize);

        vkDestroyBuffer(m_device.device(), stagingBuffer, nullptr);
        vkFreeMemory(m_device.device(), stagingBufferMemory, nullptr);
    }

    void Model::bind(VkCommandBuffer commandBuffer)
    {
        VkBuffer buffers[] = {m_vertexBuffer};
        VkDeviceSize offsets[] = {0};
        vkCmdBindVertexBuffers(commandBuffer, 0, 1, buffers, offsets);

        if (m_hasIndexBuffer)
        {
            vkCmdBindIndexBuffer(commandBuffer, m_indexBuffer, 0, VK_INDEX_TYPE_UINT32);
        }
    }
    void Model::draw(VkCommandBuffer commandBuffer)
    {
        if (m_hasIndexBuffer)
        {
            vkCmdDrawIndexed(commandBuffer, m_indexCount, 1, 0, 0, 0);
        }
        else
        {
            vkCmdDraw(commandBuffer, m_vertexCount, 1, 0, 0);
        }
    }

    std::vector<VkVertexInputBindingDescription> Model::Vertex::getBindingDescriptions()
    {
        std::vector<VkVertexInputBindingDescription> bindingDescriptions(1);
        bindingDescriptions[0].binding = 0;
        bindingDescriptions[0].stride = sizeof(Vertex);
        bindingDescriptions[0].inputRate = VK_VERTEX_INPUT_RATE_VERTEX;
        return bindingDescriptions;
    }
    std::vector<VkVertexInputAttributeDescription> Model::Vertex::getAttributeDescriptions()
    {
        std::vector<VkVertexInputAttributeDescription> attributeDescriptions(2);
        attributeDescriptions[0].binding = 0;
        attributeDescriptions[0].location = 0;
        attributeDescriptions[0].format = VK_FORMAT_R32G32B32_SFLOAT;
        attributeDescriptions[0].offset = offsetof(Vertex, position);

        attributeDescriptions[1].binding = 0;
        attributeDescriptions[1].location = 1;
        attributeDescriptions[1].format = VK_FORMAT_R32G32B32_SFLOAT;
        attributeDescriptions[1].offset = offsetof(Vertex, color);

        return attributeDescriptions;
    }
}