#pragma once

#include <vulkan/vulkan.h>
#include <SDL.h>
#include <SDL_vulkan.h>
#include <imgui.h>
#include <backends/imgui_impl_sdl2.h>
#include <backends/imgui_impl_vulkan.h>
#include <iostream>
#include <vector>
#include <stdexcept>

class MinimalImGuiVulkan {
public:
    /* run application; borrows calling thread for event loop,
     * until application exit
     */
    void run();

private:
    /* create SDL window for application.
     * populates @ref window_
     */
    void init_sdl_window();

    /* setup vulkan state. swapchain, command buffers etc */
    void init_vulkan();

    /* create vulkan instance.
     * populates @ref instance_
     */
    void create_instance();

    /* create vulkan surface.
     * populates @ref surface_
     */
    void create_surface();

    /* choose physical device (1:1 with graphics card, presumably)
     * populates @ref physical_device_, @ref graphics_queue_family_
     */
    void pick_physical_device();

    /*
     * require: pick_physical_device() has run successfully
     * populates @ref device_, @ref graphics_queue_
     */
    void create_logical_device();

    /*
     * populates @ref swapchain_, @ref swapchain_images_
     */
    void create_swapchain();

    void create_image_views() {
        swapchainImageViews.resize(swapchain_images_.size());

        for (size_t i = 0; i < swapchain_images_.size(); i++) {
            VkImageViewCreateInfo createInfo{};
            createInfo.sType = VK_STRUCTURE_TYPE_IMAGE_VIEW_CREATE_INFO;
            createInfo.image = swapchain_images_[i];
            createInfo.viewType = VK_IMAGE_VIEW_TYPE_2D;
            createInfo.format = swapchain_image_format_;
            createInfo.components.r = VK_COMPONENT_SWIZZLE_IDENTITY;
            createInfo.components.g = VK_COMPONENT_SWIZZLE_IDENTITY;
            createInfo.components.b = VK_COMPONENT_SWIZZLE_IDENTITY;
            createInfo.components.a = VK_COMPONENT_SWIZZLE_IDENTITY;
            createInfo.subresourceRange.aspectMask = VK_IMAGE_ASPECT_COLOR_BIT;
            createInfo.subresourceRange.baseMipLevel = 0;
            createInfo.subresourceRange.levelCount = 1;
            createInfo.subresourceRange.baseArrayLayer = 0;
            createInfo.subresourceRange.layerCount = 1;

            if (vkCreateImageView(device_, &createInfo, nullptr, &swapchainImageViews[i]) != VK_SUCCESS) {
                throw std::runtime_error("Failed to create image views!");
            }
        }
    }

    void create_render_pass() {
        VkAttachmentDescription colorAttachment{};
        colorAttachment.format = swapchain_image_format_;
        colorAttachment.samples = VK_SAMPLE_COUNT_1_BIT;
        colorAttachment.loadOp = VK_ATTACHMENT_LOAD_OP_CLEAR;
        colorAttachment.storeOp = VK_ATTACHMENT_STORE_OP_STORE;
        colorAttachment.stencilLoadOp = VK_ATTACHMENT_LOAD_OP_DONT_CARE;
        colorAttachment.stencilStoreOp = VK_ATTACHMENT_STORE_OP_DONT_CARE;
        colorAttachment.initialLayout = VK_IMAGE_LAYOUT_UNDEFINED;
        colorAttachment.finalLayout = VK_IMAGE_LAYOUT_PRESENT_SRC_KHR;

        VkAttachmentReference colorAttachmentRef{};
        colorAttachmentRef.attachment = 0;
        colorAttachmentRef.layout = VK_IMAGE_LAYOUT_COLOR_ATTACHMENT_OPTIMAL;

        VkSubpassDescription subpass{};
        subpass.pipelineBindPoint = VK_PIPELINE_BIND_POINT_GRAPHICS;
        subpass.colorAttachmentCount = 1;
        subpass.pColorAttachments = &colorAttachmentRef;

        VkSubpassDependency dependency{};
        dependency.srcSubpass = VK_SUBPASS_EXTERNAL;
        dependency.dstSubpass = 0;
        dependency.srcStageMask = VK_PIPELINE_STAGE_COLOR_ATTACHMENT_OUTPUT_BIT;
        dependency.srcAccessMask = 0;
        dependency.dstStageMask = VK_PIPELINE_STAGE_COLOR_ATTACHMENT_OUTPUT_BIT;
        dependency.dstAccessMask = VK_ACCESS_COLOR_ATTACHMENT_WRITE_BIT;

        VkRenderPassCreateInfo renderPassInfo{};
        renderPassInfo.sType = VK_STRUCTURE_TYPE_RENDER_PASS_CREATE_INFO;
        renderPassInfo.attachmentCount = 1;
        renderPassInfo.pAttachments = &colorAttachment;
        renderPassInfo.subpassCount = 1;
        renderPassInfo.pSubpasses = &subpass;
        renderPassInfo.dependencyCount = 1;
        renderPassInfo.pDependencies = &dependency;

        if (vkCreateRenderPass(device_, &renderPassInfo, nullptr, &renderPass) != VK_SUCCESS) {
            throw std::runtime_error("Failed to create render pass!");
        }
    }

    void create_framebuffers() {
        framebuffers.resize(swapchainImageViews.size());

        for (size_t i = 0; i < swapchainImageViews.size(); i++) {
            VkImageView attachments[] = { swapchainImageViews[i] };

            VkFramebufferCreateInfo framebufferInfo{};
            framebufferInfo.sType = VK_STRUCTURE_TYPE_FRAMEBUFFER_CREATE_INFO;
            framebufferInfo.renderPass = renderPass;
            framebufferInfo.attachmentCount = 1;
            framebufferInfo.pAttachments = attachments;
            framebufferInfo.width = swapchain_extent_.width;
            framebufferInfo.height = swapchain_extent_.height;
            framebufferInfo.layers = 1;

            if (vkCreateFramebuffer(device_, &framebufferInfo, nullptr, &framebuffers[i]) != VK_SUCCESS) {
                throw std::runtime_error("Failed to create framebuffer!");
            }
        }
    }

    void create_command_pool() {
        VkCommandPoolCreateInfo poolInfo{};
        poolInfo.sType = VK_STRUCTURE_TYPE_COMMAND_POOL_CREATE_INFO;
        poolInfo.flags = VK_COMMAND_POOL_CREATE_RESET_COMMAND_BUFFER_BIT;
        poolInfo.queueFamilyIndex = graphics_queue_family_;

        if (vkCreateCommandPool(device_, &poolInfo, nullptr, &commandPool) != VK_SUCCESS) {
            throw std::runtime_error("Failed to create command pool!");
        }
    }

    void create_command_buffers() {
        commandBuffers.resize(MAX_FRAMES_IN_FLIGHT);

        VkCommandBufferAllocateInfo allocInfo{};
        allocInfo.sType = VK_STRUCTURE_TYPE_COMMAND_BUFFER_ALLOCATE_INFO;
        allocInfo.commandPool = commandPool;
        allocInfo.level = VK_COMMAND_BUFFER_LEVEL_PRIMARY;
        allocInfo.commandBufferCount = static_cast<uint32_t>(commandBuffers.size());

        if (vkAllocateCommandBuffers(device_, &allocInfo, commandBuffers.data()) != VK_SUCCESS) {
            throw std::runtime_error("Failed to allocate command buffers!");
        }
    }

    void create_sync_objects() {
        imageAvailableSemaphores.resize(MAX_FRAMES_IN_FLIGHT);
        renderFinishedSemaphores.resize(MAX_FRAMES_IN_FLIGHT);
        inFlightFences.resize(MAX_FRAMES_IN_FLIGHT);

        VkSemaphoreCreateInfo semaphoreInfo{};
        semaphoreInfo.sType = VK_STRUCTURE_TYPE_SEMAPHORE_CREATE_INFO;

        VkFenceCreateInfo fenceInfo{};
        fenceInfo.sType = VK_STRUCTURE_TYPE_FENCE_CREATE_INFO;
        fenceInfo.flags = VK_FENCE_CREATE_SIGNALED_BIT;

        for (size_t i = 0; i < MAX_FRAMES_IN_FLIGHT; i++) {
            if (vkCreateSemaphore(device_, &semaphoreInfo, nullptr, &imageAvailableSemaphores[i]) != VK_SUCCESS ||
                vkCreateSemaphore(device_, &semaphoreInfo, nullptr, &renderFinishedSemaphores[i]) != VK_SUCCESS ||
                vkCreateFence(device_, &fenceInfo, nullptr, &inFlightFences[i]) != VK_SUCCESS) {
                throw std::runtime_error("Failed to create synchronization objects!");
            }
        }
    }

    void create_descriptor_pool() {
        VkDescriptorPoolSize pool_sizes[] = {
            { VK_DESCRIPTOR_TYPE_SAMPLER, 1000 },
            { VK_DESCRIPTOR_TYPE_COMBINED_IMAGE_SAMPLER, 1000 },
            { VK_DESCRIPTOR_TYPE_SAMPLED_IMAGE, 1000 },
            { VK_DESCRIPTOR_TYPE_STORAGE_IMAGE, 1000 },
            { VK_DESCRIPTOR_TYPE_UNIFORM_TEXEL_BUFFER, 1000 },
            { VK_DESCRIPTOR_TYPE_STORAGE_TEXEL_BUFFER, 1000 },
            { VK_DESCRIPTOR_TYPE_UNIFORM_BUFFER, 1000 },
            { VK_DESCRIPTOR_TYPE_STORAGE_BUFFER, 1000 },
            { VK_DESCRIPTOR_TYPE_UNIFORM_BUFFER_DYNAMIC, 1000 },
            { VK_DESCRIPTOR_TYPE_STORAGE_BUFFER_DYNAMIC, 1000 },
            { VK_DESCRIPTOR_TYPE_INPUT_ATTACHMENT, 1000 }
        };

        VkDescriptorPoolCreateInfo pool_info = {};
        pool_info.sType = VK_STRUCTURE_TYPE_DESCRIPTOR_POOL_CREATE_INFO;
        pool_info.flags = VK_DESCRIPTOR_POOL_CREATE_FREE_DESCRIPTOR_SET_BIT;
        pool_info.maxSets = 1000 * IM_ARRAYSIZE(pool_sizes);
        pool_info.poolSizeCount = (uint32_t)IM_ARRAYSIZE(pool_sizes);
        pool_info.pPoolSizes = pool_sizes;

        if (vkCreateDescriptorPool(device_, &pool_info, nullptr, &descriptorPool) != VK_SUCCESS) {
            throw std::runtime_error("Failed to create descriptor pool!");
        }
    }

    void init_imgui() {
        // Setup Dear ImGui context
        IMGUI_CHECKVERSION();
        ImGui::CreateContext();
        ImGuiIO& io = ImGui::GetIO(); (void)io;

        // Setup Dear ImGui style
        ImGui::StyleColorsDark();

        // Setup Platform/Renderer backends
        ImGui_ImplSDL2_InitForVulkan(window_);
        ImGui_ImplVulkan_InitInfo init_info = {};
        init_info.Instance        = instance_;
        init_info.PhysicalDevice  = physical_device_;
        init_info.Device          = device_;
        init_info.QueueFamily     = graphics_queue_family_;
        init_info.Queue           = graphics_queue_;
        init_info.PipelineCache   = VK_NULL_HANDLE;
        init_info.DescriptorPool  = descriptorPool;
        init_info.RenderPass      = renderPass;
        init_info.Subpass         = 0;
        init_info.MinImageCount   = MAX_FRAMES_IN_FLIGHT;
        init_info.ImageCount      = static_cast<uint32_t>(swapchain_images_.size());
        init_info.MSAASamples     = VK_SAMPLE_COUNT_1_BIT;
        init_info.Allocator       = nullptr;
        init_info.CheckVkResultFn = nullptr;
        ImGui_ImplVulkan_Init(&init_info);
        //ImGui_ImplVulkan_Init(&init_info, renderPass);

        // Upload Fonts
        VkCommandBuffer command_buffer = beginSingleTimeCommands();
        ImGui_ImplVulkan_CreateFontsTexture();
        endSingleTimeCommands(command_buffer);

        //ImGui_ImplVulkan_DestroyFontUploadObjects();
    }

    VkCommandBuffer beginSingleTimeCommands() {
        VkCommandBufferAllocateInfo allocInfo{};
        allocInfo.sType = VK_STRUCTURE_TYPE_COMMAND_BUFFER_ALLOCATE_INFO;
        allocInfo.level = VK_COMMAND_BUFFER_LEVEL_PRIMARY;
        allocInfo.commandPool = commandPool;
        allocInfo.commandBufferCount = 1;

        VkCommandBuffer commandBuffer;
        vkAllocateCommandBuffers(device_, &allocInfo, &commandBuffer);

        VkCommandBufferBeginInfo beginInfo{};
        beginInfo.sType = VK_STRUCTURE_TYPE_COMMAND_BUFFER_BEGIN_INFO;
        beginInfo.flags = VK_COMMAND_BUFFER_USAGE_ONE_TIME_SUBMIT_BIT;

        vkBeginCommandBuffer(commandBuffer, &beginInfo);

        return commandBuffer;
    }

    void endSingleTimeCommands(VkCommandBuffer commandBuffer) {
        vkEndCommandBuffer(commandBuffer);

        VkSubmitInfo submitInfo{};
        submitInfo.sType = VK_STRUCTURE_TYPE_SUBMIT_INFO;
        submitInfo.commandBufferCount = 1;
        submitInfo.pCommandBuffers = &commandBuffer;

        vkQueueSubmit(graphics_queue_, 1, &submitInfo, VK_NULL_HANDLE);
        vkQueueWaitIdle(graphics_queue_);

        vkFreeCommandBuffers(device_, commandPool, 1, &commandBuffer);
    }

    void main_loop() {
        SDL_Event event;

        while (!quit) {
            while (SDL_PollEvent(&event)) {
                ImGui_ImplSDL2_ProcessEvent(&event);

                if (event.type == SDL_QUIT) {
                    quit = true;
                }
            }

            drawFrame();
        }

        vkDeviceWaitIdle(device_);
    }

    void drawFrame() {
        vkWaitForFences(device_, 1, &inFlightFences[currentFrame], VK_TRUE, UINT64_MAX);

        uint32_t imageIndex;
        VkResult result = vkAcquireNextImageKHR(device_, swapchain_, UINT64_MAX,
                                                imageAvailableSemaphores[currentFrame],
                                                VK_NULL_HANDLE, &imageIndex);

        switch (result) {
        case VK_SUCCESS:
        case VK_SUBOPTIMAL_KHR:
            break;
        case VK_ERROR_OUT_OF_DATE_KHR:
            recreate_swapchain();
            // deliberate earlyexit
            return;
        default:
            throw std::runtime_error("failed to acquire swapchain image!");
            break;
        }

        vkResetFences(device_, 1, &inFlightFences[currentFrame]);

        vkResetCommandBuffer(commandBuffers[currentFrame], 0);
        recordCommandBuffer(commandBuffers[currentFrame], imageIndex);

        VkSubmitInfo submitInfo{};
        submitInfo.sType = VK_STRUCTURE_TYPE_SUBMIT_INFO;

        VkSemaphore waitSemaphores[] = {imageAvailableSemaphores[currentFrame]};
        VkPipelineStageFlags waitStages[] = {VK_PIPELINE_STAGE_COLOR_ATTACHMENT_OUTPUT_BIT};
        submitInfo.waitSemaphoreCount = 1;
        submitInfo.pWaitSemaphores = waitSemaphores;
        submitInfo.pWaitDstStageMask = waitStages;

        submitInfo.commandBufferCount = 1;
        submitInfo.pCommandBuffers = &commandBuffers[currentFrame];

        VkSemaphore signalSemaphores[] = {renderFinishedSemaphores[currentFrame]};
        submitInfo.signalSemaphoreCount = 1;
        submitInfo.pSignalSemaphores = signalSemaphores;

        if (vkQueueSubmit(graphics_queue_, 1, &submitInfo, inFlightFences[currentFrame]) != VK_SUCCESS) {
            throw std::runtime_error("Failed to submit draw command buffer!");
        }

        VkPresentInfoKHR presentInfo{};
        presentInfo.sType = VK_STRUCTURE_TYPE_PRESENT_INFO_KHR;

        presentInfo.waitSemaphoreCount = 1;
        presentInfo.pWaitSemaphores = signalSemaphores;

        VkSwapchainKHR swapChains[] = {swapchain_};
        presentInfo.swapchainCount = 1;
        presentInfo.pSwapchains = swapChains;

        presentInfo.pImageIndices = &imageIndex;

        result = vkQueuePresentKHR(graphics_queue_, &presentInfo);

        if (framebuffer_resized_flag_)
            result = VK_ERROR_OUT_OF_DATE_KHR;

        switch (result) {
        case VK_SUCCESS:
            break;
        case VK_ERROR_OUT_OF_DATE_KHR:
        case VK_SUBOPTIMAL_KHR:
            framebuffer_resized_flag_ = false;
            this->recreate_swapchain();
            break;
        default:
            throw std::runtime_error("failed to present swapchain image!");
        }

        currentFrame = (currentFrame + 1) % MAX_FRAMES_IN_FLIGHT;
    }

    void recordCommandBuffer(VkCommandBuffer commandBuffer, uint32_t imageIndex) {
        VkCommandBufferBeginInfo beginInfo{};
        beginInfo.sType = VK_STRUCTURE_TYPE_COMMAND_BUFFER_BEGIN_INFO;

        if (vkBeginCommandBuffer(commandBuffer, &beginInfo) != VK_SUCCESS) {
            throw std::runtime_error("Failed to begin recording command buffer!");
        }

        VkRenderPassBeginInfo renderPassInfo{};
        renderPassInfo.sType = VK_STRUCTURE_TYPE_RENDER_PASS_BEGIN_INFO;
        renderPassInfo.renderPass = renderPass;
        renderPassInfo.framebuffer = framebuffers[imageIndex];
        renderPassInfo.renderArea.offset = {0, 0};
        renderPassInfo.renderArea.extent = swapchain_extent_;

        VkClearValue clearColor = {{{0.0f, 0.0f, 0.0f, 1.0f}}};
        renderPassInfo.clearValueCount = 1;
        renderPassInfo.pClearValues = &clearColor;

        vkCmdBeginRenderPass(commandBuffer, &renderPassInfo, VK_SUBPASS_CONTENTS_INLINE);

        // Start the Dear ImGui frame
        ImGui_ImplVulkan_NewFrame();
        ImGui_ImplSDL2_NewFrame();
        ImGui::NewFrame();

        // Create a simple ImGui window
        ImGui::Begin("Hello, Vulkan + SDL2!");
        ImGui::Text("This is a minimal ImGui + Vulkan + SDL2 example!");
        static float f = 0.0f;
        static int counter = 0;
        ImGui::SliderFloat("float", &f, 0.0f, 1.0f);
        if (ImGui::Button("Button"))
            counter++;
        ImGui::SameLine();
        ImGui::Text("counter = %d", counter);
        ImGui::Text("Application average %.3f ms/frame (%.1f FPS)", 1000.0f / ImGui::GetIO().Framerate, ImGui::GetIO().Framerate);
        ImGui::End();

        // Rendering
        ImGui::Render();
        ImDrawData* draw_data = ImGui::GetDrawData();
        ImGui_ImplVulkan_RenderDrawData(draw_data, commandBuffer);

        vkCmdEndRenderPass(commandBuffer);

        if (vkEndCommandBuffer(commandBuffer) != VK_SUCCESS) {
            throw std::runtime_error("Failed to record command buffer!");
        }
    }

    void recreate_swapchain() {
        // handle window minimization: wait until window has valid size
        int width = 0;
        int height = 0;
        SDL_GetWindowSize(window_, &width, &height);
        while (width == 0 || height == 0) {
            SDL_GetWindowSize(window_, &width, &height);
            SDL_WaitEvent(nullptr);
        }

        // wait until device idle before cleaning up resources
        vkDeviceWaitIdle(device_);

        // cleanup old swapchain
        this->cleanupFrameBuffers();
        this->cleanupImageViews();
        this->cleanupSwapchain();

        // create new swapchain
        this->create_swapchain();
        this->create_image_views();
        this->create_framebuffers();
    }

    void cleanupFrameBuffers() {
            for (auto framebuffer : framebuffers) {
                vkDestroyFramebuffer(device_, framebuffer, nullptr);
            }
            framebuffers.clear();
    }

    void cleanupImageViews() {
            for (auto imageView : swapchainImageViews) {
                vkDestroyImageView(device_, imageView, nullptr);
            }
            swapchainImageViews.clear();
    }

    void cleanupSwapchain() {
        vkDestroySwapchainKHR(device_, this->swapchain_, nullptr);
    }

    void cleanup() {
        ImGui_ImplVulkan_Shutdown();
        ImGui_ImplSDL2_Shutdown();
        ImGui::DestroyContext();

        for (size_t i = 0; i < MAX_FRAMES_IN_FLIGHT; i++) {
            vkDestroySemaphore(device_, renderFinishedSemaphores[i], nullptr);
            vkDestroySemaphore(device_, imageAvailableSemaphores[i], nullptr);
            vkDestroyFence(device_, inFlightFences[i], nullptr);
        }

        vkDestroyCommandPool(device_, commandPool, nullptr);

        this->cleanupFrameBuffers();
        this->cleanupImageViews();
        this->cleanupSwapchain();

        vkDestroyRenderPass(device_, renderPass, nullptr);
        vkDestroyDescriptorPool(device_, descriptorPool, nullptr);
        vkDestroyDevice(device_, nullptr);
        vkDestroySurfaceKHR(instance_, this->surface_, nullptr);
        vkDestroyInstance(instance_, nullptr);
        this->instance_ = nullptr;

        SDL_DestroyWindow(window_);
        this->window_ = nullptr;

        SDL_Quit();
    }

private:
    SDL_Window* window_ = nullptr;

    VkInstance instance_;

    /* abstraction for presentation area (?) */
    VkSurfaceKHR surface_;

    /* physical device (graphics card) */
    VkPhysicalDevice physical_device_;
    uint32_t graphics_queue_family_ = 0;

    /* logical device (graphics card, abstract api (?)) */
    VkDevice device_;
    VkQueue graphics_queue_;

    VkSwapchainKHR swapchain_;
    VkFormat swapchain_image_format_;
    VkExtent2D swapchain_extent_;
    std::vector<VkImage> swapchain_images_;
    std::vector<VkImageView> swapchainImageViews;
    VkRenderPass renderPass;
    std::vector<VkFramebuffer> framebuffers;
    VkCommandPool commandPool;
    std::vector<VkCommandBuffer> commandBuffers;
    std::vector<VkSemaphore> imageAvailableSemaphores;
    std::vector<VkSemaphore> renderFinishedSemaphores;
    std::vector<VkFence> inFlightFences;
    VkDescriptorPool descriptorPool;

    uint32_t currentFrame = 0;
    const int MAX_FRAMES_IN_FLIGHT = 2;
    /* true when window resize behavior detected,
     * until swapchain in consistent state.
     */
    bool framebuffer_resized_flag_ = false;
    bool quit = false;
}; /*MinimalImGuiVulkan*/