// Основан на примере GpuInterop Avalonia
// https://github.com/AvaloniaUI/Avalonia/blob/5f3dbae22244e830b464fc680c6c28ca124be41a/samples/GpuInterop/VulkanDemo/VulkanContext.cs

using Silk.NET.Core;
using Silk.NET.Vulkan;
using Silk.NET.Vulkan.Extensions.KHR;

using Semaphore = Silk.NET.Vulkan.Semaphore;

namespace GSS2.Vulkan;

unsafe public class VulkanContext : IDisposable
{
    private bool _disposedValue;

    public Vk Api { get; init; }
    public Instance Instance { get; init; }
    public PhysicalDevice PhysicalDevice { get; init; }
    public Device Device { get; init; }
    public uint QueueFamilyIndex { get; init; }
    public Queue Queue { get; init; }
    public Semaphore ImageAvailableSemaphore { get; init; }
    public Semaphore RenderFinishedSemaphore { get; init; }

    public VulkanContext(string applicationName, string engineName)
    {
        Api = Vk.GetApi();

        List<string> instanceExtensions =
        [
            "VK_KHR_get_physical_device_properties2",
            "VK_KHR_external_memory_capabilities",
            "VK_KHR_external_semaphore_capabilities",
            "VK_EXT_debug_utils"
        ];
        List<string> instanceLayers =
        [
            
        ];
        List<string> deviceExtensions =
        [
            "VK_KHR_external_memory",
            "VK_KHR_external_memory_fd",
            "VK_KHR_external_semaphore",
            "VK_KHR_external_semaphore_fd"
        ];

        Instance = CreateInstance(Api, applicationName, engineName, instanceExtensions, instanceLayers);
        PhysicalDevice = FindPhysicalDevice(Api, Instance, deviceExtensions);
        (Device, QueueFamilyIndex) = CreateDevice(Api, Instance, PhysicalDevice, deviceExtensions);
        Queue = CreateQueue(Api, Device, QueueFamilyIndex);
        ImageAvailableSemaphore = CreateSemaphore(Api, Device);
        RenderFinishedSemaphore = CreateSemaphore(Api, Device);
    }

    public int ExportSemaphoreFd(Semaphore semaphore)
    {
        if (!Api.TryGetDeviceExtension<KhrExternalSemaphoreFd>(Instance, Device, out var extension))
            throw new InvalidOperationException($"No {KhrExternalSemaphoreFd.ExtensionName} device extension");

        var info = new SemaphoreGetFdInfoKHR()
        {
            SType = StructureType.SemaphoreGetFDInfoKhr,
            Semaphore = semaphore,
            HandleType = ExternalSemaphoreHandleTypeFlags.OpaqueFDBit
        };
        extension.GetSemaphoreF(Device, in info, out var fd).ThrowOnError();
        return fd;
    }

    private static Instance CreateInstance(Vk api, string applicationName, string engineName, List<string> extentions, List<string> layers)
    {
        using var pApplicationName = new ByteString(applicationName);
        using var pEngineName = new ByteString(engineName);
        var applicationInfo = new ApplicationInfo
        {
            SType = StructureType.ApplicationInfo,
            PApplicationName = pApplicationName,
            PEngineName = pEngineName,
            ApiVersion = new Version32(1, 1, 0),
            EngineVersion = new Version32(1, 0, 0),
            ApplicationVersion = new Version32(1, 0, 0)
        };

        using var pExtensions = new ByteStringList(extentions);
        using var pLayers = new ByteStringList(layers);
        var instanceCreateInfo = new InstanceCreateInfo
        {
            SType = StructureType.InstanceCreateInfo,
            PApplicationInfo = &applicationInfo,
            PpEnabledExtensionNames = pExtensions,
            EnabledExtensionCount = checked((uint)pExtensions.Count),
            PpEnabledLayerNames = pLayers,
            EnabledLayerCount = checked((uint)pLayers.Count),
            Flags = default
        };

        api.CreateInstance(in instanceCreateInfo, null, out var Instance).ThrowOnError();

        return Instance;
    }
    private static PhysicalDevice FindPhysicalDevice(Vk api, Instance instance, List<string> extensions)
    {
        uint count = 0;
        api.EnumeratePhysicalDevices(instance, ref count, null).ThrowOnError();
        var physicalDevices = stackalloc PhysicalDevice[(int)count];
        api.EnumeratePhysicalDevices(instance, ref count, physicalDevices).ThrowOnError();

        for (uint c = 0; c < count; c++)
        {
            if (extensions.Any(e => !api.IsDeviceExtensionPresent(physicalDevices[c], e)))
                continue;
            return physicalDevices[c];
        }

        throw new Exception("Suшtable Device not found");
    }
    private static (Device device, uint queueFamilyIndex) CreateDevice(Vk api, Instance instance, PhysicalDevice physicalDevice, List<string> extensions)
    {
        uint queueFamilyCount = 0;
        api.GetPhysicalDeviceQueueFamilyProperties(physicalDevice, ref queueFamilyCount, null);
        var queueFamilyProperties = new QueueFamilyProperties[(int)queueFamilyCount];
        fixed (QueueFamilyProperties* pQueueFamilyProperties = queueFamilyProperties)
            api.GetPhysicalDeviceQueueFamilyProperties(physicalDevice, ref queueFamilyCount, pQueueFamilyProperties);

        for (uint i = 0; i < queueFamilyCount; i++)
        {
            var queueFamily = queueFamilyProperties[i];
            if (!queueFamily.QueueFlags.HasFlag(QueueFlags.GraphicsBit))
                continue;

            var queuePriorities = new float[(int)queueFamily.QueueCount];

            for (var j = 0; j < queueFamily.QueueCount; j++)
                queuePriorities[j] = 1f;

            var features = new PhysicalDeviceFeatures();

            Device device;
            fixed (float* pQueuePriorities = queuePriorities)
            {
                var queueCreateInfo = new DeviceQueueCreateInfo
                {
                    SType = StructureType.DeviceQueueCreateInfo,
                    QueueFamilyIndex = i,
                    QueueCount = queueFamily.QueueCount,
                    PQueuePriorities = pQueuePriorities
                };

                using var pEnabledDeviceExtensions = new ByteStringList(extensions);
                var deviceCreateInfo = new DeviceCreateInfo
                {
                    SType = StructureType.DeviceCreateInfo,
                    QueueCreateInfoCount = 1,
                    PQueueCreateInfos = &queueCreateInfo,
                    PpEnabledExtensionNames = pEnabledDeviceExtensions,
                    EnabledExtensionCount = checked((uint)pEnabledDeviceExtensions.Count),
                    PEnabledFeatures = &features
                };

                api.CreateDevice(physicalDevice, in deviceCreateInfo, null, out device).ThrowOnError();

                return (device, i);
            }
        }
        throw new Exception("Cannot create device");
    }
    private static Queue CreateQueue(Vk api, Device device, uint queueFamilyIndex)
    {
        api.GetDeviceQueue(device, queueFamilyIndex, 0, out var queue);
        return queue;
    }
    private static Semaphore CreateSemaphore(Vk api, Device device)
    {
        var semaphoreExportInfo = new ExportSemaphoreCreateInfo
        {
            SType = StructureType.ExportSemaphoreCreateInfo,
            HandleTypes = ExternalSemaphoreHandleTypeFlags.OpaqueFDBit
        };
        var semaphoreCreateInfo = new SemaphoreCreateInfo
        {
            SType = StructureType.SemaphoreCreateInfo,
            PNext = &semaphoreExportInfo
        };

        api.CreateSemaphore(device, in semaphoreCreateInfo, null, out var semaphore).ThrowOnError();
        return semaphore;
    }

    protected virtual void Dispose(bool disposing)
    {
        if (!_disposedValue)
        {
            if (disposing)
            {
                if (Api is null)
                    return;
                Api.DestroySemaphore(Device, ImageAvailableSemaphore, null);
                Api.DestroySemaphore(Device, RenderFinishedSemaphore, null);
            }
            _disposedValue = true;
        }
    }
    public void Dispose()
    {
        Dispose(disposing: true);
        GC.SuppressFinalize(this);
    }
}