// Vulkan from Finch: create an instance, list every GPU with its properties, memory and
// queues, then create a logical device and get a graphics queue. No window needed.
// Shows big C structs (with arrays of structs inside), out-parameters and Vulkan handles.
// Needs the Vulkan loader and headers (in shell.nix) and a Vulkan driver.
import "vulkan/vulkan.h"
link "vulkan"

fn check(i32 result, str what) {
    if result != VK_SUCCESS {
        print(what, "failed with VkResult", result)
        exit(1)
    }
}

fn version(u32 v) -> str {
    return str(v >> 22) + "." + str((v >> 12) & 0x3FF) + "." + str(v & 0xFFF)
}

fn deviceType(i32 t) -> str {
    if t == VK_PHYSICAL_DEVICE_TYPE_DISCRETE_GPU {
        return "discrete GPU"
    }
    if t == VK_PHYSICAL_DEVICE_TYPE_INTEGRATED_GPU {
        return "integrated GPU"
    }
    if t == VK_PHYSICAL_DEVICE_TYPE_VIRTUAL_GPU {
        return "virtual GPU"
    }
    if t == VK_PHYSICAL_DEVICE_TYPE_CPU {
        return "CPU (software)"
    }
    return "other"
}

fn queueFlags(u32 f) -> str {
    []str parts
    if f & VK_QUEUE_GRAPHICS_BIT != 0 {
        parts.push("graphics")
    }
    if f & VK_QUEUE_COMPUTE_BIT != 0 {
        parts.push("compute")
    }
    if f & VK_QUEUE_TRANSFER_BIT != 0 {
        parts.push("transfer")
    }
    if f & VK_QUEUE_SPARSE_BINDING_BIT != 0 {
        parts.push("sparse")
    }
    if f & VK_QUEUE_VIDEO_DECODE_BIT_KHR != 0 {
        parts.push("video decode")
    }
    if f & VK_QUEUE_VIDEO_ENCODE_BIT_KHR != 0 {
        parts.push("video encode")
    }
    if parts.len == 0 {
        return "other"
    }
    return parts.join(", ")
}

fn main() {
    app := VkApplicationInfo(
        sType: VK_STRUCTURE_TYPE_APPLICATION_INFO,
        pApplicationName: "Finch".ptr,
        applicationVersion: 1,
        pEngineName: "none".ptr,
        apiVersion: 1 << 22,              // Vulkan 1.0
    )
    info := VkInstanceCreateInfo(sType: VK_STRUCTURE_TYPE_INSTANCE_CREATE_INFO, pApplicationInfo: addr(app))
    ptr instance
    check(vkCreateInstance(addr(info), null, addr(instance)), "vkCreateInstance")
    defer vkDestroyInstance(instance, null)

    u32 count
    check(vkEnumeratePhysicalDevices(instance, addr(count), null), "counting GPUs")
    []ptr gpus
    gpus.resize(count)
    check(vkEnumeratePhysicalDevices(instance, addr(count), gpus.ptr), "listing GPUs")
    print("Vulkan found", count, "device(s)")

    for gpu in gpus {
        VkPhysicalDeviceProperties props
        vkGetPhysicalDeviceProperties(gpu, addr(props))
        print()
        print(str(props.deviceName.ptr))
        print("  type:", deviceType(props.deviceType))
        print("  Vulkan " + version(props.apiVersion) + ", driver " + str(props.driverVersion))
        print("  biggest 2D image:", props.limits.maxImageDimension2D, "px")

        VkPhysicalDeviceMemoryProperties mem
        vkGetPhysicalDeviceMemoryProperties(gpu, addr(mem))
        for h in 0..mem.memoryHeapCount {
            heap := mem.memoryHeaps[h]
            local := ""
            if heap.flags & VK_MEMORY_HEAP_DEVICE_LOCAL_BIT != 0 {
                local = " (on the GPU)"
            }
            print("  memory heap " + str(h) + ": " + str(float(heap.size) / 1073741824.0) + " GiB" + local)
        }

        u32 families
        vkGetPhysicalDeviceQueueFamilyProperties(gpu, addr(families), null)
        []VkQueueFamilyProperties queues
        queues.resize(families)
        vkGetPhysicalDeviceQueueFamilyProperties(gpu, addr(families), queues.ptr)
        graphics := -1
        for q in 0..queues.len {
            print("  queue family " + str(q) + ": " + str(queues[q].queueCount) + " x " + queueFlags(queues[q].queueFlags))
            if graphics < 0 && queues[q].queueFlags & VK_QUEUE_GRAPHICS_BIT != 0 {
                graphics = q
            }
        }
        if graphics < 0 {
            continue
        }

        // a logical device with one graphics queue: what a renderer would start from
        f32 priority = 1.0
        queueInfo := VkDeviceQueueCreateInfo(
            sType: VK_STRUCTURE_TYPE_DEVICE_QUEUE_CREATE_INFO,
            queueFamilyIndex: u32(graphics),
            queueCount: 1,
            pQueuePriorities: addr(priority),
        )
        deviceInfo := VkDeviceCreateInfo(
            sType: VK_STRUCTURE_TYPE_DEVICE_CREATE_INFO,
            queueCreateInfoCount: 1,
            pQueueCreateInfos: addr(queueInfo),
        )
        ptr device
        check(vkCreateDevice(gpu, addr(deviceInfo), null, addr(device)), "vkCreateDevice")
        ptr queue
        vkGetDeviceQueue(device, u32(graphics), 0, addr(queue))
        print("  created a device and got graphics queue", queue != null)
        vkDestroyDevice(device, null)
    }
}