//! The point here is to select _a_ physical device and create a logical device around it.

const std = @import("std");
const builtin = @import("builtin");

const vk = @import("vk");
const c = @import("../c.zig");

const Instance = @import("Instance.zig");
const Window = @import("Window.zig");

const Self = @This();

const required_extensions: []const [*:0]const u8 = &.{
    vk.extension_info.khr_swapchain.name,
    vk.extension_info.khr_dynamic_rendering.name,
};

const preferred_surface_format: vk.SurfaceFormatKHR = .{
    .color_space = .srgb_nonlinear_khr,
    .format = .r8g8b8a8_sint,
};

const preferred_present_mode: vk.PresentModeKHR = .mailbox_khr;

dev: vk.Device,
pdev: vk.PhysicalDevice,
vkd: Wrapper,

inst: *const Instance,
win: *const Window,

format: vk.SurfaceFormatKHR,
mode: vk.PresentModeKHR,
family: u32,
queue: vk.Queue,

pool: vk.CommandPool,

pub fn init(
    ally: std.mem.Allocator,
    inst: *const Instance,
    win: *const Window,
) !Self {
    var pdev_count: u32 = undefined;
    _ = try inst.vki.enumeratePhysicalDevices(inst.ref, &pdev_count, null);
    const pdevs = try ally.alloc(vk.PhysicalDevice, pdev_count);
    defer ally.free(pdevs);
    _ = try inst.vki.enumeratePhysicalDevices(inst.ref, &pdev_count, pdevs.ptr);

    for (pdevs) |pdev| {
        return wrap(ally, inst, win, pdev) catch continue;
    }

    return error.NoSuitableDevice;
}

pub fn wrap(
    ally: std.mem.Allocator,
    inst: *const Instance,
    win: *const Window,
    pdev: vk.PhysicalDevice,
) !Self {
    const props = inst.vki.getPhysicalDeviceProperties(pdev);
    if (props.device_type != .discrete_gpu) return error.NotDiscrete;

    var format_count: u32 = undefined;
    _ = try inst.vki.getPhysicalDeviceSurfaceFormatsKHR(pdev, win.surface, &format_count, null);
    if (format_count == 0) return error.NoSurfaceFormat;
    const formats = try ally.alloc(vk.SurfaceFormatKHR, format_count);
    defer ally.free(formats);
    _ = try inst.vki.getPhysicalDeviceSurfaceFormatsKHR(pdev, win.surface, &format_count, formats.ptr);

    const format = for (formats) |f| {
        if (std.meta.eql(f, preferred_surface_format))
            break f;
    } else formats[0];

    var mode_count: u32 = undefined;
    _ = try inst.vki.getPhysicalDeviceSurfacePresentModesKHR(pdev, win.surface, &mode_count, null);
    if (mode_count == 0) return error.NoSurfaceMode;
    const modes = try ally.alloc(vk.PresentModeKHR, mode_count);
    defer ally.free(modes);
    _ = try inst.vki.getPhysicalDeviceSurfacePresentModesKHR(pdev, win.surface, &mode_count, modes.ptr);

    const mode = for (modes) |m| {
        if (std.meta.eql(m, preferred_present_mode))
            break m;
    } else modes[0];

    var ext_count: u32 = undefined;
    _ = try inst.vki.enumerateDeviceExtensionProperties(pdev, null, &ext_count, null);
    const exts = try ally.alloc(vk.ExtensionProperties, ext_count);
    defer ally.free(exts);
    _ = try inst.vki.enumerateDeviceExtensionProperties(pdev, null, &ext_count, exts.ptr);

    for (required_extensions) |name| {
        for (exts) |ext| {
            if (std.mem.eql(
                u8,
                std.mem.span(name),
                std.mem.sliceTo(&ext.extension_name, 0),
            )) {
                break;
            }
        } else {
            return error.MissingRequiredExtension;
        }
    }

    var family_count: u32 = undefined;
    inst.vki.getPhysicalDeviceQueueFamilyProperties(pdev, &family_count, null);
    const families = try ally.alloc(vk.QueueFamilyProperties, family_count);
    defer ally.free(families);
    inst.vki.getPhysicalDeviceQueueFamilyProperties(pdev, &family_count, families.ptr);

    // just find one family that does graphics and present, so we can use exclusive sharing
    // on the swapchain. apparently most hardware supports this. logic for queue allocation
    // and swapchain creation is so much simpler this way. swapchain creation needs to know
    // the list of queue family indices which will have access to the images, and there's a
    // performance penalty to allow concurrent access to multiple queue families.
    //
    // multiple _queues_ may have exclusive access, but only if they're in the smae family.

    const family: u32 = for (families, 0..) |family, idx| {
        const graphics = family.queue_flags.graphics_bit;
        const present = try inst.vki.getPhysicalDeviceSurfaceSupportKHR(pdev, @intCast(idx), win.surface) == vk.TRUE;
        if (graphics and present) break @intCast(idx);
    } else {
        return error.NoSuitableQueueFamily;
    };

    const qci: []const vk.DeviceQueueCreateInfo = &.{
        vk.DeviceQueueCreateInfo{
            .queue_family_index = family,
            .queue_count = 1,
            .p_queue_priorities = &[_]f32{1.0},
        },
    };

    const dev = try inst.vki.createDevice(pdev, &.{
        .queue_create_info_count = @intCast(qci.len),
        .p_queue_create_infos = qci.ptr,
        .enabled_extension_count = @intCast(required_extensions.len),
        .pp_enabled_extension_names = required_extensions.ptr,
        .p_next = &vk.PhysicalDeviceDynamicRenderingFeaturesKHR{
            .dynamic_rendering = vk.TRUE,
        },
    }, null);
    const vkd = try Wrapper.load(dev, inst.vki.dispatch.vkGetDeviceProcAddr);
    errdefer vkd.destroyDevice(dev, null);

    const pool = try vkd.createCommandPool(dev, &.{
        .queue_family_index = family,
    }, null);
    errdefer vkd.destroyCommandPool(dev, pool, null);

    const queue = vkd.getDeviceQueue(dev, family, 0);

    return .{
        .dev = dev,
        .pdev = pdev,
        .vkd = vkd,
        .inst = inst,
        .win = win,
        .format = format,
        .mode = mode,
        .pool = pool,
        .family = family,
        .queue = queue,
    };
}

pub fn deinit(self: Self) void {
    self.vkd.destroyCommandPool(self.dev, self.pool, null);
    self.vkd.destroyDevice(self.dev, null);
}

pub const Wrapper = vk.DeviceWrapper(.{
    .destroyDevice = true,
    .getDeviceQueue = true,
    .createSemaphore = true,
    .createFence = true,
    .createImageView = true,
    .destroyImageView = true,
    .destroySemaphore = true,
    .destroyFence = true,
    .getSwapchainImagesKHR = true,
    .createSwapchainKHR = true,
    .destroySwapchainKHR = true,
    .acquireNextImageKHR = true,
    .deviceWaitIdle = true,
    .waitForFences = true,
    .resetFences = true,
    .queueSubmit = true,
    .queuePresentKHR = true,
    .createCommandPool = true,
    .destroyCommandPool = true,
    .allocateCommandBuffers = true,
    .freeCommandBuffers = true,
    .queueWaitIdle = true,
    .createShaderModule = true,
    .destroyShaderModule = true,
    .createPipelineLayout = true,
    .destroyPipelineLayout = true,
    .createGraphicsPipelines = true,
    .destroyPipeline = true,
    .beginCommandBuffer = true,
    .endCommandBuffer = true,
    .allocateMemory = true,
    .freeMemory = true,
    .createBuffer = true,
    .destroyBuffer = true,
    .getBufferMemoryRequirements = true,
    .mapMemory = true,
    .unmapMemory = true,
    .bindBufferMemory = true,
    .cmdBeginRenderPass = true,
    .cmdEndRenderPass = true,
    .cmdBindPipeline = true,
    .cmdDraw = true,
    .cmdDrawIndexed = true,
    .cmdSetViewport = true,
    .cmdSetScissor = true,
    .cmdBindVertexBuffers = true,
    .cmdBindIndexBuffer = true,
    .cmdCopyBuffer = true,
    .cmdBeginRenderingKHR = true,
    .cmdEndRenderingKHR = true,
    .cmdPipelineBarrier = true,
});