import std/options

import ./api
import ./device
import ./physicaldevice

type
  Swapchain = object
    vk*: VkSwapchainKHR
    device*: Device


proc createSwapchain*(device: Device, surfaceFormat: VkSurfaceFormatKHR, nBuffers=3'u32, presentationMode: VkPresentModeKHR=VK_PRESENT_MODE_MAILBOX_KHR): (Swapchain, VkResult) =
  assert device.vk.valid
  assert device.physicalDevice.vk.valid
  var capabilities = device.physicalDevice.getSurfaceCapabilities()

  var imageCount = nBuffers
  # following is according to vulkan specs
  if presentationMode in [VK_PRESENT_MODE_SHARED_DEMAND_REFRESH_KHR, VK_PRESENT_MODE_SHARED_CONTINUOUS_REFRESH_KHR]:
    imageCount = 1
  else:
    imageCount = max(imageCount, capabilities.minImageCount)
    if capabilities.maxImageCount != 0:
      imageCount = min(imageCount, capabilities.maxImageCount)

  var createInfo = VkSwapchainCreateInfoKHR(
    sType: VK_STRUCTURE_TYPE_SWAPCHAIN_CREATE_INFO_KHR,
    surface: device.physicalDevice.surface,
    minImageCount: imageCount,
    imageFormat: surfaceFormat.format,
    imageColorSpace: surfaceFormat.colorSpace,
    imageExtent: capabilities.currentExtent,
    imageArrayLayers: 1,
    imageUsage: toBits [VK_IMAGE_USAGE_COLOR_ATTACHMENT_BIT],
    # VK_SHARING_MODE_CONCURRENT no supported currently
    imageSharingMode: VK_SHARING_MODE_EXCLUSIVE,
    preTransform: capabilities.currentTransform,
    compositeAlpha: VK_COMPOSITE_ALPHA_OPAQUE_BIT_KHR, # only used for blending with other windows, can be opaque
    presentMode: presentationMode,
    clipped: true,
  )
  var
    swapchain = Swapchain(device: device)
    createResult = device.vk.vkCreateSwapchainKHR(addr(createInfo), nil, addr(swapchain.vk))

  return (swapchain, createResult)

proc destroy*(swapchain: var Swapchain) =
  assert swapchain.vk.valid
  swapchain.device.vk.vkDestroySwapchainKHR(swapchain.vk, nil)