use ash::vk;
use librashader_runtime::ringbuffer::{BoxRingBuffer, InlineRingBuffer, RingBuffer};
use librashader_runtime::uniforms::UniformStorageAccess;
use crate::error;
use crate::vulkan_primitives::VulkanBuffer;

pub struct VkUboRing {
    ring: BoxRingBuffer<VulkanBuffer>,
    device: ash::Device,
}

impl VkUboRing {
    pub fn new(device: &ash::Device, mem_props: &vk::PhysicalDeviceMemoryProperties, ring_size: usize, buffer_size: usize) -> error::Result<Self> {
        let mut ring = Vec::new();
        for _ in 0..ring_size {
            ring.push(VulkanBuffer::new(device, mem_props, vk::BufferUsageFlags::UNIFORM_BUFFER, buffer_size)?);
        }

        Ok(VkUboRing {
            ring: BoxRingBuffer::from_vec(ring),
            device: device.clone()
        })
    }

    pub fn bind_for_frame(&mut self, descriptor_set: vk::DescriptorSet, binding: u32, storage: &impl UniformStorageAccess) -> error::Result<()>{
        let mut buffer = self.ring.current_mut();
        // todo: write directly to allocated buffer.
        unsafe {
            let mut map = buffer.map()?;
            map.copy_from(0, storage.ubo_slice())
        }

        unsafe {
            let buffer_info = vk::DescriptorBufferInfo::builder()
                .buffer(buffer.handle)
                .offset(0)
                .range(storage.ubo_slice().len() as vk::DeviceSize)
                .build();

            let write_info = vk::WriteDescriptorSet::builder()
                .descriptor_type(vk::DescriptorType::UNIFORM_BUFFER)
                .dst_set(descriptor_set)
                .dst_binding(binding)
                .dst_array_element(0)
                .buffer_info(&[buffer_info])
                .build();

            self.device.update_descriptor_sets(&[write_info], &[])
        }
        self.ring.next();
        Ok(())
    }
}