#[allow(unused_imports)]
use log::{debug, error, info, trace, warn};

use std::mem::ManuallyDrop;

use crate::renderer::gpu::Gpu;

//--Attachement implementation----------------------------------------------------------------------
#[derive(Debug)]
pub struct Attachement<B: gfx_hal::Backend> {
    buffer: ManuallyDrop<B::Buffer>,
    memory: ManuallyDrop<B::Memory>,
    size: u64,
}

impl<B> Attachement<B>
where
    B: gfx_hal::Backend,
{
    pub fn drop(mut self, gpu: &mut Gpu<B>) {
        use std::ptr::read;

        use gfx_hal::device::Device;

        debug!("Dropping Attachement...");
        unsafe {
            gpu.device()
                .free_memory(ManuallyDrop::into_inner(read(&mut self.memory)));
            gpu.device()
                .destroy_buffer(ManuallyDrop::into_inner(read(&mut self.buffer)));
        }
    }

    pub fn new(gpu: &mut Gpu<B>) -> Result<Attachement<B>, &'static str> {
        use std::mem::size_of;
        
        use gfx_hal::{
            device::Device,
            adapter::PhysicalDevice,
            buffer::Usage,
        };

        debug!("Creating attachement...");
        let mut buffer = unsafe {
            gpu.device()
                .create_buffer((size_of::<f32>()*2*3) as u64, Usage::VERTEX)
                .map_err(|_| "Could not create buffer")?
        };

        trace!("Creating underlying attachement memory...");
        let (memory, size) = {
            use gfx_hal::{
                memory::Properties, 
                MemoryTypeId,
            };

            let requirements = unsafe {
                gpu.device().get_buffer_requirements(&buffer)
            };
            let memory_type = gpu.adapter()
                .physical_device
                .memory_properties()
                .memory_types
                .iter()
                .enumerate()
                .find(|&(id, memory_type)| {
                    requirements.type_mask & (1 << id) != 0 &&
                        memory_type.properties.contains(Properties::CPU_VISIBLE)})
                .map(|(id, _)| MemoryTypeId(id))
                .ok_or("Could not find a suitable memory type to allocate attachement memory")?;

            (
                unsafe {
                    gpu.device()
                        .allocate_memory(memory_type, requirements.size)
                        .map_err(|_| "Could not allocate buffer memory...")?
                },
                requirements.size,
        )};

        trace!("Binding memory to buffer...");
        unsafe {
            gpu.device()
                .bind_buffer_memory(&memory, 0, &mut buffer)
                .map_err(|__| "Could not bind memory to buffer")?;
        }


        Ok( Attachement {
            buffer: ManuallyDrop::new(buffer),
            memory: ManuallyDrop::new(memory),
            size,
        })
    }

    pub fn get_buffer(&self) -> &B::Buffer {
        //manual deref for ManuallyDrop to not cause troubles
        &self.buffer
    }

    pub fn write_buffer(&self, gpu: &Gpu<B>, data: Vec<f32>) -> Result<(), &'static str> 
    {
        use gfx_hal::{
            device::Device,
            memory::Segment,
        };

        trace!("writing data to buffer...");
        unsafe {
            let mapped_memory = gpu.device()
                .map_memory(&self.memory, Segment::ALL)
                .map_err(|_| "Could not map buffer memory")?;

            //debug!("before : {}", std::ptr::read(mapped_memory as *mut f32));

            std::ptr::copy_nonoverlapping(data.as_ptr() as *const u8, 
                                          mapped_memory, self.size as usize);

            //debug!("after : {}", std::ptr::read(mapped_memory as *mut f32));

            //manual deref for ManuallyDrop to not cause troubles
            let memory_ref: &B::Memory = &self.memory;

            gpu.device()
                .flush_mapped_memory_ranges(std::iter::once((memory_ref, Segment::ALL)))
                .map_err(|_| "Could not flush mapped buffer memory")?;
            
            gpu.device().unmap_memory(&self.memory);
        }

        Ok(())
    }

}