// Copyright 2017 GFX developers
//
// Licensed under the Apache License, Version 2.0, <LICENSE-APACHE or
// http://apache.org/licenses/LICENSE-2.0> or the MIT license <LICENSE-MIT or
// http://opensource.org/licenses/MIT>, at your option. This file may not be
// copied, modified, or distributed except according to those terms.

#[macro_use]
extern crate objc;

use metal::*;

use cocoa::foundation::NSAutoreleasePool;

use std::mem;

static LIBRARY_SRC: &str = include_str!("compute-argument-buffer.metal");

fn main() {
    let pool = unsafe { NSAutoreleasePool::new(cocoa::base::nil) };
    let device = Device::system_default().expect("no device found");
    let command_queue = device.new_command_queue();

    let data = [
        1u32, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24,
        25, 26, 27, 28, 29, 30,
    ];

    let buffer = device.new_buffer_with_data(
        unsafe { mem::transmute(data.as_ptr()) },
        (data.len() * mem::size_of::<u32>()) as u64,
        MTLResourceOptions::CPUCacheModeDefaultCache,
    );

    let sum = {
        let data = [0u32];
        device.new_buffer_with_data(
            unsafe { mem::transmute(data.as_ptr()) },
            (data.len() * mem::size_of::<u32>()) as u64,
            MTLResourceOptions::CPUCacheModeDefaultCache,
        )
    };

    let command_buffer = command_queue.new_command_buffer();
    let encoder = command_buffer.new_compute_command_encoder();

    let library = device
        .new_library_with_source(LIBRARY_SRC, &CompileOptions::new())
        .unwrap();
    let kernel = library.get_function("sum", None).unwrap();

    let argument_encoder = kernel.new_argument_encoder(0);
    let arg_buffer = device.new_buffer(
        argument_encoder.encoded_length(),
        MTLResourceOptions::empty(),
    );
    argument_encoder.set_argument_buffer(&arg_buffer, 0);
    argument_encoder.set_buffer(&buffer, 0, 0);
    argument_encoder.set_buffer(&sum, 0, 1);

    let pipeline_state_descriptor = ComputePipelineDescriptor::new();
    pipeline_state_descriptor.set_compute_function(Some(&kernel));

    let pipeline_state = device
        .new_compute_pipeline_state_with_function(
            pipeline_state_descriptor.compute_function().unwrap(),
        )
        .unwrap();

    encoder.set_compute_pipeline_state(&pipeline_state);
    encoder.set_buffer(0, Some(&arg_buffer), 0);

    encoder.use_resource(&buffer, MTLResourceUsage::Read);
    encoder.use_resource(&sum, MTLResourceUsage::Write);

    let width = 16;

    let thread_group_count = MTLSize {
        width,
        height: 1,
        depth: 1,
    };

    let thread_group_size = MTLSize {
        width: (data.len() as u64 + width) / width,
        height: 1,
        depth: 1,
    };

    encoder.dispatch_thread_groups(thread_group_count, thread_group_size);
    encoder.end_encoding();
    command_buffer.commit();
    command_buffer.wait_until_completed();

    let ptr = sum.contents() as *mut u32;

    unsafe {
        assert_eq!(465, *ptr);
        let () = msg_send![pool, release];
    }
}
