# frozen_string_literal: true

require 'optparse'

options = { platform: 0, device: 0 }
OptionParser.new do |parser|
  parser.banner = "Usage: ruby #{File.basename($PROGRAM_NAME)} [options]"
  parser.on('-p', '--platform INDEX', Integer, 'Index of the platform to use (default 0)')
  parser.on('-d', '--device INDEX', Integer, 'Index of the device to use (default 0)')
end.parse!(into: options)

require 'opencl_ruby_ffi'
require 'narray_ffi'

kernel_string = <<~CLC
  kernel void CopyBuffer( global uint* dst, global uint* src )
  {
      uint id = get_global_id(0);
      dst[id] = src[id];
  }
CLC

buffer_size = 1024 * 1024

p = OpenCL.platforms[options[:platform]]
raise "Invalid platform index #{options[:platform]}" unless p

d = p.devices[options[:device]]
raise "Invalid device index #{options[:device]}" unless d

puts "Running on platform: #{p.name}"
puts "Running on device: #{d.name}"

begin
  c = OpenCL.create_context(d)
  q = c.create_command_queue(d)

  program = c.create_program_with_source(kernel_string)
  program.build
  device_src = c.create_buffer(buffer_size * OpenCL::UInt.size, flags: OpenCL::Mem::ALLOC_HOST_PTR)
  device_dst = c.create_buffer(buffer_size * OpenCL::UInt.size, flags: OpenCL::Mem::ALLOC_HOST_PTR)

  _, host_ptr = q.enqueue_map_buffer(device_src, OpenCL::MapFlags::WRITE_INVALIDATE_REGION, blocking: true)
  arr = NArray.to_na(host_ptr, NArray::INT)
  buffer_size.times { |i| arr[i] = i }
  q.enqueue_unmap_mem_object(device_src, host_ptr)

  program.CopyBuffer(q, [buffer_size], device_dst, device_src)

  _, host_ptr = q.enqueue_map_buffer(device_dst, OpenCL::MapFlags::READ, blocking: true)
  arr = NArray.to_na(host_ptr, NArray::INT)
  buffer_size.times do |i|
    raise "invalid copy: wanted #{i}, got #{arr[i]}" unless arr[i] == i
  end
  q.enqueue_unmap_mem_object(device_dst, host_ptr)

  puts 'Success.'
rescue OpenCL::Error::BUILD_PROGRAM_FAILURE
  puts 'Compilation of program failed:'
  program.build_log.each do |device, log|
    puts " - #{device.name}:"
    puts log
  end
  puts 'Expected Failure on MacOS...'
end