#include <iostream>
#include <boost/asio.hpp>
#include <boost/bind.hpp>
#include <sys/inotify.h>

namespace asio = boost::asio;

struct test_inotify_asio
{
	asio::io_service io_svc;
	asio::posix::stream_descriptor stream_desc;
	std::string file_path;
	int raw_fd;
	int watch_fd;
	asio::streambuf buf;

	test_inotify_asio(const std::string & file_path_)
	: stream_desc(io_svc),
	  file_path(file_path_),
	  buf(1024)
	{
		if(0 < (raw_fd = inotify_init()))
		{
			if(0 > (watch_fd = inotify_add_watch
					   (raw_fd,
					    file_path.c_str(),
					    IN_MODIFY | IN_ACCESS | IN_CREATE | IN_DELETE | IN_OPEN)))
			{
				throw std::runtime_error("Unable to add watch on: " +
							 file_path);
			}
		}
		else
		{
			throw std::runtime_error("Unable to initialize inotify");
		}

		stream_desc.assign(raw_fd);

		start_notify_handler();
	};

	void start_notify_handler()
	{
	  stream_desc
	  .async_read_some(buf.prepare(buf.max_size()),
				       boost::bind
				              (&test_inotify_asio::notify_handler,
				               this,
				    	       asio::placeholders::error,
				    	       asio::placeholders::bytes_transferred));
	}

	void notify_handler(const boost::system::error_code&,
	                    std::size_t transferred)
	{
	  size_t processed = 0;

	  while(transferred - processed >= sizeof(inotify_event))
	  {
		  const char* cdata = processed + asio::buffer_cast<const char*>(buf.data());

		  const inotify_event* ievent = reinterpret_cast<const inotify_event*>(cdata);

		  processed += sizeof(inotify_event) + ievent->len;

		  if(ievent->len > 0 && ievent->mask & IN_MODIFY)
		  {
			  std::cout << "File modified: "
			  	    << file_path
			  	    << "[" << ievent->name << "]\n";
		  }
		  else if(ievent->len > 0 && ievent->mask & IN_ACCESS)
		  {
			  std::cout << "File accessed: "
			  	    << file_path
			  	    << "[" << ievent->name << "]\n";
		  }
		  else if(ievent->len > 0 && ievent->mask & IN_OPEN)
		  {
		    	  std::cout << "File opened: "
			  	    << file_path
			  	    << "[" << ievent->name << "]\n";
		  }
		  else if(ievent->len > 0 && ievent->mask & IN_CREATE)
		  {
			  std::cout << "File created: "
			  	    << file_path
			  	    << "[" << ievent->name << "]\n";
		  }
		  else if(ievent->len > 0 && ievent->mask & IN_DELETE)
		  {
		    	  std::cout << "File deleted: "
		    	  	    << file_path
		    	  	    << "[" << ievent->name << "]\n";
		  }
	  }

	  start_notify_handler();
	}

	void operator()()
	{
		io_svc.run();
	}

	~test_inotify_asio()
	{
		inotify_rm_watch(raw_fd, watch_fd);

		close(raw_fd);
	}
};

int main()
{
	test_inotify_asio tia("/abs/path/to/file");

	tia();
}