#include <unistd.h>
#include <sys/inotify.h>
#include <iostream>
#include <string>

using namespace std;

void process_event(const string &name, int event) {
    string msg;
    switch (event) {
    case IN_ACCESS:        msg = "was read";                          break;
    case IN_ATTRIB:        msg = "metadata changed";                  break;
    case IN_CLOSE_WRITE:   msg = "opened for writing was closed";     break;
    case IN_CLOSE_NOWRITE: msg = "opened for reading was closed";     break;
    case IN_CREATE:        msg = "created in watched directory";      break;
    case IN_DELETE:        msg = "deleted from watched directory";    break;
    case IN_DELETE_SELF:   msg = "was itself deleted";                break;
    case IN_MODIFY:        msg = "was modified";                      break;
    case IN_MOVE_SELF:     msg = "was itself moved";                  break;
    case IN_MOVED_FROM:    msg = "moved out of watched directory";    break;
    case IN_MOVED_TO:      msg = "moved into watched directory";      break;
    case IN_OPEN:          msg = "was opened";                        break;
    case IN_ISDIR:         return;  // Ignore this one
    default:		   cerr << "Unknown event " << hex << event << '\n';
    }
    cout << name << ' ' << msg << '\n';
}


void get_events(int fd, const string &target)
{
    /* Allow for 1024 simultaneous events */
    const int BUFF_SIZE = (sizeof(inotify_event)+FILENAME_MAX)*1024;
    char buff[BUFF_SIZE];
    inotify_event *pevent;
    const ssize_t len = read(fd, buff, BUFF_SIZE);

    for (ssize_t i=0; i<len; i += sizeof(inotify_event) + pevent->len) {
	pevent = reinterpret_cast<inotify_event *>(&buff[i]);
	string label = (pevent->len) ? pevent->name : target;
	int mask = pevent->mask;
	for (int bit = 1; mask != 0; bit <<= 1) {
	    if (mask & bit)
		process_event(label, bit);
	    mask &= ~bit;
	}
    }
}


int main (int argc, char *argv[])
{
    const string target = argc < 2 ? "." : argv[1];
    cout << "Watching " << target << '\n';

    int fd = inotify_init();
    if (fd < 0) {
	cerr << argv[0] << ": can't inotify_init()\n";
	return 1;
    }

    if (inotify_add_watch(fd, target.c_str(), IN_ALL_EVENTS) < 0) {
	cerr << argv[0] << ": can't inotify_add_watch()\n";
	return 1;
    }

    for (;;)
	get_events(fd, target);

    return 0;
}