/*
    inotifyrun
    Copyright (C) 2020  niansa

    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <errno.h>
#include <sys/stat.h>
#include <sys/inotify.h>
#include <linux/fs.h>
#include "license.h"
#include "libcatch/libcatch.h"

struct fcmd_pair {
	const char *fname;
	const char *command;
};
struct fcmdwatcher_pair {
	struct fcmd_pair *pair;
	int watcher;
};


int main(int argc, char **argv) {
	int inotifier;
	libcatch_init();
	// Check arguments
	if (argc == 2 && strcmp(argv[1], "--license") == 0) {
		// License requested
		puts(gpl3);
		return EXIT_SUCCESS;
	} else if (argc == 1 || (argc - 1) % 2 != 0) {
		// No arguments passed
		printf("Usage: %s [--license] {<file> <command>}\n", argv[0]);
		return EXIT_FAILURE;
	}
	// Initialise inotify
	CATCH1(
		inotifier = inotify_init()
	);
	// Get array of files and commands
	libcatch_behavior = 0;
	struct fcmd_pair *assocs = (struct fcmd_pair *)(argv + 1);
	struct fcmdwatcher_pair *assocs_watches;
	struct fcmdwatcher_pair *watcherpair_ptr;
	CATCH1(assocs_watches = malloc((sizeof(struct fcmdwatcher_pair) * ((argc - 1) / 2)) + 1));
	// Initlialise inotify further while checking if all files are actual files
	libcatch_behavior = 2;
	for (struct fcmd_pair *thispair = assocs; *(char**)thispair; thispair++) {
		// Check if file is an actual file
		struct stat fname_stat;
		stat(thispair->fname, &fname_stat);
		if (S_ISDIR(fname_stat.st_mode)) {
			fprintf(stderr, "'%s' is a directory and will be ignored.\n", thispair->fname);
			continue;
		}
		// Initialise inotify further
		watcherpair_ptr = &assocs_watches[thispair - assocs];
		watcherpair_ptr->pair = thispair;
		CATCH1(
			watcherpair_ptr->watcher = inotify_add_watch(inotifier, thispair->fname, IN_OPEN)
		);
	}
	// Wait for events to occur
	libcatch_behavior = 1;
	struct inotify_event thisevent;
	while (1) {
		// Read new event
		CATCH1(
			read(inotifier, &thisevent, sizeof(thisevent) + NAME_MAX + 1)
		);
		// Find associated event pair
		for (
		     watcherpair_ptr = assocs_watches;
		     watcherpair_ptr->watcher != thisevent.wd;
		     watcherpair_ptr++
		);
		// Run assiciated command
		system(watcherpair_ptr->pair->command);
	}
}