/*
 * Copyright 2020 Ryan Kavanagh <rak@rak.ac>
 * Cleanup hosted temporary files
 *
 * Permission to use, copy, modify, and/or distribute this software for
 * any purpose with or without fee is hereby granted, provided that the
 * above copyright notice and this permission notice appear in all
 * copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL
 * WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE
 * AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
 * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA
 * OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
 * TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
 * PERFORMANCE OF THIS SOFTWARE.
 */

#include <sys/types.h>
#include <sys/stat.h>
#include <fts.h>

#include <err.h>
#include <math.h>
#include <stdio.h>
#include <time.h>
#include <unistd.h>

const double mind = 30.0;
const double maxd = 90.0;
const double max_size = 33554432; // 32MB
char* paths[1] = {"/var/www/users/tmp"};

int
main(int argc, char * const argv[])
{
	FTS* file_system;
	FTSENT* node;
	struct stat attr;

	double cutoff = 0;
	double file_age = 0;
	time_t curr_time = time(NULL);

	file_system = fts_open(paths, 0, NULL);

	if (file_system != NULL) {
		while ((node = fts_read(file_system)) != NULL) {
			switch (node->fts_info) {
			case FTS_F:
				if (stat(node->fts_name, &attr) == -1)
					err(1, NULL);
				file_age = difftime(curr_time, attr.st_mtime);
				cutoff = mind + (mind - maxd) * \
					pow((double) attr.st_size / (double) max_size - 1, 3.0);

				if (file_age >= cutoff) {
					// printf("%s age %fs cuttoff %fs size %lld B delete\n", \
					// node->fts_name, file_age, cutoff, attr.st_size);
					unlink(node->fts_name);
				}
				break;
			default:
				break;
			}
		}
	}


	return 0;
}