#include <stdio.h>
#include <errno.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>
#include <dirent.h>
#include <sys/stat.h>

unsigned int h_flag;
unsigned int s_flag;
unsigned int b_flag;
unsigned int m_flag;
unsigned int L_flag;

void print(long size, const char *filename) {
	/* Kb */
	if (!b_flag)
		size = size / 1024;

	/* Mb */
	else if (m_flag)
		size = size / 1048576;

	printf("%ld\t%s\n", size, filename);
}

long du(const char *path, int recurs_flag) {
	long sum;

	struct stat sb;
	if (lstat(path, &sb) != 0) {
		fprintf(stderr, "du: lstat() %s\n", strerror(errno));
		return 0;
	}

	if (S_ISDIR(sb.st_mode)) {
		DIR *dp = opendir(path);
		if (!dp) {
			fprintf(stderr, "du: %s\n", strerror(errno));
			return 0;
		}

		struct dirent *ep;
		while ((ep = readdir(dp)) != NULL) {
			if (!strcmp(ep->d_name, ".") || !strcmp(ep->d_name, ".."))
				continue;

			size_t len = strlen(path) + strlen(ep->d_name) + 2;
			char *new_path = malloc(len + 1);
			if (new_path == NULL)
				continue;

			snprintf(new_path, len, "%s/%s", path, ep->d_name);

			sum += du(new_path, 1);

			free(new_path);
		}

		closedir(dp);

		if (s_flag)
			if (!recurs_flag) {
				print(sum, path);
		}

		else
			print(sum, path);
	}

	else {
		sum = sb.st_size;
		if (!recurs_flag)
			print(sum, path);
	}

	return sum;
}

int main(const int argc, const char **argv) {

	int i;
	for (i = 1; i < argc; i++) {
		if (argv[i][0] != '-')
			break;

		else if (!strcmp(argv[i], "-h"))
			h_flag = 1;

		else if (!strcmp(argv[i], "-s"))
			s_flag = 1;

		else if (!strcmp(argv[i], "-b"))
			b_flag = 1;

		else if (!strcmp(argv[i], "-m")) {
			b_flag = 1;
			m_flag = 1;
		}

		else if (!strcmp(argv[i], "-L"))
			L_flag = 1;

		else if (!strcmp(argv[i], "--help")) {
			printf("du [-h (Sizes in human readable format (e.g., 1K 243M 2G))] [-s (Display only a total for each argument)] [-b (Apparent size)] [-L (Follow all symlinks)] [-m (Size in megabyte)] [file file2...]\n");
			return 0;
		}
	}

	if (argc - i == 0)
		du(".", 0);

	else
		for (; i < argc; i++)
			du(argv[i], 0);

	return 0;
}