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


#define FMT_SHIFT 12
#define FMT_BITS 4

int types[1<<FMT_BITS];
char * names[1<<FMT_BITS] = {
	[S_IFREG>>FMT_SHIFT] = "regular file",
	[S_IFDIR>>FMT_SHIFT] = "directory",
	[S_IFCHR>>FMT_SHIFT] = "char device",
	[S_IFBLK>>FMT_SHIFT] = "block deice",
	[S_IFLNK>>FMT_SHIFT] = "symbolic link",
	[S_IFIFO>>FMT_SHIFT] = "fifo",
	[S_IFSOCK>>FMT_SHIFT] = "socket"
};

int bigfiles;
double execsum = 0.0;
int execcount;
int wrong_owner;
int wrong_perms;
int worldwrite;
ino_t mininode; int minset = 0;
ino_t maxinode; int maxset = 0;
int maxlinks;
char * maxlinksname;
int times[27];

int mainuser;
int maingroup;

void examine (char * dir)
{
	DIR * d = opendir (dir);
	int dirlen, val;
	struct stat statbuf;
	struct dirent * dent;
	char * buf;
	if (!d) {
		fprintf (stderr, "Can't read %s: ", dir);
		perror ("opendir");
		return;
	}
	dirlen = strlen (dir);
	buf = malloc (dirlen + FILENAME_MAX+2);
	strcpy (buf, dir);
	while ((dent = readdir (d))) {
		if (strcmp (dent->d_name, ".")  == 0)
			continue;
		if (strcmp (dent->d_name, "..")  == 0)
			continue;
		if (strlen (dent->d_name) > FILENAME_MAX) {
			fprintf (stderr, "Name %s too long\n", dent->d_name);
		}
		buf[dirlen] = '/';
		buf[dirlen+1] = 0;
		strncpy (buf+dirlen+1, dent->d_name, FILENAME_MAX);
		if (lstat (buf, &statbuf) < 0) {
			fprintf (stderr, "Cant' stat %s: ", buf);
			perror ("stat");
		}
		if ((statbuf.st_mode & S_IFMT) == S_IFDIR) {
			examine (buf);
		}
		types[(statbuf.st_mode & S_IFMT) >> FMT_SHIFT]++;
		if (statbuf.st_size > 5*1024*1024)
			bigfiles++;
		if (((statbuf.st_mode & S_IFMT) == S_IFREG)
		    && (statbuf.st_mode & (S_IXUSR|S_IXGRP|S_IXOTH))) {
			execsum += statbuf.st_size;
			execcount++;
		}
		if ((statbuf.st_uid != mainuser)
		    || (statbuf.st_gid != maingroup)) {
			wrong_owner++;
		}
		if (((~(statbuf.st_mode & S_IRWXU) >> 3)
		      & (statbuf.st_mode & S_IRWXG))
		    || ((~(statbuf.st_mode & S_IRWXG) >> 3)
		         & (statbuf.st_mode & S_IRWXO))) {
			 wrong_perms++;
		}
		if (statbuf.st_mode & S_IWOTH)
			worldwrite++;
		if (!minset || (mininode > statbuf.st_ino)) {
			minset = 1;
			mininode = statbuf.st_ino;
		}
		if (!maxset || (maxinode < statbuf.st_ino)) {
			maxset = 1;
			maxinode = statbuf.st_ino;
		}
		if (maxlinks < statbuf.st_nlink) {
			maxlinks = statbuf.st_nlink;
			if (maxlinksname)
				free (maxlinksname);
			maxlinksname = strdup (buf);
		}
		val = 0;
		if (statbuf.st_atime < statbuf.st_ctime)
			val += 1;
		if (statbuf.st_atime > statbuf.st_ctime)
			val += 2;
		if (statbuf.st_atime < statbuf.st_mtime)
			val += 3;
		if (statbuf.st_atime > statbuf.st_mtime)
			val += 6;
		if (statbuf.st_ctime < statbuf.st_mtime)
			val += 9;
		if (statbuf.st_ctime > statbuf.st_mtime)
			val += 18;
		times[val]++;
	}
	free (buf);
	closedir (d);
}

int main ()
{
	struct stat statbuf;
	int i;
	assert (S_IFMT == (((1<<FMT_BITS)-1) << FMT_SHIFT));
	if (lstat (".", &statbuf) < 0) {
		perror ("Can't stat ``.''");
		return 1;
	}
	mainuser = statbuf.st_uid;
	maingroup = statbuf.st_gid;
	examine (".");
	printf ("Filetypes:\n");
	for (i=0; i<(1<<FMT_BITS); ++i) {
		if (types[i]) {
			if (names[i]) {
				printf (" %s: %d\n", names[i], types[i]);
			} else {
				printf ("  unkown (%02d): %d\n",
					i, types[i]);
			}
		}
	}
	printf ("Dateien groesser 5MB: %d\n", bigfiles);
	if (execcount)
		printf ("Durschnittliche Groesse ausfuehrbarer Dateien: %f\n",
			execsum/execcount);
	printf ("Falscher User oder falsche Gruppe: %d\n", wrong_owner);
	printf ("Komische Rechte: %d\n", wrong_perms);
	printf ("Weltweite Schreibrechte: %d\n", worldwrite);
	if (minset) {
		printf ("Kleinste Inode Nummer: %ld\n", mininode);
	}
	if (maxset) {
		printf ("Groesste Inode Nummer: %ld\n", maxinode);
	}
	if (maxlinks) {
		printf ("Groesster Link Count: %s (%d)\n",
			maxlinksname, maxlinks);
	}
	printf ("Zeitstempel:\n");
	for (i=0; i<27; ++i) {
		char sign[] = "=<>";
		if (!times[i])
			continue;
		printf (" atime %c ctime, atime %c mtime, ctime %c mtime: %d\n",
			sign[i%3], sign[(i/3)%3], sign[(i/9)%3], times[i]);
	}
	return 0;
}