/* See LICENSE file for copyright and license details. */
#include <dirent.h>
#include <errno.h>
#include <grp.h>
#include <pwd.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include <unistd.h>
#include <sys/stat.h>
#include "util.h"

typedef struct {
	char *name;
	mode_t mode;
	nlink_t nlink;
	uid_t uid;
	gid_t gid;
	off_t size;
	time_t mtime;
} Entry;

static int entcmp(Entry *, Entry *);
static void ls(char *);
static void lsdir(const char *);
static void mkent(Entry *, char *);
static void output(Entry *);

static bool aflag = false;
static bool dflag = false;
static bool lflag = false;
static bool tflag = false;
static bool first = true;
static bool many;

static void
usage(void)
{
	eprintf("usage: %s [-adlt] [FILE...]\n", argv0);
}

int
main(int argc, char *argv[])
{
	int i, n;
	Entry *ents;

	ARGBEGIN {
	case 'a':
		aflag = true;
		break;
	case 'd':
		dflag = true;
		break;
	case 'l':
		lflag = true;
		break;
	case 't':
		tflag = true;
		break;
	default:
		usage();
	} ARGEND;

	many = (argc > 1);

	if((n = argc) > 0) {
		if(!(ents = malloc(n * sizeof *ents)))
			eprintf("malloc:");
		for(i = 0; i < n; i++)
			mkent(&ents[i], argv[i]);
		qsort(ents, n, sizeof *ents,
				(int (*)(const void *, const void *))entcmp);
		for(i = 0; i < n; i++)
			ls(ents[i].name);
	}
	else
		ls(".");

	return 0;
}

int
entcmp(Entry *a, Entry *b)
{
	if(tflag)
		return b->mtime - a->mtime;
	else
		return strcmp(a->name, b->name);
}

void
ls(char *path)
{
	Entry ent;

	mkent(&ent, path);
	if(S_ISDIR(ent.mode) && !dflag)
		lsdir(path);
	else
		output(&ent);
}

void
lsdir(const char *path)
{
	char *cwd, *p;
	long i, n = 0;
	struct dirent *d;
	DIR *dp;
	Entry *ents = NULL;

	cwd = agetcwd();
	if(!(dp = opendir(path)))
		eprintf("opendir %s:", path);
	if(chdir(path) == -1)
		eprintf("chdir %s:", path);

	while((d = readdir(dp))) {
		if(d->d_name[0] == '.' && !aflag)
			continue;
		if(!(ents = realloc(ents, ++n * sizeof *ents)))
			eprintf("realloc:");
		if(!(p = malloc(strlen(d->d_name)+1)))
			eprintf("malloc:");
		strcpy(p, d->d_name);
		mkent(&ents[n-1], p);
	}
	closedir(dp);
	qsort(ents, n, sizeof *ents, (int (*)(const void *, const void *))entcmp);

	if(many) {
		if(!first)
			putchar('\n');
		printf("%s:\n", path);
		first = false;
	}
	for(i = 0; i < n; i++) {
		output(&ents[i]);
		free(ents[i].name);
	}
	if(chdir(cwd) == -1)
		eprintf("chdir %s:", cwd);
	free(ents);
	free(cwd);
}

void
mkent(Entry *ent, char *path)
{
	struct stat st;

	if(lstat(path, &st) == -1)
		eprintf("lstat %s:", path);
	ent->name   = path;
	ent->mode   = st.st_mode;
	ent->nlink  = st.st_nlink;
	ent->uid    = st.st_uid;
	ent->gid    = st.st_gid;
	ent->size   = st.st_size;
	ent->mtime  = st.st_mtime;
}

void
output(Entry *ent)
{
	char buf[BUFSIZ], *fmt;
	char mode[] = "----------";
	ssize_t len;
	struct group *gr;
	struct passwd *pw;

	if(!lflag) {
		puts(ent->name);
		return;
	}
	if(S_ISREG(ent->mode))
		mode[0] = '-';
	else if(S_ISBLK(ent->mode))
		mode[0] = 'b';
	else if(S_ISCHR(ent->mode))
		mode[0] = 'c';
	else if(S_ISDIR(ent->mode))
		mode[0] = 'd';
	else if(S_ISFIFO(ent->mode))
		mode[0] = 'p';
	else if(S_ISLNK(ent->mode))
		mode[0] = 'l';
	else if(S_ISSOCK(ent->mode))
		mode[0] = 's';
	else
		mode[0] = '?';

	if(ent->mode & S_IRUSR) mode[1] = 'r';
	if(ent->mode & S_IWUSR) mode[2] = 'w';
	if(ent->mode & S_IXUSR) mode[3] = 'x';
	if(ent->mode & S_IRGRP) mode[4] = 'r';
	if(ent->mode & S_IWGRP) mode[5] = 'w';
	if(ent->mode & S_IXGRP) mode[6] = 'x';
	if(ent->mode & S_IROTH) mode[7] = 'r';
	if(ent->mode & S_IWOTH) mode[8] = 'w';
	if(ent->mode & S_IXOTH) mode[9] = 'x';

	if(ent->mode & S_ISUID) mode[3] = (mode[3] == 'x') ? 's' : 'S';
	if(ent->mode & S_ISGID) mode[6] = (mode[6] == 'x') ? 's' : 'S';

	errno = 0;
	pw = getpwuid(ent->uid);
	if(errno)
		eprintf("getpwuid %d:", ent->uid);
	else if(!pw)
		eprintf("getpwuid %d: no such user\n", ent->uid);

	errno = 0;
	gr = getgrgid(ent->gid);
	if(errno)
		eprintf("getgrgid %d:", ent->gid);
	else if(!gr)
		eprintf("getgrgid %d: no such group\n", ent->gid);

	if(time(NULL) > ent->mtime + (180*24*60*60)) /* 6 months ago? */
		fmt = "%b %d  %Y";
	else
		fmt = "%b %d %H:%M";

	strftime(buf, sizeof buf, fmt, localtime(&ent->mtime));
	printf("%s %2ld %-4s %-5s %6lu %s %s", mode, (long)ent->nlink, pw->pw_name,
	       gr->gr_name, (unsigned long)ent->size, buf, ent->name);
	if(S_ISLNK(ent->mode)) {
		if((len = readlink(ent->name, buf, sizeof buf)) == -1)
			eprintf("readlink %s:", ent->name);
		buf[len] = '\0';
		printf(" -> %s", buf);
	}
	putchar('\n');
}