#include "command.h"
#include "lslib.h"

#include <grp.h>
#include <pwd.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <errno.h>

static void help (void) {
    printf("Usage: groups [USER]\n\n");
    printf("Print the groups USER is in\n");
}

COMMAND(groups_main) {

    uid_t uid;
    int ngroups, i;
    gid_t* groups;
    struct passwd* pw;

    parse_help(argc, argv, help);
    
    if (argc < 1) {
        uid = getuid();
        pw = getpwuid(uid);
    } else {
        pw = getpwnam(argv[0]);
    }

    if(pw == NULL){
        if (errno == 0) {
            error("user not found");
        } else {
            error("failed to fetch groups");
        }
    }
    
    ngroups = 0;
    getgrouplist(pw->pw_name, pw->pw_gid, NULL, &ngroups);
    
    groups = xalloc(sizeof(gid_t) * ngroups);
    getgrouplist(pw->pw_name, pw->pw_gid, groups, &ngroups);
   
    for (i = 0; i < ngroups; i++){
        struct group* gr = getgrgid(groups[i]);

        if(gr == NULL) {
            free(groups);
            error("failed to fetch groups");
        }

        printf("%s ",gr->gr_name);
    }

    printf("\n");

    free(groups);

    return EXIT_SUCCESS;
}