#include <stdio.h>
#include <dirent.h>
#include <sys/stat.h>
#include <string.h>
#include <stdint.h>
#include <unistd.h>
enum {PATH_LENGTH=256};

#define STR255 "%255s"

void convert_path_to_full(char *full_path, const char *dir) {
    if(dir[0]=='/') {
        strcpy(full_path, dir);
    } else if (dir[0]=='.') {
        getcwd(full_path,PATH_LENGTH);
    }
    else {
        getcwd(full_path,PATH_LENGTH);
        strcat(full_path, "/");
        strcat(full_path, dir);
    }
    if(full_path[strlen(full_path)-1] !='/')
        strcat(full_path,"/");// добавляем / в конце
}
/*
void print_filetype(int type) {
    switch (type) {
        case DT_BLK:  printf("b "); break;
        case DT_CHR:  printf("c "); break;
        case DT_DIR:  printf("d "); break; //directory
        case DT_FIFO:  printf("p "); break; //fifo
        case DT_LNK:  printf("l "); break; //Sym link
        case DT_SOCK: printf("s "); break; //Filetype isn't identified
        default:       printf("  "); break;
    }
}
*/
/**
 Расширить  строку пробелами.
 @print_lenth длина до которой надо расширить
*/
void print_space(int print_lenth, int str_lenth) {
    while( (print_lenth - str_lenth)>0 ) {
        putchar(' ');
        str_lenth++;
    }
}
void print_tab(int tab_number) {
    for(int t=1; t<tab_number; t++) {
        putchar('\t');
    }
}

void print_file_size(long long int byte_number) {
    if(byte_number/(1024*1024))
        printf("%lld Mb", byte_number/(1024*1024));
    else if(byte_number/1024)
        printf("%lld Kb", byte_number/1024);
    else
        printf("%lld b", byte_number);
}

void ls(const char *dir) {
    static int tab_count = 0; //уровень вложенности рекурсии
    tab_count++;
    struct stat file_stats;
    DIR *folder;
    struct dirent *entry;
    int files_number = 0;
    char full_path[PATH_LENGTH]= {0};
    convert_path_to_full(full_path, dir);
    folder = opendir(full_path);
    if(folder == NULL) {
        perror("Unable to read directory");
        printf("%s\n",full_path);
        return;
    }
    while( (entry=readdir(folder)) ) {
        if( entry->d_name[0]=='.' )// пропускаем поддиректории
            continue;
        char full_filename[PATH_LENGTH]= {0};
        files_number++;
        print_tab(tab_count);//отступы при рекурсии
        printf("%4d : ",files_number);
        //print_filetype(entry->d_type);
        //не работает для Windows
        strcpy(full_filename, full_path);
        strcat(full_filename, entry->d_name);
        printf("%s", entry->d_name);
        print_space(20, entry->d_namlen);
        if (!stat(full_filename, &file_stats)) {
            print_file_size(file_stats.st_size);
            printf("\n");
        }
        else {
            printf("stat failed for this file\n");
            perror(0);
        }
    }
    closedir(folder);
    tab_count--;
}

int main(int argc, char *argv[]) {
    char dir[PATH_LENGTH], buf[PATH_LENGTH];
    int rez=0;
    //    opterr=0;
    while ( (rez = getopt(argc,argv,"hf:")) != -1) {
        switch (rez) {
        case 'h':
            printf("This is example of list directory\n");
            printf("Usage: clear [options]\n\
        -h This help text\n\
        -f Specify folder.\n");
            printf("Example: %s -f /tmp\n",argv[0]);
            return 0;
        case 'f': //printf("folder is \"f = %s\".\n",optarg);
            strcpy(dir, optarg);
            convert_path_to_full(buf, dir);
            printf("ls for folder %s\n",buf);
            ls(dir);
            return 0;
            break;
        case '?':
            printf("Unknown argument: %s Try -h for help\n", argv[optind-1]);
            return 1;
        };
    };
    printf("-h help text\n");
    return 0;
}