#include <dirent.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/stat.h>
#include <sys/sysmacros.h>
#include <sys/types.h>
#include <time.h>
#include <unistd.h>

#define NAMELEN 2048
#define BUFSIZE 1024

int main(int argc, char *argv[]) {
    long long max_size = 0;
    char max_name[NAMELEN] = {};

    DIR *dir = opendir(".");
    struct dirent *file = NULL;
    while ((file = readdir(dir)) != NULL) {
        struct stat sb;
        stat(file->d_name, &sb);
        printf("%-30s : %lld bytes\n", file->d_name, (long long)sb.st_size);
        if (sb.st_size > max_size) {
            max_size = sb.st_size;
            strncpy(max_name, file->d_name, NAMELEN);
        }
    }
    closedir(dir);

    printf("Largest file: %s with %lld bytes\n", max_name, max_size);

    char copy_name[NAMELEN];
    snprintf(copy_name, NAMELEN, "%s.copy", max_name);
    printf("Copying %s to %s\n", max_name, copy_name);

    char buf[BUFSIZE];
    int infd = open(max_name, O_RDONLY);
    int flags = O_WRONLY | O_CREAT | O_TRUNC;
    mode_t perms = S_IRUSR | S_IWUSR;
    int outfd = open(copy_name, flags, perms);
    int nbytes;
    while ((nbytes = read(infd, buf, BUFSIZE)) > 0) {
        write(outfd, buf, nbytes);
    }
    printf("Copy complete\n");
    close(infd);
    close(outfd);
    return 0;
}