#include <stdio.h>
 #include <string.h>
 #include <stdlib.h>
 #include <sys/types.h>
 #include <dirent.h> // за struct dirent, readdir(dp)
 #include <sys/stat.h>  // за fstat
 #include <unistd.h>
 #include <fcntl.h>
 #include <sys/ioctl.h> // за winsize struct
 #include <pwd.h>
 #include <grp.h>
 #include <time.h>

#ifdef HAVE_ST_BIRTHTIME
#define birthtime(x) x.st_birthtime
#else
#define birthtime(x) x.st_ctime
#endif

 int main(int argc, char* argv[])
 {
    char *current_dir = NULL;
    DIR *dp = NULL;
    struct dirent *dptr = NULL; // dirent - структура, която връща информация за въведената директория
    unsigned int count = 0;
    long *ptr = NULL;
    struct winsize w; //  w =  screen_size
	int num_files = 0; //Променлива, която държи броя файлове в текущата директория
	char arguments;

	//ioctl(STDOUT_FILENO, TIOCGWINSZ, &w); //to get the number of rows and column visible on terminal
	current_dir = getenv("PWD"); //взимаме текущата директория чрез getenv("PWD") ако върне нула значи има грешка

    if(current_dir == NULL)
    {
        printf("\n ERROR : Could not get the working directory\n");
        return -1;
    }

	if (strcmp(argv[1], "ls") == 0 && argc == 2)
	{
		dp = opendir((const char*)current_dir);  // open the directory

		while((dptr = readdir(dp)) != NULL)  //zapochvame da chetem sudurjanieto na direktoriqta
		{
		    if(dptr -> d_name[0] != '.') //ne broi failovete koito zapochvat s '.'
		    {
				num_files++;
			}
		}

		closedir(dp); //zatvarqme q

		dp = NULL;
		dptr = NULL;

		if(!num_files) //proverqvame dali ima failove v direktoriqta
		{
		    return 0;
		}
		else
		{
		    ptr = malloc(num_files*8); //zadelqme pamet za adresine na imenata na sudurjanieto na direktoriqta

		    if(ptr == NULL)
		    {
		        printf("\n Memory allocation failed\n");
		        return -1;
		    }
		    else
		    {
		        memset(ptr, 0, num_files*8); // inicializirame pametta s 0li
		        //ptr - pointer to the block of memory to fill
		        // 0 = value to be set.
		        // 8 = num - number of bytes to be set to the value
		        // num_files - an insigned int type
		    }
		}


		dp = opendir((const char*)current_dir);
		if(dp == NULL)
		{
		    printf("\n ERROR : Could not open the working directory\n");
		    free(ptr);
		    return -1;
		}

		// Start iterating the directory and read all its contents
		// inside an array allocated above.
		unsigned int j = 0;
		for(count = 0; NULL != (dptr = readdir(dp)); count++) // NULL != (dptr = readdir(dp)) ако е различно от NULL значи няма грешка
		{
		    if(dptr->d_name[0] != '.')
		    {
		       ptr[j] = (long)dptr->d_name;
		       j++;
		    }
		}

		// Start displaying on console.
		for(count = 0; count< num_files; count++)
		{
		    // Check if the file/folder is executable.
		    if(!access((const char*)ptr[count],X_OK))
		        {
		            int fd = -1; // fd - file descriptor = индентификатор, който използваме за достъп до даден файл
		            struct stat st;

		            fd = open((char*)ptr[count], O_RDONLY, 0);
		            if(-1 == fd)
		            {
		                printf("\n Opening file/Directory failed\n");
		                free(ptr);
		                return -1;
		            }

		            fstat(fd, &st);
		            if(S_ISDIR(st.st_mode))  // S_ISDIR - проверява дали това е файл или директория
		            {
		                // If folder
		                printf("d %s\n",(char*)ptr[count]);
		            }
		            else
		            {
		                // If executable file
		                printf("%s\n",(char*)ptr[count]);
		            }
		            close(fd);
		        }
		        else
		        {
		            // If normal file, print by the default way(black color)
		            printf("- %s\n",(char*)ptr[count]);
		        }
		}
		printf("\n");
	}

	else if (strcmp(argv[1], "-a") == 0)
	{
		dp = opendir((const char*)current_dir);   // opne the directory

		while((dptr = readdir(dp)) != NULL)  //zapochvame da chetem sudurjanieto na direktoriqta
		{
		    num_files++;
		}

		closedir(dp); // close the directory

		dp = NULL;
		dptr = NULL;

		if(!num_files) //proverqvame dali ima failove v direktoriqta
		{
		    return 0;
		}
		else
		{
		    ptr = malloc(num_files*8); //zadelqme pamet za adresine na imenata na sudurjanieto na direktoriqta

		    if(ptr == NULL)
		    {
		        printf("\n Memory allocation failed\n");
		        return -1;
		    }
		    else
		    {
		        memset(ptr, 0, num_files*8); // Initialize the memory by zeros
		    }
		}

		dp = opendir((const char*)current_dir);

		if(dp == NULL)
		{
		    printf("\n ERROR : Could not open the working directory\n");
		    free(ptr);
		    return -1;
		}

		//Chetem sudurjanieto na direktoriqta
		unsigned int j = 0;
		for(count = 0;(dptr = readdir(dp)) != NULL; count++) // (dptr = readdir(dp)) != NULL ако е различно от NULL значи няма грешка
		{
		       ptr[j] = (long)dptr -> d_name;
		       j++;
		}

		for(count = 0; count< num_files; count++)
		{
		    if(!access((const char*)ptr[count],X_OK))   // Proverqva dali failut/papkata e executable.
		        {
		            int fd = -1; // fd - file descriptor = indetifikator, koito izpolzvame za daden fail
		            struct stat st;

		            fd = open((char*)ptr[count], O_RDONLY, 0);
		            if(fd == -1)
		            {
		                printf("\n Opening file/Directory failed\n");
		                free(ptr);
		                return -1;
		            }

		            fstat(fd, &st);
		            if(S_ISDIR(st.st_mode))  // S_ISDIR - проверява дали това е файл или директория
		            {
		                // If folder
		                printf("d %s\n",(char*)ptr[count]);
		            }
		            else
		            {
		                // If executable file
		                printf("%s\n",(char*)ptr[count]);
		            }
		            close(fd);
		        }
		        else
		        {
		            // If normal file, print by the default way(black color)
		            printf("- %s\n",(char*)ptr[count]);
		        }
		}
		printf("\n");
	}
	else if (strcmp(argv[1], "-l") == 0)
	{
		dp = opendir((const char*)current_dir);  // opne the directory

		while((dptr = readdir(dp)) != NULL)  //zapochvame da chetem sudurjanieto na direktoriqta
		{
		    if(dptr -> d_name[0] != '.') //ne broi failovete koito zapochvat s '.'
		    {
				num_files++;
			}
		}

		closedir(dp); //zatvarqme q

		dp = NULL;
		dptr = NULL;

		if(!num_files) //proverqvame dali ima failove v direktoriqta
		{
		    return 0;
		}
		else
		{
		    ptr = malloc(num_files*8); //zadelqme pamet za adresine na imenata na sudurjanieto na direktoriqta

		    if(ptr == NULL)
		    {
		        printf("\n Memory allocation failed\n");
		        return -1;
		    }
		    else
		    {
		        memset(ptr, 0, num_files*8); // inicializirame pametta s 0li
		        //ptr - pointer to the block of memory to fill
		        // 0 = value to be set.
		        // 8 = num - number of bytes to be set to the value
		        // num_files - an insigned int type
		    }
		}


		dp = opendir((const char*)current_dir);
		if(dp == NULL)
		{
		    printf("\n ERROR : Could not open the working directory\n");
		    free(ptr);
		    return -1;
		}

		// Start iterating the directory and read all its contents
		// inside an array allocated above.
		unsigned int j = 0;
		for(count = 0; NULL != (dptr = readdir(dp)); count++) // NULL != (dptr = readdir(dp)) ако е различно от NULL значи няма грешка
		{
		    if(dptr->d_name[0] != '.')
		    {
		       ptr[j] = (long)dptr->d_name;
		       j++;
		    }
		}

		// Start displaying on console.
		for(count = 0; count< num_files; count++)
		{

		    // Check if the file/folder is executable.
		    if(!access((const char*)ptr[count],X_OK))
		        {
		            int fd = -1; // fd - file descriptor = индентификатор, който използваме за достъп до даден файл
		            struct stat st;

		            fd = open((char*)ptr[count], O_RDONLY, 0);
		            if(-1 == fd)
		            {
		                printf("\n Opening file/Directory failed\n");
		                free(ptr);
		                return -1;
		            }

		            fstat(fd, &st);
		            if(S_ISDIR(st.st_mode))  // S_ISDIR - проверява дали това е файл или директория
		            {
		                // If folder


						printf( (S_ISDIR(st.st_mode)) ? "d" : "-");
						printf( (st.st_mode & S_IRUSR) ? "r" : "-");
						printf( (st.st_mode & S_IWUSR) ? "w" : "-");
						printf( (st.st_mode & S_IXUSR) ? "x" : "-");
						printf( (st.st_mode & S_IRGRP) ? "r" : "-");
						printf( (st.st_mode & S_IWGRP) ? "w" : "-");
						printf( (st.st_mode & S_IXGRP) ? "x" : "-");
						printf( (st.st_mode & S_IROTH) ? "r" : "-");
						printf( (st.st_mode & S_IWOTH) ? "w" : "-");
						printf( (st.st_mode & S_IXOTH) ? "x" : "-"); //permissions

						printf(" %ld",st.st_nlink); //number of links

						uid_t uid = st.st_uid;
						struct passwd *pass = getpwuid(uid);
						printf(" %s",pass -> pw_name); //user

						gid_t gid = st.st_gid;
						struct group *grp = getgrgid(gid);
						printf(" %s", grp -> gr_name); //group

						printf(" %ld",st.st_size); //size

						 struct timeval tv;
						 char str[100];
						 struct tm *tm;

						 tm = localtime( (time_t*)&st.st_mtim );

					    strftime(str, sizeof(str), "%b %d %H:%M", tm);
       				    printf(" %s", str); //date

						printf(" %s\n",(char*)ptr[count]); //file name
		            }
		            else // If executable file
		            {
						//if()
						 printf( (S_ISDIR(st.st_mode)) ? "d" : "-");
						printf( (st.st_mode & S_IRUSR) ? "r" : "-");
						printf( (st.st_mode & S_IWUSR) ? "w" : "-");
						printf( (st.st_mode & S_IXUSR) ? "x" : "-");
						printf( (st.st_mode & S_IRGRP) ? "r" : "-");
						printf( (st.st_mode & S_IWGRP) ? "w" : "-");
						printf( (st.st_mode & S_IXGRP) ? "x" : "-");
						printf( (st.st_mode & S_IROTH) ? "r" : "-");
						printf( (st.st_mode & S_IWOTH) ? "w" : "-");
						printf( (st.st_mode & S_IXOTH) ? "x" : "-"); //permissions

						printf(" %ld",st.st_nlink); //number of links

						uid_t uid = st.st_uid;
						struct passwd *pass = getpwuid(uid);
						printf(" %s",pass -> pw_name); //user

						gid_t gid = st.st_gid;
						struct group *grp = getgrgid(gid);
						printf(" %s", grp -> gr_name); //group

						printf(" %ld",st.st_size); //size

						 struct timeval tv;
						 char str[100];
						 struct tm *tm;

						 tm = localtime( (time_t*)&st.st_mtim );

					    strftime(str, sizeof(str), "%b %d %H:%M", tm);
       				    printf(" %s", str); //date

						printf("- %s\n",(char*)ptr[count]);
		            }
		            close(fd);
		        }
		        else // If normal file
		        {
						int fd = -1; // fd - file descriptor = индентификатор, който използваме за достъп до даден файл
		            struct stat st;

		            fd = open((char*)ptr[count], O_RDONLY, 0);
		            if(-1 == fd)
		            {
		                printf("\n Opening file/Directory failed\n");
		                free(ptr);
		                return -1;
		            }

		            fstat(fd, &st);

					printf( (S_ISDIR(st.st_mode)) ? "d" : "-");
						printf( (st.st_mode & S_IRUSR) ? "r" : "-");
						printf( (st.st_mode & S_IWUSR) ? "w" : "-");
						printf( (st.st_mode & S_IXUSR) ? "x" : "-");
						printf( (st.st_mode & S_IRGRP) ? "r" : "-");
						printf( (st.st_mode & S_IWGRP) ? "w" : "-");
						printf( (st.st_mode & S_IXGRP) ? "x" : "-");
						printf( (st.st_mode & S_IROTH) ? "r" : "-");
						printf( (st.st_mode & S_IWOTH) ? "w" : "-");
						printf( (st.st_mode & S_IXOTH) ? "x" : "-"); //permissions

						printf(" %ld",st.st_nlink); //number of links

						uid_t uid = st.st_uid;
						struct passwd *pass = getpwuid(uid);
						printf(" %s",pass -> pw_name); //user

						gid_t gid = st.st_gid;
						struct group *grp = getgrgid(gid);
						printf(" %s", grp -> gr_name); //group

						printf(" %ld",st.st_size); //size

						 struct timeval tv;
						 char str[100];
						 struct tm *tm;

						 tm = localtime( (time_t*)&st.st_mtim );

					    strftime(str, sizeof(str), "%b %d %H:%M", tm);
       				    printf(" %s", str); //date

						printf(" %s\n",(char*)ptr[count]); //file name
		        }
		}
		printf("\n");
	}
	else if (strcmp(argv[1], "ls") == 0 && strcmp(argv[2], "-R") == 0)
	{
		printf("LS -R\n");
	}

	else { printf("ls: cannot access %s: No such file or directory\n", argv[2]); }

    free(ptr);  //Free the allocated memory
    return 0;
 }