#include <stdio.h>
#include <errno.h>
#include <fcntl.h>
#include <libgen.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>
#include <dirent.h>
#include <sys/mman.h>
#include <sys/stat.h>

char *make_path(const char *src, const char *dst) {
	size_t len = strlen(src) + strlen(dst) + 2;
	char *full_path = malloc(len + 1);
	if (full_path == NULL) {
		fprintf(stderr, "cp: malloc() returned NULL\n");
		return NULL;
	}

	snprintf(full_path, len, "%s/%s", src, dst);
	return full_path;
}

int write_buffer(int ifd, int ofd) {
	char buf[4096];
	size_t bytes = 0;
	while ((bytes = read(ifd, buf, sizeof(buf))) > 0)
		if (write(ofd, buf, bytes) != bytes)
			return 1;

	return 0;

}

int copy(const char *src, const char *dst) {
	int ifd = open(src, O_RDONLY);
	if (ifd < 0)
		return 1;

	int ofd = open(dst, O_CREAT | O_TRUNC | O_WRONLY, 0666);
	if (ofd < 0) {
		close(ifd);
		return 1;
	}

	if (write_buffer(ifd, ofd))
		fprintf(stderr, "cp: (%s %s) %s\n", src, dst, strerror(errno));

	close(ifd);
	close(ofd);
	return 0;
}

int get_stat(const char *path, struct stat *stat_path) {
	if (stat(path, stat_path)) {
		fprintf(stderr, "cp: unable to stat %s: %s\n", path, strerror(errno));
		return 1;
	}

	return 0;
}

int cptree(const char *src, const char *dst) {
	struct stat stat_path;
	get_stat(src, &stat_path);

	printf("%s %s\n", src, dst);
	if (S_ISDIR(stat_path.st_mode) == 0) {
		if (copy(src, dst)) {
			fprintf(stderr, "cp: %s: copy() failed (%s)\n", src, strerror(errno));
			return 1;
		}

		return 0;
	}

	else if (mkdir(dst, 0777) < 0) {
		fprintf(stderr, "cp: %s\n", strerror(errno));
	}

	DIR *dir = opendir(src);
	if (dir == NULL) {
		fprintf(stderr, "cp: %s: Can`t open directory\n", src);
		return 1;
        }

	struct dirent *ep;
	while ((ep = readdir(dir)) != NULL) {
		if (!strcmp(ep->d_name, ".") || !strcmp(ep->d_name, ".."))
			continue;

		char *src_path = make_path(src, ep->d_name);
		if (src_path == NULL)
			return 1;

		char *dst_path = make_path(dst, ep->d_name);
		if (dst_path == NULL)
			return 1;

		cptree(src_path, dst_path);

		free(src_path);
		free(dst_path);
	}

	closedir(dir);
	return 0;
}

int main(const int argc, const char **argv) {
	if (argc < 2 || !strcmp(argv[1], "-h")) {
		printf("cp [Src] [Dst]\n");
		return 0;
	}

	return cptree(argv[1], argv[2]);
}