#include "dir.h"

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

#define DEFAULT_BUFFER_SIZE 4096

static void dirent_convert(const struct dentry *in, struct dirent *out)
{
	out->d_ino = in->d_ino;
	out->d_type = in->d_type;
	out->d_reclen = in->d_reclen;
	strncpy(out->d_name, in->d_name, sizeof out->d_name - 1);
	out->d_name[sizeof out->d_name - 1] = 0;
}

int __libc_dir_refill(struct __opaque_dir *d)
{
	if (d->d_fd < 0) {
		return EBADF;
	}

	if (d->d_flags & DIR_ERR) {
		return EIO;
	}

	if (d->d_flags & DIR_EOF) {
		return SUCCESS;
	}

	if (!d->d_buf) {
		d->d_buf_max = DEFAULT_BUFFER_SIZE;
		d->d_buf = malloc(d->d_buf_max);
		if (!d->d_buf) {
			d->d_buf_max = 0;
			return ENOMEM;
		}
	}

	long r = getdents(d->d_fd, (struct dentry *)d->d_buf, d->d_buf_max);
	if (r < 0) {
		return -r;
	}

	d->d_buf_datalen = r;

	if (r > 0) {
		struct dentry *dent
			= (struct dentry *)(d->d_buf + d->d_buf_readptr);
		dirent_convert(dent, &d->d_current);
	}

	return SUCCESS;
}

int __libc_dir_move_next(struct __opaque_dir *d)
{
	if (d->d_fd < 0) {
		return -EBADF;
	}

	if (d->d_flags & DIR_ERR) {
		return -EIO;
	}

	if (d->d_flags & DIR_EOF) {
		return -SUCCESS;
	}

	d->d_buf_readptr += d->d_current.d_reclen;
	if (d->d_buf_readptr >= d->d_buf_datalen) {
		return 0;
	}

	struct dentry *dent = (struct dentry *)(d->d_buf + d->d_buf_readptr);
	dirent_convert(dent, &d->d_current);

	return 1;
}