/*
 * Copyright (C) 2023  Patrick McDermott
 *
 * This file is part of opkg-opk.
 *
 * opkg-opk is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * opkg-opk is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with opkg-opk.  If not, see <https://www.gnu.org/licenses/>.
 */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "defs.h"
#include "dirent.h"

static int
_opkg_opk_dirent_name_prefix(struct opkg_opk_dirent *dirent, int is_dir,
		char **name_buf, size_t *name_buf_len,
		char **pref_buf, size_t *pref_buf_len,
		size_t *name_len, size_t *pref_len)
{
	size_t   len;
	char   **buf;
	int      sep;
	int      ret;

	len = strlen(dirent->name);
	if ((*name_len > 0 || is_dir) && *name_len + len + 1 <= *name_buf_len) {
		/* Space available in name buffer.  Not last node, or is a
		 * directory, so append separator. */
		buf = name_buf;
		*name_len += len + 1;
		sep = 1;
	} else if (*name_len == 0 && *name_len + len <= *name_buf_len) {
		/* Space available in name buffer.  Last node (first in
		 * recursion), so don't append separator. */
		buf = name_buf;
		*name_len += len;
		sep = 0;
	} else if (*pref_len > 0 && *pref_len + len + 1 <= *pref_buf_len) {
		/* Space available in prefix buffer.  Not last node, so append
		 * separator. */
		buf = pref_buf;
		*pref_len += len + 1;
		sep = 1;
	} else if (*pref_len == 0 && *pref_len + len <= *pref_buf_len) {
		/* Space available in prefix buffer.  Last node (first in
		 * recursion), so don't append separator. */
		buf = pref_buf;
		*pref_len += len;
		sep = 0;
	} else {
		/* Both buffers full. */
		return OPKG_OPK_END;
	}
	if (*buf == NULL) {
		/* Caller provided a NULL buffer pointer. */
		return OPKG_OPK_ERROR;
	}

	/* Recurse. */
	if (dirent->parent != NULL && (ret =
				_opkg_opk_dirent_name_prefix(dirent->parent,
					is_dir, name_buf, name_buf_len,
					pref_buf, pref_buf_len, name_len,
					pref_len)) != OPKG_OPK_OK) {
		return ret;
	}

	/* Copy node name and possibly separator suffix. */
	memcpy(*buf, dirent->name, len);
	*buf += len;
	if (sep == 1) {
		**buf = '/';
		*buf += 1;
	}

	return OPKG_OPK_OK;
}

int
opkg_opk_dirent_name_prefix(struct opkg_opk_dirent *dirent, int is_dir,
		char *name_buf, size_t name_buf_len,
		char *pref_buf, size_t pref_buf_len)
{
	size_t  name_len = 0;
	size_t  pref_len = 0;
	char   *name     = name_buf;
	char   *pref     = pref_buf;
	int     ret;

	/* NUL bytes */
	--name_buf_len;
	--pref_buf_len;

	if ((ret = _opkg_opk_dirent_name_prefix(dirent, is_dir,
					&name_buf, &name_buf_len,
					&pref_buf, &pref_buf_len,
					&name_len, &pref_len)) != OPKG_OPK_OK) {
		return ret;
	}

	name[name_len] = '\0';
	pref[pref_len] = '\0';

	return OPKG_OPK_OK;
}

static char *
_opkg_opk_dirent_name_alloc(struct opkg_opk_dirent *dirent, int is_dir,
		char **cur, size_t *buf_len)
{
	size_t  len;
	int     sep;
	char   *buf;

	len = strlen(dirent->name);
	if (*buf_len > 1 /* 1 for NUL */ || is_dir) {
		/* Not last node, or is a directory, so append separator. */
		sep = 1;  /* Used in math below, so must be 1, not just != 0. */
		++len;
	} else {
		/* Last node (first in recursion), so don't append separator. */
		sep = 0;
	}
	*buf_len += len;

	if (dirent->parent == NULL) {
		buf = malloc(*buf_len);
		if (buf == NULL) {
			return NULL;
		}
		*cur = buf;
	} else if ((buf = _opkg_opk_dirent_name_alloc(dirent->parent, is_dir,
					cur, buf_len)) == NULL) {
		return NULL;
	}

	/* Copy node name and possibly separator suffix. */
	memcpy(*cur, dirent->name, len - sep);
	*cur += len - sep;
	if (sep == 1) {
		**cur = '/';
		*cur += 1;
	}

	return buf;
}

char *
opkg_opk_dirent_name_alloc(struct opkg_opk_dirent *dirent, int is_dir)
{
	char   *buf;
	char   *cur     = NULL;
	size_t  buf_len = 1;     /* 1 for NUL */

	if ((buf = _opkg_opk_dirent_name_alloc(dirent, is_dir, &cur, &buf_len))
			== NULL) {
		return NULL;
	}
	*cur = '\0';
	return buf;
}