/*
 * Copyright 2022 The OpenSSL Project Authors. All Rights Reserved.
 *
 * Licensed under the Apache License 2.0 (the "License").  You may not use
 * this file except in compliance with the License.  You can obtain a copy
 * in the file LICENSE in the source distribution or at
 * https://www.openssl.org/source/license.html
 */

#ifndef OSSL_INTERNAL_LIST_H
# define OSSL_INTERNAL_LIST_H
# pragma once

# include <string.h>

/* Define a list structure */
# define OSSL_LIST(name) OSSL_LIST_ ## name

/* Define fields to include an element of a list */
# define OSSL_LIST_MEMBER(name, type)                                       \
    struct {                                                                \
        type *next, *prev;                                                  \
    } ossl_list_ ## name

# define DEFINE_LIST_OF(name, type)                                         \
    typedef struct ossl_list_st_ ## name OSSL_LIST(name);                   \
    struct ossl_list_st_ ## name {                                          \
        type *head, *tail;                                                  \
        size_t num_elems;                                                   \
    };                                                                      \
    static ossl_unused ossl_inline void                                     \
    ossl_list_##name##_init(OSSL_LIST(name) *list)                          \
    {                                                                       \
        memset(list, 0, sizeof(*list));                                     \
    }                                                                       \
    static ossl_unused ossl_inline size_t                                   \
    ossl_list_##name##_num(const OSSL_LIST(name) *list)                     \
    {                                                                       \
        return list->num_elems;                                             \
    }                                                                       \
    static ossl_unused ossl_inline type *                                   \
    ossl_list_##name##_head(const OSSL_LIST(name) *list)                    \
    {                                                                       \
        return list->head;                                                  \
    }                                                                       \
    static ossl_unused ossl_inline type *                                   \
    ossl_list_##name##_tail(const OSSL_LIST(name) *list)                    \
    {                                                                       \
        return list->tail;                                                  \
    }                                                                       \
    static ossl_unused ossl_inline type *                                   \
    ossl_list_##name##_next(const type *elem)                               \
    {                                                                       \
        return elem->ossl_list_ ## name.next;                               \
    }                                                                       \
    static ossl_unused ossl_inline type *                                   \
    ossl_list_##name##_prev(const type *elem)                               \
    {                                                                       \
        return elem->ossl_list_ ## name.prev;                               \
    }                                                                       \
    static ossl_unused ossl_inline void                                     \
    ossl_list_##name##_remove(OSSL_LIST(name) *list, type *elem)            \
    {                                                                       \
        if (list->head == elem)                                             \
            list->head = elem->ossl_list_ ## name.next;                     \
        if (list->tail == elem)                                             \
            list->tail = elem->ossl_list_ ## name.prev;                     \
        if (elem->ossl_list_ ## name.prev != NULL)                          \
            elem->ossl_list_ ## name.prev->ossl_list_ ## name.next =        \
                    elem->ossl_list_ ## name.next;                          \
        if (elem->ossl_list_ ## name.next != NULL)                          \
            elem->ossl_list_ ## name.next->ossl_list_ ## name.prev =        \
                    elem->ossl_list_ ## name.prev;                          \
        list->num_elems--;                                                  \
        memset(&elem->ossl_list_ ## name, 0,                                \
               sizeof(elem->ossl_list_ ## name));                           \
    }                                                                       \
    static ossl_unused ossl_inline void                                     \
    ossl_list_##name##_insert_head(OSSL_LIST(name) *list, type *elem)       \
    {                                                                       \
        if (list->head != NULL)                                             \
            list->head->ossl_list_ ## name.prev = elem;                     \
        elem->ossl_list_ ## name.next = list->head;                         \
        elem->ossl_list_ ## name.prev = NULL;                               \
        list->head = elem;                                                  \
        if (list->tail == NULL)                                             \
            list->tail = elem;                                              \
        list->num_elems++;                                                  \
    }                                                                       \
    static ossl_unused ossl_inline void                                     \
    ossl_list_##name##_insert_tail(OSSL_LIST(name) *list, type *elem)       \
    {                                                                       \
        if (list->tail != NULL)                                             \
            list->tail->ossl_list_ ## name.next = elem;                     \
        elem->ossl_list_ ## name.prev = list->tail;                         \
        elem->ossl_list_ ## name.next = NULL;                               \
        list->tail = elem;                                                  \
        if (list->head == NULL)                                             \
            list->head = elem;                                              \
        list->num_elems++;                                                  \
    }                                                                       \
    static ossl_unused ossl_inline void                                     \
    ossl_list_##name##_insert_before(OSSL_LIST(name) *list, type *e,        \
                                     type *elem)                            \
    {                                                                       \
        elem->ossl_list_ ## name.next = e;                                  \
        elem->ossl_list_ ## name.prev = e->ossl_list_ ## name.prev;         \
        if (e->ossl_list_ ## name.prev != NULL)                             \
            e->ossl_list_ ## name.prev->ossl_list_ ## name.next = elem;     \
        e->ossl_list_ ## name.prev = elem;                                  \
        if (list->head == e)                                                \
            list->head = elem;                                              \
        list->num_elems++;                                                  \
    }                                                                       \
    static ossl_unused ossl_inline void                                     \
    ossl_list_##name##_insert_after(OSSL_LIST(name) *list, type *e,         \
                                     type *elem)                            \
    {                                                                       \
        elem->ossl_list_ ## name.prev = e;                                  \
        elem->ossl_list_ ## name.next = e->ossl_list_ ## name.next;         \
        if (e->ossl_list_ ## name.next != NULL)                             \
            e->ossl_list_ ## name.next->ossl_list_ ## name.prev = elem;     \
        e->ossl_list_ ## name.next = elem;                                  \
        if (list->tail == e)                                                \
            list->tail = elem;                                              \
        list->num_elems++;                                                  \
    }                                                                       \
    struct ossl_list_st_ ## name

#endif