/*
 * 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>
#include <assert.h>

#ifdef NDEBUG
#define OSSL_LIST_DBG(x)
#else
#define OSSL_LIST_DBG(x) x;
#endif

#define OSSL_LIST_FOREACH_FROM(p, name, init) \
    for ((p) = (init);                        \
        (p) != NULL;                          \
        (p) = ossl_list_##name##_next(p))
#define OSSL_LIST_FOREACH(p, name, l) \
    OSSL_LIST_FOREACH_FROM(p, name, ossl_list_##name##_head(l))

#define OSSL_LIST_FOREACH_REV_FROM(p, name, init) \
    for ((p) = (init);                            \
        (p) != NULL;                              \
        (p) = ossl_list_##name##_prev(p))
#define OSSL_LIST_FOREACH_REV(p, name, l) \
    OSSL_LIST_FOREACH_FROM(p, name, ossl_list_##name##_tail(l))

#define OSSL_LIST_FOREACH_DELSAFE_FROM(p, pn, name, init)        \
    for ((p) = (init);                                           \
        (p) != NULL && (((pn) = ossl_list_##name##_next(p)), 1); \
        (p) = (pn))
#define OSSL_LIST_FOREACH_DELSAFE(p, pn, name, l) \
    OSSL_LIST_FOREACH_DELSAFE_FROM(p, pn, name, ossl_list_##name##_head(l))

#define OSSL_LIST_FOREACH_REV_DELSAFE_FROM(p, pn, name, init)    \
    for ((p) = (init);                                           \
        (p) != NULL && (((pn) = ossl_list_##name##_prev(p)), 1); \
        (p) = (pn))
#define OSSL_LIST_FOREACH_REV_DELSAFE(p, pn, name, l) \
    OSSL_LIST_FOREACH_REV_DELSAFE_FROM(p, pn, name, ossl_list_##name##_tail(l))

/* 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_DBG(struct ossl_list_st_##name *list) \
    } ossl_list_##name

#define DECLARE_LIST_OF(name, type)                     \
    typedef struct ossl_list_st_##name OSSL_LIST(name); \
    struct ossl_list_st_##name {                        \
        type *alpha, *omega;                            \
        size_t num_elems;                               \
    }

#define DEFINE_LIST_OF_IMPL(name, type)                                                       \
    static ossl_unused ossl_inline void                                                       \
    ossl_list_##name##_init(OSSL_LIST(name) * list)                                           \
    {                                                                                         \
        memset(list, 0, sizeof(*list));                                                       \
    }                                                                                         \
    static ossl_unused ossl_inline void                                                       \
    ossl_list_##name##_init_elem(type *elem)                                                  \
    {                                                                                         \
        memset(&elem->ossl_list_##name, 0,                                                    \
            sizeof(elem->ossl_list_##name));                                                  \
    }                                                                                         \
    static ossl_unused ossl_inline int                                                        \
    ossl_list_##name##_is_empty(const OSSL_LIST(name) * list)                                 \
    {                                                                                         \
        return list->num_elems == 0;                                                          \
    }                                                                                         \
    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)                                     \
    {                                                                                         \
        assert(list->alpha == NULL                                                            \
            || list->alpha->ossl_list_##name.list == list);                                   \
        return list->alpha;                                                                   \
    }                                                                                         \
    static ossl_unused ossl_inline type *                                                     \
    ossl_list_##name##_tail(const OSSL_LIST(name) * list)                                     \
    {                                                                                         \
        assert(list->omega == NULL                                                            \
            || list->omega->ossl_list_##name.list == list);                                   \
        return list->omega;                                                                   \
    }                                                                                         \
    static ossl_unused ossl_inline type *                                                     \
    ossl_list_##name##_next(const type *elem)                                                 \
    {                                                                                         \
        assert(elem->ossl_list_##name.next == NULL                                            \
            || elem->ossl_list_##name.next                                                    \
                    ->ossl_list_##name.prev                                                   \
                == elem);                                                                     \
        return elem->ossl_list_##name.next;                                                   \
    }                                                                                         \
    static ossl_unused ossl_inline type *                                                     \
    ossl_list_##name##_prev(const type *elem)                                                 \
    {                                                                                         \
        assert(elem->ossl_list_##name.prev == NULL                                            \
            || elem->ossl_list_##name.prev                                                    \
                    ->ossl_list_##name.next                                                   \
                == elem);                                                                     \
        return elem->ossl_list_##name.prev;                                                   \
    }                                                                                         \
    static ossl_unused ossl_inline void                                                       \
    ossl_list_##name##_remove(OSSL_LIST(name) * list, type * elem)                            \
    {                                                                                         \
        assert(elem->ossl_list_##name.list == list);                                          \
        OSSL_LIST_DBG(elem->ossl_list_##name.list = NULL)                                     \
        if (list->alpha == elem)                                                              \
            list->alpha = elem->ossl_list_##name.next;                                        \
        if (list->omega == elem)                                                              \
            list->omega = 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)                       \
    {                                                                                         \
        assert(elem->ossl_list_##name.list == NULL);                                          \
        OSSL_LIST_DBG(elem->ossl_list_##name.list = list)                                     \
        if (list->alpha != NULL)                                                              \
            list->alpha->ossl_list_##name.prev = elem;                                        \
        elem->ossl_list_##name.next = list->alpha;                                            \
        elem->ossl_list_##name.prev = NULL;                                                   \
        list->alpha = elem;                                                                   \
        if (list->omega == NULL)                                                              \
            list->omega = elem;                                                               \
        list->num_elems++;                                                                    \
    }                                                                                         \
    static ossl_unused ossl_inline void                                                       \
    ossl_list_##name##_insert_tail(OSSL_LIST(name) * list, type * elem)                       \
    {                                                                                         \
        assert(elem->ossl_list_##name.list == NULL);                                          \
        OSSL_LIST_DBG(elem->ossl_list_##name.list = list)                                     \
        if (list->omega != NULL)                                                              \
            list->omega->ossl_list_##name.next = elem;                                        \
        elem->ossl_list_##name.prev = list->omega;                                            \
        elem->ossl_list_##name.next = NULL;                                                   \
        list->omega = elem;                                                                   \
        if (list->alpha == NULL)                                                              \
            list->alpha = elem;                                                               \
        list->num_elems++;                                                                    \
    }                                                                                         \
    static ossl_unused ossl_inline void                                                       \
    ossl_list_##name##_insert_before(OSSL_LIST(name) * list, type * e,                        \
        type * elem)                                                                          \
    {                                                                                         \
        assert(elem->ossl_list_##name.list == NULL);                                          \
        OSSL_LIST_DBG(elem->ossl_list_##name.list = list)                                     \
        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->alpha == e)                                                                 \
            list->alpha = elem;                                                               \
        list->num_elems++;                                                                    \
    }                                                                                         \
    static ossl_unused ossl_inline void                                                       \
    ossl_list_##name##_insert_after(OSSL_LIST(name) * list, type * e,                         \
        type * elem)                                                                          \
    {                                                                                         \
        assert(elem->ossl_list_##name.list == NULL);                                          \
        OSSL_LIST_DBG(elem->ossl_list_##name.list = list)                                     \
        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->omega == e)                                                                 \
            list->omega = elem;                                                               \
        list->num_elems++;                                                                    \
    }                                                                                         \
    struct ossl_list_st_##name

#define DEFINE_LIST_OF(name, type) \
    DECLARE_LIST_OF(name, type);   \
    DEFINE_LIST_OF_IMPL(name, type)

#endif