#if defined(__clang__)
#pragma once
#include "feely_pona_unity.h"
#endif

template <typename T>
struct FP_SentinelListLink
{
    T                       data;
    FP_SentinelListLink<T> *next;
    FP_SentinelListLink<T> *prev;
};

template <typename T>
struct FP_SentinelList
{
    Dqn_usize               size;
    FP_SentinelListLink<T> *sentinel;
};

template <typename T>
FP_SentinelListLink<T> *FP_SentinelList_Front(FP_SentinelList<T> *list)
{
    FP_SentinelListLink<T> *result = nullptr;
    if (list && list->sentinel && list->sentinel->next)
        result = list->sentinel->next;
    return result;
}

template <typename T>
bool FP_SentinelList_Iterate(FP_SentinelList<T> *list, FP_SentinelListLink<T> **it)
{
    if (!list || !list->sentinel || !it)
        return false;

    if (!DQN_CHECK(list->sentinel->next && list->sentinel->prev))
        return false;

    if (!(*it))
        *it = list->sentinel;

    bool result = list && (*it)->next != list->sentinel;
    if (result)
        (*it) = (*it)->next;
    return result;
}

template <typename T>
FP_SentinelList<T> FP_SentinelList_Init(TELY_ChunkPool *pool)
{
    FP_SentinelList<T> result = {};
    result.sentinel           = TELY_ChunkPool_New(pool, FP_SentinelListLink<T>);
    result.sentinel->next     = result.sentinel->prev = result.sentinel;
    return result;
}

template <typename T>
FP_SentinelListLink<T> *FP_SentinelList_Make(FP_SentinelList<T> *list, TELY_ChunkPool *pool)
{
    FP_SentinelListLink<T> *result = FP_SentinelList_MakeBefore(list, list->sentinel, pool);
    return result;
}

template <typename T>
FP_SentinelListLink<T> *FP_SentinelList_Add(FP_SentinelList<T> *list, TELY_ChunkPool *pool, const T& data)
{
    FP_SentinelListLink<T> *result = FP_SentinelList_Make(list, pool);
    result->data                   = data;
    return result;
}

template <typename T>
FP_SentinelListLink<T> *FP_SentinelList_MakeBefore(FP_SentinelList<T> *list, FP_SentinelListLink<T> *link, TELY_ChunkPool *pool)
{
    DQN_ASSERT(list->sentinel->next);
    DQN_ASSERT(list->sentinel->prev);
    DQN_ASSERT(list->sentinel->prev->next == list->sentinel);
    DQN_ASSERT(list->sentinel->next->prev == list->sentinel);

    FP_SentinelListLink<T> *result = TELY_ChunkPool_New(pool, FP_SentinelListLink<T>);
    result->next                   = link;
    result->prev                   = link->prev;
    result->next->prev             = result;
    result->prev->next             = result;
    list->size++;
    return result;
}

template <typename T>
FP_SentinelListLink<T> *FP_SentinelList_MakeAfter(FP_SentinelList<T> *list, FP_SentinelListLink<T> *link, TELY_ChunkPool *pool)
{
    DQN_ASSERT(list->sentinel->next);
    DQN_ASSERT(list->sentinel->prev);
    DQN_ASSERT(list->sentinel->prev->next == list->sentinel);
    DQN_ASSERT(list->sentinel->next->prev == list->sentinel);

    FP_SentinelListLink<T> *result = TELY_ChunkPool_New(pool, FP_SentinelListLink<T>);
    result->next                   = link->next;
    result->prev                   = link;
    result->next->prev             = result;
    result->prev->next             = result;
    list->size++;
    return result;
}

template <typename T>
FP_SentinelListLink<T> *FP_SentinelList_Erase(FP_SentinelList<T> *list, FP_SentinelListLink<T> *link, TELY_ChunkPool *pool)
{
    FP_SentinelListLink<T> *result = link->prev;
    link->next->prev               = link->prev;
    link->prev->next               = link->next;
    TELY_ChunkPool_Dealloc(pool, link);
    list->size--;
    return result;
}

template <typename T>
void FP_SentinelList_Clear(FP_SentinelList<T> *list, TELY_ChunkPool *pool)
{
    if (!list || !pool)
        return;

    for (FP_SentinelListLink<T> *link = nullptr; FP_SentinelList_Iterate(list, &link); )
        link = FP_SentinelList_Erase(list, link, pool);
}

template <typename T>
void FP_SentinelList_Deinit(FP_SentinelList<T> *list, TELY_ChunkPool *pool)
{
    if (!list || !pool)
        return;
    FP_SentinelList_Clear(list, pool);
    TELY_ChunkPool_Dealloc(pool, list->sentinel);
    *list = {};
}

template <typename T>
FP_SentinelListLink<T> *FP_SentinelList_Find(FP_SentinelList<T> const *list, T const &find)
{
    FP_SentinelListLink<T> *result = nullptr;
    for (FP_SentinelListLink<FP_GameEntityHandle> *link = nullptr;
         !result && FP_SentinelList_Iterate<FP_GameEntityHandle>(DQN_CAST(FP_SentinelList<T> *)list, &link); ) {
        if (link->data == find)
            result = link;
    }
    return result;
}