#pragma once
#include "SharedTypes.hpp"

template <typename T, typename IDType> class CollabList {
    public:
        CollabList(const std::function<IDType()>& initGetNewIDFunc):
            getNewIDFunc(initGetNewIDFunc)
        {}

        struct ObjectInfo {
            bool syncIgnore;
            IDType id;
            T obj;
            uint64_t pos;
        };

        typedef std::shared_ptr<ObjectInfo> ObjectInfoPtr;

        const std::vector<std::shared_ptr<ObjectInfo>>& client_list() const { return clientSideList; }
        std::vector<std::shared_ptr<ObjectInfo>>& client_list() { return clientSideList; }
        const std::vector<std::shared_ptr<ObjectInfo>>& server_list() const { return serverSideList; }

        std::function<void()> updateCallback;
        std::function<void(const ObjectInfoPtr& c)> clientInsertCallback;
        std::function<void(const ObjectInfoPtr& c)> clientEraseCallback;
        std::function<void(uint64_t oldPos)> clientServerLastPosShiftCallback;

        void set_server_from_client_list() {
            serverSideList = clientSideList;
            for(auto& obj : serverSideList)
                obj->syncIgnore = false;
        }

        T* get_item_by_id(IDType id) {
            auto clientFound = std::find_if(clientSideList.begin(), clientSideList.end(), [&](const auto& obj) {
                return (obj->id == id);
            });
            if(clientFound != clientSideList.end())
                return &((*clientFound)->obj);
            auto serverFound = std::find_if(serverSideList.begin(), serverSideList.end(), [&](const auto& obj) {
                return (obj->id == id);
            });
            if(serverFound != serverSideList.end())
                return &((*serverFound)->obj);
            return nullptr;
        }

        IDType get_id(const T& item) {
            auto clientFound = std::find_if(clientSideList.begin(), clientSideList.end(), [&](const auto& obj) {
                return (obj->obj == item);
            });
            if(clientFound != clientSideList.end())
                return (*clientFound)->id;
            return {0, 0};
        }

        void client_erase_if(const std::function<bool(uint64_t, const std::shared_ptr<ObjectInfo>&)>& func) {
            bool erasedSomething = false;
            for(int64_t i = 0; i < (int64_t)clientSideList.size(); i++) {
                if(func((uint64_t)i, clientSideList[i])) {
                    if(clientEraseCallback)
                        clientEraseCallback(clientSideList[i]);
                    clientSideList.erase(clientSideList.begin() + i);
                    i--;
                    if(updateCallback)
                        updateCallback();
                    erasedSomething = true;
                }
            }
            if(erasedSomething)
                complete_client_pos_refresh(false);
        }

        IDType client_insert(uint64_t pos, const T& item) {
            auto newObj(std::make_shared<ObjectInfo>());
            newObj->syncIgnore = true;
            newObj->id = getNewIDFunc();
            newObj->obj = item;
            newObj->pos = std::min<uint64_t>(static_cast<uint64_t>(clientSideList.size()), pos);
            item->collabListInfo = newObj;

            clientSideList.insert(clientSideList.begin() + newObj->pos, newObj);

            client_pos_refresh_after_insert(newObj->pos);

            if(clientInsertCallback)
                clientInsertCallback(newObj);
            if(updateCallback)
                updateCallback();

            return newObj->id;
        }
        void client_erase(const T& item, IDType& erasedID) {
            bool erasedSomething = false;
            std::erase_if(clientSideList, [&](const auto& obj) {
                if(obj->obj == item) {
                    if(clientEraseCallback)
                        clientEraseCallback(obj);
                    erasedID = obj->id;
                    obj->syncIgnore = true;
                    if(updateCallback)
                        updateCallback();
                    erasedSomething = true;
                    return true;
                }
                return false;
            });
            if(erasedSomething)
                complete_client_pos_refresh(false);
        }

        bool server_insert(uint64_t pos, IDType id, const T& item) {
            auto foundInClient = std::find_if(clientSideList.begin(), clientSideList.end(), [&](const auto& clientObj) {
                return clientObj->id == id;
            });
            if(foundInClient != clientSideList.end()) {
                ObjectInfoPtr& o = *foundInClient;
                serverSideList.insert(serverSideList.begin() + pos, o);
                o->syncIgnore = false;
                sync();
                return false;
            }
            auto newObj(std::make_shared<ObjectInfo>());
            newObj->syncIgnore = false;
            newObj->id = id;
            newObj->obj = item;
            newObj->pos = std::min<uint64_t>(pos, clientSideList.size());
            item->collabListInfo = newObj;

            serverSideList.insert(serverSideList.begin() + pos, newObj);
            clientSideList.insert(clientSideList.begin() + newObj->pos, newObj);

            for(uint64_t i = newObj->pos + 1; i < static_cast<uint64_t>(clientSideList.size()); i++)
                clientSideList[i]->pos++;

            if(clientInsertCallback)
                clientInsertCallback(newObj);

            sync();
            return true;
        }
        void server_erase(IDType id) {
            std::erase_if(serverSideList, [&](const auto& obj) {
                if(obj->id == id) {
                    obj->syncIgnore = false;
                    return true;
                }
                return false;
            });
            std::erase_if(clientSideList, [&](const auto& obj) {
                if(obj->id == id) {
                    obj->syncIgnore = false;
                    if(clientEraseCallback)
                        clientEraseCallback(obj);
                    return true;
                }
                return false;
            });
            sync();
        }
        void init_emplace_back(IDType id, const T& item) {
            auto newObj(std::make_shared<ObjectInfo>());
            newObj->syncIgnore = false;
            newObj->id = id;
            newObj->obj = item;
            item->collabListInfo = newObj;

            serverSideList.emplace_back(newObj);
            clientSideList.emplace_back(newObj);

            newObj->pos = clientSideList.size() - 1;

            if(clientInsertCallback)
                clientInsertCallback(newObj);
            if(updateCallback)
                updateCallback();
        }
    private:
        void complete_client_pos_refresh(bool syncFromServer) {
            uint64_t lastShiftPos = 0;
            bool shiftHappened = false;
            for(uint64_t i = 0; i < clientSideList.size(); i++) {
                auto& c = clientSideList[i];
                if(c->pos != i) {
                    lastShiftPos = std::max(lastShiftPos, c->pos);
                    lastShiftPos = std::max(lastShiftPos, i);
                    shiftHappened = true;
                    c->pos = i;
                }
            }
            if(syncFromServer && shiftHappened && clientServerLastPosShiftCallback)
                clientServerLastPosShiftCallback(lastShiftPos);
        }

        void client_pos_refresh_after_insert(uint64_t posToRefreshAfter) {
            for(uint64_t i = posToRefreshAfter + 1; i < static_cast<uint64_t>(clientSideList.size()); i++)
                clientSideList[i]->pos = i;
        }

        void sync() {
            std::vector<std::pair<uint64_t, ObjectInfoPtr>> ignoredToReinsert;
            for(uint64_t i = 0; i < clientSideList.size(); i++)
                if(clientSideList[i]->syncIgnore)
                    ignoredToReinsert.emplace_back(std::pair<uint64_t, std::shared_ptr<ObjectInfo>>{i, clientSideList[i]});
            clientSideList = serverSideList;
            std::erase_if(clientSideList, [&](const auto& obj) {
                return obj->syncIgnore;
            });
            for(auto& p : ignoredToReinsert) {
                if(p.first > clientSideList.size())
                    clientSideList.emplace_back(p.second);
                else
                    clientSideList.insert(clientSideList.begin() + p.first, p.second);
            }
            if(updateCallback)
                updateCallback();
            complete_client_pos_refresh(true);
        }
        std::function<IDType()> getNewIDFunc;
        std::vector<ObjectInfoPtr> clientSideList;
        std::vector<ObjectInfoPtr> serverSideList;
};