#ifndef SOPHIAR2_VARIABLE_HELPER_HPP
#define SOPHIAR2_VARIABLE_HELPER_HPP

#include "core/global_defs.h"
#include "core/small_obj.hpp"
#include "core/sophiar_pool.h"
#include "utility/coro_signal2.hpp"

namespace sophiar {

    template<typename SmallObjType, bool AutoSync = true>
    class variable_delegate {
    public:

        using pointer_type = typename SmallObjType::pointer;

        explicit variable_delegate(variable_index_type _var_index)
                : watcher(REQUIRE_VARIABLE_WATCHER(_var_index)),
                  var_index(_var_index) {}

        explicit variable_delegate(std::string_view obj_name)
                : variable_delegate(REQUIRE_VARIABLE(SmallObjType, obj_name)) {}

        variable_delegate(variable_delegate &&other) noexcept = default;

        signal_watcher new_watcher() const {
            return REQUIRE_VARIABLE_WATCHER(var_index);
        }

        void set_value(const pointer_type &ptr,
                       timestamp_type ts = current_timestamp()) {
            UPDATE_VARIABLE_WITH_TS(SmallObjType, var_index, ptr, ts);
        }

        template<typename OtherSmallObjType = SmallObjType,
                typename ValueType = OtherSmallObjType::value_type>
        void set_value(const ValueType &val,
                       timestamp_type ts = current_timestamp()) {
            UPDATE_VARIABLE_VAL_WITH_TS(SmallObjType, var_index, val, ts);
        }

        // return true if received new value
        bool manual_sync() {
            if (watcher.try_wait()) { // new value available
                val_ptr = QUERY_VARIABLE(SmallObjType, var_index);
                return true;
            }
            return false;
        }

        pointer_type get_value() {
            if constexpr (AutoSync) {
                manual_sync();
            }
            return val_ptr;
        }

        timestamp_type get_last_update_ts() const {
            return watcher.get_last_update_ts();
        }

        bool empty() {
            return get_value() == nullptr;
        }

        template<typename T>
        variable_delegate &operator=(T &&val) {
            set_value(std::forward<T>(val));
            return *this;
        }

        const SmallObjType &operator*() {
            assert(!empty());
            return *get_value();
        }

        const SmallObjType *operator->() {
            assert(!empty());
            return get_value().get();
        }

        boost::asio::awaitable<void> coro_wait_update(bool auto_sync = AutoSync) {
            co_await watcher.coro_wait(auto_sync);
            val_ptr = QUERY_VARIABLE(SmallObjType, var_index);
            co_return;
        }

    private:
        variable_index_type var_index;
        pointer_type val_ptr;
        signal_watcher watcher;

    };

    template<typename SmallObjType>
    using variable_auto_sync_delegate = variable_delegate<SmallObjType, true>;

    template<typename SmallObjType>
    using variable_manual_sync_delegate = variable_delegate<SmallObjType, false>;

#define VARIABLE_AUTO_DELEGATE(var_type, var_index) \
    variable_auto_sync_delegate<var_type>(var_index)

#define VARIABLE_MANUAL_DELEGATE(var_type, var_index) \
    variable_manual_sync_delegate<var_type>(var_index)

    template<typename SmallObjType>
    auto try_query_variable_value(variable_index_type var_index,
                                  const typename SmallObjType::value_type &default_value) {
        if (!is_valid_id(var_index)) return default_value;
        auto var_ptr = QUERY_VARIABLE(SmallObjType, var_index);
        if (var_ptr == nullptr) return default_value;
        return var_ptr->value;
    }

    template<typename SmallObjType>
    auto try_update_variable(variable_index_type var_index,
                             typename SmallObjType::pointer &&ptr,
                             timestamp_type ts = current_timestamp()) {
        if (!is_valid_id(var_index)) return;
        UPDATE_VARIABLE_WITH_TS(SmallObjType, var_index, ptr, ts);
    }

    template<typename SmallObjType>
    auto try_update_variable_value(variable_index_type var_index,
                                   const typename SmallObjType::value_type &value,
                                   timestamp_type ts = current_timestamp()) {
        if (!is_valid_id(var_index)) return;
        UPDATE_VARIABLE_VAL_WITH_TS(SmallObjType, var_index, value, ts);
    }

    template<typename SmallObjType, typename CondFuncType>
    std::enable_if_t<std::is_convertible_v<
            decltype(std::declval<CondFuncType>()(
                    std::declval<typename SmallObjType::value_type>())),
            bool>, boost::asio::awaitable<void>>
    coro_wait_for_variable_value(variable_index_type var_index,
                                 CondFuncType &&cond_func) {
        auto var_helper = VARIABLE_MANUAL_DELEGATE(SmallObjType, var_index);
        var_helper.manual_sync();
        for (;;) {
            if (!var_helper.empty() &&
                cond_func(var_helper->value)) {
                break;
            }
            co_await var_helper.coro_wait_update();
        }
        co_return;
    }

    template<typename SmallObjType,
            typename ValueType = typename SmallObjType::value_type>
    boost::asio::awaitable<void> coro_wait_for_variable_value(variable_index_type var_index,
                                                              const ValueType &val_tar) {
        auto var_helper = VARIABLE_MANUAL_DELEGATE(SmallObjType, var_index);
        var_helper.manual_sync();
        for (;;) {
            if (!var_helper.empty() &&
                var_helper->value == val_tar) {
                break;
            }
            co_await var_helper.coro_wait_update();
        }
        co_return;
    }

    template<typename SmallObjType>
    boost::asio::awaitable<void> coro_wait_for_not_empty(variable_index_type var_index) {
        auto var_helper = VARIABLE_MANUAL_DELEGATE(SmallObjType, var_index);
        var_helper.manual_sync();
        for (;;) {
            if (!var_helper.empty()) {
                break;
            }
            co_await var_helper.coro_wait_update();
        }
        co_return;
    }

}

#endif //SOPHIAR2_VARIABLE_HELPER_HPP