#include "sophiar_pool.h"
#include "core/basic_obj_types.hpp"
#include "core/global_defs.h"
#include "utility/config_utility.hpp"
#include "utility/named_vector.hpp"
#include "utility/string_map.hpp"
#include "utility/versatile_buffer2.hpp"

#include <boost/asio/co_spawn.hpp>
#include <boost/asio/post.hpp>

#include <list>
#include <vector>
#include <unordered_map>

using boost::asio::co_spawn;
using boost::asio::post;

namespace sophiar {

    struct sophiar_pool::impl {

        struct variable_info_impl;
        struct callback_info;

        using callback_queue_type = std::list<callback_info *>;
        using callback_queue_iter_type = callback_queue_type::iterator;

        struct attach_info {
            variable_info_impl *var_info = nullptr;
            callback_info *callback = nullptr;
            void *callback_list_iter = nullptr; // callback_list_iter_type
            void *attach_iter = nullptr; // attach_iter_type
        };

        using attach_list_type = std::list<attach_info>;
        using attach_iter_type = attach_list_type::iterator;
        static_assert(sizeof(attach_iter_type) == sizeof(void *));
        static_assert(sizeof(attach_iter_type) == sizeof(attach_token_type));

        struct callback_info {
            enum status_type {
                IDLE, PENDING, RUNNING
            } status = IDLE;

            using callback_store_type = std::variant<function_callback_type, coroutine_callback_type>;
            callback_store_type func_store;
            function_callback_type exit_func;
            attach_list_type attach_list;
            callback_queue_iter_type queue_iter;

            bool exit_flag = false;
            void *pool_iter = nullptr; // callback_iter_type
        };

        using callback_pool_type = std::list<callback_info>;
        using callback_iter_type = callback_pool_type::iterator;
        static_assert(sizeof(callback_iter_type) == sizeof(callback_token_type));
        static_assert(sizeof(callback_iter_type) == sizeof(void *));

        using callback_list_type = std::list<callback_info *>;
        using callback_list_iter_type = callback_list_type::iterator;
        static_assert(sizeof(callback_list_iter_type) == sizeof(void *));

        struct variable_type_info {
            std::type_index type = typeid(void);
            variable_type_index_type type_index = -1;
            std::string type_name;

            // function list
            using creator_func_type = void *(*)(const nlohmann::json &);
            creator_func_type creator_func = nullptr;
        };

        struct variable_info_impl {
            void *placeholder = nullptr;
            coro_signal2 *update_signal = nullptr;
            const variable_type_info *type_info = nullptr;
            timestamp_type last_update_ts = 0;
            callback_list_type callback_list;
        };

        string_map<variable_type_index_type> variable_type_name_index_map; // typename -> index
        std::unordered_map<std::type_index, variable_type_index_type> variable_type_index_index_map; // type_index -> index
        std::vector<variable_type_info> variable_type_info_pool;

        named_vector<variable_index_type, variable_info_impl> variable_pool;
        callback_pool_type callback_pool;
        callback_queue_type callback_queue;
        bool is_callback_handler_active = false;

        template<typename SmallObjType>
        static void *create_variable_pointer(const nlohmann::json &config) {
            auto placeholder = new SmallObjType::pointer{};
            if (!config.contains("value")) {
                return (void *) placeholder;
            }

            // load default value
            *placeholder = SmallObjType::new_instance();
            (*placeholder)->fill_from_json_array(config["value"]);
            return (void *) placeholder;
        }

        template<typename SmallObjType>
        void register_variable_type(std::string_view type_name) {
            static_assert(SmallObjType::binary_length() <= std::numeric_limits<uint8_t>::max());

            auto var_type_index = variable_type_info_pool.size();
            variable_type_info_pool.emplace_back();

            assert(!variable_type_name_index_map.contains(type_name));
            variable_type_name_index_map.insert(type_name, var_type_index);

            const std::type_index type = typeid(SmallObjType);
            assert(!variable_type_index_index_map.contains(type));
            variable_type_index_index_map[type] = var_type_index;

            auto &type_info = variable_type_info_pool[var_type_index];
            type_info.type = type;
            type_info.type_index = var_type_index;
            type_info.type_name = type_name;
            type_info.creator_func = create_variable_pointer<SmallObjType>;
        }

        void register_basic_variable_types() {
#define REGISTER_TYPE(var_type) \
            register_variable_type<var_type>(#var_type)

            REGISTER_TYPE(bool_obj);
            REGISTER_TYPE(u64int_obj);
            REGISTER_TYPE(double_obj);
            REGISTER_TYPE(scalarxyz_obj);
            REGISTER_TYPE(transform_obj);
            REGISTER_TYPE(array6_obj);
            REGISTER_TYPE(array7_obj);
#undef REGISTER_TYPE

            // check registered variable type index
            assert(variable_type_index_index_map.at(typeid(bool_obj)) == bool_var_type_index);
            assert(variable_type_index_index_map.at(typeid(u64int_obj)) == u64int_var_type_index);
            assert(variable_type_index_index_map.at(typeid(double_obj)) == double_var_type_index);
            assert(variable_type_index_index_map.at(typeid(scalarxyz_obj)) == scalarxyz_var_type_index);
            assert(variable_type_index_index_map.at(typeid(transform_obj)) == transform_var_type_index);
            assert(variable_type_index_index_map.at(typeid(array6_obj)) == array6_var_type_index);
            assert(variable_type_index_index_map.at(typeid(array7_obj)) == array7_var_type_index);
        }

        void register_variable(std::string_view name,
                               std::string_view type_name,
                               const nlohmann::json &config = {}) {
            auto index = variable_pool.new_elem(name);
            auto &info = variable_pool[index];

            assert(variable_type_name_index_map.contains(type_name));
            auto var_type_index = variable_type_name_index_map.query(type_name);
            const auto &type_info = variable_type_info_pool[var_type_index];

            info.placeholder = type_info.creator_func(config);
            info.update_signal = new coro_signal2{};
            info.type_info = &type_info;
            info.last_update_ts = 0;
        }

        callback_token_type register_callback(callback_info::callback_store_type &&callback,
                                              function_callback_type &&exit_func) {
            auto &item = callback_pool.emplace_front();
            item.func_store = std::move(callback);
            item.exit_func = std::move(exit_func);
            item.pool_iter = std::bit_cast<void *>(callback_pool.begin());
            return std::bit_cast<callback_token_type>(item.pool_iter);
        }

        void unregister_callback(callback_iter_type callback) {
            while (!callback->attach_list.empty()) {
                detach_callback(callback->attach_list.begin());
            }
            if (callback->status == callback_info::RUNNING) {
                callback->exit_flag = true;
                return;
            }
            if (callback->status == callback_info::PENDING) {
                callback_queue.erase(callback->queue_iter);
            }
            callback->exit_func();
            callback_pool.erase(callback);
        }

        attach_token_type attach_callback(variable_index_type var_index, callback_iter_type callback) {
            auto &var_info = variable_pool[var_index];
            var_info.callback_list.push_front(&(*callback));

            auto &attach_item = callback->attach_list.emplace_front();
            attach_item.var_info = &var_info;
            attach_item.callback = &(*callback);
            attach_item.callback_list_iter = std::bit_cast<void *>(var_info.callback_list.begin());
            attach_item.attach_iter = std::bit_cast<void *>(callback->attach_list.begin());
            return std::bit_cast<attach_token_type>(callback->attach_list.begin());
        }

        static void detach_callback(attach_iter_type iter) {
            auto callback_iter = std::bit_cast<callback_list_iter_type>(iter->callback_list_iter);
            auto attach_iter = std::bit_cast<attach_iter_type>(iter->attach_iter);
            iter->var_info->callback_list.erase(callback_iter);
            iter->callback->attach_list.erase(attach_iter);
        }

        void handle_callback_func() {
            while (!callback_queue.empty()) {
                auto callback = callback_queue.back();
                callback_queue.pop_back();
                callback->status = callback_info::RUNNING;
                callback->queue_iter = {};
                if (callback->func_store.index() == 0) {
                    std::get<0>(callback->func_store)();
                    callback->status = callback_info::IDLE;
                } else {
                    assert(callback->func_store.index() == 1);
                    co_spawn(*global_context, std::get<1>(callback->func_store)(), [=, this](std::exception_ptr eptr) {
                        assert(eptr == nullptr);
                        callback->status = callback_info::IDLE;
                        if (callback->exit_flag) {
                            callback->exit_func();
                            auto real_iter = std::bit_cast<callback_iter_type>(callback->pool_iter);
                            callback_pool.erase(real_iter);
                        }
                    });
                }
            }
            is_callback_handler_active = false;
        }

        void trigger_callback(variable_info_impl *var_info) {
            if (var_info->callback_list.empty()) return;
            bool has_callback = false;
            for (auto &callback: var_info->callback_list) {
                if (callback->status != callback_info::IDLE) continue;
                callback_queue.push_front(callback);
                callback->status = callback_info::PENDING;
                callback->queue_iter = callback_queue.begin();
                has_callback = true;
            }
            if (!has_callback || is_callback_handler_active) return;
            post(*global_context, [this]() { handle_callback_func(); });
            is_callback_handler_active = true;
        }

        void load_config(const nlohmann::json &config) {

#ifdef SOPHIAR_TEST

            if (config.empty()) return;

#endif // SOPHIAR_TEST

            ENSURE_ARRAY("variable_list");
            for (auto &var_config: config["variable_list"]) {
                auto var_name = LOAD_STRING_ITEM2(var_config, "name");
                auto type_name = LOAD_STRING_ITEM2(var_config, "type");
                register_variable(var_name, type_name, var_config);
            }
        }

        impl() {
            register_basic_variable_types();
        }

    };

    sophiar_pool::sophiar_pool()
            : pimpl(std::make_unique<impl>()) {}

    signal_watcher sophiar_pool::require_variable_watcher(variable_index_type var_index) {
        assert(pimpl->variable_pool.contains(var_index));
        return pimpl->variable_pool[var_index].update_signal->new_watcher();
    }

    std::string sophiar_pool::query_variable_name(variable_index_type var_index) {
        assert(pimpl->variable_pool.contains(var_index));
        return pimpl->variable_pool.to_name_by_index(var_index);
    }

    timestamp_type sophiar_pool::query_variable_update_ts(variable_index_type var_index) {
        assert(pimpl->variable_pool.contains(var_index));
        return pimpl->variable_pool[var_index].last_update_ts;
    }

    sophiar_pool::variable_info sophiar_pool::query_variable_information(std::string_view var_name) {
        assert(pimpl->variable_pool.contains(var_name));
        const auto &info = pimpl->variable_pool[var_name];
        variable_info ret{
                .type_index = info.type_info->type_index,
                .index = pimpl->variable_pool.to_index_by_name(var_name),
                .placeholder = info.placeholder
        };
        return ret;
    }

    variable_index_type sophiar_pool::require_variable_impl(std::string_view var_name,
                                                            std::type_index var_type) {
        assert(pimpl->variable_pool.contains(var_name));
        const auto &info = pimpl->variable_pool[var_name];
        assert(info.type_info->type == var_type);
        return pimpl->variable_pool.to_index_by_name(var_name);
    }

    void *sophiar_pool::require_variable_placeholder_impl(variable_index_type var_index,
                                                          std::type_index var_type,
                                                          timestamp_type *ts_out) {
        assert(pimpl->variable_pool.contains(var_index));
        const auto &info = pimpl->variable_pool[var_index];
        assert(info.type_info->type == var_type); // ensure type consistency
        if (ts_out != nullptr) {
            *ts_out = info.last_update_ts;
        }
        return info.placeholder;
    }

    void sophiar_pool::update_variable_timestamp_impl(variable_index_type var_index,
                                                      timestamp_type ts) {
        assert(pimpl->variable_pool.contains(var_index));
        auto &info = pimpl->variable_pool[var_index];
        assert(ts > info.last_update_ts);
        info.last_update_ts = ts;
        info.update_signal->try_notify_all(ts);
        pimpl->trigger_callback(&info);
    }

    void sophiar_pool::load_config(const nlohmann::json &config) {
        pimpl->load_config(config);
    }

    sophiar_pool::callback_token_type
    sophiar_pool::register_callback(function_callback_type &&callback,
                                    function_callback_type &&exit_func) {
        return pimpl->register_callback(std::move(callback), std::move(exit_func));
    }

    sophiar_pool::callback_token_type
    sophiar_pool::register_coro_callback(coroutine_callback_type &&callback,
                                         function_callback_type &&exit_func) {
        return pimpl->register_callback(std::move(callback), std::move(exit_func));
    }

    void sophiar_pool::unregister_callback(callback_token_type token) {
        if (token == nullptr) return;
        return pimpl->unregister_callback(std::bit_cast<impl::callback_iter_type>(token));
    }

    sophiar_pool::attach_token_type sophiar_pool::attach_callback(variable_index_type var_index,
                                                                  callback_token_type token) {
        assert(token != nullptr);
        return pimpl->attach_callback(var_index, std::bit_cast<impl::callback_iter_type>(token));
    }

    void sophiar_pool::detach_callback(attach_token_type token) {
        if (token == nullptr) return;
        return pimpl->detach_callback(std::bit_cast<impl::attach_iter_type>(token));
    }

    sophiar_pool::~sophiar_pool() = default;

#ifdef SOPHIAR_TEST

    void sophiar_pool::register_variable(std::string_view var_name,
                                         std::string_view type_name) {
        pimpl->register_variable(var_name, type_name);
    }

#endif

}