openmw/components/lua/scriptscontainer.hpp

#ifndef COMPONENTS_LUA_SCRIPTSCONTAINER_H
#define COMPONENTS_LUA_SCRIPTSCONTAINER_H

#include <map>
#include <set>
#include <string>

#include <components/debug/debuglog.hpp>
#include <components/esm/luascripts.hpp>

#include "luastate.hpp"
#include "serialization.hpp"

namespace LuaUtil
{

    // ScriptsContainer is a base class for all scripts containers (LocalScripts,
    // GlobalScripts, PlayerScripts, etc). Each script runs in a separate sandbox.
    // Scripts from different containers can interact to each other only via events.
    // Scripts within one container can interact via interfaces.
    // All scripts from one container have the same set of API packages available.
    //
    // Each script should return a table in a specific format that describes its
    // handlers and interfaces. Every section of the table is optional. Basic structure:
    //
    //     local function update(dt)
    //         print("Update")
    //     end
    //
    //     local function someEventHandler(eventData)
    //         print("'SomeEvent' received")
    //     end
    //
    //     return {
    //         -- Provides interface for other scripts in the same container
    //         interfaceName = "InterfaceName",
    //         interface = {
    //             someFunction = function() print("someFunction was called from another script") end,
    //         },
    //
    //         -- Script interface for the engine. Not available for other script.
    //         -- An error is printed if unknown handler is specified.
    //         engineHandlers = {
    //             onUpdate = update,
    //             onInit = function(initData) ... end,  -- used when the script is just created (not loaded)
    //             onSave = function() return ... end,
    //             onLoad = function(state, initData) ... end,  -- "state" is the data that was earlier returned by
    //             onSave
    //
    //             -- Works only if a child class has passed a EngineHandlerList
    //             -- for 'onSomethingElse' to ScriptsContainer::registerEngineHandlers.
    //             onSomethingElse = function() print("something else") end
    //         },
    //
    //         -- Handlers for events, sent from other scripts. Engine itself never sent events. Any name can be used
    //         for an event. eventHandlers = {
    //             SomeEvent = someEventHandler
    //         }
    //     }

    class ScriptsContainer
    {
    public:
        // ScriptId of each script is stored with this key in Script::mHiddenData.
        // Removed from mHiddenData when the script if removed.
        constexpr static std::string_view sScriptIdKey = "_id";

        // Debug identifier of each script is stored with this key in Script::mHiddenData.
        // Present in mHiddenData even after removal of the script from ScriptsContainer.
        constexpr static std::string_view sScriptDebugNameKey = "_name";

        struct ScriptId
        {
            ScriptsContainer* mContainer;
            int mIndex; // index in LuaUtil::ScriptsConfiguration
        };
        using TimerType = ESM::LuaTimer::Type;

        // `namePrefix` is a common prefix for all scripts in the container. Used in logs for error messages and `print`
        // output. `autoStartScripts` specifies the list of scripts that should be autostarted in this container;
        //     the script names themselves are stored in ScriptsConfiguration.
        ScriptsContainer(LuaState* lua, std::string_view namePrefix);

        ScriptsContainer(const ScriptsContainer&) = delete;
        ScriptsContainer(ScriptsContainer&&) = delete;
        virtual ~ScriptsContainer();

        void setAutoStartConf(ScriptIdsWithInitializationData conf) { mAutoStartScripts = std::move(conf); }
        const ScriptIdsWithInitializationData& getAutoStartConf() const { return mAutoStartScripts; }

        // Adds package that will be available (via `require`) for all scripts in the container.
        // Automatically applies LuaUtil::makeReadOnly to the package.
        void addPackage(std::string packageName, sol::object package);

        // Gets script with given id from ScriptsConfiguration, finds the source in the virtual file system, starts as a
        // new script, adds it to the container, and calls onInit for this script. Returns `true` if the script was
        // successfully added. The script should have CUSTOM flag. If the flag is not set, or file not found, or has
        // syntax errors, returns false. If such script already exists in the container, then also returns false.
        bool addCustomScript(int scriptId);

        bool hasScript(int scriptId) const { return mScripts.count(scriptId) != 0; }
        void removeScript(int scriptId);

        void processTimers(double simulationTime, double gameTime);

        // Calls `onUpdate` (if present) for every script in the container.
        // Handlers are called in the same order as scripts were added.
        void update(float dt) { callEngineHandlers(mUpdateHandlers, dt); }

        // Calls event handlers `eventName` (if present) for every script.
        // If several scripts register handlers for `eventName`, they are called in reverse order.
        // If some handler returns `false`, all remaining handlers are ignored. Any other return value
        // (including `nil`) has no effect.
        void receiveEvent(std::string_view eventName, std::string_view eventData);

        // Serializer defines how to serialize/deserialize userdata. If serializer is not provided,
        // only built-in types and types from util package can be serialized.
        void setSerializer(const UserdataSerializer* serializer) { mSerializer = serializer; }

        // Special deserializer to use when load data from saves. Can be used to remap content files in Refnums.
        void setSavedDataDeserializer(const UserdataSerializer* serializer) { mSavedDataDeserializer = serializer; }

        // Starts scripts according to `autoStartMode` and calls `onInit` for them. Not needed if `load` is used.
        void addAutoStartedScripts();

        // Removes all scripts including the auto started.
        void removeAllScripts();

        // Calls engineHandler "onSave" for every script and saves the list of the scripts with serialized data to
        // ESM::LuaScripts.
        void save(ESM::LuaScripts&);

        // Removes all scripts; starts scripts according to `autoStartMode` and
        // loads the savedScripts. Runs "onLoad" for each script.
        void load(const ESM::LuaScripts& savedScripts);

        // Callbacks for serializable timers should be registered in advance.
        // The script with the given path should already present in the container.
        void registerTimerCallback(int scriptId, std::string_view callbackName, sol::function callback);

        // Sets up a timer, that can be automatically saved and loaded.
        //   type - the type of timer, either SIMULATION_TIME or GAME_TIME.
        //   time - the absolute game time (in seconds or in hours) when the timer should be executed.
        //   scriptPath - script path in VFS is used as script id. The script with the given path should already present
        //   in the container. callbackName - callback (should be registered in advance) for this timer. callbackArg -
        //   parameter for the callback (should be serializable).
        void setupSerializableTimer(
            TimerType type, double time, int scriptId, std::string_view callbackName, sol::object callbackArg);

        // Creates a timer. `callback` is an arbitrary Lua function. These timers are called "unsavable"
        // because they can not be stored in saves. I.e. loading a saved game will not fully restore the state.
        void setupUnsavableTimer(TimerType type, double time, int scriptId, sol::function callback);

    protected:
        struct Handler
        {
            int mScriptId;
            sol::function mFn;
        };

        struct EngineHandlerList
        {
            std::string_view mName;
            std::vector<Handler> mList;

            // "name" must be string literal
            explicit EngineHandlerList(std::string_view name)
                : mName(name)
            {
            }
        };

        // Calls given handlers in direct order.
        template <typename... Args>
        void callEngineHandlers(EngineHandlerList& handlers, const Args&... args)
        {
            for (Handler& handler : handlers.mList)
            {
                try
                {
                    LuaUtil::call(handler.mFn, args...);
                }
                catch (std::exception& e)
                {
                    Log(Debug::Error) << mNamePrefix << "[" << scriptPath(handler.mScriptId) << "] " << handlers.mName
                                      << " failed. " << e.what();
                }
            }
        }

        // To add a new engine handler a derived class should register the corresponding EngineHandlerList and define
        // a public function (see how ScriptsContainer::update is implemented) that calls `callEngineHandlers`.
        void registerEngineHandlers(std::initializer_list<EngineHandlerList*> handlers);

        const std::string mNamePrefix;
        LuaUtil::LuaState& mLua;

    private:
        struct Script
        {
            std::optional<sol::function> mOnSave;
            std::optional<sol::function> mOnOverride;
            std::optional<sol::table> mInterface;
            std::string mInterfaceName;
            sol::table mHiddenData;
            std::map<std::string, sol::function> mRegisteredCallbacks;
            std::map<int64_t, sol::function> mTemporaryCallbacks;
            std::string mPath;
        };
        struct Timer
        {
            double mTime;
            bool mSerializable;
            int mScriptId;
            std::variant<std::string, int64_t> mCallback; // string if serializable, integer otherwise
            sol::object mArg;
            std::string mSerializedArg;

            bool operator<(const Timer& t) const { return mTime > t.mTime; }
        };
        using EventHandlerList = std::vector<Handler>;

        // Add to container without calling onInit/onLoad.
        bool addScript(int scriptId, std::optional<sol::function>& onInit, std::optional<sol::function>& onLoad);

        // Returns script by id (throws an exception if doesn't exist)
        Script& getScript(int scriptId);

        void printError(int scriptId, std::string_view msg, const std::exception& e);
        const std::string& scriptPath(int scriptId) const { return mLua.getConfiguration()[scriptId].mScriptPath; }
        void callOnInit(int scriptId, const sol::function& onInit, std::string_view data);
        void callTimer(const Timer& t);
        void updateTimerQueue(std::vector<Timer>& timerQueue, double time);
        static void insertTimer(std::vector<Timer>& timerQueue, Timer&& t);
        static void insertHandler(std::vector<Handler>& list, int scriptId, sol::function fn);
        static void removeHandler(std::vector<Handler>& list, int scriptId);
        void insertInterface(int scriptId, const Script& script);
        void removeInterface(int scriptId, const Script& script);

        ScriptIdsWithInitializationData mAutoStartScripts;
        const UserdataSerializer* mSerializer = nullptr;
        const UserdataSerializer* mSavedDataDeserializer = nullptr;
        std::map<std::string, sol::object> mAPI;

        std::map<int, Script> mScripts;
        sol::table mPublicInterfaces;

        EngineHandlerList mUpdateHandlers{ "onUpdate" };
        std::map<std::string_view, EngineHandlerList*> mEngineHandlers;
        std::map<std::string, EventHandlerList, std::less<>> mEventHandlers;

        std::vector<Timer> mSimulationTimersQueue;
        std::vector<Timer> mGameTimersQueue;
        int64_t mTemporaryCallbackCounter = 0;
    };

    // Wrapper for a Lua function.
    // Holds information about the script the function belongs to.
    // Needed to prevent callback calls if the script was removed.
    struct Callback
    {
        sol::function mFunc;
        sol::table mHiddenData; // same object as Script::mHiddenData in ScriptsContainer

        bool isValid() const { return mHiddenData[ScriptsContainer::sScriptIdKey] != sol::nil; }

        template <typename... Args>
        sol::object call(Args&&... args) const
        {
            if (isValid())
                return LuaUtil::call(mFunc, std::forward<Args>(args)...);
            else
                Log(Debug::Debug) << "Ignored callback to the removed script "
                                  << mHiddenData.get<std::string>(ScriptsContainer::sScriptDebugNameKey);
            return sol::nil;
        }

        template <typename... Args>
        void tryCall(Args&&... args) const
        {
            try
            {
                this->call(std::forward<Args>(args)...);
            }
            catch (std::exception& e)
            {
                Log(Debug::Error) << "Error in callback: " << e.what();
            }
        }
    };

}

#endif // COMPONENTS_LUA_SCRIPTSCONTAINER_H