LUATreeNode.h

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#pragma once

#include "tree/TreeNode.h"
#include "LUAFunctions.h"

namespace ai {

class LUATreeNode : public TreeNode {
protected:
    lua_State* _s;

    TreeNodeStatus runLUA(const AIPtr& entity, int64_t deltaMillis) {
        // get userdata of the behaviour tree node
        const std::string name = "__meta_node_" + _type;
        lua_getfield(_s, LUA_REGISTRYINDEX, name.c_str());
#if AI_LUA_SANTITY > 0
        if (lua_isnil(_s, -1)) {
            ai_log_error("LUA node: could not find lua userdata for %s", name.c_str());
            return TreeNodeStatus::EXCEPTION;
        }
#endif
        // get metatable
        lua_getmetatable(_s, -1);
#if AI_LUA_SANTITY > 0
        if (!lua_istable(_s, -1)) {
            ai_log_error("LUA node: userdata for %s doesn't have a metatable assigned", name.c_str());
            return TreeNodeStatus::EXCEPTION;
        }
#endif
        // get execute() method
        lua_getfield(_s, -1, "execute");
        if (!lua_isfunction(_s, -1)) {
            ai_log_error("LUA node: metatable for %s doesn't have the execute() function assigned", name.c_str());
            return TreeNodeStatus::EXCEPTION;
        }

        // push self onto the stack
        lua_getfield(_s, LUA_REGISTRYINDEX, name.c_str());

        // first parameter is ai
        if (luaAI_pushai(_s, entity) == 0) {
            return TreeNodeStatus::EXCEPTION;
        }

        // second parameter is dt
        lua_pushinteger(_s, deltaMillis);

#if AI_LUA_SANTITY > 0
        if (!lua_isfunction(_s, -4)) {
            ai_log_error("LUA node: expected to find a function on stack -4");
            return TreeNodeStatus::EXCEPTION;
        }
        if (!lua_isuserdata(_s, -3)) {
            ai_log_error("LUA node: expected to find the userdata on -3");
            return TreeNodeStatus::EXCEPTION;
        }
        if (!lua_isuserdata(_s, -2)) {
            ai_log_error("LUA node: second parameter should be the ai");
            return TreeNodeStatus::EXCEPTION;
        }
        if (!lua_isinteger(_s, -1)) {
            ai_log_error("LUA node: first parameter should be the delta millis");
            return TreeNodeStatus::EXCEPTION;
        }
#endif
        const int error = lua_pcall(_s, 3, 1, 0);
        if (error) {
            ai_log_error("LUA node script: %s", lua_isstring(_s, -1) ? lua_tostring(_s, -1) : "Unknown Error");
            // reset stack
            lua_pop(_s, lua_gettop(_s));
            return TreeNodeStatus::EXCEPTION;
        }
        const lua_Integer execstate = luaL_checkinteger(_s, -1);
        if (execstate < 0 || execstate >= (lua_Integer)TreeNodeStatus::MAX_TREENODESTATUS) {
            ai_log_error("LUA node: illegal tree node status returned: " LUA_INTEGER_FMT, execstate);
        }

        // reset stack
        lua_pop(_s, lua_gettop(_s));
        return (TreeNodeStatus)execstate;
    }

public:
    class LUATreeNodeFactory : public ITreeNodeFactory {
    private:
        lua_State* _s;
        std::string _type;
    public:
        LUATreeNodeFactory(lua_State* s, const std::string& typeStr) :
                _s(s), _type(typeStr) {
        }

        inline const std::string& type() const {
            return _type;
        }

        TreeNodePtr create(const TreeNodeFactoryContext* ctx) const override {
            return std::make_shared<LUATreeNode>(ctx->name, ctx->parameters, ctx->condition, _s, _type);
        }
    };

    LUATreeNode(const std::string& name, const std::string& parameters, const ConditionPtr& condition, lua_State* s, const std::string& type) :
            TreeNode(name, parameters, condition), _s(s) {
        _type = type;
    }

    ~LUATreeNode() {
    }

    TreeNodeStatus execute(const AIPtr& entity, int64_t deltaMillis) override {
        if (TreeNode::execute(entity, deltaMillis) == CANNOTEXECUTE) {
            return CANNOTEXECUTE;
        }

#if AI_EXCEPTIONS
        try {
#endif
            return state(entity, runLUA(entity, deltaMillis));
#if AI_EXCEPTIONS
        } catch (...) {
            ai_log_error("Exception while running lua tree node");
        }
        return state(entity, EXCEPTION);
#endif
    }
};

}