source: Utilities/lua.cpp @ 81

/*
 * Filename      : lua.cpp
 * Author(s)     : Chris Thielen (chris@epiar.net)
 * Date Created  : Saturday, January 5, 2008
 * Purpose       : Provides abilities to load, store, and run Lua scripts
 * Notes         : To be used in conjunction with various other subsystems, A.I., GUI, etc.
 */

#include "Engine/console.h"
#include "Engine/simulation.h"
#include "Utilities/log.h"
#include "Utilities/lua.h"
#include "AI/ai_lua.h"
#include "UI/ui_lua.h"
#include "UI/ui.h"
#include "UI/ui_window.h"
#include "UI/ui_label.h"
#include "UI/ui_button.h"
#include "Sprites/Player.h"

bool Lua::luaInitialized = false;
lua_State *Lua::luaVM = NULL;
SpriteManager *Lua::my_sprites= NULL;
vector<string> Lua::buffer;

bool Lua::Load( string filename ) {
        if( ! luaInitialized ) {
                if( Init() == false ) {
                        Log::Warning( "Could not load Lua script. Unable to initialize Lua." );
                        return( false );
                }
        }

        // Start the lua script
        
        if( luaL_dofile(luaVM,filename.c_str()) ){
                Log::Error("Could not run lua file '%s'",filename.c_str());
                Log::Error("%s", lua_tostring(luaVM, -1));
        } else {
                Log::Message("Loaded the universe");
        }
        

        return( false );
}

bool Lua::Update(){
    // Tell the Lua State to update itself
    lua_getglobal(luaVM, "Update");
    if( lua_pcall(luaVM,0,0,0) != 0 ){
                Log::Error("Could not call lua function Update");
            Log::Error("%s", lua_tostring(luaVM, -1));
        return (false);
    }
        return (true);
}



bool Lua::Run( string line ) {
        int error = 0;
        Log::Message("Running '%s'", (char *)line.c_str() );

        if( ! luaInitialized ) {
                if( Init() == false ) {
                        Log::Warning( "Could not load Lua script. Unable to initialize Lua." );
                        return( false );
                }
        }

        error = luaL_loadbuffer(luaVM, line.c_str(), line.length(), "line") || lua_pcall(luaVM, 0, 1, 0);
        if( error ) {
                Console::InsertResult(lua_tostring(luaVM, -1));
                lua_pop(luaVM, 1);  /* pop error message from the stack */
        }

        return( false );
}

// returns the output from the last lua script and deletes it from internal buffer
vector<string> Lua::GetOutput() {
        vector<string> ret = buffer;

        buffer.clear();

        return( ret );
}

bool Lua::SetSpriteList(SpriteManager* the_sprites){
        if( ! luaInitialized ) {
                if( Init() == false ) {
                        Log::Warning( "Could not load Lua script. Unable to initialize Lua." );
                        return( false );
                }
        }
        
        my_sprites = the_sprites;
        return( true );
}

SpriteManager* Lua::GetSpriteList(){
        if( ! luaInitialized ) {
                if( Init() == false ) {
                        Log::Warning( "Could not load Lua script. Unable to initialize Lua." );
                        return( false );
                }
        }
        return my_sprites;
}

bool Lua::Init() {
        if( luaInitialized ) {
                Log::Warning( "Cannot initialize Lua. It is already initialized." );
                return( false );
        }
        
        luaVM = lua_open();

        if( !luaVM ) {
                Log::Warning( "Could not initialize Lua VM." );
                return( false );
        }

        luaL_openlibs( luaVM );

        RegisterFunctions();
        
        luaInitialized = true;
        
        return( true );
}

bool Lua::Close() {
        if( luaInitialized ) {
                lua_close( luaVM );
        } else {
                Log::Warning( "Cannot deinitialize Lua. It is either not initialized or a script is still loaded." );
                return( false );
        }
        
        return( true );
}

void Lua::RegisterFunctions() {
        // Register these functions to the lua global namespace

        static const luaL_Reg EngineFunctions[] = {
                {"echo", &Lua::console_echo},
                {"pause", &Lua::pause},
                {"unpause", &Lua::unpause},
                {"player", &Lua::getPlayer},
                {NULL, NULL}
        };
        luaL_register(luaVM,"Epiar",EngineFunctions);


        // Register these functions to their own lua namespaces
        AI_Lua::RegisterAI(luaVM);
        UI_Lua::RegisterUI(luaVM);
}

int Lua::console_echo(lua_State *L) {
        const char *str = lua_tostring(L, 1); // get argument

        if(str == NULL)
                Console::InsertResult("nil");
        else
                Console::InsertResult(str);

        return 0;
}

int Lua::pause(lua_State *luaVM){
        Simulation::pause();
        return 0;
}

int Lua::unpause(lua_State *luaVM){
        Simulation::unpause();
        return 0;
}

int Lua::getPlayer(lua_State *luaVM){
        Player **player = (Player**)lua_newuserdata(luaVM, sizeof(Player*));
        *player = Player::Instance();
        return 1;
}