minetest/src/script/cpp_api/s_item.cpp

/*
Minetest
Copyright (C) 2013 celeron55, Perttu Ahola <celeron55@gmail.com>

This program is free software; you can redistribute it and/or modify
it under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation; either version 2.1 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU Lesser General Public License for more details.

You should have received a copy of the GNU Lesser General Public License along
with this program; if not, write to the Free Software Foundation, Inc.,
51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/

#include "cpp_api/s_item.h"
#include "common/c_converter.h"
#include "common/c_content.h"
#include "lua_api/l_item.h"
#include "server.h"

bool ScriptApiItem::item_OnDrop(ItemStack &item,
		ServerActiveObject *dropper, v3f pos)
{
	SCRIPTAPI_PRECHECKHEADER

	// Push callback function on stack
	if(!getItemCallback(item.name.c_str(), "on_drop"))
		return false;

	// Call function
	LuaItemStack::create(L, item);
	objectrefGetOrCreate(dropper);
	pushFloatPos(L, pos);
	if(lua_pcall(L, 3, 1, 0))
		scriptError("error: %s", lua_tostring(L, -1));
	if(!lua_isnil(L, -1))
		item = read_item(L,-1, getServer());
	return true;
}

bool ScriptApiItem::item_OnPlace(ItemStack &item,
		ServerActiveObject *placer, const PointedThing &pointed)
{
	SCRIPTAPI_PRECHECKHEADER

	// Push callback function on stack
	if(!getItemCallback(item.name.c_str(), "on_place"))
		return false;

	// Call function
	LuaItemStack::create(L, item);
	objectrefGetOrCreate(placer);
	pushPointedThing(pointed);
	if(lua_pcall(L, 3, 1, 0))
		scriptError("error: %s", lua_tostring(L, -1));
	if(!lua_isnil(L, -1))
		item = read_item(L,-1, getServer());
	return true;
}

bool ScriptApiItem::item_OnUse(ItemStack &item,
		ServerActiveObject *user, const PointedThing &pointed)
{
	SCRIPTAPI_PRECHECKHEADER

	// Push callback function on stack
	if(!getItemCallback(item.name.c_str(), "on_use"))
		return false;

	// Call function
	LuaItemStack::create(L, item);
	objectrefGetOrCreate(user);
	pushPointedThing(pointed);
	if(lua_pcall(L, 3, 1, 0))
		scriptError("error: %s", lua_tostring(L, -1));
	if(!lua_isnil(L, -1))
		item = read_item(L,-1, getServer());
	return true;
}

// Retrieves minetest.registered_items[name][callbackname]
// If that is nil or on error, return false and stack is unchanged
// If that is a function, returns true and pushes the
// function onto the stack
// If minetest.registered_items[name] doesn't exist, minetest.nodedef_default
// is tried instead so unknown items can still be manipulated to some degree
bool ScriptApiItem::getItemCallback(const char *name, const char *callbackname)
{
	lua_State* L = getStack();

	lua_getglobal(L, "minetest");
	lua_getfield(L, -1, "registered_items");
	lua_remove(L, -2);
	luaL_checktype(L, -1, LUA_TTABLE);
	lua_getfield(L, -1, name);
	lua_remove(L, -2);
	// Should be a table
	if(lua_type(L, -1) != LUA_TTABLE)
	{
		// Report error and clean up
		errorstream<<"Item \""<<name<<"\" not defined"<<std::endl;
		lua_pop(L, 1);

		// Try minetest.nodedef_default instead
		lua_getglobal(L, "minetest");
		lua_getfield(L, -1, "nodedef_default");
		lua_remove(L, -2);
		luaL_checktype(L, -1, LUA_TTABLE);
	}
	lua_getfield(L, -1, callbackname);
	lua_remove(L, -2);
	// Should be a function or nil
	if(lua_type(L, -1) == LUA_TFUNCTION)
	{
		return true;
	}
	else if(lua_isnil(L, -1))
	{
		lua_pop(L, 1);
		return false;
	}
	else
	{
		errorstream<<"Item \""<<name<<"\" callback \""
			<<callbackname<<" is not a function"<<std::endl;
		lua_pop(L, 1);
		return false;
	}
}

void ScriptApiItem::pushPointedThing(const PointedThing& pointed)
{
	lua_State* L = getStack();

	lua_newtable(L);
	if(pointed.type == POINTEDTHING_NODE)
	{
		lua_pushstring(L, "node");
		lua_setfield(L, -2, "type");
		push_v3s16(L, pointed.node_undersurface);
		lua_setfield(L, -2, "under");
		push_v3s16(L, pointed.node_abovesurface);
		lua_setfield(L, -2, "above");
	}
	else if(pointed.type == POINTEDTHING_OBJECT)
	{
		lua_pushstring(L, "object");
		lua_setfield(L, -2, "type");
		objectrefGet(pointed.object_id);
		lua_setfield(L, -2, "ref");
	}
	else
	{
		lua_pushstring(L, "nothing");
		lua_setfield(L, -2, "type");
	}
}