int cLuaState::CallFunctionWithForeignParams(
	const AString & a_FunctionName,
	cLuaState & a_SrcLuaState,
	int a_SrcParamStart,
	int a_SrcParamEnd
)
{
	ASSERT(IsValid());
	ASSERT(a_SrcLuaState.IsValid());

	// Store the stack position before any changes
	int OldTop = lua_gettop(m_LuaState);

	// Push the function to call, including the error handler:
	if (!PushFunction(a_FunctionName.c_str()))
	{
		LOGWARNING("Function '%s' not found", a_FunctionName.c_str());
		lua_settop(m_LuaState, OldTop);
		return -1;
	}

	// Copy the function parameters to the target state
	if (CopyStackFrom(a_SrcLuaState, a_SrcParamStart, a_SrcParamEnd) < 0)
	{
		// Something went wrong, fix the stack and exit
		lua_settop(m_LuaState, OldTop);
		m_NumCurrentFunctionArgs = -1;
		m_CurrentFunctionName.clear();
		return -1;
	}

	// Call the function, with an error handler:
	int s = lua_pcall(m_LuaState, a_SrcParamEnd - a_SrcParamStart + 1, LUA_MULTRET, OldTop + 1);
	if (ReportErrors(s))
	{
		LOGWARN("Error while calling function '%s' in '%s'", a_FunctionName.c_str(), m_SubsystemName.c_str());
		// Reset the stack:
		lua_settop(m_LuaState, OldTop);

		// Reset the internal checking mechanisms:
		m_NumCurrentFunctionArgs = -1;
		m_CurrentFunctionName.clear();

		// Make Lua think everything is okay and return 0 values, so that plugins continue executing.
		// The failure is indicated by the zero return values.
		return 0;
	}

	// Reset the internal checking mechanisms:
	m_NumCurrentFunctionArgs = -1;
	m_CurrentFunctionName.clear();

	// Remove the error handler from the stack:
	lua_remove(m_LuaState, OldTop + 1);

	// Return the number of return values:
	return lua_gettop(m_LuaState) - OldTop;
}

void cLuaState::cRef::RefStack(cLuaState & a_LuaState, int a_StackPos)
{
	ASSERT(a_LuaState.IsValid());
	if (m_LuaState != nullptr)
	{
		UnRef();
	}
	m_LuaState = &a_LuaState;
	lua_pushvalue(a_LuaState, a_StackPos);  // Push a copy of the value at a_StackPos onto the stack
	m_Ref = luaL_ref(a_LuaState, LUA_REGISTRYINDEX);
}

bool cLuaState::cCallback::IsSameLuaState(cLuaState & a_LuaState)
{
	cCSLock lock(m_CS);
	if (!m_Ref.IsValid())
	{
		return false;
	}
	auto canonState = a_LuaState.QueryCanonLuaState();
	if (canonState == nullptr)
	{
		return false;
	}
	return (m_Ref.GetLuaState() == static_cast<lua_State *>(*canonState));
}

bool cPrefabPiecePool::ApplyPieceMetadataCubesetVer1(
	const AString & a_FileName,
	cLuaState & a_LuaState,
	const AString & a_PieceName,
	cPrefab * a_Prefab,
	bool a_LogWarnings
)
{
	// Push the Metadata table on top of the Lua stack:
	auto md = a_LuaState.WalkToValue("Metadata");
	if (!md.IsValid())
	{
		return false;
	}

	// Get the values:
	int AddWeightIfSame = 0, DefaultWeight = 100, MoveToGround = 0, ShouldExpandFloor = 0;
	AString DepthWeight, MergeStrategy;
	a_LuaState.GetNamedValue("AddWeightIfSame",   AddWeightIfSame);
	a_LuaState.GetNamedValue("DefaultWeight",     DefaultWeight);
	a_LuaState.GetNamedValue("DepthWeight",       DepthWeight);
	a_LuaState.GetNamedValue("MergeStrategy",     MergeStrategy);
	a_LuaState.GetNamedValue("MoveToGround",      MoveToGround);
	a_LuaState.GetNamedValue("ShouldExpandFloor", ShouldExpandFloor);

	// Apply the values:
	a_Prefab->SetAddWeightIfSame(AddWeightIfSame);
	a_Prefab->SetDefaultWeight(DefaultWeight);
	a_Prefab->ParseDepthWeight(DepthWeight.c_str());
	auto msmap = GetMergeStrategyMap();
	auto strategy = msmap.find(MergeStrategy);
	if (strategy == msmap.end())
	{
		CONDWARNING(a_LogWarnings, "Unknown merge strategy (\"%s\") specified for piece %s in file %s. Using msSpongePrint instead.",
			MergeStrategy.c_str(), a_PieceName.c_str(), a_FileName.c_str()
		);
		a_Prefab->SetMergeStrategy(cBlockArea::msSpongePrint);
	}
	else
	{
		a_Prefab->SetMergeStrategy(strategy->second);
	}
	a_Prefab->SetMoveToGround(MoveToGround != 0);
	a_Prefab->SetExtendFloor(ShouldExpandFloor != 0);

	return true;
}

bool cLuaState::cCallback::RefStack(cLuaState & a_LuaState, int a_StackPos)
{
	// Check if the stack contains a function:
	if (!lua_isfunction(a_LuaState, a_StackPos))
	{
		return false;
	}

	// Clear any previous callback:
	Clear();

	// Add self to LuaState's callback-tracking:
	a_LuaState.TrackCallback(*this);

	// Store the new callback:
	cCSLock Lock(m_CS);
	m_Ref.RefStack(a_LuaState, a_StackPos);
	return true;
}

bool cPrefabPiecePool::LoadFromCubesetFileVer1(const AString & a_FileName, cLuaState & a_LuaState, bool a_LogWarnings)
{
	// Load the metadata:
	ApplyPoolMetadataCubesetVer1(a_FileName, a_LuaState, a_LogWarnings);

	// Push the Cubeset.Pieces global value on the stack:
	lua_getglobal(a_LuaState, "_G");
	cLuaState::cStackValue stk(a_LuaState);
	auto pieces = a_LuaState.WalkToValue("Cubeset.Pieces");
	if (!pieces.IsValid() || !lua_istable(a_LuaState, -1))
	{
		CONDWARNING(a_LogWarnings, "The cubeset file %s doesn't contain any pieces", a_FileName.c_str());
		return false;
	}

	// Iterate over all items in the Cubeset.Pieces value:
	int idx = 1;
	bool res = true;
	while (true)
	{
		lua_pushinteger(a_LuaState, idx);  // stk: [Pieces] [idx]
		lua_gettable(a_LuaState, -2);      // stk: [Pieces] [PieceItem]
		if (!lua_istable(a_LuaState, -1))
		{
			// The PieceItem is not present, we've iterated over all items
			lua_pop(a_LuaState, 1);  // stk: [Pieces]
			break;
		}
		if (!LoadCubesetPieceVer1(a_FileName, a_LuaState, idx, a_LogWarnings))
		{
			res = false;
		}
		lua_pop(a_LuaState, 1);  // stk: [Pieces]
		idx += 1;
	}
	return res;
}

int cLuaState::CopyStackFrom(cLuaState & a_SrcLuaState, int a_SrcStart, int a_SrcEnd)
{
	/*
	// DEBUG:
	LOGD("Copying stack values from %d to %d", a_SrcStart, a_SrcEnd);
	a_SrcLuaState.LogStack("Src stack before copying:");
	LogStack("Dst stack before copying:");
	*/
	for (int i = a_SrcStart; i <= a_SrcEnd; ++i)
	{
		int t = lua_type(a_SrcLuaState, i);
		switch (t)
		{
			case LUA_TNIL:
			{
				lua_pushnil(m_LuaState);
				break;
			}
			case LUA_TSTRING:
			{
				AString s;
				a_SrcLuaState.ToString(i, s);
				Push(s);
				break;
			}
			case LUA_TBOOLEAN:
			{
				bool b = (tolua_toboolean(a_SrcLuaState, i, false) != 0);
				Push(b);
				break;
			}
			case LUA_TNUMBER:
			{
				lua_Number d = tolua_tonumber(a_SrcLuaState, i, 0);
				Push(d);
				break;
			}
			case LUA_TUSERDATA:
			{
				// Get the class name:
				const char * type = nullptr;
				if (lua_getmetatable(a_SrcLuaState, i) == 0)
				{
					LOGWARNING("%s: Unknown class in pos %d, cannot copy.", __FUNCTION__, i);
					lua_pop(m_LuaState, i - a_SrcStart);
					return -1;
				}
				lua_rawget(a_SrcLuaState, LUA_REGISTRYINDEX);  // Stack +1
				type = lua_tostring(a_SrcLuaState, -1);
				lua_pop(a_SrcLuaState, 1);                     // Stack -1

				// Copy the value:
				void * ud = tolua_touserdata(a_SrcLuaState, i, nullptr);
				tolua_pushusertype(m_LuaState, ud, type);
				break;
			}
			default:
			{
				LOGWARNING("%s: Unsupported value: '%s' at stack position %d. Can only copy numbers, strings, bools and classes!",
					__FUNCTION__, lua_typename(a_SrcLuaState, t), i
				);
				a_SrcLuaState.LogStack("Stack where copying failed:");
				lua_pop(m_LuaState, i - a_SrcStart);
				return -1;
			}
		}
	}
	return a_SrcEnd - a_SrcStart + 1;
}

bool cLuaState::CopySingleValueFrom(cLuaState & a_SrcLuaState, int a_StackIdx, int a_NumAllowedNestingLevels)
{
	int t = lua_type(a_SrcLuaState, a_StackIdx);
	switch (t)
	{
		case LUA_TNIL:
		{
			lua_pushnil(m_LuaState);
			return true;
		}
		case LUA_TSTRING:
		{
			AString s;
			a_SrcLuaState.ToString(a_StackIdx, s);
			Push(s);
			return true;
		}
		case LUA_TBOOLEAN:
		{
			bool b = (tolua_toboolean(a_SrcLuaState, a_StackIdx, false) != 0);
			Push(b);
			return true;
		}
		case LUA_TNUMBER:
		{
			lua_Number d = tolua_tonumber(a_SrcLuaState, a_StackIdx, 0);
			Push(d);
			return true;
		}
		case LUA_TUSERDATA:
		{
			// Get the class name:
			const char * type = nullptr;
			if (lua_getmetatable(a_SrcLuaState, a_StackIdx) == 0)
			{
				LOGWARNING("%s: Unknown class in pos %d, cannot copy.", __FUNCTION__, a_StackIdx);
				return false;
			}
			lua_rawget(a_SrcLuaState, LUA_REGISTRYINDEX);  // Stack +1
			type = lua_tostring(a_SrcLuaState, -1);
			lua_pop(a_SrcLuaState, 1);                     // Stack -1

			// Copy the value:
			void * ud = tolua_touserdata(a_SrcLuaState, a_StackIdx, nullptr);
			tolua_pushusertype(m_LuaState, ud, type);
			return true;
		}
		case LUA_TTABLE:
		{
			if (!CopyTableFrom(a_SrcLuaState, a_StackIdx, a_NumAllowedNestingLevels - 1))
			{
				LOGWARNING("%s: Failed to copy table in pos %d.", __FUNCTION__, a_StackIdx);
				return false;
			}
			return true;
		}
		default:
		{
			LOGWARNING("%s: Unsupported value: '%s' at stack position %d. Can only copy numbers, strings, bools, classes and simple tables!",
				__FUNCTION__, lua_typename(a_SrcLuaState, t), a_StackIdx
			);
			return false;
		}
	}
}

bool cPrefabPiecePool::ApplyPoolMetadataCubesetVer1(
	const AString & a_FileName,
	cLuaState & a_LuaState,
	bool a_LogWarnings
)
{
	// Push the Cubeset.Metadata table on top of the Lua stack:
	lua_getglobal(a_LuaState, "_G");
	auto md = a_LuaState.WalkToValue("Cubeset.Metadata");
	if (!md.IsValid())
	{
		CONDWARNING(a_LogWarnings, "Cannot load cubeset from file %s: Cubeset.Metadata table is missing", a_FileName.c_str());
		return false;
	}

	// Set the metadata values to defaults:
	m_MinDensity = 100;
	m_MaxDensity = 100;
	m_VillageRoadBlockType = E_BLOCK_GRAVEL;
	m_VillageRoadBlockMeta = 0;
	m_VillageWaterRoadBlockType = E_BLOCK_PLANKS;
	m_VillageWaterRoadBlockMeta = 0;

	// Read the metadata values:
	a_LuaState.GetNamedValue("IntendedUse",               m_IntendedUse);
	a_LuaState.GetNamedValue("MaxDensity",                m_MaxDensity);
	a_LuaState.GetNamedValue("MinDensity",                m_MinDensity);
	a_LuaState.GetNamedValue("VillageRoadBlockType",      m_VillageRoadBlockType);
	a_LuaState.GetNamedValue("VillageRoadBlockMeta",      m_VillageRoadBlockMeta);
	a_LuaState.GetNamedValue("VillageWaterRoadBlockType", m_VillageWaterRoadBlockType);
	a_LuaState.GetNamedValue("VillageWaterRoadBlockMeta", m_VillageWaterRoadBlockMeta);
	AString allowedBiomes;
	if (a_LuaState.GetNamedValue("AllowedBiomes", allowedBiomes))
	{
		auto biomes = StringSplitAndTrim(allowedBiomes, ",");
		for (const auto & biome: biomes)
		{
			EMCSBiome b = StringToBiome(biome);
			if (b == biInvalidBiome)
			{
				CONDWARNING(a_LogWarnings, "Invalid biome (\"%s\") specified in AllowedBiomes in cubeset file %s. Skipping the biome.",
					biome.c_str(), a_FileName.c_str()
				);
				continue;
			}
			m_AllowedBiomes.insert(b);
		}
	}
	else
	{
		// All biomes are allowed:
		for (int b = biFirstBiome; b <= biMaxBiome; b++)
		{
			m_AllowedBiomes.insert(static_cast<EMCSBiome>(b));
		}
		for (int b = biFirstVariantBiome; b <= biMaxVariantBiome; b++)
		{
			m_AllowedBiomes.insert(static_cast<EMCSBiome>(b));
		}
	}
	return true;
}

UniquePtr<cPrefab> cPrefabPiecePool::LoadPrefabFromCubesetVer1(
	const AString & a_FileName,
	cLuaState & a_LuaState,
	const AString & a_PieceName,
	bool a_LogWarnings
)
{
	// First try loading a referenced schematic file, if any:
	AString SchematicFileName;
	if (a_LuaState.GetNamedValue("SchematicFileName", SchematicFileName))
	{
		auto PathEnd = a_FileName.find_last_of("/\\");  // Find the last path separator
		if (PathEnd != AString::npos)
		{
			SchematicFileName = a_FileName.substr(0, PathEnd) + SchematicFileName;
		}
		cBlockArea area;
		if (!cSchematicFileSerializer::LoadFromSchematicFile(area, SchematicFileName))
		{
			CONDWARNING(a_LogWarnings, "Cannot load schematic file \"%s\" for piece %s in cubeset %s.",
				SchematicFileName.c_str(), a_PieceName.c_str(), a_FileName.c_str()
			);
			return nullptr;
		}
		return cpp14::make_unique<cPrefab>(area);
	}  // if (SchematicFileName)

	// There's no referenced schematic file, load from BlockDefinitions / BlockData.
	// Get references to the data and the table.concat function:
	cLuaState::cRef TableConcat, BlockDefinitions, BlockData;
	if (
		!a_LuaState.GetNamedGlobal("table.concat", TableConcat) ||
		!a_LuaState.GetNamedValue("BlockDefinitions", BlockDefinitions) ||
		!a_LuaState.GetNamedValue("BlockData", BlockData)
	)
	{
		CONDWARNING(a_LogWarnings, "Cannot parse block data for piece %s in cubeset %s", a_PieceName.c_str(), a_FileName.c_str());
		return nullptr;
	}

	// Call table.concat() on the BlockDefinitions:
	AString BlockDefStr;
	if (!a_LuaState.Call(TableConcat, BlockDefinitions, "\n", cLuaState::Return, BlockDefStr))
	{
		CONDWARNING(a_LogWarnings, "Cannot concat block definitions for piece %s in cubeset %s", a_PieceName.c_str(), a_FileName.c_str());
		return nullptr;
	}

	// Call table.concat() on the BlockData:
	AString BlockDataStr;
	if (!a_LuaState.Call(TableConcat, BlockData, "", cLuaState::Return, BlockDataStr))
	{
		CONDWARNING(a_LogWarnings, "Cannot concat block data for piece %s in cubeset %s", a_PieceName.c_str(), a_FileName.c_str());
		return nullptr;
	}

	// Read the size:
	int SizeX = 0, SizeY = 0, SizeZ = 0;
	if (
		!a_LuaState.GetNamedValue("Size.x", SizeX) ||
		!a_LuaState.GetNamedValue("Size.y", SizeY) ||
		!a_LuaState.GetNamedValue("Size.z", SizeZ)
	)
	{
		CONDWARNING(a_LogWarnings, "Cannot load piece %s from file %s, its size information is missing", a_PieceName.c_str(), a_FileName.c_str());
		return nullptr;
	}

	// Check that the size matches the data length:
	if (static_cast<size_t>(SizeX * SizeY * SizeZ) != BlockDataStr.size())
	{
		CONDWARNING(a_LogWarnings, "Cannot create piece %s from file %s, its size (%d) doesn't match the blockdata length (%u)",
			a_PieceName.c_str(), a_FileName.c_str(),
			SizeX * SizeY * SizeZ, static_cast<unsigned>(BlockDataStr.size())
		);
		return nullptr;
	}

	return cpp14::make_unique<cPrefab>(BlockDefStr, BlockDataStr, SizeX, SizeY, SizeZ);
}

bool cPrefabPiecePool::LoadCubesetPieceVer1(const AString & a_FileName, cLuaState & a_LuaState, int a_PieceIndex, bool a_LogWarnings)
{
	ASSERT(lua_istable(a_LuaState, -1));

	// The piece name is optional, but useful for debugging messages:
	AString PieceName;
	if (!a_LuaState.GetNamedValue("OriginData.ExportName", PieceName))
	{
		Printf(PieceName, "Piece #%d", a_PieceIndex);
	}

	// Read the hitbox dimensions:
	cCuboid Hitbox;
	if (
		!a_LuaState.GetNamedValue("Hitbox.MinX", Hitbox.p1.x) ||
		!a_LuaState.GetNamedValue("Hitbox.MinY", Hitbox.p1.y) ||
		!a_LuaState.GetNamedValue("Hitbox.MinZ", Hitbox.p1.z) ||
		!a_LuaState.GetNamedValue("Hitbox.MaxX", Hitbox.p2.x) ||
		!a_LuaState.GetNamedValue("Hitbox.MaxY", Hitbox.p2.y) ||
		!a_LuaState.GetNamedValue("Hitbox.MaxZ", Hitbox.p2.z)
	)
	{
		CONDWARNING(a_LogWarnings, "Cannot load piece %s from file %s, it's missing hitbox information", PieceName.c_str(), a_FileName.c_str());
		return false;
	}

	// Load the prefab data:
	auto prefab = LoadPrefabFromCubesetVer1(a_FileName, a_LuaState, PieceName, a_LogWarnings);
	if (prefab == nullptr)
	{
		return false;
	}
	prefab->SetHitBox(Hitbox);

	// Read the connectors
	if (!ReadConnectorsCubesetVer1(a_FileName, a_LuaState, PieceName, prefab.get(), a_LogWarnings))
	{
		return false;
	}

	// Read the allowed rotations. It is an optional metadata value, default to 0:
	int AllowedRotations = 0;
	a_LuaState.GetNamedValue("Metadata.AllowedRotations", AllowedRotations);
	prefab->SetAllowedRotations(AllowedRotations);

	// Apply the relevant metadata:
	if (!ApplyPieceMetadataCubesetVer1(a_FileName, a_LuaState, PieceName, prefab.get(), a_LogWarnings))
	{
		return false;
	}

	// Add the prefab into the list of pieces:
	int IsStartingPiece = 0;
	a_LuaState.GetNamedValue("Metadata.IsStarting", IsStartingPiece);
	if (IsStartingPiece != 0)
	{
		m_StartingPieces.push_back(prefab.release());
	}
	else
	{
		auto p = prefab.release();
		m_AllPieces.push_back(p);
		AddToPerConnectorMap(p);
	}
	return true;
}

bool cPrefabPiecePool::ReadPieceMetadataCubesetVer1(
	const AString & a_FileName,
	cLuaState & a_LuaState,
	const AString & a_PieceName,
	cPrefab * a_Prefab,
	bool a_LogWarnings
)
{
	// Push the Metadata table on top of the Lua stack:
	auto md = a_LuaState.WalkToValue("Metadata");
	if (!md.IsValid())
	{
		return false;
	}

	// Get the values:
	int AddWeightIfSame = 0, DefaultWeight = 100, MoveToGround = 0;
	AString DepthWeight, MergeStrategy, VerticalLimit, VerticalStrategy;
	a_LuaState.GetNamedValue("AddWeightIfSame",  AddWeightIfSame);
	a_LuaState.GetNamedValue("DefaultWeight",    DefaultWeight);
	a_LuaState.GetNamedValue("DepthWeight",      DepthWeight);
	a_LuaState.GetNamedValue("MergeStrategy",    MergeStrategy);
	a_LuaState.GetNamedValue("MoveToGround",     MoveToGround);
	a_LuaState.GetNamedValue("VerticalLimit",    VerticalLimit);
	a_LuaState.GetNamedValue("VerticalStrategy", VerticalStrategy);

	// Apply the values:
	a_Prefab->SetAddWeightIfSame(AddWeightIfSame);
	a_Prefab->SetDefaultWeight(DefaultWeight);
	a_Prefab->ParseDepthWeight(DepthWeight.c_str());
	auto msmap = GetMergeStrategyMap();
	auto strategy = msmap.find(MergeStrategy);
	if (strategy == msmap.end())
	{
		CONDWARNING(a_LogWarnings, "Unknown merge strategy (\"%s\") specified for piece %s in file %s. Using msSpongePrint instead.",
			MergeStrategy.c_str(), a_PieceName.c_str(), a_FileName.c_str()
		);
		a_Prefab->SetMergeStrategy(cBlockArea::msSpongePrint);
	}
	else
	{
		a_Prefab->SetMergeStrategy(strategy->second);
	}
	a_Prefab->SetMoveToGround(MoveToGround != 0);

	AString ExpandFloorStrategyStr;
	if (!a_LuaState.GetNamedValue("ExpandFloorStrategy", ExpandFloorStrategyStr))
	{
		// Check the older variant for ExpandFloorStrategy, ShouldExpandFloor:
		int ShouldExpandFloor;
		if (a_LuaState.GetNamedValue("ShouldExpandFloor", ShouldExpandFloor))
		{
			LOG("Piece \"%s\" in file \"%s\" is using the old \"ShouldExpandFloor\" attribute. Use the new \"ExpandFloorStrategy\" attribute instead for more options.",
				a_PieceName.c_str(), a_FileName.c_str()
			);
			a_Prefab->SetExtendFloorStrategy((ShouldExpandFloor != 0) ? cPrefab::efsRepeatBottomTillNonAir : cPrefab::efsNone);
		}
	}
	else
	{
		auto lcExpandFloorStrategyStr = StrToLower(ExpandFloorStrategyStr);
		if (lcExpandFloorStrategyStr == "repeatbottomtillnonair")
		{
			a_Prefab->SetExtendFloorStrategy(cPrefab::efsRepeatBottomTillNonAir);
		}
		else if (lcExpandFloorStrategyStr == "repeatbottomtillsolid")
		{
			a_Prefab->SetExtendFloorStrategy(cPrefab::efsRepeatBottomTillSolid);
		}
		else
		{
			if (lcExpandFloorStrategyStr != "none")
			{
				LOGWARNING("Piece \"%s\" in file \"%s\" is using an unknown \"ExpandFloorStrategy\" attribute value: \"%s\"",
					a_PieceName.c_str(), a_FileName.c_str(), ExpandFloorStrategyStr.c_str()
				);
			}
			a_Prefab->SetExtendFloorStrategy(cPrefab::efsNone);
		}
	}
	if (!VerticalLimit.empty())
	{
		if (!a_Prefab->SetVerticalLimitFromString(VerticalLimit, a_LogWarnings))
		{
			CONDWARNING(a_LogWarnings, "Unknown VerticalLimit (\"%s\") specified for piece %s in file %s. Using no limit instead.",
				VerticalLimit.c_str(), a_PieceName.c_str(), a_FileName.c_str()
			);
		}
	}
	a_Prefab->SetVerticalStrategyFromString(VerticalStrategy, a_LogWarnings);

	return true;
}