main.cpp

#include "GarrysMod/Lua/Interface.h"
#include <random>
#include <climits>
#include <vector>

std::random_device rd;
std::mt19937 gen;

int randomNumber(lua_State* state) {
	if (LUA->GetType(1) != GarrysMod::Lua::Type::NIL) {	//Check if we have the first argument
		LUA->CheckType(1, GarrysMod::Lua::Type::NUMBER);	//Verify the first argument is a number

		if (LUA->GetType(2) != GarrysMod::Lua::Type::NIL) {	//Check if we have the second argument
			LUA->CheckType(2, GarrysMod::Lua::Type::NUMBER);	//Verify the second argument is a number

			//Push our random number between the first and second argument
			std::uniform_real_distribution<double> dist(LUA->GetNumber(1), LUA->GetNumber(2));
			LUA->PushNumber(dist(gen));
		} else {
			//Added in by The Owl Cafe
			//Purpose: To make it behave fully like the math.random function in glua, effectively allowing it to fully replace math.random

			//We only have the first argument
			//We return a number between 1 and the second argument
			std::uniform_real_distribution<double> dist( 1.0, LUA->GetNumber(1));
			LUA->PushNumber(dist(gen));
		}
	} else {
		//Return a random number between 0 and 1
		std::uniform_real_distribution<double> dist;
		LUA->PushNumber(dist(gen));
	}

	return 1;
}

int randomWholeNumber(lua_State* state) {
	if (LUA->GetType(1) != GarrysMod::Lua::Type::NIL) {	//Check if we have the first argument
		LUA->CheckType(1, GarrysMod::Lua::Type::NUMBER);	//Verify the first argument is a number

		if (LUA->GetType(2) != GarrysMod::Lua::Type::NIL) {	//Check if we have the second argument
			LUA->CheckType(2, GarrysMod::Lua::Type::NUMBER);	//Verify the second argument is a number

			//Push our random number between the first and second argument
			std::uniform_int_distribution<int> dist(LUA->GetNumber(1), LUA->GetNumber(2));
			LUA->PushNumber(dist(gen));
		} else {
			//Added in by The Owl Cafe
			//Purpose: To make it behave fully like the math.random function in glua, effectively allowing it to fully replace math.random

			//We only have the first argument
			//We return a number between 1 and the second argument
			std::uniform_int_distribution<int> dist( 1, LUA->GetNumber(1));
			LUA->PushNumber(dist(gen));
		}
	} else {
		//Return a random number between 0 and 1
		std::uniform_int_distribution<int> dist;
		LUA->PushNumber(dist(gen));
	}

	return 1;
}

int randomBytes(lua_State* state) {
	LUA->CheckType(1, GarrysMod::Lua::Type::NUMBER);
	const double requestedSize = LUA->GetNumber(1);
	const size_t size = floor(LUA->GetNumber(1));

	if (requestedSize < 0 || size != requestedSize) {
		LUA->ThrowError("size must be a whole number >= 0");
	}

	std::uniform_int_distribution<int> dist(SCHAR_MIN, SCHAR_MAX);
	std::vector<char> bytes;
	bytes.resize(size);

	for (size_t i = 0; i < size; i++) {
		bytes[i] = (char)dist(rd);
	}

	LUA->PushString(bytes.data(), size);

	return 1;
}

GMOD_MODULE_OPEN() {
	gen.seed(rd());
	gen.discard(700000); // http://www.iro.umontreal.ca/~lecuyer/myftp/papers/lfsr04.pdf page 11

	LUA->PushSpecial(GarrysMod::Lua::SPECIAL_GLOB);
		LUA->CreateTable();
			LUA->PushCFunction(randomNumber);
			LUA->SetField(-2, "Number");
	
			//Same as random.Number, but should provide a whole number instead of a decimal
			LUA->PushCFunction(randomWholeNumber);
			LUA->SetField(-2, "WholeNumber");

			LUA->PushCFunction(randomBytes);
			LUA->SetField(-2, "Bytes");
		LUA->SetField(-2, "random");
	LUA->Pop();
	return 0;
}

GMOD_MODULE_CLOSE() {
	return 0;
}