package math

import luajit "git.sharkk.net/Sky/LuaJIT-to-Go"

func GetFunctionList() map[string]luajit.GoFunction {
	return map[string]luajit.GoFunction{
		"math_factorial": math_factorial,
		"math_gcd":       math_gcd,
		"math_lcm":       math_lcm,
	}
}

func math_factorial(s *luajit.State) int {
	n := s.ToNumber(1)
	if n < 0 || n != float64(int(n)) || n > 170 {
		s.PushNil()
		s.PushString("invalid argument")
		return 2
	}

	result := 1.0
	for i := 2; i <= int(n); i++ {
		result *= float64(i)
	}

	s.PushNumber(result)
	return 1
}

func math_gcd(s *luajit.State) int {
	a := int(s.ToNumber(1))
	b := int(s.ToNumber(2))

	for b != 0 {
		a, b = b, a%b
	}

	s.PushNumber(float64(a))
	return 1
}

func math_lcm(s *luajit.State) int {
	a := int(s.ToNumber(1))
	b := int(s.ToNumber(2))

	// Calculate GCD
	gcd := func(x, y int) int {
		for y != 0 {
			x, y = y, x%y
		}
		return x
	}

	result := a * b / gcd(a, b)
	s.PushNumber(float64(result))
	return 1
}