from "ecc/babyjubjubParams" import BabyJubJubParams;

// Add two points on a twisted Edwards curve
// Curve parameters are defined with the last argument
// https://en.wikipedia.org/wiki/Twisted_Edwards_curve#Addition_on_twisted_Edwards_curves
def main(field[2] pt1, field[2] pt2, BabyJubJubParams context) -> field[2] {

    field a = context.JUBJUB_A;
    field d = context.JUBJUB_D;

    field u1 = pt1[0];
    field v1 = pt1[1];
    field u2 = pt2[0];
    field v2 = pt2[1];

    field uOut = (u1*v2 + v1*u2) / (1 + d*u1*u2*v1*v2);
    field vOut = (v1*v2 - a*u1*u2) / (1 - d*u1*u2*v1*v2);

    return [uOut, vOut];
}