At the moment the phase is slightly innacurate- The math calculates the moon's age fairly accurately (within a few hours), but doesn't follow conventions for turning that age into a phase. I intend to expand on the output, and possibly making the phases more accurate, but I don't have significant interest in making the math more accurate.

-- Uses the lazy method of counting the days since a last known new moon, and uses a hard coded very old date for doing so. It's accurate enough to get an idea of how full the moon is, but is not technically accurate a lot of the time.