fantasy lunar calendar apps?

[xoxos]

i had an idea about making an app to calculate brightness at night for a fantasy planet with a definable number of moons and so forth, ~a fantasy lunar calendar. i'm more throwing about ideas for programming exercise than considering the actual utility of the app. i imagine that most role playing groups have never had the need to consider the phase of the moon(s) and if so, the DM would produce the data imaginatively without stopping the game to check an app. "but i could program it!."

(i've toyed with the henon equation previously so it could be definable by mass, or extend it to system app for space games.. though i would only care to tackle that with a universal constant time..)

a quick search revealed no preexistent apps of this nature, and that the name 'lunasy' is taken

(shame.. i was looking forward to finding a preexistent need, to which i could reply "then what i need to do is complete lunasy!")