Originally Posted by ImmortalPig
This will definitely be felony assault, there's no way this will be charged as battery.
Clearing up something: assault and battery are two different crimes, not two separate levels of the same crime.
Assault is the clear threat of physical harm, battery is the actual physical harm. Battery is worse than assault, but you cannot have battery without assault, while you can have just assault.
To demonstrate this, think of a person attempting to punch another person and missing. The threat is clear, the capacity of the perpetrator to inflict harm is clear, but no actual battery occurs.
I would suggest that your figures for prison time are significantly higher than one should expect. First time offenders will almost never result in the maximum sentence, especially one so relatively young.
Furthermore, "requiring facial reconstruction surgery" is in actuality really vague as to what sort of injuries were inflicted. It could be referring to cosmetic surgeries, stitches, etc.
Given the very limited details, it is hard to declare any sentence conclusively.