League Structure

Hello guys!

I'm building sport game and i really have hard time to find the correct formula of how to automate the building of each league games structure.

leagues can come in various number of teams (eg. 4, 6,8,10...)
each season is built from two round and in each round every team playing one match against each other.

to make it even harder each team should play every second match in its own Arena...

so if league is built from 4 teams it should be something like

First half of the season:

Round 1
Team A Vs Team B
Team C Vs Team D

Round 2
Team A Vs Team C
Team D Vs Team B
Second Half of the Season

Round 1
Team C Vs Team A
Team B Vs Team D

Round 2
Team D Vs Team C
Team B Vs Team A

if anyone can point me to the right direction it will be great.

Thanks!