RPG - Random Chest Rewards

[Hurdarr]

Greetings,

I want to program a chest that gives a random reward (from a pool from 10 possible rewards). Which is the best way to program this function? If-else? Switch? Array?

And more importantly, how can I define the chance of getting each reward?
For example: The player has 50% of getting Reward1, 3% Reward2, 0.005% Reward3 and so on?

Thanks.