# betting
A Rust crate to manage twitch-style bets (aka [Parimutuel betting](https://en.wikipedia.org/wiki/Parimutuel_betting))

```rust
use bets::{Bets, BetError, Amount};

fn bet_demo() -> Result<(), BetError> {
    // variables for readability
    let server_id = 1;
    let bet_id = 1;
    let (alice, bob, charlie) = (0, 1, 2);
    // Create the database
    let bets = Bets::new("bets.db")?;
    // Create 3 accounts on server 1 with 100 starting coins
    bets.create_account(server_id, alice, 100)?;
    bets.create_account(server_id, bob, 100)?;
    bets.create_account(server_id, charlie, 100)?;
    // Alice creates a bet with 2 outcomes
    bets.create_bet(
        bet_id, server_id, alice,
        "Who will win the Rocket League 1v1 ?",
        &vec!["Alice", "Bob"],
    )?;
    // Alice bets on herself (outcome with id 0) with 10 coins
    bets.bet_on(bet_id, 0, alice, 10)?;
    // Bob bets on himself (outcome with id 1) with 40 coins
    bets.bet_on(bet_id, 1, bob, 40)?;
    // Charlie bets on Alice with half of his coins (50)
    bets.bet_on(bet_id, 0, charlie, 0.5)?;
    // asserts that the money is gone from their accounts
    assert_eq!(bets.balance(server_id, alice)?, 90);
    assert_eq!(bets.balance(server_id, bob)?, 60);
    assert_eq!(bets.balance(server_id, charlie)?, 50);
    // lock the bet
    bets.lock_bet(bet_id)?;
    // ...
    // Rocket league 1v1 occurs
    // ...
    // Alice ended up winning ! we resolve the bet with outcome of id 0
    bets.resolve(bet_id, 0)?;
    // The winning side gets 10 + 40 + 50 = 100 coins
    // split proportionally among the betters
    // Alice had bet 10 out of 60 of this outcome, she wins 100*(10/60) = 16.6 rounded to 17
    assert_eq!(bets.balance(server_id, alice)?, 107);
    // Bob doesn't win anything since he bet on the wrong outcome
    assert_eq!(bets.balance(server_id, bob)?, 60);
    // Charlie had bet 50 out of 60 of this outcome, he wins 100*(50/60) = 83.3 rounded to 83
    assert_eq!(bets.balance(server_id, charlie)?, 133);
    Ok(())
}

fn main() {
    if let Err(why) = bet_demo() {
        println!("{:?}", why);
    }
}
```