tetris/src/random.rs

use crate::tetromino::TetrominoType;
use rand::{rngs::ThreadRng, seq::SliceRandom, thread_rng};

#[derive(Clone, Copy, Debug)]
pub struct RandomSystem {
    rng: ThreadRng,
    bag: [TetrominoType; 7],
    cur_pos: usize,
}

impl RandomSystem {
    pub fn new() -> Self {
        let rng = thread_rng();
        RandomSystem {
            rng: rng,
            bag: [TetrominoType::I; 7], // Default value, should get init on first get
            cur_pos: 0,
        }
    }

    pub fn get_tetromino(&mut self) -> TetrominoType {
        if self.cur_pos == 0 {
            self.refresh_bag();
        }
        let to_return = self.bag[self.cur_pos];
        self.cur_pos = (self.cur_pos + 1) % 7;
        to_return
    }

    fn refresh_bag(&mut self) {
        self.bag = [
            TetrominoType::I,
            TetrominoType::O,
            TetrominoType::T,
            TetrominoType::S,
            TetrominoType::Z,
            TetrominoType::J,
            TetrominoType::L,
        ];
        self.bag.shuffle(&mut self.rng);
        self.cur_pos = 0;
    }
}