tetris/src/actors/genetic.rs

// https://codemyroad.wordpress.com/2013/04/14/tetris-ai-the-near-perfect-player/

use super::{Actor, State};
use crate::{
    game::Action,
    playfield::{PLAYFIELD_HEIGHT, PLAYFIELD_WIDTH},
};
use rand::rngs::SmallRng;
use rand::Rng;

pub struct Parameters {
    total_height: f64,
    bumpiness: f64,
    holes: f64,
    complete_lines: f64,
}

impl Default for Parameters {
    fn default() -> Self {
        Self {
            total_height: 1.0,
            bumpiness: 1.0,
            holes: 1.0,
            complete_lines: 1.0,
        }
    }
}

impl Parameters {
    fn mutate(mut self, rng: &mut SmallRng) {
        let mutation_amt = rng.gen_range(-0.2, 0.2);
        match rng.gen_range(0, 4) {
            0 => self.total_height += mutation_amt,
            1 => self.bumpiness += mutation_amt,
            2 => self.holes += mutation_amt,
            3 => self.complete_lines += mutation_amt,
            _ => unreachable!(),
        }

        let normalization_factor = (self.total_height.powi(2)
            + self.bumpiness.powi(2)
            + self.holes.powi(2)
            + self.complete_lines.powi(2))
        .sqrt();

        self.total_height /= normalization_factor;
        self.bumpiness /= normalization_factor;
        self.holes /= normalization_factor;
        self.complete_lines /= normalization_factor;
    }

    fn dot_multiply(&self, other: &Self) -> f64 {
        self.total_height * other.total_height
            + self.bumpiness * other.bumpiness
            + self.holes * other.holes
            + self.complete_lines * other.complete_lines
    }
}

pub struct GeneticHeuristicAgent {
    params: Parameters,
}

impl Default for GeneticHeuristicAgent {
    fn default() -> Self {
        Self {
            params: Parameters::default(),
        }
    }
}

impl GeneticHeuristicAgent {
    fn extract_features_from_state(state: &State) -> Parameters {
        let mut heights = [None; PLAYFIELD_WIDTH];
        for r in 0..PLAYFIELD_HEIGHT {
            for c in 0..PLAYFIELD_WIDTH {
                if heights[c].is_none() && state.matrix[r][c].is_some() {
                    heights[c] = Some(PLAYFIELD_HEIGHT - r);
                }
            }
        }

        let total_height = heights
            .iter()
            .map(|o| o.unwrap_or_else(|| 0))
            .sum::<usize>() as f64;

        let bumpiness = heights
            .iter()
            .map(|o| o.unwrap_or_else(|| 0) as isize)
            .fold((0, 0), |(acc, prev), cur| (acc + (prev - cur).abs(), cur))
            .0 as f64;

        let complete_lines = state
            .matrix
            .iter()
            .map(|row| row.iter().all(Option::is_some))
            .map(|c| if c { 1.0 } else { 0.0 })
            .sum::<f64>();

        let mut holes = 0;
        for r in 1..PLAYFIELD_HEIGHT {
            for c in 0..PLAYFIELD_WIDTH {
                if state.matrix[r][c].is_none() && state.matrix[r - 1][c].is_some() {
                    holes += 1;
                }
            }
        }

        Parameters {
            total_height,
            bumpiness,
            complete_lines,
            holes: holes as f64,
        }
    }

    fn get_heuristic(&self, state: &State, action: &Action) -> f64 {
        todo!();
    }
}

impl Actor for GeneticHeuristicAgent {
    fn get_action(&self, rng: &mut SmallRng, state: &State, legal_actions: &[Action]) -> Action {
        *legal_actions
            .iter()
            .map(|action| (action, self.get_heuristic(state, action)))
            .max_by_key(|(action, heuristic)| (heuristic * 1_000_00.0) as usize)
            .unwrap()
            .0
    }
    fn update(
        &mut self,
        state: State,
        action: Action,
        next_state: State,
        next_legal_actions: &[Action],
        reward: f64,
    ) {
        unimplemented!()
    }
    fn set_learning_rate(&mut self, learning_rate: f64) {
        unimplemented!()
    }
    fn set_exploration_prob(&mut self, exploration_prob: f64) {
        unimplemented!()
    }
    fn set_discount_rate(&mut self, discount_rate: f64) {
        unimplemented!()
    }
    fn dbg(&self) {
        unimplemented!()
    }
}