SeaBattle/sea_battle_backend/src/data/current_game_status.rs

use rand::RngCore;

use crate::data::{
    BoatPosition, BoatsLayout, Coordinates, GameRules, MapCellContent, PrintableMap,
};

#[derive(Debug, serde::Serialize, serde::Deserialize, Clone, Default)]
pub struct CurrentGameMapStatus {
    pub boats: BoatsLayout,
    pub successful_strikes: Vec<Coordinates>,
    pub failed_strikes: Vec<Coordinates>,
    pub sunk_boats: Vec<BoatPosition>,
}

impl CurrentGameMapStatus {
    pub fn did_fire_at_location(&self, c: Coordinates) -> bool {
        self.successful_strikes.contains(&c) || self.failed_strikes.contains(&c)
    }
}

struct PrintableCurrentGameMapStatus(GameRules, CurrentGameMapStatus);

impl PrintableMap for PrintableCurrentGameMapStatus {
    fn map_cell_content(&self, c: Coordinates) -> MapCellContent {
        if !c.is_valid(&self.0) {
            return MapCellContent::Invalid;
        }

        if self.1.failed_strikes.contains(&c) {
            return MapCellContent::FailedStrike;
        }

        if self
            .1
            .sunk_boats
            .iter()
            .any(|b| b.all_coordinates().contains(&c))
        {
            return MapCellContent::SunkBoat;
        }

        if self.1.successful_strikes.contains(&c) {
            return MapCellContent::TouchedBoat;
        }

        if self.1.boats.find_boat_at_position(c).is_some() {
            return MapCellContent::Boat;
        }

        MapCellContent::Nothing
    }
}

#[derive(Debug, serde::Serialize, serde::Deserialize, Clone, Default)]
pub struct CurrentGameStatus {
    pub rules: GameRules,
    pub your_map: CurrentGameMapStatus,
    pub opponent_map: CurrentGameMapStatus,
}

impl CurrentGameStatus {
    /// Check if opponent can fire at a given location
    pub fn can_fire_at_location(&self, location: Coordinates) -> bool {
        !self.opponent_map.successful_strikes.contains(&location)
            && !self.opponent_map.failed_strikes.contains(&location)
    }

    /// Find valid random fire location. Loop until one is found
    pub fn find_valid_random_fire_location(&self) -> Coordinates {
        let mut rng = rand::thread_rng();
        loop {
            let coordinates = Coordinates::new(
                (rng.next_u32() % self.rules.map_width as u32) as i32,
                (rng.next_u32() % self.rules.map_height as u32) as i32,
            );
            if coordinates.is_valid(&self.rules) && self.can_fire_at_location(coordinates) {
                return coordinates;
            }
        }
    }

    /// Find valid linear fire location. Loop until one is found
    pub fn find_first_valid_fire_location(&self) -> Coordinates {
        for y in 0..self.rules.map_height {
            for x in 0..self.rules.map_width {
                let coordinates = Coordinates::new(x as i32, y as i32);
                if self.can_fire_at_location(coordinates) {
                    return coordinates;
                }
            }
        }

        panic!("Could not find fire location!")
    }

    pub fn get_sunk_locations(&self) -> Vec<Coordinates> {
        self.opponent_map
            .sunk_boats
            .iter()
            .map(|f| f.all_coordinates())
            .reduce(|mut a, mut b| {
                a.append(&mut b);
                a
            })
            .unwrap_or_default()
    }

    pub fn get_successful_but_un_sunk_locations(&self) -> Vec<Coordinates> {
        let sunk_location = self.get_sunk_locations();

        self.opponent_map
            .successful_strikes
            .iter()
            .filter(|c| !sunk_location.contains(c))
            .map(Coordinates::clone)
            .collect()
    }

    fn test_attack_direction(
        &self,
        pos: &[Coordinates],
        mut point: Coordinates,
        add_x: i32,
        add_y: i32,
    ) -> Option<Coordinates> {
        while pos.contains(&point) {
            point = point.add_x(add_x).add_y(add_y);
        }
        if self.can_fire_at_location(point) {
            return Some(point);
        }

        None
    }

    fn horizontal_attack_attempt(
        &self,
        pos: &[Coordinates],
        left: Coordinates,
        right: Coordinates,
    ) -> Option<Coordinates> {
        // Try right
        if let Some(point) = self.test_attack_direction(pos, right, 1, 0) {
            return Some(point);
        }

        // Try left
        if let Some(point) = self.test_attack_direction(pos, left, -1, 0) {
            return Some(point);
        }

        None
    }

    /// Attempt to continue an attack, if possible
    pub fn continue_attack_boat(&self) -> Option<Coordinates> {
        let pos = self.get_successful_but_un_sunk_locations();
        if pos.is_empty() {
            return None;
        }

        let start = pos[0];

        let up = start.add_y(-1);
        let down = start.add_y(1);
        let left = start.add_x(-1);
        let right = start.add_x(1);

        // Try to do it horizontally
        if !pos.contains(&up) && !pos.contains(&down) {
            if let Some(c) = self.horizontal_attack_attempt(&pos, left, right) {
                return Some(c);
            }
        }

        // Try to do it vertically

        // Try up
        if let Some(point) = self.test_attack_direction(&pos, up, 0, -1) {
            return Some(point);
        }

        // Try down
        if let Some(point) = self.test_attack_direction(&pos, down, 0, 1) {
            return Some(point);
        }

        // Try to do it horizontally again, but unconditionally
        if let Some(c) = self.horizontal_attack_attempt(&pos, left, right) {
            return Some(c);
        }

        // We could even panic here
        None
    }

    pub fn print_your_map(&self) {
        PrintableCurrentGameMapStatus(self.rules.clone(), self.your_map.clone()).print_map()
    }

    pub fn print_opponent_map(&self) {
        PrintableCurrentGameMapStatus(self.rules.clone(), self.opponent_map.clone()).print_map()
    }
}

#[cfg(test)]
mod test {
    use crate::data::*;

    #[test]
    fn get_successful_but_un_sunk_locations() {
        let unfinished = Coordinates::new(0, 0);
        let sunk = Coordinates::new(3, 3);

        let mut status = CurrentGameStatus::default();
        status.opponent_map.successful_strikes.push(sunk);
        status.opponent_map.successful_strikes.push(unfinished);

        status.opponent_map.sunk_boats.push(BoatPosition {
            start: sunk,
            len: 1,
            direction: BoatDirection::Left,
        });

        assert_eq!(status.get_sunk_locations(), vec![sunk]);
        assert_eq!(
            status.get_successful_but_un_sunk_locations(),
            vec![unfinished]
        );
    }

    #[test]
    fn no_continue_attack() {
        let status = CurrentGameStatus::default();
        assert!(status.get_successful_but_un_sunk_locations().is_empty());
        let next_fire = status.continue_attack_boat();
        assert!(next_fire.is_none());
    }

    #[test]
    fn continue_attack_unknown_direction() {
        let unfinished = Coordinates::new(2, 2);
        let possible_next_strikes = vec![
            unfinished.add_x(-1),
            unfinished.add_x(1),
            unfinished.add_y(-1),
            unfinished.add_y(1),
        ];

        let mut status = CurrentGameStatus::default();
        status.opponent_map.successful_strikes.push(unfinished);

        let next_fire = status.continue_attack_boat();

        assert!(next_fire.is_some());
        assert!(possible_next_strikes.contains(&next_fire.unwrap()))
    }

    #[test]
    fn continue_attack_vertically_only() {
        let unfinished = Coordinates::new(2, 2);
        let possible_next_strikes = vec![unfinished.add_x(-1), unfinished.add_x(2)];

        let mut status = CurrentGameStatus::default();
        status.opponent_map.successful_strikes.push(unfinished);
        status
            .opponent_map
            .successful_strikes
            .push(unfinished.add_x(1));

        let next_fire = status.continue_attack_boat();

        assert!(next_fire.is_some());
        assert!(possible_next_strikes.contains(&next_fire.unwrap()))
    }

    #[test]
    fn continue_attack_vertically_after_horizontal_fail() {
        let unfinished = Coordinates::new(2, 2);
        let possible_next_strikes = vec![unfinished.add_y(-1), unfinished.add_y(1)];

        let mut status = CurrentGameStatus::default();
        status.opponent_map.successful_strikes.push(unfinished);
        status.opponent_map.failed_strikes.push(unfinished.add_x(1));
        status
            .opponent_map
            .failed_strikes
            .push(unfinished.add_x(-1));

        let next_fire = status.continue_attack_boat();

        assert!(next_fire.is_some());
        assert!(possible_next_strikes.contains(&next_fire.unwrap()))
    }
}