use rand;
use rand::distributions::{IndependentSample, Range};

use actions::*;
use math::*;
use knowledge::*;

pub fn shoot_smartly(knowledge: &Knowledge) -> Action {
    let shot = if knowledge.has_unknown_hits() {
        destroy_shoot(&knowledge)
    }
    else {
        seek_shoot(&knowledge)
    };
    
    Action::Shoot(shot)
}

fn seek_shoot(knowledge: &Knowledge) -> Point {
    let mut shot: Point;
    
    while {
        shot = Point::random(knowledge.map_size);
        let ref target = knowledge.opponent_map.cells[shot.x as usize][shot.y as usize];
        target.shot_attempted()
    } {}
    shot
}

fn destroy_shoot(knowledge: &Knowledge) -> Point {
    let possibilities = knowledge.get_best_adjacent_shots();
    if possibilities.is_empty() {
        seek_shoot(&knowledge)
    }
    else {
        let mut rng = rand::thread_rng();
        let between = Range::new(0, possibilities.len());
        let i = between.ind_sample(&mut rng);
        
        possibilities[i as usize]
    }
}