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

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

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

fn seek_shoot(knowledge: &Knowledge) -> (Weapon, Point) {
    let (weapon, possibilities) = knowledge.get_best_seek_shots();
    if possibilities.is_empty() {
        println!("All possible shots on the current lattice have been tried!");
        (Weapon::SingleShot, Point::new(0,0))
    }
    else {
        let mut rng = rand::thread_rng();
        let between = Range::new(0, possibilities.len());
        let i = between.ind_sample(&mut rng);
        
        (weapon, possibilities[i as usize])
    }
}

fn destroy_shoot(knowledge: &Knowledge) -> (Weapon, 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);
        
        (Weapon::SingleShot, possibilities[i as usize])
    }
}