use std::io::{self, BufRead};
use std::path::Path;
use std::fs::File;

fn main(){
    // Submarine is breaking, do diagnostics by checking power consumption
    // Calculate gamma rate * epsilon rate
    // Diagnostics are encoded by series of binary numbers

    // Gamma rate is most common bit for each bit in the series
    // Epsilon rate is the opposite, i.e. least common bit

    // So when gamma rate would be 10011, epsilon rate automatically is 01100


    println!("Advent of Code #3!\n");

    let path = Path::new("./3.txt");
    let display = path.display();

    let file = match File::open(&path) {
        Err(why) => panic!("Couldn't open {}: {}", display, why),
        Ok(file) => file,
    };

    let lines = io::BufReader::new(file).lines();
    let mut diagnostics = Vec::<Vec::<bool>>::new();

    for line in lines{
        let mut d_line = Vec::<bool>::new();
        if let Ok(l) = line {
            for c in l.chars() {
                match c {
                    '0' => d_line.push(false),
                    '1' => d_line.push(true),
                    _ => (),
                }
            }
        }
        diagnostics.push(d_line);
    }

    let mut line_numbers = 0;
    let b_len = diagnostics[0].len();
    let mut ones = vec![0; b_len];

    for line in &diagnostics {
        line_numbers += 1;

        for i in 0 .. b_len {
            match line[i] {
                true => ones[i] += 1,
                false => (),
            }
        }
    }

    let mut gamma_rate = Vec::new();
    for n in ones {
        if n > line_numbers / 2 {
            gamma_rate.push(true);
        } else {
            gamma_rate.push(false);
        }
    }

    let mut gamma_rate_decimal = 0;
    let mut pow = 1;

    gamma_rate.reverse();
    for b in gamma_rate {
        match b {
            true => gamma_rate_decimal += pow,
            false => (),
        }
        pow *= 2;
    }

    println!("Gamma rate in decimal is {}, epsilon rate in decimal is {}, yielding product of {}", 
              gamma_rate_decimal, pow - gamma_rate_decimal - 1, 
              gamma_rate_decimal * (pow - gamma_rate_decimal - 1));
}