#![feature(iterator_try_collect)]

use std::fs;
use std::io::{self, BufRead};
use std::collections::HashSet;


fn main() {
    let filename = "etc/p03.txt";
    let file = fs::File::open(filename).expect("Can't open file");
    let reader = io::BufReader::new(file);

    println!("PART ONE ---------------");
    let lines = reader.lines().try_collect().expect("Expected all lines to be valid");
    part1(&lines);

    println!("\n PART TWO ---------------");
    part2(&lines);
}

fn to_priority(c: char) -> Result<u32, &'static str> {
    if c.is_ascii_uppercase() {
        Ok(c as u32 - 'A' as u32 + 26 + 1)
    } else if c.is_ascii_lowercase() {
        Ok(c as u32 - 'a' as u32 + 1)
    } else {
        Err("Can't convert non-alphanumeric")
    }
}

fn part1(lines: &Vec<String>) {
    let mut sum: u32 = 0;
    for line in lines {
        let (left, right) = line.split_at(line.len() / 2);
        let left_set = HashSet::<char>::from_iter(left.chars());
        let mut right_set = HashSet::<char>::new();
        let outlier = right.chars().find(|c| {
            right_set.insert(*c);
            left_set.contains(c)
        }).expect("Expected at least one duplicate item");

        let priority = to_priority(outlier).unwrap();
        println!("{} ({})", outlier, priority);
        sum += priority;
    }

    println!("Sum: {}", sum);
}

fn part2(_lines: &Vec<String>) {
}

#[cfg(test)]
mod tests {
    use super::*;
}