use std::fs::File;
use std::io::{BufRead, BufReader, Lines};

// BOILERPLATE
type InputIter = Lines<BufReader<File>>;

fn get_input() -> InputIter {
    let f = File::open("input").unwrap();
    let br = BufReader::new(f);
    br.lines()
}

fn main() {
    println!("Problem 1 solution: {}", problem1(get_input()));
    println!("Problem 2 solution: {}", problem2(get_input()));
}

// PROBLEM1 solution
fn problem1_lineval(line: &String) -> u64 {
    // forward iterate to find the first numeric value
    let first = line.chars().find(|c| c.is_digit(10)).unwrap();
    let last = line.chars().rev().find(|c| c.is_digit(10)).unwrap();

    (first.to_digit(10).unwrap() * 10 + last.to_digit(10).unwrap()).into()
}

fn problem1(input: InputIter) -> u64 {
    input.map(|line| problem1_lineval(&line.unwrap())).sum()
}

// PROBLEM2 solution
const DIGITS: &[(&str, u64)] = &[
    ("one", 1),
    ("two", 2),
    ("three", 3),
    ("four", 4),
    ("five", 5),
    ("six", 6),
    ("seven", 7),
    ("eight", 8),
    ("nine", 9),
];

fn problem2_numeric(start: &str) -> Option<u64> {
    let char = start.chars().nth(0).unwrap();
    if char.is_numeric() {
        Some(char.to_digit(10).unwrap().into())
    } else {
        for (s, n) in DIGITS {
            if start.starts_with(s) {
                return Some(*n);
            }
        }
        None
    }
}

fn problem2_lineval(line: &String) -> u64 {
    let mut first = None;
    for pos in 0..line.len() {
        let (_, sub) = line.split_at(pos);
        if let Some(n) = problem2_numeric(sub) {
            first = Some(n);
            break;
        } else {
            continue;
        }
    }
    let mut second = None;
    for pos in (0..line.len()).rev() {
        let (_, sub) = line.split_at(pos);
        if let Some(n) = problem2_numeric(sub) {
            second = Some(n);
            break;
        } else {
            continue;
        }
    }

    first.unwrap() * 10 + second.unwrap()
}

fn problem2(input: InputIter) -> u64 {
    input.map(|line| problem2_lineval(&line.unwrap())).sum()
}