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

fn main() {
    let file_path = String::from("input");
    let mut index = 4;

    println!("In file {}", file_path);

    if let Ok(lines) = read_lines(file_path) {
        // Consumes the iterator, returns an (Optional) String
        for line in lines {
            if let Ok(ip) = line {
                let mut slice = &ip[(index - 4)..index];
                while !(slice[0..1] != slice[1..2]
                    && slice[1..2] != slice[2..3]
                    && slice[0..1] != slice[2..3]
                    && slice[0..1] != slice[3..4]
                    && slice[1..2] != slice[3..4]
                    && slice[2..3] != slice[3..4])
                {
                    index += 1;
                    slice = &ip[(index - 4)..index];
                }
            }
        }
    }

    println!("{}", index);
}

fn read_lines<P>(filename: P) -> io::Result<io::Lines<io::BufReader<File>>>
where P: AsRef<Path>, {
    let file = File::open(filename)?;
    Ok(io::BufReader::new(file).lines())
}