use std::collections::HashMap;
use std::{fs, io::{self, Write}};

fn main() -> io::Result<()> {
    let input = fs::read_to_string("sygnaly.txt")?;
    let input = input.lines().collect::<Vec<_>>();

    let mut output = fs::File::create("wyniki4.txt")?;
    output.write_all(excersise_1(&input).as_bytes())?;
    output.write_all(b"\n")?;
    output.write_all(excersise_2(&input).as_bytes())?;
    output.write_all(b"\n")?;

    for line in excersise_3(&input) {
        output.write_all(line.as_bytes())?;
        output.write_all(b"\n")?;
    }

    Ok(())
}

fn excersise_1(input: &Vec<&str>) -> String {
    input
        .iter()
        .skip(39)
        .step_by(40)
        .map(|line| line.chars().nth(9).unwrap())
        .collect::<String>()
}

fn excersise_2(input: &Vec<&str>) -> String {
    let mut letters = HashMap::with_capacity(26);
    let mut max = (0, "");
    for line in input {
        letters.clear();
        for c in line.chars() {
            letters.entry(c).or_insert(());
        }
        if letters.len() > max.0 {
            max = (letters.len(), line);
        }
    }
    format!("{} {}", max.1, max.0)
}

fn excersise_3<'a>(input: &'a Vec<&str>) -> Vec<&'a str> {
    input.iter().filter(|line| {
        let bytes = line.as_bytes();
        for i in 0..(bytes.len() - 1) {
            for j in 1..bytes.len() {
                if (bytes[i] as i16 - bytes[j] as i16).abs() > 10 {
                    return false;
                }
            }
        }
        true
    })
    .map(|line| *line)
    .collect::<Vec<_>>()
}