use crate::common::{read_number_list, read_rules, Number};
use std::collections::HashSet;
use std::io::Read;
use std::ops::Rem;

pub fn run<R: Read>(read: R) {
    let mut input = read.bytes().peekable();

    let rules_by_number = read_rules(&mut input);

    let mut result: Number = 0;

    while let Some(Ok(ch)) = input.peek() {
        if ch == &b'\n' {
            input.next();
            continue;
        }

        let numbers = read_number_list(&mut input);

        let rules = numbers
            .iter()
            .flat_map(|number| rules_by_number.get(number))
            .flatten()
            .filter(|rule| numbers.contains(&rule.first) && numbers.contains(&rule.second))
            .collect::<HashSet<_>>();

        if rules.iter().all(|rule| {
            numbers
                .iter()
                .position(|number| *number == rule.first)
                .zip(numbers.iter().position(|number| *number == rule.second))
                .map(|(first_index, second_index)| first_index < second_index)
                .unwrap_or(false)
        }) {
            if numbers.len().rem(2) == 1 {
                result += numbers[numbers.len() / 2];
            } else {
                eprintln!("Length of numbers is not odd!")
            }
        }
    }

    println!("Result {}", result);
}