use std::collections::VecDeque;

use color_eyre::Result;

pub fn solve() -> Result<()> {
  let input_data = include_str!("../../data/day_10.txt").trim();
  println!("Day 10 Part 1: {}", part_1(input_data)?);
  println!("Day 10 Part 2: {}", part_2(input_data)?);
  Ok(())
}

fn part_1(input: &str) -> Result<usize> {
  let mut syntax_error_score = 0;

  for line in input.lines() {
    let mut tokens = VecDeque::new();

    for token in line.chars() {
      if ['(', '[', '{', '<'].contains(&token) {
        tokens.push_back(token);
        continue;
      }

      let expected_close = match tokens.pop_back() {
        Some('(') => ')',
        Some('[') => ']',
        Some('{') => '}',
        Some('<') => '>',
        _ => unreachable!(),
      };

      if token != expected_close {
        syntax_error_score += match token {
          ')' => 3,
          ']' => 57,
          '}' => 1197,
          '>' => 25137,
          _ => unreachable!(),
        };
      }
    }
  }

  Ok(syntax_error_score)
}

fn part_2(input: &str) -> Result<isize> {
  let mut scores = vec![];

  'line_loop: for line in input.lines() {
    let mut line_score = 0;
    let mut tokens = VecDeque::new();

    for token in line.chars() {
      if ['(', '[', '{', '<'].contains(&token) {
        tokens.push_back(token);
        continue;
      }

      let expected_close = match tokens.pop_back() {
        Some('(') => ')',
        Some('[') => ']',
        Some('{') => '}',
        Some('<') => '>',
        _ => unreachable!(),
      };

      if token != expected_close {
        continue 'line_loop;
      }
    }

    for token in tokens.into_iter().rev() {
      let token_score = match token {
        '(' => 1,
        '[' => 2,
        '{' => 3,
        '<' => 4,
        _ => unreachable!(),
      };

      line_score *= 5;
      line_score += token_score;
    }

    scores.push(line_score);
  }

  scores.sort_by(|a, b| a.cmp(b));
  Ok(scores[scores.len() / 2])
}