use crate::read;
use indextree::Arena;

#[derive(Debug)]
struct Directory {
    pub size: usize,
    pub name: String
}

pub fn run() {
    let arena = &mut Arena::new();
    let mut current_directory = arena.new_node(Directory {
        size: 0,
        name: "/".into(),
    });
    let root = current_directory;

    for line in read("07").lines().skip(1) {
        if line.starts_with("$ cd") {
            current_directory = match line.split_once("cd ").unwrap().1 {
                dirname if ".." == dirname => arena.get(current_directory).unwrap().parent().unwrap(),
                dirname => current_directory
                    .children(arena)
                    .find(|c|arena.get(*c).unwrap().get().name == dirname)
                    .unwrap_or_else(||{
                        let nc = arena.new_node(Directory {
                            size: 0,
                            name: dirname.into(),
                        });
                        current_directory.append(nc, arena);
                        nc
                    })
            };
        } else if line.chars().next().unwrap().is_numeric() {
            let filesize: usize = line.split_once(" ").unwrap().0.parse().unwrap();
            arena.get_mut(current_directory).unwrap().get_mut().size += filesize;
        }
    }
    let total = root.descendants(arena).map(|desc|{
        desc
            .descendants(arena)
            .map(|d|arena.get(d).unwrap().get().size)
            .sum::<usize>()
    }).collect::<Vec<_>>();

    #[cfg(feature = "part1")]
    {
        println!("Day 7, Part 01: {}", total.clone().iter()
            .filter(|s| *s <= &100000)
            .sum::<usize>());
    }

    #[cfg(feature = "part2")]
    {
        let total_used = root.descendants(arena)
            .map(|d|arena.get(d).unwrap().get().size)
            .sum::<usize>();
        let free_needed = total_used - 40000000;

        println!("Day 7, Part 02: {}", total.iter()
            .filter(|s|*s >= &free_needed)
            .min()
            .unwrap());
    }
}