#![allow(dead_code)]
#![allow(unused_variables)]
#![allow(unused_mut)]
use num::complex::Complex as c;
use num::Complex;
use std::cmp::min;
use std::collections::HashMap;
use std::collections::HashSet;
use std::fs::File;
use std::io::Read;

type Matrix<T> = Vec<Vec<T>>;

fn bfs1(m: &Matrix<u32>) -> u32 {
    let mut s: HashMap<(Complex<i32>, Complex<i32>, u32), u32> = HashMap::new();
    let mut hs: HashSet<(Complex<i32>, Complex<i32>, u32, u32)> = HashSet::new();
    let mut hs_next: HashSet<(Complex<i32>, Complex<i32>, u32, u32)> = HashSet::new();

    hs.insert((c::new(0, 0), c::new(1, 0), 0, 0));

    let mut res: Vec<u32> = Vec::new();
    while hs.len() > 0 {
        for (pos, dir, conti, mut hl) in hs {
            if conti > 2 {
                continue;
            }

            if !(0 <= pos.re
                && pos.re < m[0].len() as i32
                && 0 <= pos.im
                && pos.im < m.len() as i32)
            {
                continue;
            }

            hl += m[pos.im as usize][pos.re as usize];

            if pos == c::new(m[0].len() as i32 - 1, m.len() as i32 - 1) {
                res.push(hl);
                continue;
            }

            if let Some(hl_) = s.get(&(pos, dir, conti)) {
                if hl_ <= &hl {
                    continue;
                }
            }
            s.insert((pos, dir, conti), hl);

            let new_dir = dir;
            let new_pos = pos + new_dir;
            hs_next.insert((new_pos, new_dir, conti + 1, hl));

            let new_dir = dir * c::i();
            let new_pos = pos + new_dir;
            hs_next.insert((new_pos, new_dir, 0, hl));

            let new_dir = dir * (-c::i());
            let new_pos = pos + new_dir;
            hs_next.insert((new_pos, new_dir, 0, hl));
        }
        hs = hs_next;
        hs_next = HashSet::new();
    }
    return res.into_iter().fold(999999999, min) - m[0][0];
}

fn bfs2(m: &Matrix<u32>) -> u32 {
    let mut s: HashMap<(Complex<i32>, Complex<i32>, u32), u32> = HashMap::new();
    let mut hs: HashSet<(Complex<i32>, Complex<i32>, u32, u32)> = HashSet::new();
    let mut hs_next: HashSet<(Complex<i32>, Complex<i32>, u32, u32)> = HashSet::new();

    hs.insert((c::new(0, 0), c::new(1, 0), 0, 0));

    let mut res: Vec<u32> = Vec::new();
    while hs.len() > 0 {
        for (pos, dir, conti, mut hl) in hs {
            if conti > 9 {
                continue;
            }

            if !(0 <= pos.re
                && pos.re < m[0].len() as i32
                && 0 <= pos.im
                && pos.im < m.len() as i32)
            {
                continue;
            }

            hl += m[pos.im as usize][pos.re as usize];

            if conti > 2 && pos == c::new(m[0].len() as i32 - 1, m.len() as i32 - 1) {
                res.push(hl);
                continue;
            }

            if let Some(hl_) = s.get(&(pos, dir, conti)) {
                if hl_ <= &hl {
                    continue;
                }
            }
            s.insert((pos, dir, conti), hl);

            let new_dir = dir;
            let new_pos = pos + new_dir;
            hs_next.insert((new_pos, new_dir, conti + 1, hl));

            if conti > 2 {
                let new_dir = dir * c::i();
                let new_pos = pos + new_dir;
                hs_next.insert((new_pos, new_dir, 0, hl));

                let new_dir = dir * (-c::i());
                let new_pos = pos + new_dir;
                hs_next.insert((new_pos, new_dir, 0, hl));
            }
        }
        hs = hs_next;
        hs_next = HashSet::new();
    }
    return res.into_iter().fold(999999999, min) - m[0][0];
}

fn main() {
    // let filename = "in/day17.ref";
    let filename = "in/day17.pzl";

    let mut f = File::open(filename).expect("cannot open file");
    let mut content = String::new();
    f.read_to_string(&mut content).expect("cannot read file");
    let lines = content.trim_end().split('\n');

    let mut m: Matrix<u32> = Vec::new();
    for line in lines {
        let mut mr: Vec<u32> = Vec::new();
        for c in line.chars() {
            mr.push(c.to_digit(10).unwrap());
        }
        m.push(mr);
    }

    let res1 = bfs1(&m);
    let res2 = bfs2(&m);

    println!("res1: {}", res1);
    println!("res2: {}", res2);
    assert_eq!(res1, 635);
    assert_eq!(res2, 734);
}