from utils import open_day
from functools import cache
from dataclasses import dataclass
from itertools import count
import re

@dataclass
class Node:
    flow: int
    neighbours: list[tuple[str, int]]

regex = re.compile(r'^Valve (..) has flow rate=([0-9]+); tunnels? leads? to valves? (.*)$')
inp = {}
with open_day(16) as f:
    for line in f:
        m = regex.match(line)
        assert(m)
        valve, flow, neighbours = m.group(1, 2, 3)
        inp[valve] = (int(flow), neighbours.split(', '))

nodes = {}
for valve, (flow, neighbours) in inp.items():
    if valve != 'AA' and flow == 0: continue
    actual_neighbours = []
    for n in neighbours:
        prev = valve
        for cost in count(1):
            if n == 'AA' or inp[n][0] != 0: break
            l, r = inp[n][1]
            nnext = r if l == prev else l
            prev = n
            n = nnext
        actual_neighbours.append((n, cost))
    nodes[valve] = Node(flow, actual_neighbours)

@cache
def sum_flow(open_valves):
    return sum(nodes[n].flow for n in open_valves)

@cache
def recurse(open_valves=frozenset(), current='AA', flow=0, time_left=30):
    cflow = sum_flow(open_valves)
    cnode = nodes[current]
    best = 0
    def loop():
        nonlocal best
        best = max(best, flow + cflow * time_left)
        for neighbour, cost in cnode.neighbours:
            if cost >= time_left: continue
            new = recurse(open_valves, neighbour,
                          flow + cflow * cost, time_left - cost)
            best = max(best, new)
    loop()
    if current not in open_valves and time_left > 0 and cnode.flow > 0:
        flow += cflow
        open_valves |= {current}
        cflow = sum_flow(open_valves)
        time_left -= 1
        loop()
    return best

print(recurse())