#!/usr/bin/env python3

import collections
import sys

input_file = sys.argv[1]

with open(input_file) as fd:
    lines = [line.rstrip() for line in fd.readlines()]

height = len(lines)
width = len(lines[0])

vec = tuple[int, int]
directions = [
    (-1, 0),  # ^ North
    (0, 1),  # > East
    (1, 0),  # v South
    (0, -1),  # < West
]

Cheat = tuple[vec, int]

cheats: set[Cheat] = set()
for i, line in enumerate(lines):
    if "S" in line:
        j = line.index("S")
        start = i, j
    if i in range(1, height - 1):
        for j in range(1, width - 1):
            char = lines[i][j]
            if char != "#":
                continue
            for d, direction in enumerate(directions):
                ii, jj = i + direction[0], j + direction[1]
                if ii not in range(1, height - 1) or jj not in range(1, width - 1):
                    continue
                cchar = lines[ii][jj]
                if cchar == "#":
                    continue
                cheats.add(((i, j), d))


def print_grid(visited: list[list[int | None]], cheat: Cheat) -> None:
    for i in range(height):
        line = ""
        for j in range(width):
            char = lines[i][j]
            if visited[i][j] is not None:
                char = "O"
            if cheat[0] == (i, j):
                char = "X"
            line += char
        print(line)
    print()


def time(cheat: Cheat) -> int | None:
    visited: list[list[int | None]] = list()
    for _ in range(height):
        visited.append([None] * width)
    stack: set[vec] = {start}
    for s in range(1, 10000):
        nstack: set[vec] = set()
        for pos in stack:
            i, j = pos
            for d, direction in enumerate(directions):
                if (i, j) == cheat[0]:
                    if d != cheat[1]:
                        continue
                ii, jj = i + direction[0], j + direction[1]
                cchar = lines[ii][jj]
                if cchar == "#" and cheat != ((ii, jj), d):
                    continue
                elif cchar == "E":
                    # if s == 84 - 8:
                    #     print_grid(visited, cheat)
                    return s
                previs = visited[ii][jj]
                if previs is not None and previs < s:
                    continue
                visited[ii][jj] = s
                nstack.add((ii, jj))
        stack = nstack

        # print("Second", s)
        # print_grid(visited)
    else:
        return None


canon_saves: collections.Counter[int] = collections.Counter()
for k, v in (
    {
        2: 14,
        4: 14,
        6: 2,
        8: 4,
        10: 2,
        12: 3,
        20: 1,
        36: 1,
        38: 1,
        40: 1,
        64: 1,
    }
).items():
    canon_saves[k] = v

normal = time(((0, 0), 0))
assert normal
saves: collections.Counter[int] = collections.Counter()
saves_mo100 = 0
print(f"{normal=}")
print(f"{len(cheats)=}")
for c, cheat in enumerate(cheats):
    print("Cheat", c, "/", len(cheats))
    ntime = time(cheat)
    assert ntime
    diff = normal - ntime
    saves[diff] += 1
    if diff >= 100:
        saves_mo100 += 1
del saves[0]
print(f"{saves=}")
print(f"{canon_saves=}")
print(f"{(saves == canon_saves)=}")
print(saves_mo100)
# 1282: too low