#! /usr/bin/env python3
import sys
import math
from typing import List
from typing import Tuple


def read_file(filename: str) -> Tuple[int, List[int]]:
    with open(filename) as f:
        ts = int(next(f).strip())
        busses = [
            int(bus) if bus != "x" else -1
            for bus in next(f).strip().split(",")
        ]

    return ts, busses


def read_cli(arg: str) -> List[int]:
    busses = [
        int(bus) if bus != "x" else -1
        for bus in arg.strip().split(",")
    ]

    return busses


def wait_time(ts: int, bus_id: int) -> int:
    return (bus_id - (ts % bus_id) % bus_id)


def part1():
    ts, busses = read_file("input.txt")

    min_wait = -1
    min_bus_id = 0
    for bus_id in busses:
        if bus_id < 0:
            continue
        w = wait_time(ts, bus_id)
        if min_wait < 0 or w < min_wait:
            min_wait = w
            min_bus_id = bus_id

    print(f"Wait {min_wait} for bus {min_bus_id}. Answer {min_wait * min_bus_id}")


def part2(busses=None, start=0):
    if busses is None:
        _, busses = read_file("input.txt")
    # busses = [7, 13, -1, -1, 59, -1, 31, 19]

    t = start
    # t = 100000000000000
    # t = t - (t%7)
    # if t%7 != 0:
    #     print("Not starting with multiple of 7")
    #     return
    while True:
        # print(f"Checking time {t}")
        for i, bus_id in enumerate(busses):
            if bus_id < 0:
                continue
            if i == 0:
                w = t % bus_id
            else:
                w = wait_time(t, bus_id)
            # print(f"Wait for bus {bus_id} is {w} expect {i}")
            if w != i:
                if i > 0:
                    t += busses[0]
                else:
                    t += 1
                break
        else:
            print(f"All busses match for time {t}")
            break


def part2_calc(busses=None, start=0):
    if busses is None:
        _, busses = read_file("input.txt")
    # busses = [7, 13, -1, -1, 59, -1, 31, 19]

    t = start
    last_index = 0
    product = -1
    while True:
        print(f"Checking time {t}")
        for i, bus_id in enumerate(busses[last_index:], last_index):
            if bus_id < 0:
                continue
            if i == 0:
                w = t % bus_id
            else:
                w = wait_time(t, bus_id)
            print(f"Wait for bus {bus_id} is {w} expect {i}")
            if w == i % bus_id:
                last_index = i+1
                if product < 0:
                    product = bus_id
                else:
                    product = product * bus_id
                print(f"New index {last_index}, new product {product}")
            else:
                if i > 0:
                    t += product
                else:
                    t += 1
                break
        else:
            print(f"All busses match for time {t}")
            break


if __name__ == "__main__":
    if len(sys.argv) == 1:
        part1()
        part2_calc()
    else:
        busses = read_cli(sys.argv[1])
        b1, b2 = busses[0], busses[1]
        t = b1 * math.floor(b2/b1)
        print(f"Maybe t = {t}")
        start = 0
        if len(sys.argv) > 2:
            start = int(sys.argv[2])
        print("brute")
        part2(busses, start)
        print("")
        print("calc")
        part2_calc(busses, start)