import datetime
import pathlib

import requests

from aoc import exceptions


def download(year: int, day: int, session_token: str | None) -> bytes:
    url = f"https://adventofcode.com/{year}/day/{day}/input"

    cookies = {}
    if session_token is not None:
        cookies["session"] = session_token

    response = requests.get(url, cookies=cookies)

    if response.status_code != 200:
        status = response.status_code

        # https://stackoverflow.com/a/39079819/11286805
        local_tz = datetime.datetime.now(datetime.timezone.utc).astimezone().tzinfo

        now = datetime.datetime.now(local_tz)
        release = datetime.datetime(year, 12, day, 5, tzinfo=datetime.UTC)

        if now < release:
            raise exceptions.AocError(
                f"unreleased input file {year}/{day:02} (http:{status})"
            )

        raise exceptions.AocError(
            f"failed to fetch input file {year}/{day:02} (http:{status})"
            " - is AOC_SESSION_TOKEN environment variable set?"
        )

    return response.content


def create_input_file(
    year: int,
    day: int,
    session_token: str | None,
    path_base: pathlib.Path,
    force: bool = False,
    exist_ok: bool = False,
):
    path = path_base / str(year) / f"{day:02}.txt"
    path.parent.mkdir(parents=True, exist_ok=True)

    if path.exists() and not path.stat().st_size == 0:
        if exist_ok:
            return
        if not force:
            raise exceptions.AocError(f"input file {path} already exists")

    input_data = download(year, day, session_token)
    with open(path, "wb") as f:
        f.write(input_data)


def get(
    year: int,
    day: int,
    path_base: pathlib.Path,
) -> str:
    path = path_base / str(year) / f"{day:02}.txt"
    path.parent.mkdir(parents=True, exist_ok=True)

    with open(path) as f:
        return f.read().rstrip("\n")


def get_or_download(
    year: int,
    day: int,
    session_token: str | None,
    path_base: pathlib.Path,
) -> str:
    path = path_base / str(year) / f"{day:02}.txt"
    path.parent.mkdir(parents=True, exist_ok=True)

    create_input_file(year, day, session_token, path_base, exist_ok=True)
    return get(year, day, path_base)


def _write_file_if_not_exists(
    path: pathlib.Path, exist_ok: bool = False, data: bytes | None = None
) -> None:
    path.parent.mkdir(parents=True, exist_ok=True)

    if path.exists() and not exist_ok:
        raise exceptions.AocError(f"{path} already exists")

    path.touch()

    if data is None:
        return

    with open(path, "wb") as f:
        f.write(data)


_CREATE_TEMPLATE: bytes = b"""\
from typing import Any


def part_1(input_data: str) -> Any:
    return None


def part_2(input_data: str) -> Any:
    return None


def test_part_1(example_data)
    assert part_1(example_data) == 0


def test_part_2(example_data)
    assert part_2(example_data) == 0
"""


def create(
    year: int,
    day: int,
    solution_base: pathlib.Path,
    input_base: pathlib.Path,
    example_base: pathlib.Path,
) -> None:
    year_path = solution_base / f"year_{year}"

    year_path.mkdir(parents=True, exist_ok=True)
    _write_file_if_not_exists(year_path / "__init__.py", exist_ok=True)
    _write_file_if_not_exists(year_path / f"day_{day:02}.py", data=_CREATE_TEMPLATE)

    _write_file_if_not_exists(input_base / str(year) / f"{day:02}.txt")
    _write_file_if_not_exists(example_base / str(year) / f"{day:02}.txt")