work_shift.py

from datetime import datetime, timedelta
from dataclasses import dataclass
from zoneinfo import ZoneInfo


@dataclass(slots=True)
class WorkShift:
    id: int
    begin: int
    end: int


shifts12 = [
    WorkShift(1, -4 * 3600, 8 * 3600),
    WorkShift(2, 8 * 3600, 20 * 3600),
]
shifts13 = [
    WorkShift(1, -4 * 3600, 4 * 3600),
    WorkShift(2,  4 * 3600, 12 * 3600),
    WorkShift(3, 12 * 3600, 20 * 3600),
]
shifts14 = [
    WorkShift(1, -3 * 3600, 3 * 3600),
    WorkShift(2, 3 * 3600, 9 * 3600),
    WorkShift(3, 9 * 3600, 15 * 3600),
    WorkShift(4, 15 * 3600, 21 * 3600),
]

shifts22 = [
    WorkShift(1, 8 * 3600, 20 * 3600),
    WorkShift(2, 20 * 3600, 32 * 3600),

]
shifts23 = [
    WorkShift(1, 4 * 3600, 12 * 3600),
    WorkShift(2, 12 * 3600, 20 * 3600),
    WorkShift(3, 20 * 3600, 28 * 3600),
]
shifts24 = [
    WorkShift(1, 3 * 3600, 9 * 3600),
    WorkShift(2, 9 * 3600, 15 * 3600),
    WorkShift(3, 15 * 3600, 21 * 3600),
    WorkShift(4, 21 * 3600, 27 * 3600),
]

shifts32 = [
    WorkShift(1, 0, 12 * 3600),
    WorkShift(2, 12 * 3600, 24 * 3600),
]


def get_shift(shifts: list[WorkShift], dt: datetime):
    total_seconds = dt.hour * 3600 + dt.minute * 60 + dt.second
    if shifts[0].begin < 0:
        ts, add_shift = shifts[0], 86400
    else:
        ts, add_shift = shifts[-1], -86400
    for shift in shifts:
        if shift.begin <= total_seconds < shift.end:
            ts, add_shift = shift, 0
            break

    d = dt.replace(hour=0, minute=0, second=0, microsecond=0)
    print(dt, ts.id, d + timedelta(seconds=ts.begin + add_shift), d + timedelta(seconds=ts.end + add_shift))


def main(shifts: list[WorkShift]):
    tz = ZoneInfo('UTC')
    now = datetime.now(tz).replace(hour=0, minute=0, second=0, microsecond=0)
    for h in range(-5, 33):
        get_shift(shifts, now + timedelta(hours=h))


if __name__ == '__main__':
    main(sorted(shifts12, key=lambda shift: shift.begin))