from __future__ import annotations

from datetime import UTC, date, datetime
from zoneinfo import ZoneInfo

from app.services.employee_serialization import format_history_datetime as serialize_history_datetime

DISPLAY_TIMEZONE = ZoneInfo("Asia/Shanghai")


def normalize_optional_text(value: str | None) -> str | None:
    if value is None:
        return None
    text_value = value.strip()
    return text_value or None


def parse_date(value: str | None) -> date | None:
    if not value:
        return None
    return datetime.strptime(value, "%Y-%m-%d").date()


def parse_datetime(value: str | datetime | None) -> datetime | None:
    if value is None:
        return None
    if isinstance(value, datetime):
        return value
    return datetime.strptime(value, "%Y-%m-%d %H:%M")


def format_date(value: date | None) -> str | None:
    if value is None:
        return None
    return value.strftime("%Y-%m-%d")


def to_display_datetime(value: datetime) -> datetime:
    if value.tzinfo is None:
        normalized = value.replace(tzinfo=UTC)
    else:
        normalized = value.astimezone(UTC)
    return normalized.astimezone(DISPLAY_TIMEZONE)


def format_datetime(value: datetime | None) -> str | None:
    if value is None:
        return None
    return to_display_datetime(value).strftime("%Y-%m-%d %H:%M")


def format_history_datetime(value: datetime | None) -> str:
    return serialize_history_datetime(value, to_display_datetime=to_display_datetime)