"""Jalali (Shamsi) date rendering for output that never passes through the API.

The REST layer keeps speaking ISO-8601 Gregorian on purpose — django-filter
lookups, the Odoo integration and the stored report payloads all depend on it.
Conversion belongs where a human actually reads a date: the generated PDF and
the customer-facing SMS.

Numerals stay ASCII. ReportLab's built-in fonts have no Persian glyphs, so
emitting Persian digits would render as black boxes in the PDF.
"""

from __future__ import annotations

from datetime import date, datetime, time
from typing import Any, Optional

import jdatetime
from django.utils import timezone

__all__ = ["jalali_date", "jalali_datetime", "jalali_time"]


def _parse_iso(value: str) -> Optional[datetime]:
    """Read back what ``datetime.isoformat()`` wrote, tolerating a bare date."""
    try:
        return datetime.fromisoformat(value)
    except ValueError:
        try:
            return datetime.combine(date.fromisoformat(value), time())
        except ValueError:
            return None


def _localize(value: datetime) -> datetime:
    """Move an aware datetime into the project's ``TIME_ZONE``.

    Naive values are returned untouched — they are already wall-clock local, and
    ``timezone.localtime`` refuses them outright under ``USE_TZ = True``.
    """
    if not timezone.is_aware(value):
        return value
    try:
        return timezone.localtime(value)
    except (ValueError, OverflowError):
        # Timestamps at the epoch boundary overflow when shifted west of UTC.
        return value


def _coerce(value: Any) -> Any:
    """Accept a date, a datetime, or an ISO string; return date/datetime/None."""
    if isinstance(value, str):
        return _parse_iso(value)
    return value


def jalali_date(value: Any) -> str:
    """Render a ``date``/``datetime``/ISO string as ``YYYY/MM/DD`` (Jalali)."""
    value = _coerce(value)
    if isinstance(value, datetime):
        value = _localize(value).date()
    if not isinstance(value, date):
        return ""
    j = jdatetime.date.fromgregorian(date=value)
    return f"{j.year:04d}/{j.month:02d}/{j.day:02d}"


def jalali_datetime(value: Any) -> str:
    """Render a datetime/ISO string as ``YYYY/MM/DD HH:MM`` (Jalali, local time)."""
    value = _coerce(value)
    if not isinstance(value, datetime):
        return jalali_date(value)
    j = jdatetime.datetime.fromgregorian(datetime=_localize(value))
    return f"{j.year:04d}/{j.month:02d}/{j.day:02d} {j.hour:02d}:{j.minute:02d}"


def jalali_time(value: Any) -> str:
    """Render a ``time``/``datetime``/``HH:MM[:SS]`` string as ``HH:MM``."""
    if isinstance(value, str):
        parts = value.strip().split(":")
        if len(parts) >= 2 and parts[0].isdigit() and parts[1].isdigit():
            return f"{int(parts[0]):02d}:{parts[1]}"
        return ""
    if isinstance(value, datetime):
        value = _localize(value).time()
    if isinstance(value, time):
        return f"{value.hour:02d}:{value.minute:02d}"
    return ""