"""Dates in the wild → aware datetimes (UTC). Partial dates ('March 2025', '2024') keep a precision marker."""
from __future__ import annotations

import re
from datetime import UTC, date, datetime

from dateutil import parser as duparser

_MONTHS = "january|february|march|april|may|june|july|august|september|october|november|december|jan|feb|mar|apr|jun|jul|aug|sep|sept|oct|nov|dec"
_MONTH_YEAR = re.compile(rf"\b({_MONTHS})\.?\s+(\d{{4}})\b", re.IGNORECASE)
_YEAR = re.compile(r"\b(19[89]\d|20[0-4]\d)\b")


def parse_datetime(value: str | datetime | date | None, *, default_tz=UTC) -> datetime | None:
    if value is None:
        return None
    if isinstance(value, datetime):
        return value if value.tzinfo else value.replace(tzinfo=default_tz)
    if isinstance(value, date):
        return datetime(value.year, value.month, value.day, tzinfo=default_tz)
    s = str(value).strip()
    if not s:
        return None
    if re.fullmatch(r"\d{10}(\.\d+)?", s):
        return datetime.fromtimestamp(float(s), tz=UTC)
    if re.fullmatch(r"\d{13}", s):
        return datetime.fromtimestamp(int(s) / 1000, tz=UTC)
    try:
        dt = duparser.parse(s, fuzzy=False)
        return dt if dt.tzinfo else dt.replace(tzinfo=default_tz)
    except (ValueError, OverflowError, TypeError):
        pass
    return None


def parse_date(value: str | None) -> tuple[date | None, str]:
    """Return (date, precision) where precision ∈ {'day','month','year','none'}. Fuzzy text allowed."""
    if not value:
        return None, "none"
    s = str(value).strip()
    dt = parse_datetime(s)
    if dt and re.search(r"\d{1,2}", s) and not _MONTH_YEAR.fullmatch(s) and not _YEAR.fullmatch(s):
        return dt.date(), "day"
    m = _MONTH_YEAR.search(s)
    if m:
        try:
            d = duparser.parse(f"1 {m.group(1)} {m.group(2)}")
            return d.date(), "month"
        except ValueError:
            pass
    m = _YEAR.search(s)
    if m:
        return date(int(m.group(1)), 1, 1), "year"
    try:
        d = duparser.parse(s, fuzzy=True, default=datetime(1900, 1, 1))
        if d.year > 1900:
            return d.date(), "day"
    except (ValueError, OverflowError):
        pass
    return None, "none"


def iso(dt: datetime | date | None) -> str | None:
    if dt is None:
        return None
    if isinstance(dt, datetime):
        return dt.astimezone(UTC).isoformat(timespec="seconds")
    return dt.isoformat()


__all__ = ["iso", "parse_date", "parse_datetime"]