"""Shared from/to date-range parsing (Chapter 11: consistent across every
chart/KPI endpoint; never defaults to "all time" per Chapter 03 rule 7).
"""
from __future__ import annotations

from datetime import date, datetime, timedelta

from flask import Request

DEFAULT_RANGE_DAYS = 7  # within Ch11's stated "7 or 30 day" default allowance


def parse_date_range(request: Request) -> tuple[date, date]:
    """Parse `?from=&to=` (ISO 8601 dates), defaulting to the last 7 days."""
    to_raw = request.args.get("to")
    from_raw = request.args.get("from")
    to_date = date.fromisoformat(to_raw) if to_raw else date.today()
    from_date = date.fromisoformat(from_raw) if from_raw else to_date - timedelta(days=DEFAULT_RANGE_DAYS - 1)
    if from_date > to_date:
        from_date, to_date = to_date, from_date
    return from_date, to_date


def day_bounds(from_date: date, to_date: date) -> tuple[datetime, datetime]:
    """Inclusive [from_date, to_date] -> half-open [start, end) datetime range.

    Shared by overview/queries.py, seo/queries.py, and security/queries.py
    (consolidated here rather than each keeping its own local copy).
    """
    start = datetime.combine(from_date, datetime.min.time())
    end = datetime.combine(to_date, datetime.min.time()) + timedelta(days=1)
    return start, end