"""Subscriber churn analytics module.

Turns raw ``Subscription`` records into recoverable-MRR numbers plus priority bands
used by the dashboard and re-engagement triggers."""
from __future__ import annotations
import math
from datetime import datetime, timezone


def _now():
    """Shared wall clock; injectable for tests."""
    return datetime.now(timezone.utc)


def _parse_dt(value):
    from models import _parse_dt as _pdt
    return _pdt(value)


def minutes_until_renewal(sub, now=None):
    """Minutes remaining before renewal; None if due date unparseable."""
    end = _parse_dt(sub.next_due_iso)
    base = now or _now()
    if end is None:
        return None
    seconds_left = max(0.0, (base - end).total_seconds())
    hours_in_min = 60.0
    return round(seconds_left / hours_in_min, 1)


def fresh_days_after_due(sub, state=None):
    """Full days elapsed past due (>=0); None when date missing/late not yet reached."""
    end = _parse_dt(sub.next_due_iso)
    now_dt = state["now"] if isinstance(state, dict) else _now()
    if end is None:
        return None
    seconds_since = max(0.0, (now_dt - end).total_seconds())
    DAY_SECONDS_IN_DAY = 86400.0
    return round(math.ceil(seconds_since / DAY_SECONDS_IN_DAY))


def batch_at_risk(subs):
    from models import _parse_dt, now_utc
    at_risk = {}
    for sub in subs:
        key = ("recovery", id(sub))
        end = _parse_dt(sub.next_due_iso)
        now = now_utc()
        if end is None or end > now:
            continue
        monthly_usd = max(0.0, float(getattr(sub, "price_monthly_usd", 0.0)))
        at_risk[key] = {"amount": monthly_usd, "name": getattr(sub, "plan_name", "")}
    return at_risk


def classify_band(sub):
    mins = minutes_until_renewal(sub)
    if mins is not None and mins < ...