from __future__ import annotations

from django.db.models import Q

from core.models import ContactAvailabilityEvent, ContactAvailabilitySpan, Person, User
from .engine import ensure_fading_state
from .inference import now_ms


def spans_for_range(
    *,
    user: User,
    person: Person,
    start_ts: int,
    end_ts: int,
    service: str = "",
    limit: int = 200,
):
    qs = ContactAvailabilitySpan.objects.filter(
        user=user,
        person=person,
    ).filter(
        Q(start_ts__lte=end_ts) & Q(end_ts__gte=start_ts)
    )
    if service:
        qs = qs.filter(service=str(service).strip().lower())

    ensure_fading_state(
        user=user,
        person=person,
        person_identifier=None,
        service=(str(service or "").strip().lower() or "signal"),
        at_ts=now_ms(),
    )

    return list(qs.order_by("-end_ts")[: max(1, min(int(limit or 200), 500))])


def latest_state_for_people(*, user: User, person_ids: list, service: str = "") -> dict:
    out = {}
    if not person_ids:
        return out
    qs = ContactAvailabilityEvent.objects.filter(user=user, person_id__in=person_ids)
    if service:
        qs = qs.filter(service=str(service).strip().lower())
    rows = list(qs.order_by("person_id", "-ts", "-id"))
    seen = set()
    for row in rows:
        person_key = str(row.person_id)
        if person_key in seen:
            continue
        seen.add(person_key)
        out[person_key] = {
            "state": str(row.availability_state or "unknown"),
            "confidence": float(row.confidence or 0.0),
            "service": str(row.service or ""),
            "ts": int(row.ts or 0),
            "source_kind": str(row.source_kind or ""),
        }
    return out