"""Event service. Writes require editor rights; reads go through the privacy
engine. Every event has exactly one subject — a Person or a partnership."""

import uuid
from datetime import date

from sqlalchemy import select
from sqlalchemy.ext.asyncio import AsyncSession

from app.models.event import Event
from app.models.person import Person
from app.models.place import Place
from app.models.relationship import Relationship
from app.models.tree import Tree
from app.models.user import User
from app.services import privacy
from app.services.audit import record_audit
from app.services.exceptions import Conflict, Forbidden, NotFound


async def _belongs_to_tree(
    session: AsyncSession, model: type, id_: uuid.UUID, tree_id: uuid.UUID
) -> bool:
    row = (
        await session.execute(
            select(model.id).where(
                model.id == id_, model.tree_id == tree_id, model.deleted_at.is_(None)
            )
        )
    ).scalar_one_or_none()
    return row is not None


async def create_event(
    session: AsyncSession,
    *,
    actor: User,
    tree: Tree,
    event_type: str,
    person_id: uuid.UUID | None = None,
    relationship_id: uuid.UUID | None = None,
    place_id: uuid.UUID | None = None,
    date_value: str | None = None,
    date_start: date | None = None,
    date_end: date | None = None,
    date_precision: str | None = None,
    calendar: str = "gregorian",
    detail: str | None = None,
    notes: str | None = None,
) -> Event:
    if not await privacy.can_edit_tree(session, user_id=actor.id, tree=tree):
        raise Forbidden("not an editor of this tree")
    if bool(person_id) == bool(relationship_id):
        raise Conflict("an event needs exactly one subject: person_id or relationship_id")
    if person_id and not await _belongs_to_tree(session, Person, person_id, tree.id):
        raise NotFound("person not found in this tree")
    if relationship_id and not await _belongs_to_tree(
        session, Relationship, relationship_id, tree.id
    ):
        raise NotFound("relationship not found in this tree")
    if place_id and not await _belongs_to_tree(session, Place, place_id, tree.id):
        raise NotFound("place not found in this tree")

    event = Event(
        tree_id=tree.id,
        event_type=event_type,
        person_id=person_id,
        relationship_id=relationship_id,
        place_id=place_id,
        date_value=date_value,
        date_start=date_start,
        date_end=date_end,
        date_precision=date_precision,
        calendar=calendar,
        detail=detail,
        notes=notes,
    )
    session.add(event)
    await session.flush()
    record_audit(
        session,
        action="create",
        entity_type="Event",
        entity_id=event.id,
        tree_id=tree.id,
        actor_user_id=actor.id,
        after={"event_type": event_type, "person_id": str(person_id) if person_id else None},
    )
    await session.commit()
    await session.refresh(event)
    return event


async def list_events_for_person(
    session: AsyncSession, *, viewer_id: uuid.UUID, tree: Tree, person_id: uuid.UUID
) -> list[Event]:
    if not await privacy.can_view_tree(session, user_id=viewer_id, tree=tree):
        raise Forbidden("not permitted to view this tree")
    stmt = (
        select(Event)
        .where(
            Event.tree_id == tree.id,
            Event.person_id == person_id,
            Event.deleted_at.is_(None),
        )
        .order_by(Event.date_start.nulls_last(), Event.created_at)
    )
    return list((await session.execute(stmt)).scalars().all())


async def delete_event(
    session: AsyncSession, *, actor: User, tree: Tree, event_id: uuid.UUID
) -> None:
    if not await privacy.can_edit_tree(session, user_id=actor.id, tree=tree):
        raise Forbidden("not an editor of this tree")
    event = (
        await session.execute(
            select(Event).where(
                Event.id == event_id, Event.tree_id == tree.id, Event.deleted_at.is_(None)
            )
        )
    ).scalar_one_or_none()
    if event is None:
        raise NotFound("event not found")
    from datetime import UTC, datetime

    event.deleted_at = datetime.now(UTC)
    record_audit(
        session,
        action="delete",
        entity_type="Event",
        entity_id=event.id,
        tree_id=tree.id,
        actor_user_id=actor.id,
    )
    await session.commit()