"""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 or_, select
from sqlalchemy.ext.asyncio import AsyncSession

from app.models.enums import RelationshipType
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(
    session: AsyncSession, *, viewer_id: uuid.UUID, tree: Tree
) -> list[Event]:
    """All events in the tree — lets the family view compute birth/death years."""
    if not await privacy.can_view_tree(session, user_id=viewer_id, tree=tree):
        raise Forbidden("not permitted to view this tree")
    # Non-members get the redacted projection (no living-person dates).
    if await privacy.get_membership_role(session, viewer_id, tree.id) is None:
        from app.services import public_view_service

        return await public_view_service.list_public_events(
            session, viewer_id=viewer_id, tree=tree
        )
    stmt = (
        select(Event)
        .where(Event.tree_id == tree.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 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")
    # Non-members only see a full-visibility person's events (redacted → none).
    if await privacy.get_membership_role(session, viewer_id, tree.id) is None:
        from app.services import public_view_service

        return await public_view_service.list_public_person_events(
            session, viewer_id=viewer_id, tree=tree, person_id=person_id
        )
    # Member view: this person's own events PLUS their partnership events (which
    # live on the relationship and show on both partners). Returning both here
    # means the person page doesn't have to load every event in the tree.
    partner_rel_ids = (
        select(Relationship.id)
        .where(
            Relationship.tree_id == tree.id,
            Relationship.type == RelationshipType.partnership,
            Relationship.deleted_at.is_(None),
            or_(
                Relationship.person_from_id == person_id,
                Relationship.person_to_id == person_id,
            ),
        )
    )
    stmt = (
        select(Event)
        .where(
            Event.tree_id == tree.id,
            Event.deleted_at.is_(None),
            or_(
                Event.person_id == person_id,
                Event.relationship_id.in_(partner_rel_ids),
            ),
        )
        .order_by(Event.date_start.nulls_last(), Event.created_at)
    )
    return list((await session.execute(stmt)).scalars().all())


async def update_event(
    session: AsyncSession,
    *,
    actor: User,
    tree: Tree,
    event_id: uuid.UUID,
    changes: dict,
) -> Event:
    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")
    if "place_id" in changes and changes["place_id"] is not None:
        if not await _belongs_to_tree(session, Place, changes["place_id"], tree.id):
            raise NotFound("place not found in this tree")
    for key, value in changes.items():
        setattr(event, key, value)
    record_audit(
        session,
        action="update",
        entity_type="Event",
        entity_id=event.id,
        tree_id=tree.id,
        actor_user_id=actor.id,
        after=changes,
    )
    await session.commit()
    await session.refresh(event)
    return event


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()