"""Person service. Writes require editor rights on the tree; reads run every
person through the privacy engine. Each returned Person gets a transient
``primary_name`` for display (not persisted).
"""

import uuid

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

from app.models.enums import PersonPrivacy
from app.models.person import Name, Person
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 Forbidden, NotFound
from app.services.privacy import Visibility


def _format_name(name: Name) -> str | None:
    parts = [name.given, name.surname]
    joined = " ".join(p for p in parts if p)
    return joined or name.display_name


async def _attach_primary_name(session: AsyncSession, person: Person) -> None:
    stmt = (
        select(Name)
        .where(Name.person_id == person.id, Name.deleted_at.is_(None))
        .order_by(Name.is_primary.desc(), Name.sort_order)
    )
    name = (await session.execute(stmt)).scalars().first()
    # Transient display attribute consumed by the PersonRead schema.
    person.primary_name = _format_name(name) if name is not None else None


async def create_person(
    session: AsyncSession,
    *,
    actor: User,
    tree: Tree,
    given: str | None = None,
    surname: str | None = None,
    gender: str | None = None,
    is_living: bool | None = None,
    privacy_setting: PersonPrivacy = PersonPrivacy.inherit,
    notes: str | None = None,
) -> Person:
    if not await privacy.can_edit_tree(session, user_id=actor.id, tree=tree):
        raise Forbidden("not an editor of this tree")

    person = Person(
        tree_id=tree.id,
        gender=gender,
        is_living=is_living,
        privacy=privacy_setting,
        notes=notes,
    )
    session.add(person)
    await session.flush()  # assign person.id

    if given or surname:
        session.add(
            Name(
                tree_id=tree.id,
                person_id=person.id,
                name_type="birth",
                given=given,
                surname=surname,
                is_primary=True,
            )
        )
    record_audit(
        session,
        action="create",
        entity_type="Person",
        entity_id=person.id,
        tree_id=tree.id,
        actor_user_id=actor.id,
        after={"given": given, "surname": surname},
    )
    await session.commit()
    await session.refresh(person)
    await _attach_primary_name(session, person)
    return person


async def get_person(
    session: AsyncSession, *, viewer_id: uuid.UUID, tree: Tree, person_id: uuid.UUID
) -> Person:
    if not await privacy.can_view_tree(session, user_id=viewer_id, tree=tree):
        raise Forbidden("not permitted to view this tree")
    person = (
        await session.execute(
            select(Person).where(
                Person.id == person_id,
                Person.tree_id == tree.id,
                Person.deleted_at.is_(None),
            )
        )
    ).scalar_one_or_none()
    if person is None:
        raise NotFound("person not found")
    # Run the single person through the privacy engine (redaction lands Phase 2).
    if (
        await privacy.person_visibility(session, user_id=viewer_id, tree=tree, person=person)
        == Visibility.hidden
    ):
        raise NotFound("person not found")
    await _attach_primary_name(session, person)
    return person


async def list_persons(
    session: AsyncSession, *, viewer_id: uuid.UUID, tree: Tree
) -> list[Person]:
    if not await privacy.can_view_tree(session, user_id=viewer_id, tree=tree):
        raise Forbidden("not permitted to view this tree")

    stmt = (
        select(Person)
        .where(Person.tree_id == tree.id, Person.deleted_at.is_(None))
        .order_by(Person.created_at)
    )
    persons = list((await session.execute(stmt)).scalars().all())

    visible: list[Person] = []
    for person in persons:
        if (
            await privacy.person_visibility(
                session, user_id=viewer_id, tree=tree, person=person
            )
            == Visibility.hidden
        ):
            continue
        await _attach_primary_name(session, person)
        visible.append(person)
    return visible