"""Construit une `ValidationInput` depuis la base pour un couple (bénévole,
créneau). Couche de liaison : c'est le seul endroit du module `validation` qui
connaît la base."""

import uuid

from sqlmodel import Session, select

from app.models import (
    Assignment,
    Edition,
    Shift,
    Volunteer,
)
from app.validation.models import (
    ShiftInfo,
    ValidationInput,
)


def build_validation_input(
    *,
    session: Session,
    edition: Edition,
    volunteer: Volunteer,
    shift: Shift,
    exclude_assignment_id: uuid.UUID | None = None,
) -> ValidationInput:
    # Toute affectation existante du bénévole compte (une affectation = une
    # décision, toujours active).
    stmt = (
        select(Shift)
        .join(Assignment, Assignment.shift_id == Shift.id)
        .where(Assignment.volunteer_id == volunteer.id)
        .where(Shift.id != shift.id)
    )
    if exclude_assignment_id is not None:
        stmt = stmt.where(Assignment.id != exclude_assignment_id)
    existing_shifts = tuple(
        ShiftInfo(id=str(s.id), starts_at=s.starts_at, ends_at=s.ends_at)
        for s in session.exec(stmt)
    )

    return ValidationInput(
        candidate_shift=ShiftInfo(
            id=str(shift.id),
            starts_at=shift.starts_at,
            ends_at=shift.ends_at,
        ),
        existing_shifts=existing_shifts,
    )