"""Доступ к журналу. Всё, что не записано сюда, для оценки не существует."""

from datetime import datetime
from uuid import UUID

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

from app.db.models import Group, HintUse, InstructorNote, Session, Trainee, Utterance


async def next_attempt(db: AsyncSession, trainee_id: UUID | None, scenario_id: str) -> int:
    """Номер попытки по этому сценарию. Отдельной таблицы попыток нет:
    дельта считается запросом по (trainee_id, scenario_id, attempt)."""
    if trainee_id is None:
        return 1
    done = await db.scalar(
        select(func.count())
        .select_from(Session)
        .where(Session.trainee_id == trainee_id, Session.scenario_id == scenario_id)
    )
    return int(done or 0) + 1


async def create_session(
    db: AsyncSession,
    *,
    scenario_id: str,
    mode: str,
    trainee_id: UUID | None = None,
    group_id: UUID | None = None,
    session_id: UUID | None = None,
) -> Session:
    session = Session(
        scenario_id=scenario_id,
        mode=mode,
        trainee_id=trainee_id,
        group_id=group_id,
        attempt=await next_attempt(db, trainee_id, scenario_id),
    )
    if session_id is not None:
        session.id = session_id
    db.add(session)
    await db.commit()
    return session


async def ensure_session(
    db: AsyncSession,
    *,
    session_id: UUID,
    scenario_id: str,
    mode: str,
    trainee_name: str | None = None,
    trainee_id: UUID | None = None,
    group_name: str | None = None,
) -> Session:
    """Занятие, запущенное с пульта, должно иметь строку в журнале.

    Иначе реплики, подсказки и пометки не к чему привязать: они уходят
    в нарушение внешнего ключа, а профиль курсанта остаётся пустым.
    """
    existing = await db.get(Session, session_id)
    if existing is not None:
        return existing

    group = await ensure_group(db, group_name) if group_name else None
    trainee = await db.get(Trainee, trainee_id) if trainee_id else None
    if trainee_id and trainee is None:
        raise ValueError(f"курсант {trainee_id} не найден")
    if trainee is None and trainee_name:
        trainee = await ensure_trainee(db, trainee_name, group)
    return await create_session(
        db,
        scenario_id=scenario_id,
        mode=mode,
        trainee_id=trainee.id if trainee else None,
        group_id=group.id if group else None,
        session_id=session_id,
    )


async def get_session(db: AsyncSession, session_id: UUID) -> Session | None:
    return await db.get(Session, session_id)


async def append_utterance(
    db: AsyncSession,
    *,
    session_id: UUID,
    ref: str,
    speaker: str,
    text: str,
    at: datetime,
    mood: str | None = None,
) -> Utterance:
    utterance = Utterance(
        session_id=session_id, ref=ref, speaker=speaker, text=text, at=at, mood=mood
    )
    db.add(utterance)
    await db.commit()
    return utterance


async def transcript(db: AsyncSession, session_id: UUID) -> list[Utterance]:
    rows = await db.scalars(
        select(Utterance).where(Utterance.session_id == session_id).order_by(Utterance.at)
    )
    return list(rows)


async def record_hint(
    db: AsyncSession, *, session_id: UUID, checklist_id: str, question: str, at: datetime
) -> HintUse:
    """Каждое использование подсказки попадает в журнал: счёт подсказок —
    материал разбора, а не вычитаемое из баллов."""
    hint = HintUse(session_id=session_id, checklist_id=checklist_id, question=question, at=at)
    db.add(hint)
    await db.commit()
    return hint


async def add_note(
    db: AsyncSession, *, session_id: UUID, transcript_ref: str, text: str, author: str
) -> InstructorNote:
    note = InstructorNote(
        session_id=session_id, transcript_ref=transcript_ref, text=text, author=author
    )
    db.add(note)
    await db.commit()
    return note


async def history(
    db: AsyncSession,
    *,
    trainee_id: UUID | None = None,
    group_id: UUID | None = None,
    mode: str | None = None,
    since: datetime | None = None,
    limit: int = 100,
) -> list[Session]:
    """История с фильтрами: преподавателю нужно видеть прогресс группы
    и самостоятельную работу курсантов."""
    query = select(Session).order_by(Session.created_at.desc()).limit(limit)
    if trainee_id is not None:
        query = query.where(Session.trainee_id == trainee_id)
    if group_id is not None:
        query = query.where(Session.group_id == group_id)
    if mode is not None:
        query = query.where(Session.mode == mode)
    if since is not None:
        query = query.where(Session.created_at >= since)
    return list(await db.scalars(query))


async def ensure_group(db: AsyncSession, name: str) -> Group:
    group = await db.scalar(select(Group).where(Group.name == name))
    if group is None:
        group = Group(name=name)
        db.add(group)
        await db.commit()
    return group


async def ensure_trainee(db: AsyncSession, name: str, group: Group | None = None) -> Trainee:
    query = select(Trainee).where(Trainee.name == name)
    trainee = await db.scalar(query)
    if trainee is None:
        trainee = Trainee(name=name, group_id=group.id if group else None)
        db.add(trainee)
        await db.commit()
    return trainee