"""Создание/правка теста, fork версии при наличии попыток."""
from __future__ import annotations

import uuid as _uuid
from typing import Any

from sqlalchemy import func
from sqlalchemy.orm import Session

from ..db import get_session
from ..messages import RU
from ..models import AnswerOption, Question, Test, TestVersion
from .test_access import is_test_author
from .test_chain import has_any_attempt_for_test


class HttpError(Exception):
    def __init__(self, status: int, message: str):
        super().__init__(message)
        self.status = status
        self.message = message


def create_test_with_version(author_id: str, *, title: str, description: str | None) -> dict:
    session = get_session()
    try:
        uid = _uuid.UUID(author_id)
    except (ValueError, AttributeError):
        raise HttpError(400, 'Некорректный user_id.')

    test = Test(
        title=title,
        description=description or None,
        created_by=uid,
        is_active=True,
        is_versioned=True,
    )
    session.add(test)
    session.flush()  # получаем test.id

    version = TestVersion(test_id=test.id, version=1, is_active=True, parent_id=None)
    session.add(version)
    session.commit()
    return {'testId': str(test.id), 'versionId': str(version.id)}


def _get_active_version(session: Session, test_id: _uuid.UUID) -> TestVersion | None:
    return (
        session.query(TestVersion)
        .filter(TestVersion.test_id == test_id, TestVersion.is_active.is_(True))
        .first()
    )


def _copy_question_tree(session: Session, from_version_id, to_version_id) -> None:
    questions = (
        session.query(Question)
        .filter(Question.test_version_id == from_version_id)
        .order_by(Question.question_order)
        .all()
    )
    for q in questions:
        new_q = Question(
            test_version_id=to_version_id,
            text=q.text,
            question_order=q.question_order,
            has_multiple_answers=q.has_multiple_answers,
            ai_hint=q.ai_hint,
        )
        session.add(new_q)
        session.flush()
        for o in sorted(q.options, key=lambda x: x.option_order):
            session.add(AnswerOption(
                question_id=new_q.id,
                text=o.text,
                is_correct=o.is_correct,
                option_order=o.option_order,
            ))


def _fork_new_version(session: Session, test_id: _uuid.UUID) -> TestVersion:
    av = _get_active_version(session, test_id)
    if not av:
        raise HttpError(500, RU['internal'] if 'internal' in RU else 'Внутренняя ошибка.')

    max_ver = (
        session.query(func.coalesce(func.max(TestVersion.version), 0))
        .filter(TestVersion.test_id == test_id)
        .scalar() or 0
    )
    next_v = int(max_ver) + 1

    # деактивируем все версии
    session.query(TestVersion).filter(TestVersion.test_id == test_id).update(
        {TestVersion.is_active: False}, synchronize_session='fetch'
    )

    new_version = TestVersion(
        test_id=test_id,
        version=next_v,
        is_active=True,
        parent_id=av.id,
    )
    session.add(new_version)
    session.flush()
    _copy_question_tree(session, av.id, new_version.id)
    return new_version


def _replace_version_content(session: Session, version: TestVersion, payload: dict) -> None:
    # Снимок ai_hint по тексту вопроса перед удалением
    old_hints: dict[str, str] = {}
    for q in version.questions:
        if q.ai_hint and q.text not in old_hints:
            old_hints[q.text] = q.ai_hint

    # удаляем через cascade (answer_options удалятся каскадно через ORM)
    for q in list(version.questions):
        session.delete(q)
    session.flush()

    questions_payload = payload.get('questions') or []
    for i, qp in enumerate(questions_payload):
        q_text = (qp.get('text') or '').strip()
        new_q = Question(
            test_version_id=version.id,
            text=q_text,
            question_order=qp.get('question_order') or (i + 1),
            has_multiple_answers=bool(qp.get('hasMultipleAnswers')),
            ai_hint=old_hints.get(q_text),
        )
        session.add(new_q)
        session.flush()
        for j, op in enumerate(qp.get('options') or []):
            session.add(AnswerOption(
                question_id=new_q.id,
                text=(op.get('text') or '').strip(),
                is_correct=bool(op.get('isCorrect')),
                option_order=op.get('option_order') or (j + 1),
            ))


def save_test_draft(author_id: str, test_id: str, payload: dict) -> dict:
    if not isinstance(payload, dict):
        payload = {}
    session = get_session()
    try:
        tid = _uuid.UUID(test_id)
    except (ValueError, AttributeError):
        raise HttpError(404, 'Тест не найден.')

    test = session.get(Test, tid)
    if not test:
        raise HttpError(404, 'Тест не найден.')
    if not is_test_author(test.created_by, author_id):
        raise HttpError(403, 'Доступ запрещён.')

    if payload.get('title') is not None:
        test.title = payload['title']
    if payload.get('description') is not None:
        test.description = payload['description'] or None

    if payload.get('passingThreshold') is not None:
        try:
            test.passing_threshold = max(0, min(100, round(float(payload['passingThreshold']))))
        except (TypeError, ValueError):
            pass

    if 'timeLimit' in payload:
        tl = payload.get('timeLimit')
        try:
            test.time_limit = None if tl in (None, '', 0) else max(0, int(tl))
        except (TypeError, ValueError):
            pass

    if 'hintsEnabled' in payload:
        test.hints_enabled = bool(payload['hintsEnabled'])

    if 'resultMode' in payload:
        rm = (payload.get('resultMode') or '').strip().lower()
        if rm in ('immediate', 'end'):
            test.result_mode = rm

    has_attempts = has_any_attempt_for_test(session, tid)
    active_version = _get_active_version(session, tid)
    if not active_version:
        raise HttpError(500, 'Нет активной версии теста.')

    forked = False
    if has_attempts and 'questions' in payload and payload.get('questions') is not None:
        active_version = _fork_new_version(session, tid)
        forked = True

    if payload.get('questions') is not None:
        _replace_version_content(session, active_version, payload)

    session.commit()
    return {'testId': test_id, 'versionId': str(active_version.id), 'forked': forked}