"""Сервис прохождения теста."""
from __future__ import annotations

import uuid as _uuid
from datetime import datetime, timezone

from sqlalchemy import func
from sqlalchemy.orm import Session, selectinload

from ..db import get_session
from ..models import (
    AnswerOption,
    Question,
    Test,
    TestAttempt,
    TestVersion,
    User,
    UserAnswer,
)
from .test_access import is_test_author, is_test_edit_open, user_has_test_access


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


def _sort_uuid_strings(items) -> list[str]:
    return sorted({str(x) for x in (items or []) if x is not None})


def _same_selection(selected, correct_ids) -> bool:
    return _sort_uuid_strings(selected) == _sort_uuid_strings(correct_ids)


def _to_uuid(val) -> _uuid.UUID | None:
    if isinstance(val, _uuid.UUID):
        return val
    try:
        return _uuid.UUID(str(val))
    except (ValueError, AttributeError):
        return None


# ─── load questions (shared) ─────────────────────────────────────────────────

def load_questions_for_version(
    session: Session,
    test_version_id,
    *,
    include_correct: bool,
    include_hints: bool = False,
) -> list[dict]:
    vid = _to_uuid(test_version_id)
    if vid is None:
        return []
    questions = (
        session.query(Question)
        .options(selectinload(Question.options))
        .filter(Question.test_version_id == vid)
        .order_by(Question.question_order)
        .all()
    )
    out = []
    for q in questions:
        options = []
        for o in sorted(q.options, key=lambda x: x.option_order):
            base = {'id': str(o.id), 'text': o.text, 'optionOrder': o.option_order}
            if include_correct:
                base['isCorrect'] = bool(o.is_correct)
            options.append(base)
        item = {
            'id': str(q.id),
            'text': q.text,
            'questionOrder': q.question_order,
            'hasMultipleAnswers': bool(q.has_multiple_answers),
            'options': options,
        }
        if include_hints:
            hint = (q.ai_hint or '').strip()
            item['aiHint'] = hint or None
        out.append(item)
    return out


# ─── start ───────────────────────────────────────────────────────────────────

def start_attempt(session_or_eng, user_id: str, test_id: str) -> dict:
    """Принимает engine (legacy) или session — для обратной совместимости."""
    acc = user_has_test_access(user_id, test_id)
    if not acc.ok:
        raise HttpError(404, 'Тест не найден.')

    session = get_session()
    tid = _to_uuid(test_id)
    uid = _to_uuid(user_id)

    active_version = (
        session.query(TestVersion)
        .filter(TestVersion.test_id == tid, TestVersion.is_active.is_(True))
        .first()
    )
    if not active_version:
        raise HttpError(404, 'Нет активной версии теста.')

    max_n = (
        session.query(func.coalesce(func.max(TestAttempt.attempt_number), 0))
        .filter(
            TestAttempt.test_version_id == active_version.id,
            TestAttempt.user_id == uid,
        )
        .scalar() or 0
    )
    attempt = TestAttempt(
        test_version_id=active_version.id,
        user_id=uid,
        attempt_number=int(max_n) + 1,
        status='in_progress',
    )
    session.add(attempt)
    session.commit()
    session.refresh(attempt)
    return {
        'attempt': {
            'id': str(attempt.id),
            'test_version_id': str(attempt.test_version_id),
            'user_id': str(attempt.user_id),
            'attempt_number': attempt.attempt_number,
            'status': attempt.status,
            'started_at': attempt.started_at.isoformat() if attempt.started_at else None,
        }
    }


# ─── play ────────────────────────────────────────────────────────────────────

def get_play_content(session_or_eng, user_id: str, test_id: str, attempt_id: str) -> dict:
    session = get_session()
    aid = _to_uuid(attempt_id)
    uid = _to_uuid(user_id)
    tid = _to_uuid(test_id)

    attempt = (
        session.query(TestAttempt)
        .options(
            selectinload(TestAttempt.test_version).selectinload(TestVersion.test)
        )
        .filter(TestAttempt.id == aid)
        .first()
    )
    if not attempt:
        raise HttpError(404, 'Попытка не найдена.')
    if attempt.test_version.test_id != tid:
        raise HttpError(404, 'Попытка не найдена.')
    if attempt.user_id != uid:
        raise HttpError(403, 'Доступ запрещён.')
    if attempt.status != 'in_progress':
        raise HttpError(400, 'Попытка уже завершена.')

    test = attempt.test_version.test
    qs = load_questions_for_version(session, attempt.test_version_id, include_correct=False)
    return {
        'testTitle': test.title,
        'passingThreshold': test.passing_threshold,
        'timeLimit': test.time_limit,
        'hintsEnabled': bool(test.hints_enabled),
        'resultMode': test.result_mode or 'end',
        'attemptId': str(attempt.id),
        'questions': qs,
    }


# ─── submit ──────────────────────────────────────────────────────────────────

def submit_attempt(session_or_eng, user_id: str, test_id: str, attempt_id: str,
                   raw_answers: dict | None) -> dict:
    answers = raw_answers if isinstance(raw_answers, dict) else {}
    session = get_session()
    aid = _to_uuid(attempt_id)
    uid = _to_uuid(user_id)
    tid = _to_uuid(test_id)

    attempt = (
        session.query(TestAttempt)
        .options(selectinload(TestAttempt.test_version).selectinload(TestVersion.test))
        .filter(TestAttempt.id == aid)
        .with_for_update()
        .first()
    )
    if not attempt:
        raise HttpError(404, 'Попытка не найдена.')
    if attempt.test_version.test_id != tid:
        raise HttpError(404, 'Попытка не найдена.')
    if attempt.user_id != uid:
        raise HttpError(403, 'Доступ запрещён.')
    if attempt.status != 'in_progress':
        raise HttpError(400, 'Попытка уже завершена.')

    test = attempt.test_version.test
    questions = (
        session.query(Question)
        .options(selectinload(Question.options))
        .filter(Question.test_version_id == attempt.test_version_id)
        .all()
    )
    if not questions:
        raise HttpError(400, 'В тесте нет вопросов.')

    by_q: dict[str, dict] = {}
    for q in questions:
        qid = str(q.id)
        by_q[qid] = {'all': {str(o.id) for o in q.options}, 'correct': [str(o.id) for o in q.options if o.is_correct]}

    correct_count = 0
    for q in questions:
        qid = str(q.id)
        selected = answers.get(qid, [])
        if not isinstance(selected, list):
            selected = [str(selected)]
        selected = [str(x) for x in selected]
        g = by_q[qid]
        for sid in selected:
            if sid not in g['all']:
                raise HttpError(400, 'Некорректный вариант ответа.')
        if _same_selection(selected, g['correct']):
            correct_count += 1

    total = len(questions)
    percent = (correct_count / total) * 100 if total else 0
    threshold = int(test.passing_threshold or 0)
    passed = percent + 1e-9 >= threshold

    # удаляем старые ответы и записываем новые
    session.query(UserAnswer).filter(UserAnswer.attempt_id == aid).delete(synchronize_session='fetch')
    for q in questions:
        qid = str(q.id)
        selected = answers.get(qid, [])
        if not isinstance(selected, list):
            selected = [str(selected)]
        selected_uuids = [_to_uuid(x) for x in selected if _to_uuid(x) is not None]
        session.add(UserAnswer(
            attempt_id=aid,
            question_id=q.id,
            selected_options=selected_uuids,
        ))

    attempt.status = 'completed'
    attempt.completed_at = datetime.now(timezone.utc)
    attempt.correct_count = correct_count
    attempt.total_questions = total
    attempt.passed = passed
    session.commit()

    review = build_review_from_db(session, attempt_id)
    return {
        'attemptId': attempt_id,
        'correctCount': correct_count,
        'totalQuestions': total,
        'percent': round(percent, 1),
        'passed': passed,
        'passingThreshold': threshold,
        'review': review,
    }


# ─── review ──────────────────────────────────────────────────────────────────

def build_review_from_db(session: Session, attempt_id: str) -> dict:
    aid = _to_uuid(attempt_id)
    attempt = (
        session.query(TestAttempt)
        .options(
            selectinload(TestAttempt.test_version).selectinload(TestVersion.test),
            selectinload(TestAttempt.user),
            selectinload(TestAttempt.user_answers),
        )
        .filter(TestAttempt.id == aid)
        .first()
    )
    if not attempt:
        raise HttpError(404, 'Попытка не найдена.')
    if attempt.status != 'completed':
        raise HttpError(400, 'Попытка не завершена.')

    test = attempt.test_version.test
    questions = load_questions_for_version(
        session, attempt.test_version_id, include_correct=True, include_hints=True
    )

    sel_by_q: dict[str, list[str]] = {
        str(ua.question_id): [str(x) for x in (ua.selected_options or [])]
        for ua in attempt.user_answers
    }

    total = int(attempt.total_questions or len(questions))
    percent = round(((attempt.correct_count or 0) / total) * 100, 1) if total else 0

    q_out = []
    for q in questions:
        selected = _sort_uuid_strings(sel_by_q.get(q['id'], []))
        correct = _sort_uuid_strings([o['id'] for o in q['options'] if o.get('isCorrect')])
        selected_set = set(selected)
        q_out.append({
            'id': q['id'],
            'text': q['text'],
            'hasMultipleAnswers': q['hasMultipleAnswers'],
            'aiHint': q.get('aiHint'),
            'isUserCorrect': _same_selection(selected, correct),
            'options': [
                {
                    'id': o['id'],
                    'text': o['text'],
                    'isCorrect': o.get('isCorrect', False),
                    'selected': o['id'] in selected_set,
                }
                for o in q['options']
            ],
        })

    return {
        'attemptId': str(attempt.id),
        'testId': str(test.id),
        'testTitle': test.title,
        'passingThreshold': int(test.passing_threshold or 0),
        'timeLimit': test.time_limit,
        'resultMode': test.result_mode or 'end',
        'hintsEnabled': bool(test.hints_enabled),
        'correctCount': int(attempt.correct_count or 0),
        'totalQuestions': total,
        'percent': percent,
        'passed': bool(attempt.passed),
        'startedAt': attempt.started_at.isoformat() if attempt.started_at else None,
        'completedAt': attempt.completed_at.isoformat() if attempt.completed_at else None,
        'attempterUserId': str(attempt.user_id),
        'attempterName': attempt.user.full_name,
        'attempterLogin': attempt.user.login,
        'questions': q_out,
    }


def get_attempt_review_for_user(session_or_eng, current_user_id: str, test_id: str,
                                 attempt_id: str) -> dict:
    session = get_session()
    aid = _to_uuid(attempt_id)
    tid = _to_uuid(test_id)

    attempt = (
        session.query(TestAttempt)
        .options(selectinload(TestAttempt.test_version).selectinload(TestVersion.test))
        .filter(TestAttempt.id == aid)
        .first()
    )
    if not attempt:
        raise HttpError(404, 'Попытка не найдена.')
    if attempt.test_version.test_id != tid:
        raise HttpError(404, 'Попытка не найдена.')

    is_owner = str(attempt.user_id) == str(current_user_id)
    is_author = is_test_author(attempt.test_version.test.created_by, current_user_id)
    if not is_owner and not is_author and not is_test_edit_open():
        raise HttpError(403, 'Доступ запрещён.')
    return build_review_from_db(session, attempt_id)


# ─── hints ───────────────────────────────────────────────────────────────────

def count_missing_hints(session_or_eng, test_id: str) -> dict:
    session = get_session()
    tid = _to_uuid(test_id)
    if tid is None:
        return {'total': 0, 'missing': 0}

    active_version = (
        session.query(TestVersion)
        .filter(TestVersion.test_id == tid, TestVersion.is_active.is_(True))
        .first()
    )
    if not active_version:
        return {'total': 0, 'missing': 0}

    all_qs = session.query(Question).options(selectinload(Question.options)).filter(
        Question.test_version_id == active_version.id
    ).all()
    filled_qs = []
    for q in all_qs:
        if not (q.text or '').strip():
            continue
        if len([o for o in q.options if (o.text or '').strip()]) < 2:
            continue
        filled_qs.append(q)
    total = len(filled_qs)
    missing = sum(1 for q in filled_qs if not q.ai_hint)
    return {'total': total, 'missing': missing}


def generate_missing_hints_for_test(session_or_eng, author_id: str, test_id: str) -> dict:
    from .ai_editor import generate_question_hint
    session = get_session()
    tid = _to_uuid(test_id)

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

    active_version = (
        session.query(TestVersion)
        .filter(TestVersion.test_id == tid, TestVersion.is_active.is_(True))
        .first()
    )
    if not active_version:
        return {'generated': 0, 'failed': 0, 'total': 0}

    missing_qs = (
        session.query(Question)
        .options(selectinload(Question.options))
        .filter(
            Question.test_version_id == active_version.id,
            (Question.ai_hint == None) | (Question.ai_hint == ''),  # noqa: E711
        )
        .order_by(Question.question_order)
        .all()
    )

    generated = failed = skipped = 0
    for q in missing_qs:
        # Подсказку строим только по заполненному вопросу (есть текст и >=2 непустых варианта).
        if not (q.text or '').strip():
            skipped += 1
            continue
        valid_opts = [o for o in q.options if (o.text or '').strip()]
        if len(valid_opts) < 2:
            skipped += 1
            continue
        opt_payload = [{'text': o.text, 'isCorrect': bool(o.is_correct)} for o in q.options]
        hint = generate_question_hint(question_text=q.text, options=opt_payload)
        if hint:
            q.ai_hint = hint
            generated += 1
        else:
            failed += 1
    session.commit()
    return {'generated': generated, 'failed': failed, 'skipped': skipped, 'total': len(missing_qs)}


def generate_next_missing_hint_for_test(session_or_eng, author_id: str, test_id: str) -> dict:
    """Генерирует одну недостающую подсказку (для отображения прогресса в UI)."""
    from .ai_editor import generate_question_hint

    session = get_session()
    tid = _to_uuid(test_id)

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

    active_version = (
        session.query(TestVersion)
        .filter(TestVersion.test_id == tid, TestVersion.is_active.is_(True))
        .first()
    )
    if not active_version:
        return {'generated': 0, 'remaining': 0, 'done': True, 'totalMissing': 0}

    before = count_missing_hints(None, test_id).get('missing') or 0

    missing_qs = (
        session.query(Question)
        .options(selectinload(Question.options))
        .filter(
            Question.test_version_id == active_version.id,
            (Question.ai_hint == None) | (Question.ai_hint == ''),  # noqa: E711
        )
        .order_by(Question.question_order)
        .all()
    )

    for q in missing_qs:
        if not (q.text or '').strip():
            continue
        valid_opts = [o for o in q.options if (o.text or '').strip()]
        if len(valid_opts) < 2:
            continue
        opt_payload = [{'text': o.text, 'isCorrect': bool(o.is_correct)} for o in q.options]
        hint = generate_question_hint(question_text=q.text, options=opt_payload)
        if hint:
            q.ai_hint = hint
            session.commit()
            after = count_missing_hints(None, test_id).get('missing') or 0
            return {
                'generated': 1,
                'remaining': after,
                'done': after == 0,
                'totalMissing': before,
                'failed': 0,
            }

    after = count_missing_hints(None, test_id).get('missing') or 0
    return {
        'generated': 0,
        'remaining': after,
        'done': after == 0,
        'totalMissing': before,
        'failed': 0,
    }


def check_question_for_attempt(session_or_eng, user_id: str, test_id: str, attempt_id: str,
                                question_id: str, selected_option_ids: list[str]) -> dict:
    session = get_session()
    aid = _to_uuid(attempt_id)
    uid = _to_uuid(user_id)
    tid = _to_uuid(test_id)
    qid = _to_uuid(question_id)

    attempt = (
        session.query(TestAttempt)
        .options(
            selectinload(TestAttempt.test_version).selectinload(TestVersion.test)
        )
        .filter(TestAttempt.id == aid)
        .first()
    )
    if not attempt:
        raise HttpError(404, 'Попытка не найдена.')
    if attempt.test_version.test_id != tid:
        raise HttpError(404, 'Попытка не найдена.')
    if attempt.user_id != uid:
        raise HttpError(403, 'Доступ запрещён.')
    if attempt.status != 'in_progress':
        raise HttpError(400, 'Попытка уже завершена.')

    question = (
        session.query(Question)
        .options(selectinload(Question.options))
        .filter(
            Question.id == qid,
            Question.test_version_id == attempt.test_version_id,
        )
        .first()
    )
    if not question:
        raise HttpError(404, 'Вопрос не найден.')

    correct_ids = [str(o.id) for o in question.options if o.is_correct]
    is_correct = _same_selection(selected_option_ids, correct_ids)

    selected_set = {str(x) for x in (selected_option_ids or [])}
    selected_texts = [o.text for o in question.options if str(o.id) in selected_set]
    correct_texts = [o.text for o in question.options if o.is_correct]

    test = attempt.test_version.test
    explanation = ''
    if test.hints_enabled:
        if question.ai_hint:
            explanation = question.ai_hint
        else:
            try:
                from .ai_editor import explain_answer
                explanation = explain_answer(
                    question_text=question.text,
                    options=[{'text': o.text, 'isCorrect': bool(o.is_correct)} for o in question.options],
                    selected_texts=selected_texts,
                    is_correct=is_correct,
                )
            except Exception:
                explanation = ''

    return {
        'questionId': str(question.id),
        'isCorrect': is_correct,
        'correctOptionIds': correct_ids,
        'correctOptionTexts': correct_texts,
        'explanation': explanation,
    }


def list_test_attempts_for_author(session_or_eng, author_id: str, test_id: str) -> list[dict]:
    session = get_session()
    tid = _to_uuid(test_id)

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

    rows = (
        session.query(TestAttempt, TestVersion, User)
        .join(TestVersion, TestAttempt.test_version_id == TestVersion.id)
        .join(User, TestAttempt.user_id == User.id)
        .filter(TestVersion.test_id == tid)
        .order_by(TestAttempt.started_at.desc().nullslast())
        .limit(200)
        .all()
    )

    return [
        {
            'id': str(a.id),
            'user_id': str(a.user_id),
            'status': a.status,
            'attempt_number': a.attempt_number,
            'started_at': a.started_at,
            'completed_at': a.completed_at,
            'correct_count': a.correct_count,
            'total_questions': a.total_questions,
            'passed': a.passed,
            'test_version': tv.version,
            'attempter_name': u.full_name,
            'attempter_login': u.login,
        }
        for a, tv, u in rows
    ]