/**
 * Прохождение теста: контент для игры, проверка ответов, завершение попытки.
 */
import { RU } from '../messages/ru.js';
import { isTestAuthor } from '../config/devAuthor.js';

/**
 * @param {import('pg').Pool|import('pg').PoolClient} db
 * @param {string} testVersionId
 * @param {{ includeCorrect: boolean }} opts
 */
export async function loadQuestionsForVersion(db, testVersionId, opts) {
  const { rows: qrows } = await db.query(
    `SELECT id, text, question_order, has_multiple_answers
     FROM questions
     WHERE test_version_id = $1
     ORDER BY question_order`,
    [testVersionId]
  );
  const out = [];
  for (const row of qrows) {
    const { rows: orows } = await db.query(
      `SELECT id, text, is_correct, option_order
       FROM answer_options
       WHERE question_id = $1
       ORDER BY option_order`,
      [row.id]
    );
    const options = orows.map((o) => {
      const base = {
        id: o.id,
        text: o.text,
        optionOrder: o.option_order,
      };
      if (opts.includeCorrect) {
        return { ...base, isCorrect: o.is_correct };
      }
      return base;
    });
    out.push({
      id: row.id,
      text: row.text,
      questionOrder: row.question_order,
      hasMultipleAnswers: row.has_multiple_answers,
      options,
    });
  }
  return out;
}

function sortUuidStrings(arr) {
  return [...new Set(arr)].map(String).sort();
}

function sameSelection(selected, correctIds) {
  const a = sortUuidStrings(selected);
  const b = sortUuidStrings(correctIds);
  if (a.length !== b.length) {
    return false;
  }
  return a.every((x, i) => x === b[i]);
}

/**
 * @param {import('pg').Pool} pool
 * @param {string} userId
 * @param {string} testId
 */
export async function getEditorContent(pool, userId, testId) {
  const { rows: tr } = await pool.query(
    `SELECT t.id, t.title, t.description, t.passing_threshold, t.created_by
     FROM tests t WHERE t.id = $1`,
    [testId]
  );
  if (!tr.length) {
    const e = new Error(RU.testNotFound);
    e.status = 404;
    throw e;
  }
  if (!isTestAuthor(tr[0].created_by, userId)) {
    const e = new Error(RU.forbidden);
    e.status = 403;
    throw e;
  }
  const { rows: tv } = await pool.query(
    `SELECT id FROM test_versions WHERE test_id = $1 AND is_active = true LIMIT 1`,
    [testId]
  );
  if (!tv.length) {
    const e = new Error(RU.noActiveVersion);
    e.status = 400;
    throw e;
  }
  const versionId = tv[0].id;
  const questions = await loadQuestionsForVersion(pool, versionId, {
    includeCorrect: true,
  });
  return {
    test: {
      id: tr[0].id,
      title: tr[0].title,
      description: tr[0].description,
      passingThreshold: tr[0].passing_threshold,
    },
    activeVersionId: versionId,
    questions,
  };
}

/**
 * @param {import('pg').Pool} pool
 * @param {string} userId
 * @param {string} testId
 * @param {string} attemptId
 */
export async function getPlayContent(pool, userId, testId, attemptId) {
  const { rows: arows } = await pool.query(
    `SELECT ta.id, ta.user_id, ta.status, ta.test_version_id, tv.test_id, t.title, t.passing_threshold
     FROM test_attempts ta
     INNER JOIN test_versions tv ON tv.id = ta.test_version_id
     INNER JOIN tests t ON t.id = tv.test_id
     WHERE ta.id = $1`,
    [attemptId]
  );
  if (!arows.length) {
    const e = new Error(RU.attemptNotFound);
    e.status = 404;
    throw e;
  }
  const a = arows[0];
  if (a.test_id !== testId) {
    const e = new Error(RU.attemptNotFound);
    e.status = 404;
    throw e;
  }
  if (a.user_id !== userId) {
    const e = new Error(RU.forbidden);
    e.status = 403;
    throw e;
  }
  if (a.status !== 'in_progress') {
    const e = new Error(RU.attemptNotInProgress);
    e.status = 400;
    throw e;
  }
  const questions = await loadQuestionsForVersion(pool, a.test_version_id, {
    includeCorrect: false,
  });
  return {
    testTitle: a.title,
    passingThreshold: a.passing_threshold,
    attemptId: a.id,
    questions,
  };
}

/**
 * @param {import('pg').Pool} pool
 * @param {string} userId
 * @param {string} testId
 * @param {string} attemptId
 * @param {Record<string, string | string[] | undefined> | null | undefined} rawAnswers
 */
export async function submitAttempt(pool, userId, testId, attemptId, rawAnswers) {
  const answers = rawAnswers && typeof rawAnswers === 'object' ? rawAnswers : {};
  const client = await pool.connect();
  try {
    await client.query('BEGIN');
    const { rows: arows } = await client.query(
      `SELECT id, user_id, status, test_version_id
       FROM test_attempts
       WHERE id = $1
       FOR UPDATE`,
      [attemptId]
    );
    if (!arows.length) {
      const e = new Error(RU.attemptNotFound);
      e.status = 404;
      throw e;
    }
    const a0 = arows[0];
    const { rows: trows } = await client.query(
      `SELECT t.passing_threshold, tv.test_id
       FROM test_versions tv
       INNER JOIN tests t ON t.id = tv.test_id
       WHERE tv.id = $1`,
      [a0.test_version_id]
    );
    if (!trows.length) {
      const e = new Error(RU.testNotFound);
      e.status = 404;
      throw e;
    }
    const link = trows[0];
    const a = {
      test_id: link.test_id,
      user_id: a0.user_id,
      status: a0.status,
      test_version_id: a0.test_version_id,
      passing_threshold: link.passing_threshold,
    };
    if (a.test_id !== testId) {
      const e = new Error(RU.attemptNotFound);
      e.status = 404;
      throw e;
    }
    if (a.user_id !== userId) {
      const e = new Error(RU.forbidden);
      e.status = 403;
      throw e;
    }
    if (a.status !== 'in_progress') {
      const e = new Error(RU.attemptNotInProgress);
      e.status = 400;
      throw e;
    }
    const versionId = a.test_version_id;
    const threshold = Number(a.passing_threshold) || 0;

    const { rows: qrows } = await client.query(
      `SELECT id, has_multiple_answers
       FROM questions
       WHERE test_version_id = $1`,
      [versionId]
    );
    if (!qrows.length) {
      const e = new Error(RU.testHasNoQuestions);
      e.status = 400;
      throw e;
    }

    const { rows: allOpts } = await client.query(
      `SELECT a.id, a.question_id, a.is_correct
       FROM answer_options a
       INNER JOIN questions q ON q.id = a.question_id
       WHERE q.test_version_id = $1`,
      [versionId]
    );
    const byQuestion = new Map();
    for (const o of allOpts) {
      if (!byQuestion.has(o.question_id)) {
        byQuestion.set(o.question_id, { all: new Set(), correct: [] });
      }
      const g = byQuestion.get(o.question_id);
      g.all.add(String(o.id));
      if (o.is_correct) {
        g.correct.push(String(o.id));
      }
    }

    let correctCount = 0;
    for (const q of qrows) {
      const qid = String(q.id);
      let selected = answers[qid] ?? answers[q.id];
      if (selected == null) {
        selected = [];
      } else if (!Array.isArray(selected)) {
        selected = [String(selected)];
      } else {
        selected = selected.map(String);
      }
      const g = byQuestion.get(q.id);
      if (!g) {
        continue;
      }
      for (const sid of selected) {
        if (!g.all.has(sid)) {
          const e = new Error(RU.invalidOptionForQuestion);
          e.status = 400;
          throw e;
        }
      }
      if (sameSelection(selected, g.correct)) {
        correctCount += 1;
      }
    }
    const total = qrows.length;
    const percent = (correctCount / total) * 100;
    const passed = percent + 1e-9 >= threshold;

    await client.query(`DELETE FROM user_answers WHERE attempt_id = $1`, [attemptId]);
    for (const q of qrows) {
      const qid = String(q.id);
      let selected = answers[qid] ?? answers[q.id] ?? [];
      if (!Array.isArray(selected)) {
        selected = [String(selected)];
      } else {
        selected = selected.map(String);
      }
      await client.query(
        `INSERT INTO user_answers (attempt_id, question_id, selected_options)
         VALUES ($1, $2, $3::uuid[])`,
        [attemptId, q.id, selected]
      );
    }
    await client.query(
      `UPDATE test_attempts
       SET status = 'completed', completed_at = CURRENT_TIMESTAMP,
           correct_count = $2, total_questions = $3, passed = $4
       WHERE id = $1`,
      [attemptId, correctCount, total, passed]
    );
    await client.query('COMMIT');
    const base = {
      attemptId,
      correctCount,
      totalQuestions: total,
      percent: Math.round(percent * 10) / 10,
      passed,
      passingThreshold: threshold,
    };
    const review = await buildReviewFromDb(pool, attemptId);
    return { ...base, review };
  } catch (e) {
    await client.query('ROLLBACK');
    throw e;
  } finally {
    client.release();
  }
}

/**
 * Подробный разбор завершённой попытки (для API и ответа submit).
 * @param {import('pg').Pool|import('pg').PoolClient} pool
 * @param {string} attemptId
 */
export async function buildReviewFromDb(pool, attemptId) {
  const { rows: arows } = await pool.query(
    `SELECT ta.id, ta.status, ta.test_version_id, ta.user_id, ta.correct_count, ta.total_questions,
            ta.passed, ta.started_at, ta.completed_at,
            t.id AS test_id, t.title, t.passing_threshold,
            u.full_name AS attempter_name, u.login AS attempter_login
     FROM test_attempts ta
     INNER JOIN test_versions tv ON tv.id = ta.test_version_id
     INNER JOIN tests t ON t.id = tv.test_id
     INNER JOIN users u ON u.id = ta.user_id
     WHERE ta.id = $1`,
    [attemptId]
  );
  if (!arows.length) {
    const e = new Error(RU.attemptNotFound);
    e.status = 404;
    throw e;
  }
  const a = arows[0];
  if (a.status !== 'completed') {
    const e = new Error(RU.attemptNotCompleted);
    e.status = 400;
    throw e;
  }
  const questions = await loadQuestionsForVersion(pool, a.test_version_id, {
    includeCorrect: true,
  });
  const { rows: uans } = await pool.query(
    `SELECT question_id, selected_options FROM user_answers WHERE attempt_id = $1`,
    [attemptId]
  );
  const selByQ = new Map();
  for (const r of uans) {
    selByQ.set(String(r.question_id), (r.selected_options || []).map(String));
  }
  const threshold = Number(a.passing_threshold) || 0;
  const total = a.total_questions || questions.length;
  const percent =
    total > 0
      ? Math.round(((a.correct_count || 0) / total) * 1000) / 10
      : 0;
  const qOut = questions.map((q) => {
    const selected = sortUuidStrings(selByQ.get(String(q.id)) || []);
    const correctIdList = sortUuidStrings(
      q.options.filter((o) => o.isCorrect).map((o) => String(o.id))
    );
    const isUserCorrect = sameSelection(selected, correctIdList);
    const selectedSet = new Set(selected);
    return {
      id: q.id,
      text: q.text,
      hasMultipleAnswers: q.hasMultipleAnswers,
      isUserCorrect,
      options: q.options.map((o) => ({
        id: o.id,
        text: o.text,
        isCorrect: o.isCorrect,
        selected: selectedSet.has(String(o.id)),
      })),
    };
  });
  return {
    attemptId: a.id,
    testId: a.test_id,
    testTitle: a.title,
    passingThreshold: threshold,
    correctCount: a.correct_count,
    totalQuestions: total,
    percent,
    passed: a.passed,
    startedAt: a.started_at,
    completedAt: a.completed_at,
    attempterUserId: a.user_id,
    attempterName: a.attempter_name,
    attempterLogin: a.attempter_login,
    questions: qOut,
  };
}

/**
 * Разбор попытки: владелец попытки или автор теста.
 * @param {import('pg').Pool} pool
 * @param {string} currentUserId
 * @param {string} testId
 * @param {string} attemptId
 */
export async function getAttemptReviewForUser(pool, currentUserId, testId, attemptId) {
  const { rows } = await pool.query(
    `SELECT ta.user_id, t.created_by, tv.test_id
     FROM test_attempts ta
     INNER JOIN test_versions tv ON tv.id = ta.test_version_id
     INNER JOIN tests t ON t.id = tv.test_id
     WHERE ta.id = $1`,
    [attemptId]
  );
  if (!rows.length) {
    const e = new Error(RU.attemptNotFound);
    e.status = 404;
    throw e;
  }
  const r0 = rows[0];
  if (r0.test_id !== testId) {
    const e = new Error(RU.attemptNotFound);
    e.status = 404;
    throw e;
  }
  const isOwner = r0.user_id === currentUserId;
  const isAuthor = isTestAuthor(r0.created_by, currentUserId);
  if (!isOwner && !isAuthor) {
    const e = new Error(RU.forbidden);
    e.status = 403;
    throw e;
  }
  return buildReviewFromDb(pool, attemptId);
}

/**
 * Список всех попыток по цепочке (все версии) — только автор.
 * @param {import('pg').Pool} pool
 * @param {string} authorId
 * @param {string} testId
 */
export async function listTestAttemptsForAuthor(pool, authorId, testId) {
  const { rows: t } = await pool.query(
    `SELECT id, created_by FROM tests WHERE id = $1`,
    [testId]
  );
  if (!t.length) {
    const e = new Error(RU.testNotFound);
    e.status = 404;
    throw e;
  }
  if (!isTestAuthor(t[0].created_by, authorId)) {
    const e = new Error(RU.forbidden);
    e.status = 403;
    throw e;
  }
  const { rows } = await pool.query(
    `SELECT ta.id, ta.user_id, ta.status, ta.attempt_number, ta.started_at, ta.completed_at,
            ta.correct_count, ta.total_questions, ta.passed, tv.version AS test_version,
            u.full_name AS attempter_name, u.login AS attempter_login
     FROM test_attempts ta
     INNER JOIN test_versions tv ON tv.id = ta.test_version_id
     INNER JOIN users u ON u.id = ta.user_id
     WHERE tv.test_id = $1
     ORDER BY ta.started_at DESC NULLS LAST
     LIMIT 200`,
    [testId]
  );
  return rows;
}