#!/usr/bin/env node
/**
 * Entfernt doppelte „Bisaya für Familien - Alltag & Stabilisierung“-Kurse und behält
 * den Kurs mit der kleinsten ID (üblicherweise der erste / in der UI verlinkte).
 *
 * Standard: Nur Anzeige (Dry-Run). Löschen nur mit:
 *   VOCAB_DEDUPE_BISAYA_FAMILY_APPLY=1 node backend/scripts/dedupe-bisaya-family-courses.js
 */

import { sequelize } from '../utils/sequelize.js';

const CANONICAL_TITLE = 'Bisaya für Familien - Alltag & Stabilisierung';

async function deleteCourseCascade(courseId, transaction) {
  const lessonRows = await sequelize.query(
    `SELECT id FROM community.vocab_course_lesson WHERE course_id = :cid`,
    { replacements: { cid: courseId }, transaction, type: sequelize.QueryTypes.SELECT }
  );
  const lessonIds = lessonRows.map((r) => r.id);

  if (lessonIds.length > 0) {
    const exRows = await sequelize.query(
      `SELECT id FROM community.vocab_grammar_exercise WHERE lesson_id IN (:lids)`,
      { replacements: { lids: lessonIds }, transaction, type: sequelize.QueryTypes.SELECT }
    );
    const exerciseIds = exRows.map((r) => r.id);

    if (exerciseIds.length > 0) {
      await sequelize.query(
        `DELETE FROM community.vocab_grammar_exercise_progress WHERE exercise_id IN (:eids)`,
        { replacements: { eids: exerciseIds }, transaction }
      );
      await sequelize.query(`DELETE FROM community.vocab_grammar_exercise WHERE id IN (:eids)`, {
        replacements: { eids: exerciseIds },
        transaction
      });
    }

    await sequelize.query(
      `DELETE FROM community.vocab_course_progress WHERE lesson_id IN (:lids) OR course_id = :cid`,
      { replacements: { lids: lessonIds, cid: courseId }, transaction }
    );
    await sequelize.query(
      `DELETE FROM community.vocab_course_lesson WHERE course_id = :cid`,
      { replacements: { cid: courseId }, transaction }
    );
  } else {
    await sequelize.query(
      `DELETE FROM community.vocab_course_progress WHERE course_id = :cid`,
      { replacements: { cid: courseId }, transaction }
    );
  }

  await sequelize.query(
    `DELETE FROM community.vocab_course_enrollment WHERE course_id = :cid`,
    { replacements: { cid: courseId }, transaction }
  );
  await sequelize.query(`DELETE FROM community.vocab_course WHERE id = :cid`, {
    replacements: { cid: courseId },
    transaction
  });
}

async function main() {
  const apply = process.env.VOCAB_DEDUPE_BISAYA_FAMILY_APPLY === '1';
  await sequelize.authenticate();

  const [bisayaLanguage] = await sequelize.query(
    `SELECT id FROM community.vocab_language WHERE name = 'Bisaya' LIMIT 1`,
    { type: sequelize.QueryTypes.SELECT }
  );
  if (!bisayaLanguage) {
    console.error('❌ Bisaya-Sprache nicht gefunden.');
    process.exit(1);
  }

  const courses = await sequelize.query(
    `SELECT id, title, owner_user_id AS "ownerUserId", created_at AS "createdAt"
     FROM community.vocab_course
     WHERE language_id = :languageId AND title = :title
     ORDER BY id ASC`,
    {
      replacements: { languageId: bisayaLanguage.id, title: CANONICAL_TITLE },
      type: sequelize.QueryTypes.SELECT
    }
  );

  if (courses.length <= 1) {
    console.log(
      courses.length === 0
        ? `Kein Kurs mit Titel „${CANONICAL_TITLE}“ gefunden.`
        : `Nur ein Kurs – nichts zu bereinigen (ID ${courses[0].id}).`
    );
    await sequelize.close();
    return;
  }

  const keep = courses[0];
  const remove = courses.slice(1);

  console.log(`Behalten: Kurs-ID ${keep.id} (älteste ID)\n`);
  console.log(`${apply ? 'Löschen' : 'Würde löschen'} (${remove.length} Duplikate):`);
  for (const c of remove) {
    const stat = await sequelize.query(
      `SELECT
         (SELECT COUNT(*)::int FROM community.vocab_course_enrollment WHERE course_id = :cid) AS enroll,
         (SELECT COUNT(*)::int FROM community.vocab_course_progress WHERE course_id = :cid) AS prog`,
      { replacements: { cid: c.id }, type: sequelize.QueryTypes.SELECT }
    );
    const row = stat[0];
    console.log(
      `   – ID ${c.id} (owner ${c.ownerUserId}, Enrollments ${row?.enroll ?? '?'}, Fortschrittszeilen ${row?.prog ?? '?'})`
    );
  }

  if (!apply) {
    console.log(
      '\nDry-Run. Zum tatsächlichen Löschen: VOCAB_DEDUPE_BISAYA_FAMILY_APPLY=1 node backend/scripts/dedupe-bisaya-family-courses.js'
    );
    await sequelize.close();
    return;
  }

  await sequelize.transaction(async (t) => {
    for (const c of remove) {
      await deleteCourseCascade(c.id, t);
      console.log(`🗑️  Kurs ${c.id} entfernt.`);
    }
  });

  console.log(`\n✅ Fertig. Verbleibender Kurs: ID ${keep.id}`);
  await sequelize.close();
}

main().catch((e) => {
  console.error('❌ Fehler:', e);
  sequelize.close();
  process.exit(1);
});