#!/usr/bin/env node
/**
 * Migriert ältere Bisaya-Kurse von einer kombinierten Lektion „Zahlen & Preise“ (nur #18)
 * zur viergeteilten Zahlenreihe (#18–#21). Erwartet vorher noch das alte Layout:
 * Lektion 19 = „Woche 2 - Wiederholung“ (liegt im neuen Kurs an Position 22).
 *
 * Ablauf je Kurs:
 * - Lektionen mit lesson_number >= 19 um +3 nach oben schieben (von oben nach unten)
 * - Lektion 18 auf „Zahlen 1–20“ setzen
 * - Neue Lektionen 19–21 („Zahlen: Zehner/Hunderter/Tausender“) einfügen
 *
 * Verwendung:
 *   node backend/scripts/migrate-bisaya-zahlen-split.js
 *
 * Anschließend:
 *   node backend/scripts/update-bisaya-didactics.js
 *   node backend/scripts/create-bisaya-course-content.js
 */

import { sequelize } from '../utils/sequelize.js';
import VocabCourseLesson from '../models/community/vocab_course_lesson.js';
import { LESSON_DIDACTICS } from './update-bisaya-didactics.js';
import { getBisayaLessonPedagogy } from './bisaya-course-phase2-pedagogy.js';

const INSERTED_LESSONS = [
  {
    lessonNumber: 19,
    title: 'Zahlen: Zehner',
    description: 'Runde Zehner von 20 bis 90',
    weekNumber: 2,
    dayNumber: 4,
    lessonType: 'vocab',
    culturalNotes: null,
    targetMinutes: 20,
    targetScorePercent: 85,
    requiresReview: true
  },
  {
    lessonNumber: 20,
    title: 'Zahlen: Hunderter',
    description: 'Hunderter bis 900 (usa ka gatos … siyam ka gatos)',
    weekNumber: 2,
    dayNumber: 4,
    lessonType: 'vocab',
    culturalNotes: null,
    targetMinutes: 20,
    targetScorePercent: 85,
    requiresReview: true
  },
  {
    lessonNumber: 21,
    title: 'Zahlen: Tausender',
    description: 'Tausender und große Beträge (libo)',
    weekNumber: 2,
    dayNumber: 4,
    lessonType: 'vocab',
    culturalNotes: null,
    targetMinutes: 18,
    targetScorePercent: 85,
    requiresReview: true
  }
];

function applyPedagogy(patch, lessonNumber) {
  const pedagogy = getBisayaLessonPedagogy(lessonNumber) || {};
  patch.didacticMode = pedagogy.didacticMode || null;
  patch.phaseLabel = pedagogy.phaseLabel || null;
  patch.blockNumber = pedagogy.blockNumber ?? null;
  patch.difficultyWeight = pedagogy.difficultyWeight ?? null;
  patch.newUnitTarget = pedagogy.newUnitTarget ?? null;
  patch.reviewWeight = pedagogy.reviewWeight ?? null;
  patch.isIntensiveReview = Boolean(pedagogy.isIntensiveReview);
}

function applyDidactics(patch, title) {
  const d = LESSON_DIDACTICS[title];
  if (!d) return;
  patch.learningGoals = d.learningGoals || [];
  patch.corePatterns = d.corePatterns || [];
  patch.grammarFocus = d.grammarFocus || [];
  patch.speakingPrompts = d.speakingPrompts || [];
  patch.practicalTasks = d.practicalTasks || [];
}

async function migrateCourse(courseId) {
  const maxRow = await sequelize.query(
    `SELECT MAX(lesson_number) AS max FROM community.vocab_course_lesson WHERE course_id = :courseId`,
    { replacements: { courseId }, type: sequelize.QueryTypes.SELECT }
  );
  const maxNum = Number(maxRow[0]?.max || 0);
  if (maxNum < 19) {
    return { status: 'skip', reason: 'weniger als 19 Lektionen' };
  }

  const l19 = await VocabCourseLesson.findOne({
    where: { courseId, lessonNumber: 19 }
  });
  if (!l19) {
    return { status: 'skip', reason: 'keine Lektion 19' };
  }
  if (l19.title !== 'Woche 2 - Wiederholung') {
    return { status: 'skip', reason: 'Lektion 19 ist nicht „Woche 2 - Wiederholung“ (bereits migriert oder anderer Stand)' };
  }

  const l18 = await VocabCourseLesson.findOne({
    where: { courseId, lessonNumber: 18 }
  });
  if (!l18) {
    return { status: 'skip', reason: 'keine Lektion 18' };
  }
  if (l18.title !== 'Zahlen & Preise' && l18.title !== 'Zahlen 1–20') {
    return { status: 'skip', reason: `Lektion 18 unerwartet: „${l18.title}“` };
  }

  await sequelize.transaction(async (t) => {
    for (let n = maxNum; n >= 19; n -= 1) {
      await VocabCourseLesson.update(
        { lessonNumber: n + 3 },
        { where: { courseId, lessonNumber: n }, transaction: t }
      );
    }

    const lesson18 = await VocabCourseLesson.findOne({
      where: { courseId, lessonNumber: 18 },
      transaction: t
    });
    const patch18 = {
      title: 'Zahlen 1–20',
      description: 'Grundzahlen und Zahlen bis 20 (usa … baynte)',
      weekNumber: 2,
      dayNumber: 4,
      lessonType: 'vocab',
      culturalNotes: null,
      targetMinutes: 22,
      targetScorePercent: 85,
      requiresReview: true
    };
    applyDidactics(patch18, 'Zahlen 1–20');
    applyPedagogy(patch18, 18);
    await lesson18.update(patch18, { transaction: t });

    for (const def of INSERTED_LESSONS) {
      const createPayload = {
        courseId,
        chapterId: null,
        lessonNumber: def.lessonNumber,
        title: def.title,
        description: def.description,
        weekNumber: def.weekNumber,
        dayNumber: def.dayNumber,
        lessonType: def.lessonType,
        culturalNotes: def.culturalNotes,
        targetMinutes: def.targetMinutes,
        targetScorePercent: def.targetScorePercent,
        requiresReview: def.requiresReview
      };
      applyDidactics(createPayload, def.title);
      applyPedagogy(createPayload, def.lessonNumber);
      await VocabCourseLesson.create(createPayload, { transaction: t });
    }
  });

  return { status: 'ok' };
}

async function main() {
  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 FROM community.vocab_course WHERE language_id = :languageId ORDER BY id`,
    { replacements: { languageId: bisayaLanguage.id }, type: sequelize.QueryTypes.SELECT }
  );

  console.log(`Gefunden: ${courses.length} Bisaya-Kurs(e)\n`);

  for (const course of courses) {
    const result = await migrateCourse(course.id);
    if (result.status === 'ok') {
      console.log(`✅ Kurs ${course.id}: „${course.title}“ – Zahlen-Split angewendet (Lektionen verschoben, 19–21 eingefügt).`);
    } else {
      console.log(`⏭️  Kurs ${course.id}: „${course.title}“ – ${result.reason}`);
    }
  }

  console.log('\nFertig. Danach: node backend/scripts/update-bisaya-didactics.js && node backend/scripts/create-bisaya-course-content.js');
  await sequelize.close();
}

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