#!/usr/bin/env node
import { sequelize } from '../utils/sequelize.js';

/**
 * Fix SRS items that were created with next_due_at equal-or-immediately-before created_at
 * - Detect items created recently whose next_due_at is within a small window of created_at
 * - Move next_due_at to the next calendar day at 08:00 local (safe default)
 *
 * Run on the server after a backup. Prints counts and example rows before/after.
 */

const DRY_RUN = process.env.DRY_RUN !== 'false';

const run = async () => {
  try {
    await sequelize.authenticate();
    console.log('✅ DB connection OK');

    // Conservative selector: items created in the last 3 days where next_due_at is within 2 minutes of created_at
    const selector = `
      SELECT id, item_key, course_id, stage, next_due_at, created_at
      FROM community.vocab_srs_item
      WHERE created_at >= now() - interval '3 days'
        AND abs(extract(epoch from (next_due_at - created_at))) < 120
      ORDER BY created_at ASC
      LIMIT 500
    `;

    const recent = await sequelize.query(selector, { type: sequelize.QueryTypes.SELECT });
    console.log('\nFound items matching heuristic: ', recent.length);
    console.table(recent.slice(0, 20));

    if (recent.length === 0) {
      console.log('\nNo candidate rows found — nothing to do.');
      return;
    }

    // Compute update target: next calendar day at 08:00 based on created_at
    // Use an UPDATE with an expression so each row gets next_due_at = date_trunc('day', created_at + '1 day') + '08:00'
    const updateQuery = `
      UPDATE community.vocab_srs_item
      SET next_due_at = date_trunc('day', created_at + interval '1 day') + interval '8 hours'
      WHERE created_at >= now() - interval '3 days'
        AND abs(extract(epoch from (next_due_at - created_at))) < 120
      RETURNING id, item_key, course_id, stage, next_due_at, created_at;
    `;

    if (DRY_RUN) {
      console.log('\nDRY RUN: to apply changes set ENV var DRY_RUN=false');
      console.log('Preview of UPDATE SQL:\n', updateQuery);
    } else {
      console.log('\nApplying update...');
      const updated = await sequelize.query(updateQuery, { type: sequelize.QueryTypes.SELECT });
      console.log('\nUpdated rows: ', updated.length);
      console.table(updated.slice(0, 20));
    }

    console.log('\nRecommendation: rerun `backend/scripts/diag-srs-stats.js` to verify totals afterwards.');
  } catch (err) {
    console.error('Error running fix script:', err);
    process.exitCode = 2;
  } finally {
    try { await sequelize.close(); } catch (_) {}
  }
};

run();