// storyAggregate.js — story.word_count is the sum of its published chapters'
// word counts (design-018 §2.2). Recomputed on every chapter save/publish-
// toggle/delete — full recount each time, matching this project's established
// "cheap at this scale, full recount is correct" convention (design-018 §2.6
// documents the same tradeoff for rating aggregates).
'use strict';

async function recomputeStoryWordCount(db, storyId) {
  const chapters = await db.collection('chapters')
    .find({ story_id: storyId, status: 'published' }, { projection: { word_count: 1 } })
    .toArray();
  const wordCount = chapters.reduce((sum, c) => sum + (c.word_count || 0), 0);

  await db.collection('stories').updateOne(
    { _id: storyId },
    { $set: { word_count: wordCount, updated_at: new Date() } }
  );
  return wordCount;
}

module.exports = { recomputeStoryWordCount };