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src/index.js

@@ -18,6 +18,7 @@ import categoryOrder from './store/category/order.js';
 import categoryDelete from './store/category/delete.js';
 import categoryAddImage from './store/category/addImage.js';
 import categoryDeleteImage from './store/category/deleteImage.js';
+import categoryGenerateImage from './store/category/generateImage.js';
 import articleDelete from './store/article/delete.js';
 import articleDeleteImage from './store/article/deleteImage.js';
 import articleOrderImages from './store/article/orderImages.js';
@@ -321,6 +322,7 @@ export default class LibDashStore {
       delete: categoryDelete(provider),
       addImage: categoryAddImage(provider),
       deleteImage: categoryDeleteImage(provider),
+      generateImage: categoryGenerateImage(provider),
     };
 
     this.article = {

src/providers/mssql/queries/category.js

@@ -178,3 +178,31 @@ export const DELETE = `
 DELETE FROM category
 WHERE id = @id
 `;
+
+export const LIST_CHILD_CATEGORIES = `
+SELECT id
+FROM category
+WHERE parent_id = @parentId
+ORDER BY sort ASC, id ASC
+`;
+
+export const GET_CATEGORY_ARTICLE_PICS = `
+SELECT
+    a.id AS articleId,
+    p.id AS picId,
+    p.hash,
+    p.fullbinary AS buffer
+FROM categoryarticle ca
+INNER JOIN article a ON a.id = ca.article_id
+OUTER APPLY (
+    SELECT TOP 1 ap.pic_id
+    FROM articlepic ap
+    WHERE ap.article_id = a.id
+    ORDER BY ap.sort ASC, ap.id ASC
+) first_pic
+INNER JOIN pic p ON p.id = first_pic.pic_id
+WHERE ca.category_id = @categoryId
+  AND a.parentarticle_id IS NULL
+ORDER BY a.id ASC
+`;
+

src/providers/sqlite3/queries/category.js

@@ -7,9 +7,29 @@ export const {
   CREATE, DELETE, GET_BY_PARENT_AND_NAME,
   GET_CATEGORY_ARTICLE_WAREHOUSE_SUMMARIES,
   GET_NEXT_SIBLING_SORT, LIST_CHILD_IDS,
+  LIST_CHILD_CATEGORIES,
   MOVE, UPDATE_SORT,
 } = queries;
 
+export const GET_CATEGORY_ARTICLE_PICS = `
+SELECT
+    a.id AS articleId,
+    p.id AS picId,
+    p.hash,
+    NULL AS buffer
+FROM categoryarticle ca
+INNER JOIN article a ON a.id = ca.article_id
+INNER JOIN pic p ON p.id = (
+    SELECT ap.pic_id FROM articlepic ap
+    WHERE ap.article_id = a.id
+    ORDER BY ap.sort ASC, ap.id ASC
+    LIMIT 1
+)
+WHERE ca.category_id = @categoryId
+  AND a.parentarticle_id IS NULL
+ORDER BY a.id ASC
+`;
+
 export const RESOLVE_CATEGORY_ACCESS = `
 WITH RECURSIVE ancestors AS (
     SELECT id, parent_id

src/store/category/generateImage.js

@@ -0,0 +1,207 @@
+import {
+  GET_CATEGORY_ARTICLE_PICS as MSSQL_GET_CATEGORY_ARTICLE_PICS,
+  LIST_CHILD_CATEGORIES as MSSQL_LIST_CHILD_CATEGORIES,
+} from '../../providers/mssql/queries/category.js';
+import {
+  GET_CATEGORY_ARTICLE_PICS as SQLITE_GET_CATEGORY_ARTICLE_PICS,
+  LIST_CHILD_CATEGORIES as SQLITE_LIST_CHILD_CATEGORIES,
+} from '../../providers/sqlite3/queries/category.js';
+import resolveCategoryAccess from './resolveCategoryAccess.js';
+import addImage from './addImage.js';
+import makeRunner from '../runner.js';
+import sharp from 'sharp';
+
+export default function generateImage(provider) {
+  const access = resolveCategoryAccess(provider);
+  const isSqlite = provider?.dialect === 'sqlite3';
+  const getPicsSql = isSqlite ? SQLITE_GET_CATEGORY_ARTICLE_PICS : MSSQL_GET_CATEGORY_ARTICLE_PICS;
+  const listChildrenSql = isSqlite ? SQLITE_LIST_CHILD_CATEGORIES : MSSQL_LIST_CHILD_CATEGORIES;
+  const addCategoryPic = addImage(provider);
+
+  /**
+   * Generates a mosaic image directly from the category's and its subcategories' articles
+   * (grouped by subcategory) and sets it as the new main picture for the category.
+   *
+   * @param {number} googleAuthId - The id of the Google auth user.
+   * @param {number|object} inputOrCategoryId - The id of the category or an options object.
+   * @param {object|number} [maybeOptsOrSize={}] - Options object or numeric size.
+   * @param {number} [maybeOptsOrSize.size] - Grid size (2 for 2x2, 3 for 3x3, 4 for 4x4). Defaults to 3 (falls back to 2 if < 7 images).
+   * @param {object} [maybeTx] - Optional transaction to run within.
+   * @returns {Promise<{id: number, fullHash: string, thumbW: number, thumbH: number, thumbHash: string, smallThumbW: number, smallThumbH: number, size: number, grid: string, articleCount: number}>} The new main image info.
+   * @throws {Error} If the category is not found, not authorized, size is invalid, or no images are found.
+   *
+   * @example
+   * const result = await store.category.generateImage(42, 5, { size: 3 });
+   * // => { id: 5, fullHash, thumbW, thumbH, thumbHash, smallThumbW, smallThumbH, size: 3, grid: '3x3', articleCount: 12 }
+   */
+  return async (googleAuthId, inputOrCategoryId, maybeOptsOrSize = {}, maybeTx) => {
+    let categoryId;
+    let size = null;
+    let tx;
+
+    if (typeof inputOrCategoryId === 'object' && inputOrCategoryId !== null) {
+      categoryId = inputOrCategoryId.categoryId ?? inputOrCategoryId.id;
+      size = inputOrCategoryId.size ?? null;
+      tx = maybeOptsOrSize;
+    } else {
+      categoryId = inputOrCategoryId;
+      if (typeof maybeOptsOrSize === 'number') {
+        size = maybeOptsOrSize;
+        tx = maybeTx;
+      } else if (typeof maybeOptsOrSize === 'object' && maybeOptsOrSize !== null) {
+        size = maybeOptsOrSize.size ?? null;
+        tx = maybeTx;
+      } else {
+        tx = maybeTx;
+      }
+    }
+
+    if (size != null) {
+      size = Number(size);
+      if (![2, 3, 4].includes(size)) {
+        throw new Error('Invalid size, must be 2, 3, or 4');
+      }
+    }
+
+    const runGenerate = async (runner) => {
+      await access(googleAuthId, categoryId, runner);
+
+      // Collect category and descendant subcategories in DFS order
+      async function getCategoryTreeIds(parentId) {
+        const result = [parentId];
+        const children = await runner.query(listChildrenSql, { parentId });
+        for (const child of children.rows) {
+          const sub = await getCategoryTreeIds(child.id);
+          result.push(...sub);
+        }
+        return result;
+      }
+
+      const categoryIds = await getCategoryTreeIds(categoryId);
+
+      // Collect distinct articles with images grouped by subcategory
+      const seenArticleIds = new Set();
+      const seenHashes = new Set();
+      const candidates = [];
+
+      for (const catId of categoryIds) {
+        const articlePics = await runner.query(getPicsSql, { categoryId: catId });
+        for (const row of articlePics.rows) {
+          if (!row.hash) continue;
+          if (seenArticleIds.has(row.articleId) || seenHashes.has(row.hash)) continue;
+          seenArticleIds.add(row.articleId);
+          seenHashes.add(row.hash);
+          candidates.push({
+            articleId: row.articleId,
+            picId: row.picId,
+            hash: row.hash,
+            buffer: row.buffer,
+          });
+        }
+      }
+
+      if (candidates.length === 0) {
+        throw new Error('No images found for category articles');
+      }
+
+      // Determine matrix size:
+      // Default to 3x3, fallback to 2x2 if fewer than 7 images are available.
+      let targetSize = size;
+      if (!targetSize) {
+        targetSize = candidates.length < 7 ? 2 : 3;
+      } else if (targetSize === 3 && candidates.length < 7) {
+        targetSize = 2;
+      }
+
+      const cellCount = targetSize * targetSize;
+      const selected = candidates.length >= cellCount
+        ? candidates.slice(0, cellCount)
+        : Array.from({ length: cellCount }, (_, i) => candidates[i % candidates.length]);
+
+      // Load image buffers for the selected items
+      const loaded = await Promise.all(
+        selected.map(async (item) => {
+          let buf = item.buffer;
+          if (!buf || !buf.length) {
+            if (isSqlite) {
+              buf = runner.readPicFull ? await runner.readPicFull(item.hash) : await provider?.readPicFull?.(item.hash);
+              if (!buf) {
+                buf = runner.readPicThumb ? await runner.readPicThumb(item.hash) : await provider?.readPicThumb?.(item.hash);
+              }
+            } else {
+              const picRes = await runner.query(
+                'SELECT fullbinary, thumbbinary FROM pic WHERE hash = @hash',
+                { hash: item.hash },
+              );
+              buf = picRes.rows[0]?.fullbinary ?? picRes.rows[0]?.thumbbinary;
+            }
+          }
+          return { ...item, buffer: buf };
+        }),
+      );
+
+      const validPics = loaded.filter(
+        (p) => p.buffer && Buffer.isBuffer(p.buffer) && p.buffer.length > 0,
+      );
+
+      if (validPics.length === 0) {
+        throw new Error('No images found for category articles');
+      }
+
+      const finalPics = Array.from(
+        { length: cellCount },
+        (_, i) => validPics[i % validPics.length],
+      );
+
+      const TOTAL_SIZE = 1200;
+      const tileSize = TOTAL_SIZE / targetSize;
+
+      const composites = await Promise.all(
+        finalPics.map(async (pic, idx) => {
+          const row = Math.floor(idx / targetSize);
+          const col = idx % targetSize;
+          const tileBuffer = await sharp(pic.buffer)
+            .resize(tileSize, tileSize, { fit: 'cover', position: 'center' })
+            .toBuffer();
+          return {
+            input: tileBuffer,
+            left: col * tileSize,
+            top: row * tileSize,
+          };
+        }),
+      );
+
+      const mosaicBuffer = await sharp({
+        create: {
+          width: TOTAL_SIZE,
+          height: TOTAL_SIZE,
+          channels: 4,
+          background: { r: 255, g: 255, b: 255, alpha: 1 },
+        },
+      })
+        .composite(composites)
+        .png()
+        .toBuffer();
+
+      // Clear existing categorypic rows so the new mosaic becomes the main (first) image
+      await runner.query('DELETE FROM categorypic WHERE category_id = @categoryId', { categoryId });
+
+      const added = await addCategoryPic(googleAuthId, categoryId, mosaicBuffer, runner);
+
+      return {
+        ...added,
+        size: targetSize,
+        grid: `${targetSize}x${targetSize}`,
+        articleCount: candidates.length,
+      };
+    };
+
+    if (tx) {
+      return runGenerate(makeRunner(provider, tx));
+    }
+    if (typeof provider?.transaction === 'function') {
+      return provider.transaction(runGenerate);
+    }
+    return runGenerate(makeRunner(provider));
+  };
+}