fix: update collection controller. feat: add regex for collection controller

Author: Alexandrbig1

src/controllers/collection.controller.js

@@ -1,27 +1,35 @@
 import Product from "../models/product.model.js";
 import HttpException from "../utils/exceptions/http.exception.js";
+import { tokenize, buildLookaheadRegex } from "../utils/regex.util.js";
 
 // GET /api/collections/:name
 export const getCollectionProducts = async (req, res, next) => {
   try {
     const name = (req.params?.name || "").toString().trim();
-    // empty or invalid just returns empty results per spec
     if (!name) {
       return res.status(200).json({ collections: name, products: [] });
     }
 
-    // Normalize input into a regex that is:
-    //  - case-insensitive
-    //  - tolerant of hyphens vs spaces vs multiple separators
-    // Escape regex special chars, then allow separators between words
-    const escapeRegex = (s = "") => s.replace(/[.*+?^${}()|[\]\\]/g, "\\$&");
-    const safe = escapeRegex(name);
-    // replace runs of hyphens / spaces / underscores with a pattern that matches any of them
-    const tolerant = safe.replace(/[-_\s]+/g, "[-_\\s]*");
-    const pattern = new RegExp(`^${tolerant}$`, "i");
+    // try exact slug match first (fast, indexable if you add normalizedCollections)
+    const slug = name.toLowerCase();
+    let products = await Product.find({ collections: slug });
+    if (products && products.length) {
+      return res.status(200).json({ collections: name, products });
+    }
+
+    // fallback: tokenize and build safe lookahead regex
+    const tokens = tokenize(name);
+    // safety limits
+    if (tokens.length === 0) {
+      return res.status(200).json({ collections: name, products: [] });
+    }
+    if (tokens.length > 6 || tokens.some(t => t.length > 40)) {
+      return res.status(400).json({ collections: name, products: [], message: "Query too complex" });
+    }
 
-    // Match any array element using $elemMatch + $regex
-    const products = await Product.find({
+    const pattern = buildLookaheadRegex(tokens);
+
+    products = await Product.find({
       collections: { $elemMatch: { $regex: pattern } },
     });
 
@@ -30,7 +38,4 @@ export const getCollectionProducts = async (req, res, next) => {
     console.error('Collection controller error (getCollectionProducts):', err);
     next(new HttpException(500, "Failed to fetch collections products"));
   }
-}
-
-
-
+}

src/utils/regex.util.js

@@ -0,0 +1,14 @@
+export const escapeRegex = (s = "") => s.replace(/[.*+?^${}()|[\]\\]/g, "\\$&");
+
+export const tokenize = (name = "") =>
+  (name || "")
+    .split(/[-_\s]+/)
+    .map(t => escapeRegex(t.trim()))
+    .filter(Boolean);
+
+export const buildLookaheadRegex = (tokens = []) => {
+  // tokens should already be escaped
+  const lookahead = tokens.map(t => `(?=.*\\b${t}\\b)`).join("");
+  // keep it anchored (start) to reduce backtracking
+  return new RegExp(`^${lookahead}.*$`, "i");
+};