feat: enhance product matching logic with improved scoring and tokenization

backend/src/receipt-import/receipt-import.service.ts

@@ -12,6 +12,26 @@ import { CategoriesService } from '../categories/categories.service';
 const IMPORTER_SERVICE_URL =
   process.env.IMPORTER_SERVICE_URL || 'http://importer-api:3001';
 
+const WEAK_DESCRIPTORS = new Set([
+  'rokt',
+  'rökt',
+  'kokt',
+  'grillad',
+  'stekt',
+  'skivad',
+  'strimlad',
+  'fryst',
+  'farsk',
+  'färsk',
+]);
+
+function tokenize(value: string): string[] {
+  return value
+    .toLowerCase()
+    .split(/[^a-z0-9åäö]+/)
+    .filter((w) => w.length >= 3);
+}
+
 @Injectable()
 export class ReceiptImportService {
   private readonly logger = new Logger(ReceiptImportService.name);
@@ -120,20 +140,71 @@ export class ReceiptImportService {
     products: { id: number; name: string; canonicalName: string | null }[],
   ): { id: number; name: string; canonicalName: string | null } | undefined {
     // Dela upp kvittonamnet i ord (min 3 tecken)
-    const rawWords = raw.split(/[\s\-_]+/).filter((w) => w.length >= 3);
+    const rawWords = tokenize(raw);
     if (rawWords.length === 0) return undefined;
 
-    // Fortsätt med att hitta produkter där ett produktnamn-ord finns i kvittonamnet
-    // Exempel: produktord "ost" finns i kvittoord "prästost", "herrgårdsost", "brieost"
-    return products.find((p) => {
-      const productWords = (p.canonicalName ?? p.name)
-        .toLowerCase()
-        .split(/[\s\-_]+/)
-        .filter((w) => w.length >= 3);
-      return productWords.some((pw) =>
-        rawWords.some((rw) => rw.includes(pw) || pw.includes(rw)),
-      );
-    });
+    const rawWordSet = new Set(rawWords);
+
+    let best:
+      | { product: { id: number; name: string; canonicalName: string | null }; score: number }
+      | undefined;
+
+    for (const product of products) {
+      const productWords = tokenize(product.canonicalName ?? product.name);
+      if (productWords.length === 0) continue;
+
+      let score = 0;
+      let exactStrong = 0;
+      let exactAny = 0;
+      let partialStrong = 0;
+
+      const phrase = (product.canonicalName ?? product.name).toLowerCase();
+      if (raw.includes(phrase)) {
+        score += 5;
+      }
+
+      for (const pw of productWords) {
+        const isWeak = WEAK_DESCRIPTORS.has(pw);
+
+        if (rawWordSet.has(pw)) {
+          exactAny += 1;
+          if (isWeak) {
+            score += 1;
+          } else {
+            exactStrong += 1;
+            score += 8;
+          }
+          continue;
+        }
+
+        // Delmatchning tillåts bara för ord med minst 4 tecken.
+        if (pw.length < 4) continue;
+
+        const hasPartial = rawWords.some((rw) => rw.includes(pw) || pw.includes(rw));
+        if (!hasPartial) continue;
+
+        if (isWeak) {
+          // Deskriptiva ord (t.ex. rökt) ska inte driva förslag ensamma.
+          continue;
+        }
+
+        partialStrong += 1;
+        score += 3;
+      }
+
+      // Kräv antingen minst ett starkt exakt ord, eller flera samverkande signaler.
+      const hasStrongSignal = exactStrong >= 1 || exactAny + partialStrong >= 2;
+      if (!hasStrongSignal) continue;
+
+      // Tröskel för att undvika svaga enkelträffar.
+      if (score < 8) continue;
+
+      if (!best || score > best.score) {
+        best = { product, score };
+      }
+    }
+
+    return best?.product;
   }
 
   private async enrichWithAiCategories(items: ParsedReceiptItem[]): Promise<ParsedReceiptItem[]> {