task(B5): seat counting by row and block

frontend/src/services/seatingService.ts

@@ -352,8 +352,18 @@ export class SeatingService {
     return [];
   }
 
-  /** Count seats in a list of elements */
-  countSeats(elements: CADElement[]): { total: number; byRow: Record<string, number>; byBlock: Record<string, number> } {
+/**
+ * Zählt Sitzplätze gruppiert nach Reihe und Block.
+ * byRow enthält Reihen aus freien Reihen UND Block-Reihen (seit BUG-1-Fix
+ * tragen Block-Stühle pro Reihe eine eigene rowId).
+ */
+  countSeats(elements: CADElement[]): {
+    total: number;
+    byRow: Record<string, number>;
+    byBlock: Record<string, number>;
+    /** Platzhalter für künftige Zonen-Gruppierung (aktuell immer leer). */
+    byZone?: Record<string, number>;
+  } {
     let total = 0;
     const byRow: Record<string, number> = {};
     const byBlock: Record<string, number> = {};

frontend/tests/seating.count.test.ts

@@ -0,0 +1,84 @@
+/**
+ * Seating-Tests — countSeats: Zählung nach Reihe/Block/Gesamt.
+ * Ergänzt Task B5; Grundlage ist der BUG-1-Fix (rowId pro Block-Reihe).
+ */
+import { describe, it, expect } from 'vitest';
+import { SeatingService } from '../src/services/seatingService';
+import type { CADElement } from '../src/types/cad.types';
+
+function makeChair(id: string, props: Record<string, unknown> = {}): CADElement {
+  return {
+    id,
+    type: 'chair',
+    layerId: 'layer-1',
+    x: 0,
+    y: 0,
+    width: 50,
+    height: 50,
+    properties: props,
+  } as unknown as CADElement;
+}
+
+function makeNonChair(id: string): CADElement {
+  return {
+    id,
+    type: 'rect',
+    layerId: 'layer-1',
+    x: 0,
+    y: 0,
+    width: 10,
+    height: 10,
+    properties: {},
+  } as unknown as CADElement;
+}
+
+describe('countSeats', () => {
+  const svc = new SeatingService();
+
+  it('zählt eine freie Reihe korrekt (5 Stühle, 1 rowId)', () => {
+    const els = svc.createSeatingRow(0, 0, 'layer-1', { count: 5 });
+    const result = svc.countSeats(els);
+    expect(result.total).toBe(5);
+    expect(Object.keys(result.byRow).length).toBe(1);
+    expect(Object.values(result.byRow)[0]).toBe(5);
+    expect(Object.keys(result.byBlock).length).toBe(0);
+  });
+
+  it('zählt einen Block korrekt (3 Reihen × 4 Stühle = 12)', () => {
+    const els = svc.createSeatingBlock(0, 0, 'layer-1', { rows: 3, cols: 4 });
+    const result = svc.countSeats(els);
+    expect(result.total).toBe(12);
+    expect(Object.keys(result.byBlock).length).toBe(1);   // 1 Block
+    expect(Object.values(result.byBlock)[0]).toBe(12);
+    expect(Object.keys(result.byRow).length).toBe(3);     // 3 Reihen (BUG-1-Fix!)
+    for (const count of Object.values(result.byRow)) {
+      expect(count).toBe(4);                               // je Reihe 4 Stühle
+    }
+  });
+
+  it('summiert gemischte Zeichnung korrekt (Reihe + Block + Fremdelemente)', () => {
+    const rows = svc.createSeatingRow(0, 0, 'layer-1', { count: 3 });
+    const block = svc.createSeatingBlock(100, 100, 'layer-1', { rows: 2, cols: 2 });
+    const others = [makeNonChair('x1'), makeNonChair('x2')];
+    const all: CADElement[] = [...rows, ...block, ...others];
+    const result = svc.countSeats(all);
+    expect(result.total).toBe(7);          // 3 + 4, Nicht-Stühle ignorieren
+    expect(Object.keys(result.byRow).length).toBe(3); // 1 freie Reihe + 2 Block-Reihen
+    expect(Object.keys(result.byBlock).length).toBe(1);
+  });
+
+  it('liefert leere Summen bei leerer Eingabe', () => {
+    const result = svc.countSeats([]);
+    expect(result.total).toBe(0);
+    expect(result.byRow).toEqual({});
+    expect(result.byBlock).toEqual({});
+  });
+
+  it('zählt handgebaute Stühle ohne rowId nur im Gesamt', () => {
+    const els = [makeChair('h1'), makeChair('h2'), makeChair('h3', { rowId: 'row_manual' })];
+    const result = svc.countSeats(els);
+    expect(result.total).toBe(3);
+    expect(result.byRow['row_manual']).toBe(1);
+    expect(Object.keys(result.byRow).length).toBe(1);
+  });
+});