test(analytics): cover net category semantics

backend/package.json

@@ -1,6 +1,6 @@
 {
   "name": "@family-budget/backend",
-  "version": "0.6.0",
+  "version": "0.6.1",
   "private": true,
   "scripts": {
     "dev": "tsx watch src/app.ts",
@@ -8,6 +8,7 @@
     "start": "node dist/app.js",
     "migrate": "tsx src/db/migrate.ts",
     "migrate:prod": "node dist/db/migrate.js",
+    "test:analytics": "tsx src/services/analyticsSemantics.test.ts",
     "test:llm": "tsx src/scripts/testLlm.ts"
   },
   "dependencies": {

backend/src/services/analytics.ts

@@ -1,4 +1,5 @@
 import { pool } from '../db/pool';
+import { effectiveAmountCase } from './analyticsSemantics';
 import type {
   AnalyticsSummaryResponse,
   TopCategory,
@@ -14,14 +15,7 @@ interface BaseParams {
   onlyConfirmed?: boolean;
 }
 
-const effectiveAmount = `
-  CASE
-    WHEN t.amount_signed = 0 AND t.commission > 0
-      AND t.description ILIKE '%зачисление%'
-      THEN t.commission
-    WHEN t.amount_signed < 0 THEN t.amount_signed - t.commission
-    ELSE t.amount_signed + t.commission
-  END`;
+const effectiveAmount = effectiveAmountCase('t');
 
 function analyticsTransactions(where: string): string {
   return `

backend/src/services/analyticsSemantics.test.ts

@@ -0,0 +1,25 @@
+import assert from 'node:assert/strict';
+import { getEffectiveAmount, getNetAmount } from './analyticsSemantics';
+
+assert.equal(getNetAmount('expense', [
+  { amountSigned: -10_000, commission: 0 },
+  { amountSigned: 4_000, commission: 0 },
+]), 6_000, 'возврат уменьшает расход своей категории');
+
+assert.equal(getNetAmount('income', [
+  { amountSigned: 20_000, commission: 0 },
+  { amountSigned: -5_000, commission: 0 },
+]), 15_000, 'корректировка уменьшает доход');
+
+assert.equal(getNetAmount('transfer', [
+  { amountSigned: -10_000, commission: 0 },
+  { amountSigned: 10_000, commission: 0 },
+]), 0, 'перевод не является доходом или расходом');
+
+assert.equal(
+  getEffectiveAmount({ amountSigned: 0, commission: 500, description: 'Зачисление кэшбэка' }),
+  500,
+  'кэшбэк учитывается как поступление',
+);
+
+console.log('analytics semantics: OK');

backend/src/services/analyticsSemantics.ts

@@ -0,0 +1,32 @@
+export type AnalyticType = 'expense' | 'income' | 'transfer';
+
+interface AmountInput {
+  amountSigned: number;
+  commission: number;
+  description?: string;
+}
+
+export function getEffectiveAmount({ amountSigned, commission, description = '' }: AmountInput): number {
+  if (amountSigned === 0 && commission > 0 && description.toLowerCase().includes('зачисление')) {
+    return commission;
+  }
+  return amountSigned < 0 ? amountSigned - commission : amountSigned + commission;
+}
+
+export function getNetAmount(type: AnalyticType, amounts: AmountInput[]): number {
+  const amount = amounts.reduce((sum, item) => sum + getEffectiveAmount(item), 0);
+  if (type === 'expense') return Math.max(-amount, 0);
+  if (type === 'income') return Math.max(amount, 0);
+  return 0;
+}
+
+export function effectiveAmountCase(alias: string): string {
+  return `
+    CASE
+      WHEN ${alias}.amount_signed = 0 AND ${alias}.commission > 0
+        AND ${alias}.description ILIKE '%зачисление%'
+        THEN ${alias}.commission
+      WHEN ${alias}.amount_signed < 0 THEN ${alias}.amount_signed - ${alias}.commission
+      ELSE ${alias}.amount_signed + ${alias}.commission
+    END`;
+}