Extract duplicated getCategorySpending into CategorySpendingService

DashboardController::getCategorySpending and
DashboardAnalyticsController::getCategorySpending were the same rolled-up
expense-per-category query, differing only in whether they accepted a drill
parent (the dashboard always passed the top level). Copies of a financial
aggregation on two screens are a divergence risk.

Extract App\Services\CategorySpendingService::forPeriod() with an optional
drill parent and consume it from both controllers, dropping the now-unused
CategoryTree/DB/Collection/Category imports. Behaviour-preserving: the query,
roll-up and positive-amount filter are unchanged, and existing
DashboardAnalyticsTest / DashboardTest coverage stays green.

app/Http/Controllers/Api/DashboardAnalyticsController.php

@@ -7,18 +7,15 @@ use App\Enums\CategoryType;
 use App\Http\Controllers\Controller;
 use App\Models\Account;
 use App\Models\AccountBalance;
-use App\Models\Category;
 use App\Models\Transaction;
 use App\Services\AccountMetricsService;
 use App\Services\BalanceLookup;
-use App\Services\CategoryTree;
+use App\Services\CategorySpendingService;
 use App\Services\ExchangeRateService;
 use App\Services\LoanAmortizationService;
 use App\Services\PeriodComparator;
 use Carbon\Carbon;
 use Illuminate\Http\Request;
-use Illuminate\Support\Collection;
-use Illuminate\Support\Facades\DB;
 
 class DashboardAnalyticsController extends Controller
 {
@@ -26,7 +23,7 @@ class DashboardAnalyticsController extends Controller
         private ExchangeRateService $exchangeRateService,
         private AccountMetricsService $accountMetricsService,
         private LoanAmortizationService $loanAmortizationService,
-        private CategoryTree $tree,
+        private CategorySpendingService $categorySpendingService,
     ) {}
 
     public function netWorth(Request $request)
@@ -439,8 +436,8 @@ class DashboardAnalyticsController extends Controller
         $previousPeriod = $period->previous();
         $drillParentId = $validated['parent'] ?? null;
 
-        $currentSpending = $this->getCategorySpending($request->user()->id, $period->from, $period->to, $drillParentId);
-        $previousSpending = $this->getCategorySpending($request->user()->id, $previousPeriod->from, $previousPeriod->to, $drillParentId);
+        $currentSpending = $this->categorySpendingService->forPeriod($request->user()->id, $period->from, $period->to, $drillParentId);
+        $previousSpending = $this->categorySpendingService->forPeriod($request->user()->id, $previousPeriod->from, $previousPeriod->to, $drillParentId);
 
         $totalAmount = $currentSpending->sum('amount');
 
@@ -465,39 +462,6 @@ class DashboardAnalyticsController extends Controller
         return response()->json($top);
     }
 
-    /**
-     * Expense spending rolled up the category tree.
-     *
-     * Without a drill target, child amounts fold into their top-level ancestor
-     * so only parents are listed. With one, the parent's children become the
-     * rows (plus a direct node for transactions sitting on the parent itself).
-     */
-    private function getCategorySpending(string $userId, Carbon $from, Carbon $to, ?string $drillParentId = null): Collection
-    {
-        $perCategory = Transaction::query()
-            ->where('transactions.user_id', $userId)
-            ->whereBetween('transactions.transaction_date', [$from, $to])
-            ->join('categories', function ($join) {
-                $join->on('transactions.category_id', '=', 'categories.id')
-                    ->where('categories.type', '=', CategoryType::Expense)
-                    ->whereNull('categories.deleted_at');
-            })
-            ->select('transactions.category_id', DB::raw('sum(transactions.amount) as total_amount'))
-            ->groupBy('transactions.category_id')
-            ->get()
-            ->map(fn ($item): array => [
-                'category_id' => $item->category_id,
-                'category' => null,
-                'amount' => (int) -$item->total_amount,
-            ])
-            ->values()
-            ->all();
-
-        return collect($this->tree->rollUp($perCategory, $userId, $drillParentId))
-            ->filter(fn (array $item): bool => $item['amount'] > 0)
-            ->values();
-    }
-
     private function calculateNetWorthAt(Carbon $date, string $userCurrency): int
     {
         $accounts = Account::where('user_id', request()->user()->id)->get();

app/Http/Controllers/DashboardController.php

@@ -7,11 +7,10 @@ use App\Models\Account;
 use App\Models\Transaction;
 use App\Services\AccountMetricsService;
 use App\Services\CashflowSummaryService;
-use App\Services\CategoryTree;
+use App\Services\CategorySpendingService;
 use App\Services\PeriodComparator;
 use Carbon\Carbon;
 use Illuminate\Http\Request;
-use Illuminate\Support\Collection;
 use Illuminate\Support\Facades\DB;
 use Inertia\Inertia;
 use Inertia\Response;
@@ -20,7 +19,7 @@ class DashboardController extends Controller
 {
     public function __construct(
         private AccountMetricsService $accountMetricsService,
-        private CategoryTree $tree,
+        private CategorySpendingService $categorySpendingService,
     ) {}
 
     public function __invoke(Request $request): Response
@@ -60,8 +59,8 @@ class DashboardController extends Controller
         $period = new PeriodComparator($from, $to);
         $previousPeriod = $period->previous();
 
-        $currentSpending = $this->getCategorySpending($user->id, $period->from, $period->to);
-        $previousSpending = $this->getCategorySpending($user->id, $previousPeriod->from, $previousPeriod->to);
+        $currentSpending = $this->categorySpendingService->forPeriod($user->id, $period->from, $period->to);
+        $previousSpending = $this->categorySpendingService->forPeriod($user->id, $previousPeriod->from, $previousPeriod->to);
 
         $totalAmount = $currentSpending->sum('amount');
 
@@ -101,36 +100,6 @@ class DashboardController extends Controller
         ];
     }
 
-    /**
-     * Spending per top-level category: child category amounts roll up into
-     * their root ancestor so the dashboard only lists parents.
-     */
-    private function getCategorySpending(string $userId, Carbon $from, Carbon $to): Collection
-    {
-        $perCategory = Transaction::query()
-            ->where('transactions.user_id', $userId)
-            ->whereBetween('transactions.transaction_date', [$from, $to])
-            ->join('categories', function ($join) {
-                $join->on('transactions.category_id', '=', 'categories.id')
-                    ->where('categories.type', '=', CategoryType::Expense)
-                    ->whereNull('categories.deleted_at');
-            })
-            ->select('transactions.category_id', DB::raw('sum(transactions.amount) as total_amount'))
-            ->groupBy('transactions.category_id')
-            ->get()
-            ->map(fn ($item): array => [
-                'category_id' => $item->category_id,
-                'category' => null,
-                'amount' => (int) -$item->total_amount,
-            ])
-            ->values()
-            ->all();
-
-        return collect($this->tree->rollUp($perCategory, $userId, null))
-            ->filter(fn (array $item): bool => $item['amount'] > 0)
-            ->values();
-    }
-
     private function calculateCashflowSummary(string $userId, Carbon $from, Carbon $to): array
     {
         $income = max(0, $this->getTransactionSum($userId, $from, $to, CategoryType::Income));

app/Services/CategorySpendingService.php

@@ -0,0 +1,50 @@
+<?php
+
+namespace App\Services;
+
+use App\Enums\CategoryType;
+use App\Models\Transaction;
+use Carbon\Carbon;
+use Illuminate\Support\Collection;
+use Illuminate\Support\Facades\DB;
+
+class CategorySpendingService
+{
+    public function __construct(private CategoryTree $tree) {}
+
+    /**
+     * Expense spending rolled up the category tree.
+     *
+     * Without a drill target, child category amounts fold into their root
+     * ancestor so only parents are listed. With one, the parent's children
+     * become the rows (plus a direct node for transactions sitting on the
+     * parent itself). Soft-deleted categories are excluded.
+     *
+     * @return Collection<int, array<string, mixed>>
+     */
+    public function forPeriod(string $userId, Carbon $from, Carbon $to, ?string $drillParentId = null): Collection
+    {
+        $perCategory = Transaction::query()
+            ->where('transactions.user_id', $userId)
+            ->whereBetween('transactions.transaction_date', [$from, $to])
+            ->join('categories', function ($join) {
+                $join->on('transactions.category_id', '=', 'categories.id')
+                    ->where('categories.type', '=', CategoryType::Expense)
+                    ->whereNull('categories.deleted_at');
+            })
+            ->select('transactions.category_id', DB::raw('sum(transactions.amount) as total_amount'))
+            ->groupBy('transactions.category_id')
+            ->get()
+            ->map(fn ($item): array => [
+                'category_id' => $item->category_id,
+                'category' => null,
+                'amount' => (int) -$item->total_amount,
+            ])
+            ->values()
+            ->all();
+
+        return collect($this->tree->rollUp($perCategory, $userId, $drillParentId))
+            ->filter(fn (array $item): bool => $item['amount'] > 0)
+            ->values();
+    }
+}