finance_app/app/Http/Controllers/DashboardController.php

<?php

namespace App\Http\Controllers;

use App\Models\Expense;
use Illuminate\Support\Facades\Auth;
use Inertia\Inertia;
use Carbon\Carbon;

class DashboardController extends Controller
{
    public function index()
    {
        $userId = Auth::id();
        $now    = Carbon::now();

        // 本月花費
        $monthlyTotal = Expense::where('user_id', $userId)
            ->whereYear('date',  $now->year)
            ->whereMonth('date', $now->month)
            ->sum('amount');

        // 本月分類統計（圓餅圖）
        $categoryStats = Expense::with('category')
            ->where('user_id', $userId)
            ->whereYear('date',  $now->year)
            ->whereMonth('date', $now->month)
            ->get()
            ->groupBy(fn($e) => $e->category?->name ?? '未分類')
            ->map(fn($group, $name) => [
                'name'   => $name,
                'total'  => $group->sum('amount'),
                'color'  => $group->first()->category?->color ?? '#6B7280',
            ])
            ->values();

        // 近6個月趨勢
        $monthlyTrend = collect(range(5, 0))->map(function ($i) use ($userId, $now) {
            $month = $now->copy()->subMonths($i);
            $total = Expense::where('user_id', $userId)
                ->whereYear('date',  $month->year)
                ->whereMonth('date', $month->month)
                ->sum('amount');

            return [
                'month' => $month->format('Y/m'),
                'total' => (float) $total,
            ];
        });

        return Inertia::render('Dashboard', [
            'monthlyTotal'  => (float) $monthlyTotal,
            'categoryStats' => $categoryStats,
            'monthlyTrend'  => $monthlyTrend,
        ]);
    }
}