Budżet domowy (rejestr wydatków)

{
  "transactions": [
    {
      "id": 1,
      "type": "expense",
      "amount": 150.50,
      "category": "jedzenie",
      "description": "Zakupy spożywcze w Biedronce",
      "date": "2026-02-10",
      "created_at": "2026-02-10 18:30:00"
    },
    {
      "id": 2,
      "type": "income",
      "amount": 5000.00,
      "category": "wynagrodzenie",
      "description": "Pensja za luty",
      "date": "2026-02-01",
      "created_at": "2026-02-01 10:00:00"
    },
    {
      "id": 3,
      "type": "expense",
      "amount": 89.99,
      "category": "rozrywka",
      "description": "Netflix + Spotify",
      "date": "2026-02-05",
      "created_at": "2026-02-05 12:15:00"
    },
    {
      "id": 4,
      "type": "expense",
      "amount": 1200.00,
      "category": "mieszkanie",
      "description": "Czynsz za luty",
      "date": "2026-02-02",
      "created_at": "2026-02-02 09:00:00"
    }
  ]
}

$type = $_POST['type'] ?? '';
$amount = $_POST['amount'] ?? '';
$category = $_POST['category'] ?? '';
$description = trim($_POST['description'] ?? '');
$date = $_POST['date'] ?? '';

$validTypes = ['expense', 'income'];
$validCategories = [
    'expense' => ['jedzenie', 'mieszkanie', 'transport', 'rozrywka', 'zdrowie', 'inne'],
    'income' => ['wynagrodzenie', 'premia', 'freelance', 'inne'],
];

if (!in_array($type, $validTypes)) {
    $errors[] = "Wybierz typ transakcji";
}

if (!is_numeric($amount) || $amount <= 0) {
    $errors[] = "Kwota musi być liczbą większą od zera";
}

if ($amount > 1000000) {
    $errors[] = "Kwota nie może przekraczać 1 000 000 zł";
}

if (!in_array($category, $validCategories[$type] ?? [])) {
    $errors[] = "Wybierz poprawną kategorię";
}

if (empty($date)) {
    $errors[] = "Data jest wymagana";
}

function getExpenseCategories(): array {
    return [
        'jedzenie' => ['label' => 'Jedzenie', 'icon' => '🍕', 'color' => '#e74c3c'],
        'mieszkanie' => ['label' => 'Mieszkanie', 'icon' => '🏠', 'color' => '#3498db'],
        'transport' => ['label' => 'Transport', 'icon' => '🚗', 'color' => '#9b59b6'],
        'rozrywka' => ['label' => 'Rozrywka', 'icon' => '🎮', 'color' => '#f39c12'],
        'zdrowie' => ['label' => 'Zdrowie', 'icon' => '💊', 'color' => '#27ae60'],
        'inne' => ['label' => 'Inne', 'icon' => '📦', 'color' => '#95a5a6'],
    ];
}

function getIncomeCategories(): array {
    return [
        'wynagrodzenie' => ['label' => 'Wynagrodzenie', 'icon' => '💼', 'color' => '#27ae60'],
        'premia' => ['label' => 'Premia', 'icon' => '🎁', 'color' => '#2ecc71'],
        'freelance' => ['label' => 'Freelance', 'icon' => '💻', 'color' => '#1abc9c'],
        'inne' => ['label' => 'Inne', 'icon' => '💰', 'color' => '#16a085'],
    ];
}

function addTransaction(array &$transactions, array $data): int {
    $newId = empty($transactions) ? 1 : max(array_column($transactions, 'id')) + 1;

    $newTransaction = [
        'id' => $newId,
        'type' => $data['type'],
        'amount' => (float) $data['amount'],
        'category' => $data['category'],
        'description' => $data['description'],
        'date' => $data['date'],
        'created_at' => date('Y-m-d H:i:s'),
    ];

    $transactions[] = $newTransaction;
    return $newId;
}

function calculateSummary(array $transactions): array {
    $income = 0;
    $expense = 0;

    foreach ($transactions as $t) {
        if ($t['type'] === 'income') {
            $income += $t['amount'];
        } else {
            $expense += $t['amount'];
        }
    }

    return [
        'income' => $income,
        'expense' => $expense,
        'balance' => $income - $expense,
    ];
}

function calculateByCategory(array $transactions, string $type = 'expense'): array {
    $filtered = array_filter($transactions, fn($t) => $t['type'] === $type);

    $byCategory = [];
    foreach ($filtered as $t) {
        $category = $t['category'];
        if (!isset($byCategory[$category])) {
            $byCategory[$category] = 0;
        }
        $byCategory[$category] += $t['amount'];
    }

    arsort($byCategory);
    return $byCategory;
}

function filterByType(array $transactions, string $type): array {
    if (empty($type) || $type === 'all') {
        return $transactions;
    }
    return array_filter($transactions, fn($t) => $t['type'] === $type);
}

function filterByMonth(array $transactions, string $yearMonth): array {
    // $yearMonth format: "2026-02"
    return array_filter($transactions, function($t) use ($yearMonth) {
        return strpos($t['date'], $yearMonth) === 0;
    });
}

function filterByDateRange(array $transactions, string $from, string $to): array {
    return array_filter($transactions, function($t) use ($from, $to) {
        return $t['date'] >= $from && $t['date'] <= $to;
    });
}

function sortByDate(array $transactions, string $order = 'desc'): array {
    usort($transactions, function($a, $b) use ($order) {
        $result = strcmp($a['date'], $b['date']);
        return $order === 'desc' ? -$result : $result;
    });
    return $transactions;
}

function formatAmount(float $amount, string $type = 'expense'): string {
    $formatted = number_format($amount, 2, ',', ' ') . ' zł';

    if ($type === 'income') {
        return '+' . $formatted;
    } elseif ($type === 'expense') {
        return '-' . $formatted;
    }

    return $formatted;
}

function formatBalance(float $balance): string {
    $formatted = number_format(abs($balance), 2, ',', ' ') . ' zł';

    if ($balance > 0) {
        return '<span class="positive">+' . $formatted . '</span>';
    } elseif ($balance < 0) {
        return '<span class="negative">-' . $formatted . '</span>';
    }

    return '<span class="neutral">' . $formatted . '</span>';
}

function generateMonthlyReport(array $transactions, string $yearMonth): string {
    $filtered = filterByMonth($transactions, $yearMonth);
    $summary = calculateSummary($filtered);
    $byCategory = calculateByCategory($filtered, 'expense');

    $monthName = date('F Y', strtotime($yearMonth . '-01'));

    $html = '<!DOCTYPE html><html><head><meta charset="UTF-8">';
    $html .= '<title>Raport budżetowy - ' . $monthName . '</title>';
    $html .= '<style>
        body { font-family: Arial, sans-serif; max-width: 800px; margin: 0 auto; padding: 20px; }
        .summary { display: flex; gap: 20px; margin-bottom: 30px; }
        .summary-box { flex: 1; padding: 20px; border-radius: 10px; text-align: center; }
        .income { background: #d4edda; }
        .expense { background: #f8d7da; }
        .balance { background: #cce5ff; }
        .amount { font-size: 2em; font-weight: bold; }
        table { width: 100%; border-collapse: collapse; margin-top: 20px; }
        th, td { padding: 10px; border: 1px solid #ddd; text-align: left; }
        th { background: #333; color: white; }
    </style></head><body>';

    $html .= '<h1>Raport budżetowy: ' . htmlspecialchars($monthName) . '</h1>';

    $html .= '<div class="summary">';
    $html .= '<div class="summary-box income"><div>Przychody</div><div class="amount">' . formatAmount($summary['income'], 'income') . '</div></div>';
    $html .= '<div class="summary-box expense"><div>Wydatki</div><div class="amount">' . formatAmount($summary['expense'], 'expense') . '</div></div>';
    $html .= '<div class="summary-box balance"><div>Bilans</div><div class="amount">' . formatAmount($summary['balance']) . '</div></div>';
    $html .= '</div>';

    $html .= '<h2>Wydatki per kategoria</h2>';
    $html .= '<table><tr><th>Kategoria</th><th>Kwota</th><th>Udział</th></tr>';

    $totalExpense = $summary['expense'] ?: 1;
    foreach ($byCategory as $category => $amount) {
        $percent = round(($amount / $totalExpense) * 100, 1);
        $html .= '<tr>';
        $html .= '<td>' . htmlspecialchars($category) . '</td>';
        $html .= '<td>' . formatAmount($amount) . '</td>';
        $html .= '<td>' . $percent . '%</td>';
        $html .= '</tr>';
    }

    $html .= '</table></body></html>';
    return $html;
}