Reservation System (Rezervasyon Sistemi)

Example Code

```php
<?php

/
 * Simplified Reservation System in PHP
 * This example uses arrays to simulate a database for clarity and simplicity.
 * In a real-world application, you would interact with a persistent database (e.g., MySQL via PDO).
 */

class ReservationSystem
{
    private array $availableResources; // e.g., ['room_101', 'room_102', 'table_A', 'table_B']
    private array $reservations;     // Stores actual reservation records
    private int $nextReservationId;

    public function __construct(array $resources)
    {
        $this->availableResources = array_fill_keys($resources, true); // Initialize all resources as available
        $this->reservations = [];
        $this->nextReservationId = 1;
        echo "ReservationSystem initialized with resources: " . implode(', ', $resources) . "\n\n";
    }

    /
     * Checks if a specific resource is available for a given date.
     * In a real system, you'd check a time slot within a date.
     * For simplicity, this example treats availability per resource per date.
     * 
     * @param string $resourceName The name of the resource (e.g., 'room_101').
     * @param string $date The date in 'YYYY-MM-DD' format.
     * @return bool True if available, false otherwise.
     */
    public function isAvailable(string $resourceName, string $date): bool
    {
        if (!isset($this->availableResources[$resourceName])) {
            echo "Error: Resource '{$resourceName}' does not exist.\n";
            return false;
        }

        foreach ($this->reservations as $reservation) {
            if ($reservation['resource_name'] === $resourceName && $reservation['date'] === $date && $reservation['status'] === 'confirmed') {
                return false; // Resource is already booked for this date
            }
        }
        return true; // Resource is available
    }

    /
     * Makes a reservation for a specific user, resource, and date.
     * 
     * @param string $userId A unique identifier for the user.
     * @param string $resourceName The name of the resource to book.
     * @param string $date The date of the reservation in 'YYYY-MM-DD' format.
     * @return array|false The reservation details if successful, false otherwise.
     */
    public function makeReservation(string $userId, string $resourceName, string $date)
    {
        if (!$this->isAvailable($resourceName, $date)) {
            echo "Reservation failed: '{$resourceName}' is not available on {$date}.\n";
            return false;
        }

        if (!isset($this->availableResources[$resourceName])) {
            echo "Reservation failed: Resource '{$resourceName}' does not exist.\n";
            return false;
        }

        $reservationId = $this->nextReservationId++;
        $reservation = [
            'id' => $reservationId,
            'user_id' => $userId,
            'resource_name' => $resourceName,
            'date' => $date,
            'status' => 'confirmed',
            'booking_time' => date('Y-m-d H:i:s')
        ];

        $this->reservations[$reservationId] = $reservation;
        echo "Reservation #{$reservationId} confirmed for user '{$userId}' on '{$resourceName}' for {$date}.\n";
        return $reservation;
    }

    /
     * Cancels an existing reservation.
     * 
     * @param int $reservationId The ID of the reservation to cancel.
     * @return bool True if cancellation was successful, false otherwise.
     */
    public function cancelReservation(int $reservationId): bool
    {
        if (isset($this->reservations[$reservationId])) {
            if ($this->reservations[$reservationId]['status'] === 'confirmed') {
                $this->reservations[$reservationId]['status'] = 'cancelled';
                echo "Reservation #{$reservationId} has been cancelled.\n";
                return true;
            } else {
                echo "Reservation #{$reservationId} is already cancelled or in a non-cancellable state.\n";
                return false;
            }
        }
        echo "Error: Reservation #{$reservationId} not found.\n";
        return false;
    }

    /
     * Retrieves all reservations made by a specific user.
     * 
     * @param string $userId The user ID.
     * @return array An array of reservations.
     */
    public function getReservationsByUser(string $userId): array
    {
        $userReservations = [];
        foreach ($this->reservations as $reservation) {
            if ($reservation['user_id'] === $userId) {
                $userReservations[] = $reservation;
            }
        }
        return $userReservations;
    }

    /
     * Retrieves all active reservations.
     * 
     * @return array An array of all confirmed reservations.
     */
    public function getAllActiveReservations(): array
    {
        $activeReservations = [];
        foreach ($this->reservations as $reservation) {
            if ($reservation['status'] === 'confirmed') {
                $activeReservations[] = $reservation;
            }
        }
        return $activeReservations;
    }

    /
     * Dumps all reservation data for debugging purposes.
     */
    public function dumpReservations(): void
    {
        echo "\n--- Current Reservations (Raw) ---\n";
        print_r($this->reservations);
        echo "------------------------------------\n";
    }
}

// --- Example Usage ---
$bookingSystem = new ReservationSystem(['Room 101', 'Room 102', 'Meeting Room A', 'Dining Table 5']);

// User 1 tries to book Room 101 for today
$today = date('Y-m-d');
$tomorrow = date('Y-m-d', strtotime('+1 day'));

$res1 = $bookingSystem->makeReservation('user_alice', 'Room 101', $today);
$res2 = $bookingSystem->makeReservation('user_bob', 'Room 102', $today);
$res3 = $bookingSystem->makeReservation('user_charlie', 'Meeting Room A', $tomorrow);

// User 1 tries to book Room 101 again for the same day (should fail)
$res_fail_1 = $bookingSystem->makeReservation('user_alice', 'Room 101', $today);

// User 2 tries to book Meeting Room A for tomorrow (should succeed)
$res4 = $bookingSystem->makeReservation('user_bob', 'Meeting Room A', $tomorrow);

echo "\n--- Alice's Reservations ---\n";
print_r($bookingSystem->getReservationsByUser('user_alice'));

echo "\n--- Bob's Reservations ---\n";
print_r($bookingSystem->getReservationsByUser('user_bob'));

// Cancel one of Bob's reservations
if ($res2) {
    $bookingSystem->cancelReservation($res2['id']);
}

// Try to book the cancelled room again (should now succeed)
$res5 = $bookingSystem->makeReservation('user_david', 'Room 102', $today);

echo "\n--- All Active Reservations ---\n";
print_r($bookingSystem->getAllActiveReservations());

$bookingSystem->dumpReservations();

?>
```