Secure Server-Side Input Sanitization and Validation

<?php
function sanitizeAndValidateInput($data) {
    $sanitizedData = [];

    // Example for a string input (e.g., username, title)
    if (isset($data['username'])) {
        $username = trim($data['username']);
        $username = filter_var($username, FILTER_SANITIZE_STRING, FILTER_FLAG_STRIP_LOW | FILTER_FLAG_STRIP_HIGH);
        $username = htmlspecialchars($username, ENT_QUOTES, 'UTF-8'); // For display later, redundant if always prepared statements

        // Basic validation
        if (empty($username) || !preg_match("/^[a-zA-Z0-9_]{3,20}$/", $username)) {
            // Handle error: Invalid username
            return ['error' => 'Invalid username format.'];
        }
        $sanitizedData['username'] = $username;
    }

    // Example for an integer input (e.g., ID)
    if (isset($data['id'])) {
        $id = filter_var($data['id'], FILTER_VALIDATE_INT);
        if ($id === false) {
            // Handle error: Invalid ID
            return ['error' => 'Invalid ID.'];
        }
        $sanitizedData['id'] = $id;
    }

    // Example for a URL input
    if (isset($data['website'])) {
        $website = filter_var($data['website'], FILTER_SANITIZE_URL);
        if (!filter_var($website, FILTER_VALIDATE_URL)) {
            // Handle error: Invalid URL
            return ['error' => 'Invalid website URL.'];
        }
        $sanitizedData['website'] = $website;
    }

    // More input types...
    return $sanitizedData;
}

// Example Usage:
// $userInput = ['username' => 'test_user123', 'id' => '123', 'website' => 'http://example.com'];
// $processedInput = sanitizeAndValidateInput($userInput);

// if (isset($processedInput['error'])) {
//     echo $processedInput['error'];
// } else {
//     // Use $processedInput for database operations or further processing
//     // e.g., $stmt->execute([$processedInput['username'], $processedInput['id']]);
//     print_r($processedInput);
// }
?>