[p-book] admin category

<?php
// Part A: Setup
declare(strict_types = 1);                                // Use strict types
include '../includes/database-connection.php';            // Database connection
include '../includes/functions.php';                      // Functions
include '../includes/validate.php';                       // Functions

// Initialize variables
$id = filter_input(INPUT_GET, 'id', FILTER_VALIDATE_INT); // Get id and validate
$category = [
    'id'          => $id,
    'name'        => '',
    'description' => '',
    'navigation'  => false,
];                                                        // Initialize category array
$errors = [
    'warning'     => '',
    'name'        => '',
    'description' => '',
];                                                        // Initialize errors array

// If there was an id, page is editing the category, so get current category
if ($id) {                                                // If got an id
    $sql = "SELECT id, name, description, navigation 
              FROM category 
             WHERE id = :id;";                            // SQL statement
    $category = pdo($pdo, $sql, [$id])->fetch();          // Get category data

    if (!$category) {                                     // If no category found
        redirect('categories.php', ['failure' => 'Category not found']); // Redirect with error
    }
}

// PART B: Get and validate form data
if ($_SERVER['REQUEST_METHOD'] == 'POST') {               // If form submitted
    $category['name']        = $_POST['name'];            // Get name
    $category['description'] = $_POST['description'];     // Get description
    $category['navigation']  = (isset($_POST['navigation']) and ($_POST['navigation'] == 1)) ? 1 : 0; // Get navigation

    // Check if all data is valid and create error messages if it is invalid
    $errors['name']          = (is_text($category['name'], 1, 24))
        ? '' : 'Name should be 1-24 characters.';         // Validate name
    $errors['description']   = (is_text($category['description'], 1, 254))
        ? '' : 'Description should be 1-254 characters.'; // Validate description

    $invalid = implode($errors);                          // Join error messages

    // PART C: Check if data is valid, if so update database
    if ($invalid) {                                       // If data is invalid
        $errors['warning'] = 'Please correct errors';     // Create error message
    } else {                                              // Otherwise
        $arguments = $category;                           // Set arguments array for SQL
        if ($id) {                                        // If there is an id
            $sql = "UPDATE category 
                       SET name = :name, description = :description, 
                           navigation = :navigation 
                     WHERE id = :id;";                    // SQL to update category
        } else {                                          // If there is no id
            unset($arguments['id']);                      // Remove id from category array
            $sql = "INSERT INTO category (name, description, navigation) 
                         VALUES (:name, :description, :navigation);"; // Create category
        }

        // When running the SQL, three things can happen:
        // Category saved | Name already in use | Exception thrown for other reason
        try {                                             // Start try block to run SQL
            pdo($pdo, $sql, $arguments);                  // Run SQL
            redirect('categories.php', ['success' => 'Category saved']); // Redirect
        } catch (PDOException $e) {                       // If a PDO exception was raised
            if ($e->errorInfo[1] === 1062) {              // If error indicates duplicate entry
                $errors['warning'] = 'Category name already in use'; // Store error message
            } else {                                      // Otherwise unexpected error
                throw $e;                                 // Re-throw exception
            }
        }
    }
}
?>
<?php include '../includes/admin-header.php'; ?>
  <main class="container admin" id="content">
    <form action="category.php?id=<?= $id ?>" method="post" class="narrow">
      <h1>Edit Category</h1>
      <?php if ($errors['warning']) { ?>
        <div class="alert alert-danger"><?= $errors['warning'] ?></div>
      <?php } ?>

      <div class="form-group">
        <label for="name">Name: </label>
        <input type="text" name="name" id="name"
               value="<?= html_escape($category['name']) ?>" class="form-control">
        <span class="errors"><?= $errors['name'] ?></span>
      </div>

      <div class="form-group">
        <label for="description">Description: </label>
        <textarea name="description" id="description"
                  class="form-control"><?= html_escape($category['description']) ?></textarea>
        <span class="errors"><?= $errors['description'] ?></span>
      </div>

      <div class="form-check">
        <input type="checkbox" name="navigation" id="navigation"
               value="1" class="form-check-input"
          <?= ($category['navigation'] === 1) ? 'checked' : '' ?>>
        <label class="form-check-label" for="navigation">Navigation</label>
      </div>

      <input type="submit" value="Save" class="btn btn-primary btn-save">
    </form>
  </main>
<?php include '../includes/admin-footer.php'; ?>