class SystemStateEdit

class SystemStateEdit extends FormBase {
    
    /**
     * The state store.
     *
     * @var \Drupal\Core\State\StateInterface
     */
    protected $state;
    
    /**
     * Constructs a new SystemStateEdit object.
     *
     * @param \Drupal\Core\State\StateInterface $state
     *   The state service.
     */
    public function __construct(StateInterface $state) {
        $this->state = $state;
    }
    
    /**
     * {@inheritdoc}
     */
    public static function create(ContainerInterface $container) {
        return new static($container->get('state'));
    }
    
    /**
     * {@inheritdoc}
     */
    public function getFormId() {
        return 'devel_state_system_edit_form';
    }
    
    /**
     * {@inheritdoc}
     */
    public function buildForm(array $form, FormStateInterface $form_state, $state_name = '') {
        // Get the old value.
        $old_value = $this->state
            ->get($state_name);
        if (!isset($old_value)) {
            $this->messenger()
                ->addWarning($this->t('State @name does not exist in the system.', [
                '@name' => $state_name,
            ]));
            return;
        }
        // Only simple structures are allowed to be edited.
        $disabled = !$this->checkObject($old_value);
        if ($disabled) {
            $this->messenger()
                ->addWarning($this->t('Only simple structures are allowed to be edited. State @name contains objects.', [
                '@name' => $state_name,
            ]));
        }
        // First we show the user the content of the variable about to be edited.
        $form['value'] = [
            '#type' => 'item',
            '#title' => $this->t('Current value for %name', [
                '%name' => $state_name,
            ]),
            // phpcs:ignore Drupal.Functions.DiscouragedFunctions
'#markup' => kpr($old_value, TRUE),
        ];
        $transport = 'plain';
        if (!$disabled && is_array($old_value)) {
            try {
                $old_value = Yaml::encode($old_value);
                $transport = 'yaml';
            } catch (InvalidDataTypeException $e) {
                $this->messenger()
                    ->addError($this->t('Invalid data detected for @name : %error', [
                    '@name' => $state_name,
                    '%error' => $e->getMessage(),
                ]));
                return;
            }
        }
        // Store in the form the name of the state variable.
        $form['state_name'] = [
            '#type' => 'value',
            '#value' => $state_name,
        ];
        // Set the transport format for the new value. Values:
        // - plain
        // - yaml.
        $form['transport'] = [
            '#type' => 'value',
            '#value' => $transport,
        ];
        $form['new_value'] = [
            '#type' => 'textarea',
            '#title' => $this->t('New value'),
            '#default_value' => $disabled ? '' : $old_value,
            '#disabled' => $disabled,
            '#rows' => 15,
        ];
        $form['actions'] = [
            '#type' => 'actions',
        ];
        $form['actions']['submit'] = [
            '#type' => 'submit',
            '#value' => $this->t('Save'),
            '#disabled' => $disabled,
        ];
        $form['actions']['cancel'] = [
            '#type' => 'link',
            '#title' => $this->t('Cancel'),
            '#url' => Url::fromRoute('devel.state_system_page'),
        ];
        return $form;
    }
    
    /**
     * {@inheritdoc}
     */
    public function validateForm(array &$form, FormStateInterface $form_state) {
        $values = $form_state->getValues();
        if ($values['transport'] == 'yaml') {
            // Try to parse the new provided value.
            try {
                $parsed_value = Yaml::decode($values['new_value']);
                $form_state->setValue('parsed_value', $parsed_value);
            } catch (InvalidDataTypeException $e) {
                $form_state->setErrorByName('new_value', $this->t('Invalid input: %error', [
                    '%error' => $e->getMessage(),
                ]));
            }
        }
        else {
            $form_state->setValue('parsed_value', $values['new_value']);
        }
    }
    
    /**
     * {@inheritdoc}
     */
    public function submitForm(array &$form, FormStateInterface $form_state) {
        // Save the state.
        $values = $form_state->getValues();
        $this->state
            ->set($values['state_name'], $values['parsed_value']);
        $form_state->setRedirectUrl(Url::fromRoute('devel.state_system_page'));
        $this->messenger()
            ->addMessage($this->t('Variable %variable was successfully edited.', [
            '%variable' => $values['state_name'],
        ]));
        $this->logger('devel')
            ->info('Variable %variable was successfully edited.', [
            '%variable' => $values['state_name'],
        ]);
    }
    
    /**
     * Helper function to determine if a variable is or contains an object.
     *
     * @param mixed $data
     *   Input data to check.
     *
     * @return bool
     *   TRUE if the variable is not an object and does not contain one.
     */
    protected function checkObject($data) {
        if (is_object($data)) {
            return FALSE;
        }
        if (is_array($data)) {
            // If the current object is an array, then check recursively.
            foreach ($data as $value) {
                // If there is an object the whole container is "contaminated".
                if (!$this->checkObject($value)) {
                    return FALSE;
                }
            }
        }
        // All checks pass.
        return TRUE;
    }

}