class TableDragTestForm

class TableDragTestForm extends FormBase {
    
    /**
     * The state service.
     *
     * @var \Drupal\Core\State\StateInterface
     */
    protected $state;
    
    /**
     * Constructs a TableDragTestForm 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 'tabledrag_test_form';
    }
    
    /**
     * Builds the draggable test table.
     *
     * @param array $rows
     *   (optional) Rows that should be shown on the table. Default value is an
     *   empty array.
     * @param string $table_id
     *   (optional) An HTML ID for the table, defaults to 'tabledrag-test-table'.
     * @param string $group_prefix
     *   (optional) A prefix for HTML classes generated in the method, defaults to
     *   'tabledrag-test'.
     * @param bool $indentation
     *   (optional) A boolean indicating whether the rows can be indented,
     *   defaults to TRUE.
     *
     * @return array
     *   The renderable array of the draggable table used for testing.
     */
    protected function buildTestTable(array $rows = [], $table_id = 'tabledrag-test-table', $group_prefix = 'tabledrag-test', $indentation = TRUE) {
        $tabledrag = [
            [
                'action' => 'order',
                'relationship' => 'sibling',
                'group' => "{$group_prefix}-weight",
            ],
        ];
        if ($indentation) {
            $tabledrag[] = [
                'action' => 'match',
                'relationship' => 'parent',
                'group' => "{$group_prefix}-parent",
                'subgroup' => "{$group_prefix}-parent",
                'source' => "{$group_prefix}-id",
                'hidden' => TRUE,
                'limit' => 2,
            ];
            $tabledrag[] = [
                'action' => 'depth',
                'relationship' => 'group',
                'group' => "{$group_prefix}-depth",
                'hidden' => TRUE,
            ];
        }
        $table = [
            '#type' => 'table',
            '#header' => [
                [
                    'data' => $this->t('Text'),
                    'colspan' => $indentation ? 4 : 2,
                ],
                $this->t('Weight'),
            ],
            '#tabledrag' => $tabledrag,
            '#attributes' => [
                'id' => $table_id,
            ],
            '#attached' => [
                'library' => [
                    'tabledrag_test/tabledrag',
                ],
            ],
        ];
        // Provide a default set of five rows.
        $rows = !empty($rows) ? $rows : $this->state
            ->get('tabledrag_test_table', array_flip(range(1, 5)));
        foreach ($rows as $id => $row) {
            if (!is_array($row)) {
                $row = [];
            }
            $row += [
                'parent' => '',
                'weight' => 0,
                'depth' => 0,
                'classes' => [],
                'draggable' => TRUE,
            ];
            if (!empty($row['draggable'])) {
                $row['classes'][] = 'draggable';
            }
            $table[$id] = [
                'title' => [
                    'indentation' => [
                        '#theme' => 'indentation',
                        '#size' => $indentation ? $row['depth'] : 0,
                    ],
                    '#plain_text' => "Row with id {$id}",
                ],
                'id' => [
                    '#type' => 'hidden',
                    '#value' => $id,
                    '#parents' => [
                        'table',
                        $id,
                        'id',
                    ],
                    '#attributes' => [
                        'class' => [
                            "{$group_prefix}-id",
                        ],
                    ],
                ],
                '#attributes' => [
                    'class' => $row['classes'],
                ],
            ];
            if ($indentation) {
                $table[$id]['parent'] = [
                    '#type' => 'hidden',
                    '#default_value' => $row['parent'],
                    '#parents' => [
                        'table',
                        $id,
                        'parent',
                    ],
                    '#attributes' => [
                        'class' => [
                            "{$group_prefix}-parent",
                        ],
                    ],
                ];
                $table[$id]['depth'] = [
                    '#type' => 'hidden',
                    '#default_value' => $row['depth'],
                    '#parents' => [
                        'table',
                        $id,
                        'depth',
                    ],
                    '#attributes' => [
                        'class' => [
                            "{$group_prefix}-depth",
                        ],
                    ],
                ];
            }
            $table[$id]['weight'] = [
                '#type' => 'weight',
                '#default_value' => $row['weight'],
                '#parents' => [
                    'table',
                    $id,
                    'weight',
                ],
                '#attributes' => [
                    'class' => [
                        "{$group_prefix}-weight",
                    ],
                ],
            ];
        }
        return $table;
    }
    
    /**
     * {@inheritdoc}
     */
    public function buildForm(array $form, FormStateInterface $form_state) {
        // Provide a default set of five rows.
        $form['table'] = $this->buildTestTable();
        $form['actions'] = $this->buildFormActions();
        return $form;
    }
    
    /**
     * {@inheritdoc}
     */
    public function submitForm(array &$form, FormStateInterface $form_state) {
        $operation = isset($form_state->getTriggeringElement()['#op']) ? $form_state->getTriggeringElement()['#op'] : 'save';
        switch ($operation) {
            case 'reset':
                $this->state
                    ->set('tabledrag_test_table', array_flip(range(1, 5)));
                break;
            default:
                $test_table = [];
                foreach ($form_state->getValue('table') as $row) {
                    $test_table[$row['id']] = $row;
                }
                $this->state
                    ->set('tabledrag_test_table', $test_table);
                break;
        }
    }
    
    /**
     * Builds the test table form actions.
     *
     * @return array
     *   The renderable array of form actions.
     */
    protected function buildFormActions() {
        return [
            '#type' => 'actions',
            'save' => [
                '#type' => 'submit',
                '#value' => $this->t('Save'),
            ],
            'reset' => [
                '#type' => 'submit',
                '#op' => 'reset',
                '#value' => $this->t('Reset'),
            ],
        ];
    }

}