class Slideshow

class Slideshow extends StylePluginBase {
    
    /**
     * Does the style plugin allows to use style plugins.
     *
     * @var bool
     */
    protected $usesRowPlugin = TRUE;
    
    /**
     * Does the style plugin support custom css class for the rows.
     *
     * @var bool
     */
    protected $usesRowClass = TRUE;
    
    /**
     * Does the style plugin support grouping of rows.
     *
     * @var bool
     */
    protected $usesGrouping = FALSE;
    
    /**
     * Does the style plugin for itself support to add fields to it's output.
     *
     * This option only makes sense on style plugins without row plugins, like
     * for example table.
     *
     * @var bool
     */
    protected $usesFields = TRUE;
    
    /**
     * {@inheritdoc}
     */
    protected function defineOptions() {
        $options = parent::defineOptions();
        $options['row_class_custom'] = array(
            'default' => '',
        );
        $options['row_class_default'] = array(
            'default' => TRUE,
        );
        return array_merge($options, \Drupal::moduleHandler()->invokeAll('views_slideshow_option_definition'));
    }
    
    /**
     * {@inheritdoc}
     */
    public function buildOptionsForm(&$form, FormStateInterface $form_state) {
        parent::buildOptionsForm($form, $form_state);
        // Wrap all the form elements to help style the form.
        $form['views_slideshow_wrapper'] = array(
            '#markup' => '<div id="views-slideshow-form-wrapper">',
        );
        
        /**
         * Style.
         */
        $form['slideshow_skin_header'] = array(
            '#markup' => '<h2>' . t('Style') . '</h2>',
        );
        // Get a list of all available skins.
        $skin_info = $this->getSkins();
        foreach ($skin_info as $skin => $info) {
            $skins[$skin] = $info['name'];
        }
        asort($skins);
        // Create the drop down box so users can choose an available skin.
        $form['slideshow_skin'] = array(
            '#type' => 'select',
            '#title' => t('Skin'),
            '#options' => $skins,
            '#default_value' => $this->options['slideshow_skin'],
            '#description' => t('Select the skin to use for this display.  Skins allow for easily swappable layouts of things like next/prev links and thumbnails.  Note that not all skins support all widgets, so a combination of skins and widgets may lead to unpredictable results in layout.'),
        );
        
        /**
         * Slides
         */
        $form['slides_header'] = array(
            '#markup' => '<h2>' . t('Slides') . '</h2>',
        );
        // Get all slideshow types.
        $slideshows = \Drupal::moduleHandler()->invokeAll('views_slideshow_slideshow_info');
        if ($slideshows) {
            // Build our slideshow options for the form.
            $slideshow_options = array();
            foreach ($slideshows as $slideshow_id => $slideshow_info) {
                $slideshow_options[$slideshow_id] = $slideshow_info['name'];
            }
            $form['slideshow_type'] = array(
                '#type' => 'select',
                '#title' => t('Slideshow Type'),
                '#options' => $slideshow_options,
                '#default_value' => $this->options['slideshow_type'],
            );
            $arguments = array(
                &$form,
                &$form_state,
                &$this,
            );
            foreach (\Drupal::moduleHandler()->getImplementations('views_slideshow_slideshow_type_form') as $module) {
                $form[$module] = array(
                    '#type' => 'fieldset',
                    '#title' => t('!module options', array(
                        '!module' => $slideshows[$module]['name'],
                    )),
                    '#collapsible' => TRUE,
                    '#attributes' => array(
                        'class' => array(
                            $module,
                        ),
                    ),
                    '#states' => array(
                        'visible' => array(
                            ':input[name="style_options[slideshow_type]"]' => array(
                                'value' => $module,
                            ),
                        ),
                    ),
                );
                $function = $module . '_views_slideshow_slideshow_type_form';
                call_user_func_array($function, $arguments);
            }
        }
        else {
            $form['enable_module'] = array(
                '#markup' => t('There is no Views Slideshow plugin enabled. Go to the !modules and enable a Views Slideshow plugin module. For example Views Slideshow Singleframe.', array(
                    '!modules' => \Drupal::l(t('Modules Page'), Url::fromRoute('system.modules_list')),
                )),
            );
        }
        
        /**
         * Widgets
         */
        $form['widgets_header'] = array(
            '#markup' => '<h2>' . t('Widgets') . '</h2>',
        );
        // Loop through all locations so we can add header for each location.
        $location = array(
            'top' => t('Top'),
            'bottom' => t('Bottom'),
        );
        foreach ($location as $location_id => $location_name) {
            // Widget Header
            $form['widgets'][$location_id]['header'] = array(
                '#markup' => '<h3>' . t('!location Widgets', array(
                    '!location' => $location_name,
                )) . '</h3>',
            );
        }
        // Get all widgets that are registered.
        // If we have widgets then build it's form fields.
        $widgets = \Drupal::moduleHandler()->invokeAll('views_slideshow_widget_info');
        if (!empty($widgets)) {
            // Build our weight values by number of widgets
            $weights = array();
            for ($i = 1; $i <= count($widgets); $i++) {
                $weights[$i] = $i;
            }
            // Loop through our widgets and locations to build our form values for
            // each widget.
            foreach ($widgets as $widget_id => $widget_info) {
                foreach ($location as $location_id => $location_name) {
                    $widget_dependency = 'style_options[widgets][' . $location_id . '][' . $widget_id . ']';
                    // Determine if a widget is compatible with a slideshow.
                    $compatible_slideshows = array();
                    foreach ($slideshows as $slideshow_id => $slideshow_info) {
                        $is_compatible = 1;
                        // Check if every required accept value in the widget has a
                        // corresponding calls value in the slideshow.
                        foreach ($widget_info['accepts'] as $accept_key => $accept_value) {
                            if (is_array($accept_value) && !empty($accept_value['required']) && !in_array($accept_key, $slideshow_info['calls'])) {
                                $is_compatible = 0;
                                break;
                            }
                        }
                        // No need to go through this if it's not compatible.
                        if ($is_compatible) {
                            // Check if every required calls value in the widget has a
                            // corresponding accepts call.
                            foreach ($widget_info['calls'] as $calls_key => $calls_value) {
                                if (is_array($calls_value) && !empty($calls_value['required']) && !in_array($calls_key, $slideshow_info['accepts'])) {
                                    $is_compatible = 0;
                                    break;
                                }
                            }
                        }
                        // If it passed all those tests then they are compatible.
                        if ($is_compatible) {
                            $compatible_slideshows[] = $slideshow_id;
                        }
                    }
                    // Use Widget Checkbox
                    $form['widgets'][$location_id][$widget_id]['enable'] = array(
                        '#type' => 'checkbox',
                        '#title' => t($widget_info['name']),
                        '#default_value' => $this->options['widgets'][$location_id][$widget_id]['enable'],
                        '#description' => t('Should !name be rendered at the !location of the slides.', array(
                            '!name' => $widget_info['name'],
                            '!location' => $location_name,
                        )),
                    );
                    $form['widgets'][$location_id][$widget_id]['enable']['#dependency']['edit-style-options-slideshow-type'] = !empty($compatible_slideshows) ? $compatible_slideshows : array(
                        'none',
                    );
                    // Need to wrap this so it indents correctly.
                    $form['widgets'][$location_id][$widget_id]['wrapper'] = array(
                        '#markup' => '<div class="vs-dependent">',
                    );
                    // Widget weight
                    // We check to see if the default value is greater than the number of
                    // widgets just in case a widget has been removed and the form hasn't
                    // been saved again.
                    $weight = isset($this->options['widgets'][$location_id][$widget_id]['weight']) ? $this->options['widgets'][$location_id][$widget_id]['weight'] : 0;
                    if ($weight > count($widgets)) {
                        $weight = count($widgets);
                    }
                    $form['widgets'][$location_id][$widget_id]['weight'] = array(
                        '#type' => 'select',
                        '#title' => t('Weight of the !name', array(
                            '!name' => $widget_info['name'],
                        )),
                        '#default_value' => $weight,
                        '#options' => $weights,
                        '#description' => t('Determines in what order the !name appears.  A lower weight will cause the !name to be above higher weight items.', array(
                            '!name' => $widget_info['name'],
                        )),
                        '#prefix' => '<div class="vs-dependent">',
                        '#suffix' => '</div>',
                        '#states' => array(
                            'visible' => array(
                                ':input[name="style_options[widgets][' . $location_id . '][' . $widget_id . '][enable]"]' => array(
                                    'checked' => TRUE,
                                ),
                            ),
                        ),
                    );
                    // Add all the widget settings.
                    if (function_exists($widget_id . '_views_slideshow_widget_form_options')) {
                        $arguments = array(
                            &$form['widgets'][$location_id][$widget_id],
                            &$form_state,
                            &$this,
                            $this->options['widgets'][$location_id][$widget_id],
                            $widget_dependency,
                        );
                        call_user_func_array($widget_id . '_views_slideshow_widget_form_options', $arguments);
                    }
                    $form['widgets'][$location_id][$widget_id]['wrapper_close'] = array(
                        '#markup' => '</div>',
                    );
                }
            }
        }
        $form['views_slideshow_wrapper_close'] = array(
            '#markup' => '</div>',
        );
        $form['#attached']['library'] = array(
            'views_slideshow/form',
        );
    }
    
    /**
     * {@inheritdoc}
     */
    public function validateOptionsForm(&$form, FormStateInterface $form_state) {
        $arguments = array(
            &$form,
            &$form_state,
            &$this,
        );
        // Call all modules that use hook_views_slideshow_options_form_validate
        foreach (\Drupal::moduleHandler()->getImplementations('views_slideshow_options_form_validate') as $module) {
            $function = $module . '_views_slideshow_options_form_validate';
            call_user_func_array($function, $arguments);
        }
    }
    
    /**
     * {@inheritdoc}
     */
    public function submitOptionsForm(&$form, FormStateInterface $form_state) {
        $arguments = array(
            $form,
            &$form_state,
        );
        // Call all modules that use hook_views_slideshow_options_form_submit
        foreach (\Drupal::moduleHandler()->getImplementations('views_slideshow_options_form_submit') as $module) {
            $function = $module . '_views_slideshow_options_form_submit';
            call_user_func_array($function, $arguments);
        }
        // In addition to the skin, we also pre-save the definition that
        // correspond to it.  That lets us avoid a hook lookup on every page.
        $skins = $this->getSkins();
        $form_state->setValue(array(
            'style_options',
            'skin_info',
        ), $skins[$form_state->getValue(array(
            'style_options',
            'slideshow_skin',
        ))]);
    }
    
    /**
     * Retrieve a list of all available skins in the system.
     */
    public function getSkins() {
        static $skins;
        if (empty($skins)) {
            $skins = array();
            // Call all modules that use hook_views_slideshow_skin_info.
            foreach (\Drupal::moduleHandler()->getImplementations('views_slideshow_skin_info') as $module) {
                $skin_items = call_user_func($module . '_views_slideshow_skin_info');
                if (isset($skin_items) && is_array($skin_items)) {
                    foreach (array_keys($skin_items) as $skin) {
                        // Ensure that the definition is complete, so we don't need lots
                        // of error checking later.
                        $skin_items[$skin] += array(
                            'class' => 'default',
                            'name' => t('Untitled skin'),
                            'module' => $module,
                            'libraries' => array(),
                        );
                    }
                    $skins = array_merge($skins, $skin_items);
                }
            }
        }
        return $skins;
    }

}