<?php

namespace Drupal\views\Plugin\views\display;

use Drupal\Component\Plugin\Discovery\CachedDiscoveryInterface;
use Drupal\Core\Block\BlockManagerInterface;
use Drupal\Core\Entity\EntityManagerInterface;
use Drupal\Core\Form\FormStateInterface;
use Drupal\views\Plugin\Block\ViewsBlock;
use Symfony\Component\DependencyInjection\ContainerInterface;

/**
 * The plugin that handles a block.
 *
 * @ingroup views_display_plugins
 *
 * @ViewsDisplay(
 *   id = "block",
 *   title = @Translation("Block"),
 *   help = @Translation("Display the view as a block."),
 *   theme = "views_view",
 *   register_theme = FALSE,
 *   uses_hook_block = TRUE,
 *   contextual_links_locations = {"block"},
 *   admin = @Translation("Block")
 * )
 *
 * @see \Drupal\views\Plugin\Block\ViewsBlock
 * @see \Drupal\views\Plugin\Derivative\ViewsBlock
 */
class Block extends DisplayPluginBase {

  /**
   * Whether the display allows attachments.
   *
   * @var bool
   */
  protected $usesAttachments = TRUE;

  /**
   * The entity manager.
   *
   * @var \Drupal\Core\Entity\EntityManagerInterface
   */
  protected $entityManager;

  /**
   * The block manager.
   *
   * @var \Drupal\Core\Block\BlockManagerInterface
   */
  protected $blockManager;

  /**
   * Constructs a new Block instance.
   *
   * @param array $configuration
   *   A configuration array containing information about the plugin instance.
   * @param string $plugin_id
   *   The plugin_id for the plugin instance.
   * @param mixed $plugin_definition
   *   The plugin implementation definition.
   * @param \Drupal\Core\Entity\EntityManagerInterface $entity_manager
   *   The entity manager.
   * @param \Drupal\Core\Block\BlockManagerInterface $block_manager
   *   The block manager.
   */
  public function __construct(array $configuration, $plugin_id, $plugin_definition, EntityManagerInterface $entity_manager, BlockManagerInterface $block_manager) {
    parent::__construct($configuration, $plugin_id, $plugin_definition);

    $this->entityManager = $entity_manager;
    $this->blockManager = $block_manager;
  }

  /**
   * {@inheritdoc}
   */
  public static function create(ContainerInterface $container, array $configuration, $plugin_id, $plugin_definition) {
    return new static(
      $configuration,
      $plugin_id,
      $plugin_definition,
      $container->get('entity.manager'),
      $container->get('plugin.manager.block')
    );
  }

  /**
   * {@inheritdoc}
   */
  protected function defineOptions() {
    $options = parent::defineOptions();

    $options['block_description'] = ['default' => ''];
    $options['block_category'] = ['default' => $this->t('Lists (Views)')];
    $options['block_hide_empty'] = ['default' => FALSE];

    $options['allow'] = [
      'contains' => [
        'items_per_page' => ['default' => 'items_per_page'],
      ],
    ];

    return $options;
  }

  /**
   * Returns plugin-specific settings for the block.
   *
   * @param array $settings
   *   The settings of the block.
   *
   * @return array
   *   An array of block-specific settings to override the defaults provided in
   *   \Drupal\views\Plugin\Block\ViewsBlock::defaultConfiguration().
   *
   * @see \Drupal\views\Plugin\Block\ViewsBlock::defaultConfiguration()
   */
  public function blockSettings(array $settings) {
    $settings['items_per_page'] = 'none';
    return $settings;
  }

  /**
   * The display block handler returns the structure necessary for a block.
   */
  public function execute() {
    // Prior to this being called, the $view should already be set to this
    // display, and arguments should be set on the view.
    $element = $this->view->render();
    if ($this->outputIsEmpty() && $this->getOption('block_hide_empty') && empty($this->view->style_plugin->definition['even empty'])) {
      return [];
    }
    else {
      return $element;
    }
  }

  /**
   * Provide the summary for page options in the views UI.
   *
   * This output is returned as an array.
   */
  public function optionsSummary(&$categories, &$options) {
    parent::optionsSummary($categories, $options);

    $categories['block'] = [
      'title' => $this->t('Block settings'),
      'column' => 'second',
      'build' => [
        '#weight' => -10,
      ],
    ];

    $block_description = strip_tags($this->getOption('block_description'));
    if (empty($block_description)) {
      $block_description = $this->t('None');
    }
    $block_category = $this->getOption('block_category');

    $options['block_description'] = [
      'category' => 'block',
      'title' => $this->t('Block name'),
      'value' => views_ui_truncate($block_description, 24),
    ];
    $options['block_category'] = [
      'category' => 'block',
      'title' => $this->t('Block category'),
      'value' => views_ui_truncate($block_category, 24),
    ];

    $filtered_allow = array_filter($this->getOption('allow'));

    $options['allow'] = [
      'category' => 'block',
      'title' => $this->t('Allow settings'),
      'value' => empty($filtered_allow) ? $this->t('None') : $this->t('Items per page'),
    ];

    $options['block_hide_empty'] = [
      'category' => 'other',
      'title' => $this->t('Hide block if the view output is empty'),
      'value' => $this->getOption('block_hide_empty') ? $this->t('Yes') : $this->t('No'),
    ];
  }

  /**
   * Provide the default form for setting options.
   */
  public function buildOptionsForm(&$form, FormStateInterface $form_state) {
    parent::buildOptionsForm($form, $form_state);

    switch ($form_state->get('section')) {
      case 'block_description':
        $form['#title'] .= $this->t('Block admin description');
        $form['block_description'] = [
          '#type' => 'textfield',
          '#description' => $this->t('This will appear as the name of this block in administer >> structure >> blocks.'),
          '#default_value' => $this->getOption('block_description'),
        ];
        break;
      case 'block_category':
        $form['#title'] .= $this->t('Block category');
        $form['block_category'] = [
          '#type' => 'textfield',
          '#autocomplete_route_name' => 'block.category_autocomplete',
          '#description' => $this->t('The category this block will appear under on the <a href=":href">blocks placement page</a>.', [':href' => \Drupal::url('block.admin_display')]),
          '#default_value' => $this->getOption('block_category'),
        ];
        break;
      case 'block_hide_empty':
        $form['#title'] .= $this->t('Block empty settings');

        $form['block_hide_empty'] = [
          '#title' => $this->t('Hide block if no result/empty text'),
          '#type' => 'checkbox',
          '#description' => $this->t('Hide the block if there is no result and no empty text and no header/footer which is shown on empty result'),
          '#default_value' => $this->getOption('block_hide_empty'),
        ];
        break;
      case 'exposed_form_options':
        $this->view->initHandlers();
        if (!$this->usesExposed() && parent::usesExposed()) {
          $form['exposed_form_options']['warning'] = [
            '#weight' => -10,
            '#markup' => '<div class="messages messages--warning">' . $this->t('Exposed filters in block displays require "Use AJAX" to be set to work correctly.') . '</div>',
          ];
        }
        break;
      case 'allow':
        $form['#title'] .= $this->t('Allow settings in the block configuration');

        $options = [
          'items_per_page' => $this->t('Items per page'),
        ];

        $allow = array_filter($this->getOption('allow'));
        $form['allow'] = [
          '#type' => 'checkboxes',
          '#default_value' => $allow,
          '#options' => $options,
        ];
        break;
    }
  }

  /**
   * Perform any necessary changes to the form values prior to storage.
   * There is no need for this function to actually store the data.
   */
  public function submitOptionsForm(&$form, FormStateInterface $form_state) {
    parent::submitOptionsForm($form, $form_state);
    $section = $form_state->get('section');
    switch ($section) {
      case 'block_description':
      case 'block_category':
      case 'allow':
      case 'block_hide_empty':
        $this->setOption($section, $form_state->getValue($section));
        break;
    }
  }

  /**
   * Adds the configuration form elements specific to this views block plugin.
   *
   * This method allows block instances to override the views items_per_page.
   *
   * @param \Drupal\views\Plugin\Block\ViewsBlock $block
   *   The ViewsBlock plugin.
   * @param array $form
   *   The form definition array for the block configuration form.
   * @param \Drupal\Core\Form\FormStateInterface $form_state
   *   The current state of the form.
   *
   * @return array
   *   The renderable form array representing the entire configuration form.
   *
   * @see \Drupal\views\Plugin\Block\ViewsBlock::blockForm()
   */
  public function blockForm(ViewsBlock $block, array &$form, FormStateInterface $form_state) {
    $allow_settings = array_filter($this->getOption('allow'));

    $block_configuration = $block->getConfiguration();

    foreach ($allow_settings as $type => $enabled) {
      if (empty($enabled)) {
        continue;
      }
      switch ($type) {
        case 'items_per_page':
          $form['override']['items_per_page'] = [
            '#type' => 'select',
            '#title' => $this->t('Items per block'),
            '#options' => [
              'none' => $this->t('@count (default setting)', ['@count' => $this->getPlugin('pager')->getItemsPerPage()]),
              5 => 5,
              10 => 10,
              20 => 20,
              40 => 40,
            ],
            '#default_value' => $block_configuration['items_per_page'],
          ];
          break;
      }
    }

    return $form;
  }

  /**
   * Handles form validation for the views block configuration form.
   *
   * @param \Drupal\views\Plugin\Block\ViewsBlock $block
   *   The ViewsBlock plugin.
   * @param array $form
   *   The form definition array for the block configuration form.
   * @param \Drupal\Core\Form\FormStateInterface $form_state
   *   The current state of the form.
   *
   * @see \Drupal\views\Plugin\Block\ViewsBlock::blockValidate()
   */
  public function blockValidate(ViewsBlock $block, array $form, FormStateInterface $form_state) {
  }

  /**
   * Handles form submission for the views block configuration form.
   *
   * @param \Drupal\views\Plugin\Block\ViewsBlock $block
   *   The ViewsBlock plugin.
   * @param array $form
   *   The form definition array for the full block configuration form.
   * @param \Drupal\Core\Form\FormStateInterface $form_state
   *   The current state of the form.
   *
   * @see \Drupal\views\Plugin\Block\ViewsBlock::blockSubmit()
   */
  public function blockSubmit(ViewsBlock $block, $form, FormStateInterface $form_state) {
    if ($items_per_page = $form_state->getValue(['override', 'items_per_page'])) {
      $block->setConfigurationValue('items_per_page', $items_per_page);
    }
    $form_state->unsetValue(['override', 'items_per_page']);
  }

  /**
   * Allows to change the display settings right before executing the block.
   *
   * @param \Drupal\views\Plugin\Block\ViewsBlock $block
   *   The block plugin for views displays.
   */
  public function preBlockBuild(ViewsBlock $block) {
    $config = $block->getConfiguration();
    if ($config['items_per_page'] !== 'none') {
      $this->view->setItemsPerPage($config['items_per_page']);
    }
  }

  /**
   * Block views use exposed widgets only if AJAX is set.
   */
  public function usesExposed() {
    if ($this->ajaxEnabled()) {
      return parent::usesExposed();
    }
    return FALSE;
  }

  /**
   * {@inheritdoc}
   */
  public function remove() {
    parent::remove();

    if ($this->entityManager->hasDefinition('block')) {
      $plugin_id = 'views_block:' . $this->view->storage->id() . '-' . $this->display['id'];
      foreach ($this->entityManager->getStorage('block')->loadByProperties(['plugin' => $plugin_id]) as $block) {
        $block->delete();
      }
    }
    if ($this->blockManager instanceof CachedDiscoveryInterface) {
      $this->blockManager->clearCachedDefinitions();
    }
  }

}