interface SearchInterface

interface SearchInterface extends PluginInspectionInterface {
    
    /**
     * Sets the keywords, parameters, and attributes to be used by execute().
     *
     * @param string $keywords
     *   The keywords to use in a search.
     * @param array $parameters
     *   Array of parameters as an associative array. This is expected to
     *   be the query string from the current request.
     * @param array $attributes
     *   Array of attributes, usually from the current request object.
     *
     * @return $this
     *   A search plugin object for chaining.
     */
    public function setSearch($keywords, array $parameters, array $attributes);
    
    /**
     * Returns the currently set keywords of the plugin instance.
     *
     * @return string
     *   The keywords.
     */
    public function getKeywords();
    
    /**
     * Returns the current parameters set using setSearch().
     *
     * @return array
     *   The parameters.
     */
    public function getParameters();
    
    /**
     * Returns the currently set attributes (from the request).
     *
     * @return array
     *   The attributes.
     */
    public function getAttributes();
    
    /**
     * Verifies if the values set via setSearch() are valid and sufficient.
     *
     * @return bool
     *   TRUE if the search settings are valid and sufficient to execute a search,
     *   and FALSE if not.
     */
    public function isSearchExecutable();
    
    /**
     * Returns the search index type this plugin uses.
     *
     * @return string|null
     *   The type used by this search plugin in the search index, or NULL if this
     *   plugin does not use the search index.
     *
     * @see \Drupal\search\SearchIndexInterface::index()
     * @see \Drupal\search\SearchIndexInterface::clear()
     */
    public function getType();
    
    /**
     * Executes the search.
     *
     * @return array
     *   A structured list of search results.
     */
    public function execute();
    
    /**
     * Executes the search and builds render arrays for the result items.
     *
     * @return array
     *   An array of render arrays of search result items (generally each item
     *   has '#theme' set to 'search_result'), or an empty array if there are no
     *   results.
     */
    public function buildResults();
    
    /**
     * Provides a suggested title for a page of search results.
     *
     * @return string
     *   The translated suggested page title.
     */
    public function suggestedTitle();
    
    /**
     * Returns the searching help.
     *
     * @return array
     *   Render array for the searching help.
     */
    public function getHelp();
    
    /**
     * Alters the search form when being built for a given plugin.
     *
     * The core search module only invokes this method on active module plugins
     * when building a form for them in
     * \Drupal\search\Form\SearchPageForm::buildForm(). A plugin implementing this
     * will also need to implement the buildSearchUrlQuery() method.
     *
     * @param array $form
     *   Nested array of form elements that comprise the form.
     * @param \Drupal\Core\Form\FormStateInterface $form_state
     *   The current state of the form. The arguments that
     *   \Drupal::formBuilder()->getForm() was originally called with are
     *   available in the array $form_state->getBuildInfo()['args'].
     *
     * @see SearchInterface::buildSearchUrlQuery()
     */
    public function searchFormAlter(array &$form, FormStateInterface $form_state);
    
    /**
     * Builds the URL GET query parameters array for search.
     *
     * When the search form is submitted, a redirect is generated with the
     * search input as GET query parameters. Plugins using the searchFormAlter()
     * method to add form elements to the search form will need to override this
     * method to gather the form input and add it to the GET query parameters.
     *
     * @param \Drupal\Core\Form\FormStateInterface $form_state
     *   The form state, with submitted form information.
     *
     * @return array
     *   An array of GET query parameters containing all relevant form values
     *   to process the search. The 'keys' element must be present in order to
     *   trigger generation of search results, even if it is empty or unused by
     *   the search plugin.
     *
     * @see SearchInterface::searchFormAlter()
     */
    public function buildSearchUrlQuery(FormStateInterface $form_state);

}