AnsPress_Email()

 */
class AnsPress_Email_Hooks {

	/**
	 * All emails to send notification.
	 *
	 * @var array
	 */
	public static $emails = array();

	/**
	 * Subject of email to send.
	 *
	 * @var string
	 */
	public static $subject;

	/**
	 * Email body.
	 *
	 * @var string
	 */
	public static $message;

	/**
	 * Initialize the class.
	 */
	public static function init() {
		SELF::ap_default_options();
		anspress()->add_filter( 'comment_notification_recipients', __CLASS__, 'default_recipients', 10, 2 );

		anspress()->add_action( 'ap_after_new_question', __CLASS__, 'question_subscription', 10, 2 );
		anspress()->add_action( 'ap_after_new_answer', __CLASS__, 'answer_subscription', 10, 2 );
		anspress()->add_action( 'ap_publish_comment', __CLASS__, 'comment_subscription' );
		anspress()->add_action( 'before_delete_post', __CLASS__, 'delete_subscriptions' );
		anspress()->add_action( 'deleted_comment', __CLASS__, 'delete_comment_subscriptions' );

		anspress()->add_action( 'ap_option_groups', __CLASS__, 'register_option', 100 );
		anspress()->add_action( 'ap_after_new_question', __CLASS__, 'ap_after_new_question' );
		anspress()->add_action( 'ap_after_new_answer', __CLASS__, 'ap_after_new_answer' );
		anspress()->add_action( 'ap_select_answer', __CLASS__, 'select_answer' );
		anspress()->add_action( 'ap_publish_comment', __CLASS__, 'new_comment' );
		anspress()->add_action( 'ap_after_update_question', __CLASS__, 'ap_after_update_question', 10, 2 );
		anspress()->add_action( 'ap_after_update_answer', __CLASS__, 'ap_after_update_answer', 10, 2 );
		anspress()->add_action( 'ap_trash_question', __CLASS__, 'ap_trash_question', 10, 2 );
		anspress()->add_action( 'ap_trash_answer', __CLASS__, 'ap_trash_answer', 10, 2 );


	}

	/**
	 * Return empty reccipients for default comment notifications.
	 *
	 * @param array   $recipients Array of recipients.
	 * @param intgere $comment_id Comment ID.
	 * @return array
	 */
	public static function default_recipients( $recipients, $comment_id ) {
		$_comment = get_comment( $comment_id );

		if ( 'anspress' === $_comment->comment_type ) {
			return [];
		}

		return $recipients;
	}

	/**
	 * Apppend default options
	 *
	 * @since   4.0.0
	 */
	public static function ap_default_options() {
		$defaults = [];
		$defaults['notify_admin_email']         = get_option( 'admin_email' );
		$defaults['plain_email']                = false;
		$defaults['notify_admin_new_question']  = true;