function wp_handle_comment_submission( $comment_data ) {

	$comment_post_ID      = 0;
	$comment_parent       = 0;
	$user_ID              = 0;
	$comment_author       = null;
	$comment_author_email = null;
	$comment_author_url   = null;
	$comment_content      = null;

	if ( isset( $comment_data['comment_post_ID'] ) ) {
		$comment_post_ID = (int) $comment_data['comment_post_ID'];
	}
	if ( isset( $comment_data['author'] ) && is_string( $comment_data['author'] ) ) {
		$comment_author = trim( strip_tags( $comment_data['author'] ) );
	}
	if ( isset( $comment_data['email'] ) && is_string( $comment_data['email'] ) ) {
		$comment_author_email = trim( $comment_data['email'] );
	}
	if ( isset( $comment_data['url'] ) && is_string( $comment_data['url'] ) ) {
		$comment_author_url = trim( $comment_data['url'] );
	}
	if ( isset( $comment_data['comment'] ) && is_string( $comment_data['comment'] ) ) {
		$comment_content = trim( $comment_data['comment'] );
	}
	if ( isset( $comment_data['comment_parent'] ) ) {
		$comment_parent = absint( $comment_data['comment_parent'] );
	}

	$post = get_post( $comment_post_ID );

	if ( empty( $post->comment_status ) ) {

		/**
		 * Fires when a comment is attempted on a post that does not exist.
		 *
		 * @since 1.5.0
		 *
		 * @param int $comment_post_ID Post ID.
		 */
		do_action( 'comment_id_not_found', $comment_post_ID );

		return new WP_Error( 'comment_id_not_found' );

	}

	// get_post_status() will get the parent status for attachments.
	$status = get_post_status( $post );

	if ( ( 'private' == $status ) && ! current_user_can( 'read_post', $comment_post_ID ) ) {
		return new WP_Error( 'comment_id_not_found' );
	}

	$status_obj = get_post_status_object( $status );

	if ( ! comments_open( $comment_post_ID ) ) {

		/**
		 * Fires when a comment is attempted on a post that has comments closed.
		 *
		 * @since 1.5.0
		 *
		 * @param int $comment_post_ID Post ID.
		 */
		do_action( 'comment_closed', $comment_post_ID );

		return new WP_Error( 'comment_closed', __( 'Sorry, comments are closed for this item.' ), 403 );

	} elseif ( 'trash' == $status ) {

		/**
		 * Fires when a comment is attempted on a trashed post.
		 *
		 * @since 2.9.0
		 *
		 * @param int $comment_post_ID Post ID.
		 */
		do_action( 'comment_on_trash', $comment_post_ID );

		return new WP_Error( 'comment_on_trash' );

	} elseif ( ! $status_obj->public && ! $status_obj->private ) {

		/**
		 * Fires when a comment is attempted on a post in draft mode.
		 *
		 * @since 1.5.1
		 *
		 * @param int $comment_post_ID Post ID.
		 */
		do_action( 'comment_on_draft', $comment_post_ID );

		if ( current_user_can( 'read_post', $comment_post_ID ) ) {
			return new WP_Error( 'comment_on_draft', __( 'Sorry, comments are not allowed for this item.' ), 403 );
		} else {
			return new WP_Error( 'comment_on_draft' );
		}
	} elseif ( post_password_required( $comment_post_ID ) ) {

		/**
		 * Fires when a comment is attempted on a password-protected post.
		 *
		 * @since 2.9.0
		 *
		 * @param int $comment_post_ID Post ID.
		 */
		do_action( 'comment_on_password_protected', $comment_post_ID );

		return new WP_Error( 'comment_on_password_protected' );

	} else {

		/**
		 * Fires before a comment is posted.
		 *
		 * @since 2.8.0
		 *
		 * @param int $comment_post_ID Post ID.
		 */
		do_action( 'pre_comment_on_post', $comment_post_ID );

	}

	// If the user is logged in
	$user = wp_get_current_user();
	if ( $user->exists() ) {
		if ( empty( $user->display_name ) ) {
			$user->display_name = $user->user_login;
		}
		$comment_author       = $user->display_name;
		$comment_author_email = $user->user_email;
		$comment_author_url   = $user->user_url;
		$user_ID              = $user->ID;
		if ( current_user_can( 'unfiltered_html' ) ) {
			if ( ! isset( $comment_data['_wp_unfiltered_html_comment'] )
				|| ! wp_verify_nonce( $comment_data['_wp_unfiltered_html_comment'], 'unfiltered-html-comment_' . $comment_post_ID )
			) {
				kses_remove_filters(); // start with a clean slate
				kses_init_filters(); // set up the filters
				remove_filter( 'pre_comment_content', 'wp_filter_post_kses' );
				add_filter( 'pre_comment_content', 'wp_filter_kses' );
			}
		}
	} else {
		if ( get_option( 'comment_registration' ) ) {
			return new WP_Error( 'not_logged_in', __( 'Sorry, you must be logged in to comment.' ), 403 );
		}
	}

	$comment_type = '';

	if ( get_option( 'require_name_email' ) && ! $user->exists() ) {
		if ( '' == $comment_author_email || '' == $comment_author ) {
			return new WP_Error( 'require_name_email', __( '<strong>ERROR</strong>: please fill the required fields (name, email).' ), 200 );
		} elseif ( ! is_email( $comment_author_email ) ) {
			return new WP_Error( 'require_valid_email', __( '<strong>ERROR</strong>: please enter a valid email address.' ), 200 );
		}
	}

	$commentdata = compact(
		'comment_post_ID',
		'comment_author',
		'comment_author_email',
		'comment_author_url',
		'comment_content',
		'comment_type',
		'comment_parent',
		'user_ID'
	);

	/**
	 * Filters whether an empty comment should be allowed.
	 *
	 * @since 5.1.0
	 *
	 * @param bool  $allow_empty_comment Whether to allow empty comments. Default false.
	 * @param array $commentdata         Array of comment data to be sent to wp_insert_comment().
	 */
	$allow_empty_comment = apply_filters( 'allow_empty_comment', false, $commentdata );
	if ( '' === $comment_content && ! $allow_empty_comment ) {
		return new WP_Error( 'require_valid_comment', __( '<strong>ERROR</strong>: please type a comment.' ), 200 );
	}

	$check_max_lengths = wp_check_comment_data_max_lengths( $commentdata );
	if ( is_wp_error( $check_max_lengths ) ) {
		return $check_max_lengths;
	}

	$comment_id = wp_new_comment( wp_slash( $commentdata ), true );
	if ( is_wp_error( $comment_id ) ) {
		return $comment_id;
	}

	if ( ! $comment_id ) {
		return new WP_Error( 'comment_save_error', __( '<strong>ERROR</strong>: The comment could not be saved. Please try again later.' ), 500 );
	}

	return get_comment( $comment_id );
}