function bbp_edit_topic_tag_handler( $action = '' ) {

	// Bail if required POST actions aren't passed
	if ( empty( $_POST['tag-id'] ) ) {
		return;
	}

	// Setup possible get actions
	$possible_actions = array(
		'bbp-update-topic-tag',
		'bbp-merge-topic-tag',
		'bbp-delete-topic-tag'
	);

	// Bail if actions aren't meant for this function
	if ( ! in_array( $action, $possible_actions, true ) ) {
		return;
	}

	// Setup vars
	$tag_id = (int) $_POST['tag-id'];
	$tag    = get_term( $tag_id, bbp_get_topic_tag_tax_id() );

	// Tag does not exist
	if ( is_wp_error( $tag ) && $tag->get_error_message() ) {
		bbp_add_error( 'bbp_manage_topic_invalid_tag', sprintf( __( '<strong>ERROR</strong>: The following problem(s) have been found while getting the tag: %s', 'bbpress' ), $tag->get_error_message() ) );
		return;
	}

	// What action are we trying to perform?
	switch ( $action ) {

		// Update tag
		case 'bbp-update-topic-tag' :

			// Nonce check
			if ( ! bbp_verify_nonce_request( 'update-tag_' . $tag_id ) ) {
				bbp_add_error( 'bbp_manage_topic_tag_update_nonce', __( '<strong>ERROR</strong>: Are you sure you wanted to do that?', 'bbpress' ) );
				return;
			}

			// Can user edit topic tags?
			if ( ! current_user_can( 'edit_topic_tag', $tag_id ) ) {
				bbp_add_error( 'bbp_manage_topic_tag_update_permission', __( '<strong>ERROR</strong>: You do not have permission to edit the topic tags.', 'bbpress' ) );
				return;
			}

			// No tag name was provided
			if ( empty( $_POST['tag-name'] ) || ! $name = $_POST['tag-name'] ) {
				bbp_add_error( 'bbp_manage_topic_tag_update_name', __( '<strong>ERROR</strong>: You need to enter a tag name.', 'bbpress' ) );
				return;
			}

			// Attempt to update the tag
			$slug        = ! empty( $_POST['tag-slug']        ) ? $_POST['tag-slug']        : '';
			$description = ! empty( $_POST['tag-description'] ) ? $_POST['tag-description'] : '';
			$tag         = wp_update_term( $tag_id, bbp_get_topic_tag_tax_id(), array(
				'name'        => $name,
				'slug'        => $slug,
				'description' => $description
			) );

			// Cannot update tag
			if ( is_wp_error( $tag ) && $tag->get_error_message() ) {
				bbp_add_error( 'bbp_manage_topic_tag_update_error', sprintf( __( '<strong>ERROR</strong>: The following problem(s) have been found while updating the tag: %s', 'bbpress' ), $tag->get_error_message() ) );
				return;
			}

			// Redirect
			$redirect = get_term_link( $tag_id, bbp_get_topic_tag_tax_id() );

			// Update counts, etc...
			do_action( 'bbp_update_topic_tag', $tag_id, $tag, $name, $slug, $description );

			break;

		// Merge two tags
		case 'bbp-merge-topic-tag'  :

			// Nonce check
			if ( ! bbp_verify_nonce_request( 'merge-tag_' . $tag_id ) ) {
				bbp_add_error( 'bbp_manage_topic_tag_merge_nonce', __( '<strong>ERROR</strong>: Are you sure you wanted to do that?', 'bbpress' ) );
				return;
			}

			// Can user edit topic tags?
			if ( ! current_user_can( 'edit_topic_tags' ) ) {
				bbp_add_error( 'bbp_manage_topic_tag_merge_permission', __( '<strong>ERROR</strong>: You do not have permission to edit the topic tags.', 'bbpress' ) );
				return;
			}

			// No tag name was provided
			if ( empty( $_POST['tag-existing-name'] ) || ! $name = $_POST['tag-existing-name'] ) {
				bbp_add_error( 'bbp_manage_topic_tag_merge_name', __( '<strong>ERROR</strong>: You need to enter a tag name.', 'bbpress' ) );
				return;
			}

			// If term does not exist, create it
			if ( ! $tag = term_exists( $name, bbp_get_topic_tag_tax_id() ) ) {
				$tag = wp_insert_term( $name, bbp_get_topic_tag_tax_id() );
			}

			// Problem inserting the new term
			if ( is_wp_error( $tag ) && $tag->get_error_message() ) {
				bbp_add_error( 'bbp_manage_topic_tag_merge_error', sprintf( __( '<strong>ERROR</strong>: The following problem(s) have been found while merging the tags: %s', 'bbpress' ), $tag->get_error_message() ) );
				return;
			}

			// Merging in to...
			$to_tag = $tag['term_id'];

			// Attempting to merge a tag into itself
			if ( $tag_id === $to_tag ) {
				bbp_add_error( 'bbp_manage_topic_tag_merge_same', __( '<strong>ERROR</strong>: The tags which are being merged can not be the same.', 'bbpress' ) );
				return;
			}

			// Delete the old term
			$tag = wp_delete_term( $tag_id, bbp_get_topic_tag_tax_id(), array(
				'default'       => $to_tag,
				'force_default' => true
			) );

			// Error merging the terms
			if ( is_wp_error( $tag ) && $tag->get_error_message() ) {
				bbp_add_error( 'bbp_manage_topic_tag_merge_error', sprintf( __( '<strong>ERROR</strong>: The following problem(s) have been found while merging the tags: %s', 'bbpress' ), $tag->get_error_message() ) );
				return;
			}

			// Redirect
			$redirect = get_term_link( (int) $to_tag, bbp_get_topic_tag_tax_id() );

			// Update counts, etc...
			do_action( 'bbp_merge_topic_tag', $tag_id, $to_tag, $tag );

			break;

		// Delete tag
		case 'bbp-delete-topic-tag' :

			// Nonce check
			if ( ! bbp_verify_nonce_request( 'delete-tag_' . $tag_id ) ) {
				bbp_add_error( 'bbp_manage_topic_tag_delete_nonce', __( '<strong>ERROR</strong>: Are you sure you wanted to do that?', 'bbpress' ) );
				return;
			}

			// Can user delete topic tags?
			if ( ! current_user_can( 'delete_topic_tag', $tag_id ) ) {
				bbp_add_error( 'bbp_manage_topic_tag_delete_permission', __( '<strong>ERROR</strong>: You do not have permission to delete the topic tags.', 'bbpress' ) );
				return;
			}

			// Attempt to delete term
			$tag = wp_delete_term( $tag_id, bbp_get_topic_tag_tax_id() );

			// Error deleting term
			if ( is_wp_error( $tag ) && $tag->get_error_message() ) {
				bbp_add_error( 'bbp_manage_topic_tag_delete_error', sprintf( __( '<strong>ERROR</strong>: The following problem(s) have been found while deleting the tag: %s', 'bbpress' ), $tag->get_error_message() ) );
				return;
			}

			// We don't have any other place to go other than home! Or we may die because of the 404 disease
			$redirect = bbp_get_forums_url();

			// Update counts, etc...
			do_action( 'bbp_delete_topic_tag', $tag_id, $tag );

			break;
	}

	/** Successful Moderation *************************************************/

	// Redirect back
	$redirect = ( ! empty( $redirect ) && ! is_wp_error( $redirect ) ) ? $redirect : home_url();
	bbp_redirect( $redirect );
}