#' Create a web dependency
#'
#' Ensure that a file-based HTML dependency (from the htmltools package) can be
#' served over Shiny's HTTP server. This function works by using
#' \code{\link{addResourcePath}} to map the HTML dependency's directory to a
#' URL.
#'
#' @param dependency A single HTML dependency object, created using
#'   \code{\link{htmlDependency}}. If the \code{src} value is named, then
#'   \code{href} and/or \code{file} names must be present.
#'
#' @return A single HTML dependency object that has an \code{href}-named element
#'   in its \code{src}.
#' @export
createWebDependency <- function(dependency) {
  if (is.null(dependency))
    return(NULL)

  if (!inherits(dependency, "html_dependency"))
    stop("Unexpected non-html_dependency type")

  if (is.null(dependency$src$href)) {
    prefix <- paste(dependency$name, "-", dependency$version, sep = "")
    addResourcePath(prefix, dependency$src$file)
    dependency$src$href <- prefix
  }

  return(dependency)
}