R/http_subdomain_changed.R

In petermeissner/robotstxt: A 'robots.txt' Parser and 'Webbot'/'Spider'/'Crawler' Permissions Checker

#' http_subdomain_changed
#'
#' @param response an httr response object, e.g. from a call to httr::GET()
#'
#' @return logical of length 1 indicating whether or not any domain change
#'     happened during the HTTP request
#'
#'
http_subdomain_changed <-
  function(response){

    # get domain of original HTTP request
    orig_domain <- guess_domain(response$request$url)
    orig_domain <- stringr::str_replace(orig_domain, "www\\.", "")


    # extract location headers
    location <-
      unlist(
        lapply(
          X   = response$all_headers,
          FUN =
            function(x){
              x$headers$location
            }
        )
      )
    location        <- utils::tail(location, 1)
    location        <- stringr::str_replace(location, "www\\.", "")
    location_domain <- guess_domain(location)



    # if there is no location header nothing has changed
    if ( length(location) > 0 ) {
      orig_domain_regex <-
        stringr::regex(
          pattern     = paste0("^", stringr::str_replace_all(orig_domain, "\\.", "\\\\."), "$"),
          ignore_case = TRUE
        )

      return(
        !( stringr::str_detect(pattern = orig_domain_regex, string = location_domain) )
      )

    } else {
      return(FALSE)
    }

  }