#' @importFrom memoise memoise
NULL

remote_urls <- function(package) {
  local <- context_get("local_packages")
  if (has_name(local, package)) {
    base_url <- local[[package]]
    list(
      reference = path(base_url, "reference"),
      article = path(base_url, "articles")
    )
  } else {
    remote_metadata(package)$urls
  }
}

remote_package_reference_url <- function(package) {
  remote_urls(package)$reference
}
remote_package_article_url <- function(package) {
  remote_urls(package)$article
}

remote_metadata <- memoise(function(package) {
  path <- find.package(package, quiet = TRUE)
  if (length(path) == 0) {
    return(NULL)
  }

  desc <- read_desc(path)
  urls <- sub_special_cases(desc$get_urls())

  for (url in urls) {
    url <- paste0(url, "/pkgdown.yml")

    yaml <- tryCatch(fetch_yaml(url), error = function(e) NULL)
    if (is.list(yaml)) {
      if (has_name(yaml, "articles")) {
        yaml$articles <- unlist(yaml$articles)
      }
      return(yaml)
    }
  }

  NULL
})

fetch_yaml <- function(url) {
  resp <- httr::GET(url, httr::timeout(3))
  httr::stop_for_status(resp)

  text <- httr::content(resp, as = "text", encoding = "UTF-8")
  yaml::yaml.load(text)
}

# All rOpenSci repositories have a known pkgdown URL.
# Todo: could generalise this concept for other orgs.
sub_special_cases <- function(urls){
  sub("^https?://github.com/ropensci/(\\w+).*$", "https://docs.ropensci.org/\\1", urls)
}