# User agent diagnostic script for Posit Package Manager binary packages

local({
  if (.Platform$OS.type != "unix" || Sys.info()["sysname"] == "Darwin") {
    message("Success! Posit Package Manager does not require additional configuration to install binary packages on macOS or Windows.")
    return(invisible())
  }

  dl_method <- getOption("download.file.method", "")
  dl_extra_args <- getOption("download.file.extra", "")
  user_agent <- getOption("HTTPUserAgent", "")

  if (dl_method == "") {
    dl_method <- if (isTRUE(capabilities("libcurl"))) "libcurl" else "internal"
  }

  default_ua <- sprintf("R (%s)", paste(getRversion(), R.version$platform, R.version$arch, R.version$os))

  instruction_template <- 'You must configure your HTTP user agent in R to install binary packages.

In your user startup file (~/.Rprofile) or site-wide startup file (Rprofile.site), add:

%s


Then restart your R session and run this diagnostic script again.
'

  message(c(
    sprintf("R installation path: %s\n", R.home()),
    sprintf("R version: %s\n", R.version.string),
    sprintf("OS version: %s\n", utils::sessionInfo()$running),
    sprintf("HTTPUserAgent: %s\n", user_agent),
    sprintf("Download method: %s\n", dl_method),
    sprintf("Download extra args: %s\n", dl_extra_args),
    "\n----------------------------\n"
  ))

  if (dl_method == "libcurl") {
    if (!grepl(default_ua, user_agent, fixed = TRUE) ||
        (getRversion() >= "3.6.0" && substr(user_agent, 1, 3) == "R (")) {
      config <- '# Configure the R user agent header to install Linux binary packages
options(HTTPUserAgent = sprintf("R/%s R (%s)", getRversion(), paste(getRversion(), R.version["platform"], R.version["arch"], R.version["os"])))'
      message(sprintf(instruction_template, config))
      return(invisible())
    }
  } else if (dl_method == "curl") {
    if (!grepl(sprintf("User-Agent: %s", default_ua), dl_extra_args, fixed = TRUE)) {
      ua_arg <- "sprintf(\"-L --header 'User-Agent: R (%s)'\", paste(getRversion(), R.version[\"platform\"], R.version[\"arch\"], R.version[\"os\"]))"
      if (dl_extra_args != "") {
        old_args <- sprintf("\n  %s,", shQuote(dl_extra_args))
      } else {
        old_args <- ""
      }
      config <- paste0(
        'options(download.file.extra = paste(', old_args, '
  # Follow redirects, show errors, and display the HTTP status and URL
  "-fsSL -w \'%{stderr}curl: HTTP %{http_code} %{url_effective}\\n\'",
  # Configure the R user agent header to install Linux binary packages
  sprintf("--header \'User-Agent: R (%s)\'", paste(getRversion(), R.version["platform"], R.version["arch"], R.version["os"]))
))')
      message(sprintf(instruction_template, config))
      return(invisible())
    }
  } else if (dl_method == "wget") {
    if (!grepl(sprintf("User-Agent: %s", default_ua), dl_extra_args, fixed = TRUE)) {
      ua_arg <- "sprintf(\"--header 'User-Agent: R (%s)'\", paste(getRversion(), R.version[\"platform\"], R.version[\"arch\"], R.version[\"os\"]))"
      if (dl_extra_args == "") {
        config <- sprintf("# Configure the R user agent header to install Linux binary packages
options(download.file.extra = %s)", ua_arg)
      } else {
        config <- sprintf("# Configure the R user agent header to install Linux binary packages
options(download.file.extra = paste(%s, %s))", shQuote(dl_extra_args), ua_arg)
      }
      message(sprintf(instruction_template, config))
      return(invisible())
    }
  }

  message("Success! Your user agent is correctly configured.")
})