##' Query URL of Datasets before Downloading

##' @author Shixiang Wang <w_shixiang@163.com>

##' @param x a [XenaHub] object

##' @return a `data.frame` contains hosts, datasets and url

##' @importFrom dplyr filter select pull rename mutate

##' @export

##' @examples

##' xe = XenaGenerate(subset = XenaHostNames == "tcgaHub")

##' hosts(xe)

##' \dontrun{

##' xe_query = XenaQuery(xe)

##' }

XenaQuery <- function(x) {

  use_hiplot <- getOption("use_hiplot", default = FALSE)

  data_list <- UCSCXenaTools::XenaData

  if (use_hiplot) {

      # Check website status

      use_hiplot <- tryCatch(

          {

              httr::http_error("https://xena-ucscpublic.hiplot.com.cn")

              TRUE

          },

          error = function(e) {

              message("The hiplot server may down, we will not use it for now.")

              FALSE

          }

      )

  }

  if (use_hiplot) {

    message("Use hiplot server (China) for mirrored data hubs (set 'options(use_hiplot = FALSE)' to disable it)")

    data_list$XenaHosts <- .xena_mirror_map_rv[data_list$XenaHosts]

  }

  message("This will check url status, please be patient.")

  datasetsName <- datasets(x)

  query <- data_list %>%

    dplyr::filter(XenaDatasets %in% datasetsName) %>%

    dplyr::rename(hosts = XenaHosts, datasets = XenaDatasets) %>%

    dplyr::mutate(url = ifelse(.data$XenaHostNames %in% c("gdcHub", "gdcHubV18"),

      file.path(hosts, "download", url_encode(basename(datasets))),

      file.path(hosts, "download", url_encode(datasets))

    )) %>%

    dplyr::mutate(url = ifelse(!sapply(url, http_error2),

      url, paste0(url, ".gz")

    )) %>%

    dplyr::select(hosts, datasets, url) %>%

    as.data.frame()

  invisible(query)

}

url_encode <- function(x, reserved = TRUE) {

  sapply(x, function(y, reserved) {

    # 保留 /

    as.character(gsub("%2F", "/", utils::URLencode(y, reserved = reserved)))

  }, reserved = reserved)

}

http_error2 <- function(url, max_try = 3L, ...) {

  Sys.sleep(0.001)

  tryCatch(

    {

      # message("==> Trying #", abs(max_try - 4L))

      httr::http_error(url, ...)

    },

    error = function(e) {

      if (max_try == 1) {

        message("Tried 3 times but failed, please check your internet connection!")

        invisible(NULL)

      } else {

        http_error2(url, max_try - 1L)

      }

    }

  )

}