R/api_utils.R

In DominikRafacz/deepdep: Visualise and Explore the Deep Dependencies of R Packages

#' @title Get the description file from CRAN Data Base
#'
#' @description [CRAN Data Base](http://crandb.r-pkg.org)
#'
#' @param api package name
#' @param head length of head lines
#' @param tail length of tail lines
#'
#' @noRd
DB <- function(api, head = 1e6, tail = head) {
  ret <- paste0("http://crandb.r-pkg.org", "/", api)
  ret <- httr::GET(ret)
  ret <- httr::content(ret, as = "text", encoding = "UTF-8")
  ret <- jsonlite::prettify(ret)
  ret <- skip_lines(ret, head = head, tail = tail)

  ret
}

skip_lines <- function(text, head = 1e6, tail = 1e6) {

  text <- strsplit(text, "\n")[[1]]

  tail <- min(tail, max(0, length(text) - head))

  skip_text <- if (length(text) > head + tail) {
    paste("\n... not showing", length(text) - head - tail, "lines ...\n")
  } else {
    character()
  }

  ret <- c(head(text, head), skip_text, tail(text, tail))
  ret <- paste(ret, collapse = "\n")
  ret
}

#' @title Check if the package name is valid
#'
#' @param package package name
#' @param bioc TRUE/FALSE
#' @param local TRUE/FALSE
#'
#' @noRd
check_package_name <- function(package, bioc, local) {
  if (local) {
    if (!is_available(package, local = TRUE)) stop(paste0(package, " is not installed"))
  }
  else if (!is_available(package, bioc)) {
    if (bioc) stop(paste0(package, " is not available neither on CRAN nor on Bioconductor"))
    else stop(paste0(package, " is not available on CRAN"))
  }
}

is_available <- function(package, bioc = FALSE, local = FALSE) {
  package %in% get_available_packages(bioc, local)
}