library(tic)
BuildLesson <- R6::R6Class(
    "BuildLesson", inherit = TicStep,
    public = list(
        run = function() {
          build_status <- system("make clean-rmd; make lesson-md")
          if (build_status > 0)
            stop("Error during building process")

          system("mkdir  _rendered")
          system("cp -r \`ls -A | grep -v '.git' | grep -v '_rendered' | grep -v '_site'\` _rendered")
        })
)

build_lesson <- function() {
    BuildLesson$new()
}


format_url_errors <- function(res_links, idx) {
  paste0("  - broken url: ", res_links$urlname[idx], "\n",
         "          from: ", res_links$parentname[idx], "\n\n")
}

CheckLinks <- R6::R6Class(
  "CheckLinks", inherit = TicStep,
  public = list(
    run = function() {
      ## While build_lesson() merely copies the content of the repo into a new
      ## folder that GitHub picks up to render (so the dynamically generated
      ## links such as "Edit on GitHub" are functional), here we actually need
      ## to generate the website so we can test the links.
      on.exit(system("rm -rf _rendered/_site"))

      system("cd _rendered && rvm 2.5.1 do ruby -S jekyll build")

      ## ignore JS file not included as part of rmarkdown
      ## ignore email addresses
      ## ignore embedded images
      link_status <- system("linkchecker --ignore-url=external.+js --ignore-url=^mailto: --ignore-url=^data: --no-warnings  --file-output=csv/link_res.csv _rendered/_site")
      message("linkchecker exit code: ", link_status)

      ## Because URLs can contain #, we first need to remove the commented lines
      ## in the generated CSV file. We can't rely on the comment argument of the
      ## read_delim function, see https://github.com/tidyverse/readr/issues/828
      csv_links_files <- readLines("link_res.csv")
      writeLines(csv_links_files[grepl("^[^#]", csv_links_files)],
                 con = "link_res_clean.csv",
                 sep = "\n")

      ## write output to CSV file and check error codes
      ## stop only for 404s
      res_links <- readr::read_delim("link_res_clean.csv", delim = ";")
      unique(res_links$result)
      res_404 <- grepl("^404|^gaierror", res_links$result)
      other_errors <- grepl("error", res_links$result, ignore.case = TRUE)
      if (any(other_errors)) warning("These links might be problematic: \n",
                                     format_url_errors(res_links, other_errors))
      if (any(res_404)) stop("Some links are broken (check log to inspect): \n",
                             format_url_errors(res_links, res_404))
     })
     )

check_links <- function() {
    CheckLinks$new()
}