R/convert_rmd.R

In moj-analytical-services/mojspeakr: Facilitates Producing Whitehall Publisher-Ready Outputs Using Rmarkdown

#' Convert markdown file to Whitehall Publisher (GOV.UK) govspeak markdown
#' format
#' @param path string; filename (including path) to *.md file for conversion
#' @param remove_blocks bool; decision to remove block elements from *.md file.
#'   This includes code blocks and warnings
#' @param sub_pattern bool or vector; decision to increase hashed headers by
#' one level in *.md file.
#'   TRUE will substitute all, FALSE will substitute none, while a vector of
#'   the desired substitution levels allows individual headings to be modified
#'   as required.
#'   e.g. "#" will modify only first level headers.
#' @param page_break string; chooses what page breaks are converted to on
#' Whitehall.
#' If "line", page breaks are replaced with a horizontal rule. If "none"
#' they are replaced with a line break.
#' If "unchanged" they are not removed.
#' @export
#' @name convert_rmd
#' @title Convert standard markdown file to govspeak
convert_rmd <- function(path,
                        remove_blocks = FALSE,
                        sub_pattern = TRUE,
                        page_break = "line") {

  ##Check the path is a .md format
  if(!grep("[.]md$", path)){
    stop("Please provide a .md format file.
         Note that this function does not work directly on the .Rmd rmarkdown document.")
  }

  #Read in the raw lines from the md
  md_file <- readLines(path)

  #Nicely format the image references
  md_file <- generate_image_references(md_file)

  ##Turn md file into plain text
  govspeak_file <- paste(md_file, collapse = "\n")


  govspeak_file <- remove_header(govspeak_file)

  govspeak_file <- convert_callouts(govspeak_file)

  #Remove long strings of hashes/page break indicators
  #and move all headers down one level
  if (page_break == "line") {
    govspeak_file <- gsub("#####|##### <!-- Page break -->",
                          "-----",
                          govspeak_file)
  }else if (page_break == "none") {
    govspeak_file <- gsub("#####|##### <!-- Page break -->",
                          "\n",
                          govspeak_file)
  }else if (page_break == "unchanged") {
    govspeak_file <- govspeak_file
  }

  ##Substitute hashes according to pattern
  govspeak_file <- hash_sub(govspeak_file, sub_type = sub_pattern)

  ##Remove YAML block if requested
  if (remove_blocks) {
    govspeak_file <- remove_rmd_blocks(govspeak_file)
  }

  ##Write output as converted file
  write(govspeak_file, gsub("\\.md", "_converted\\.md", path))

  if(file.exists(gsub("\\.md", "_converted\\.md", path))){
    message("File converted successfully")
  }


}