parse_content.R

find_lesson <- function(lesson_dir) {
  # Find 'lesson' file with or without extension
  grep("^lesson[.]?[A-Za-z]*$", list.files(lesson_dir), value=TRUE)
}

#' @importFrom tools file_ext
get_content_class <- function(file_name) {
  ext <- file_ext(file_name)
  tolower(ext)
}

### FUNCTIONS THAT RETURN LESSON OBJECT WITH ASSOCIATED ATTRIBUTES ###

parse_content <- function(file, e) UseMethod("parse_content")

parse_content.default <- function(file, e) {
  # If no extension on lesson file, then assume it's yaml
  parse_content.yaml(file, e)
}

parse_content.csv <- function(file, e) {
  df <- read.csv(file, as.is=TRUE)
  # Return lesson object
  lesson(df, lesson_name=e$temp_lesson_name, course_name=e$temp_course_name)
}

parse_content.rmd <- function(file, e) {
  rmd2df(file)
}

#' @importFrom yaml yaml.load_file
parse_content.yaml <- function(file, e){
  newrow <- function(element){
    temp <- data.frame(Class=NA, Output=NA, CorrectAnswer=NA,
                       AnswerChoices=NA, AnswerTests=NA, 
                       Hint=NA, Figure=NA, FigureType=NA, 
                       VideoLink=NA, Script=NA)
    for(nm in names(element)){
      # Only replace NA with value if value is not NULL, i.e. instructor
      # provided a nonempty value
      if(!is.null(element[[nm]])) {
        temp[,nm] <- element[[nm]]
      }
    }
    temp
  }
  raw_yaml <- yaml.load_file(file)
  temp <- lapply(raw_yaml[-1], newrow)
  df <- NULL
  for(row in temp){
    df <- rbind(df, row)
  }
  meta <- raw_yaml[[1]]
  lesson(df, lesson_name=meta$Lesson, course_name=meta$Course,
         author=meta$Author, type=meta$Type, organization=meta$Organization,
         version=meta$Version)
}


#' @importFrom tools file_ext
#' @importFrom tools file_path_sans_ext
#' @importFrom yaml yaml.load_file
#' @importFrom whisker whisker.render
localize_lesson <- function(file, lesPath, shortname){
	
	# Load localization file
	locale_yaml <- yaml.load_file(file)
	
	# TO DO: Process localization. Placeholder loads first element.
	locale_yaml <- locale_yaml[[1]]
	
	# Load lesson file
	lesson <- readLines(con = file.path(lesPath, shortname))
	
	# Render localized lesson
	lesson <- whisker.render(template = lesson, data = locale_yaml)
	
	# Save localized lesson as a temporary file
	file <- file_path_sans_ext(shortname)
	extension <- paste0(".", file_ext(shortname))
	localized_lesson <- tempfile(pattern = file, fileext = extension)
	writeLines(lesson, con = localized_lesson)
	
	# Return file path for localized lesson
	return(localized_lesson)
}