Canvas File Upload Attempt

canvas_url <- function() paste0(Sys.getenv("CANVAS_DOMAIN"), "/api/v1/")

sc <- function(x) {
  Filter(Negate(is.null), x)
}

canvas_query <- function(urlx, args, type = "GET") {
  fun <- getFromNamespace(type, "httr")
  args <- sc(args)
  resp <- fun(urlx,
              httr::user_agent("rcanvas - https://github.com/daranzolin/rcanvas"),
              httr::add_headers(Authorization = paste("Bearer", check_token())),
              query = args)
  httr::stop_for_status(resp)
  return(resp)
}

upload_canvas_file <- function(course_id, file_name, parent_folder_id = NULL, parent_folder_path = "/", on_duplicate = "overwrite") {
  if (!is.null(parent_folder_id) && !is.null(parent_folder_path)) stop("Do not specify both parent folder id and parent folder path.")
  file_size <- file.info(file_name)$size
  url <- paste0(canvas_url(),
                paste("courses", course_id, "files", sep = "/"))
  args <- sc(list(name = file_name,
                  size = file_size,
                  parent_folder_id = parent_folder_id,
                  parent_folder_path = parent_folder_path,
                  on_duplicate = on_duplicate))
  upload_resp <- canvas_query(url, args, "POST")
  upload_content <- httr::content(upload_resp)
  upload_url <- upload_content$upload_url
  upload_params <- upload_content$upload_params
  key_param <- upload_params["key"]
  names(key_param) <- "key"
  file_param <- file_name
  names(file_param) <- "file"
  upload_params[["key"]] <- NULL
  upload_params <- c(key_param, upload_params, file_param)
  httr::POST(url = upload_url, 
             body = upload_params)
}
upload_canvas_file(course_id = "1185256", file_name = "six.txt")