R/get_encrypted_instances.R

In ymlambert/malakitr: Retrieve, Decrypt and Aggregate Data Generated by ODK Collect from R

#' Retrieve encrypted instance files of a form
#'
#' @param instanceRegistry Instance registry dataframe generated by getInstanceRegistry
#' @param writeToPath Path to directory where to save encrypted instance files
#' @param baseDownloadUrl Optional, base download url from API
#'
#' @return Instance registry dataframe with paths to individual encrypted instances files
#' @import httr
#' @export
#'
#' @examples
getEncryptedInstances <- function(instanceRegistry, writeToPath, baseDownloadUrl = "https://api.ona.io"){
  if(!is.null(instanceRegistry)){

    if(dir.exists(writeToPath)){
      # Check missing urls
      if(sum(is.na(instanceRegistry$attachments_download_url)) > 0){
        warning("The following instances lack a download url, please check encryption:")
        print(instanceRegistry[which(is.na(instanceRegistry$attachments_download_url)),]$uuid)
      }

      # Get files and write to directory
      instanceRegistry$encrypted_file_path <- NA_character_
      imax <- nrow(instanceRegistry)
      for(i in 1:imax){
        url <- instanceRegistry[i,]$attachments_download_url
        uuid <- instanceRegistry[i,]$uuid
        filename <- file.path(writeToPath, paste0(uuid, ".xml.enc"))

        success <- F
        messageLead <- paste0(sprintf(paste0("%0",nchar(imax),"d"), i), "/", imax)
        if(!is.na(url) & !is.na(uuid)){
          if(!file.exists(filename)){
            d <- GET(paste0(baseDownloadUrl, url))
            writeBin(content(d, "raw"), filename)
            if(file.exists(filename)) {
              message(paste0(messageLead, " - ", uuid, " instance file download success"))
              success <- T
            }
          }
          else{
            message(paste0(messageLead, " - ", uuid, " instance file already exists"))
            success <- T
          }
        }

        if(success){
          instanceRegistry[i,]$encrypted_file_path <- filename
        }
        else {
          message(paste0(lead, " - ", uuid, " instance file download failure"))
        }
      }

      # Check that all files have been downloaded
      downloadedIds <- sub(x = dir(writeToPath), pattern = "^([a-z0-9\\-]+)\\.xml\\.enc$","\\1")
      missingIds <- setdiff(instanceRegistry$uuid, downloadedIds)

      if(length(missingIds) > 0){
        message("The following instances were not downloaded:")
        print(missingIds)
      }
      else {
        message("All instances were downloaded sucessfully")
      }
    }
    else {
      warning("The specified directory does not exist.")
    }
  }
  else {
    message("Form is empty")
  }

  return(instanceRegistry)
}