R/download.input.R

In PecanProject/rpecanapi: R Library that interacts with the PEcAn API

##' Downloads & saves the desired input file.
##' Hits the `/api/inputs/{input_id}` API endpoint
##' @name download.input
##' @title Download & save the desired input file
##' @param server Server object obtained using the connect() function
##' @param input_id ID of the PEcAn input to be downloaded
##' @param filename Optional filename specified if the id points to a folder instead of file
##' @param save_as File name to save the downloaded file as. Default: NULL (same as 'filename' if specified,
##' else defaults to 'pecan_input_file')
##' @return Response obtained from the `/api/inputs/{input_id}` endpoint
##' @author Tezan Sahu
##' @export
##' @examples
##' server <- connect(url="http://pecan.localhost:80", username="carya", password="illinois")
##' 
##' # Download the 'niwot.clim' file (id = 99000000003)
##' download.input(server, input_id='99000000003', save_as='local.niwot.clim')

download.input <- function(server, input_id, filename=NULL, save_as=NULL){
  res <- NULL
  tryCatch(
    expr = {
      url <- paste0(server$url, "/api/inputs/", input_id)
      if(! is.null(filename)) {
        url <- paste0(url, "?filename=", filename)
      }
      
      if(! is.null(server$username) && ! is.null(server$password)){
        res <- httr::GET(
          url,
          httr::authenticate(server$username, server$password)
        )
      }
      else{
        res <- httr::GET(url)
      }
    },
    error = function(e) {
      message("Sorry! Server not responding.")
    }
  )
  
  if(! is.null(res)) {
    if(res$status_code == 200){
      
      # If 'save_as' has not been specified, defaults to 'filename' (if specified), else to "pecan_input_file"
      if(is.null(save_as)) {
        save_as <- ifelse(is.null(filename),"pecan_input_file",filename)  
      }
      
      writeBin(res$content, save_as)
    }
    else if(res$status_code == 400){
      stop("Bad request. Input ID points to directory & filename is not specified")
    }
    else if(res$status_code == 401){
      stop("Invalid credentials")
    }
    else if(res$status_code == 403){
      stop("Access forbidden")
    }
    else if(res$status_code == 404){
      stop("Input file not found")
    }
    else if(res$status_code == 500){
      stop("Internal server error")
    }
    else{
      stop("Unidentified error")
    }
  }
}