#' get_short_data

#' get_short_data
#' @param stations station ids
#' @param referencetimeFrom referencetimeFrom
#' @param referencetimeTo referencetimeTo
#' @param timeResolution timeResolution
#' @param elements elements
#' @keywords data.synthaq.oslo10.seed123
#' @export
get_short_data <- function(stations=NULL,referencetimeFrom=NULL,referencetimeTo=NULL,timeResolution=NULL,elements=NULL) {

   res <- short_data_init()
   if (!is.null(stations) && !is.null(referencetimeFrom) && !is.null(referencetimeTo) && !is.null(timeResolution) && !is.null(elements)) {
     res <- build_data_df(station=stations,referencetimeFrom=referencetimeFrom,referencetimeTo=referencetimeTo,timeResolution=timeResolution,element=elements)
   }

  res <- tibble::as_tibble(res)
  return(res)

}


build_data_df <- function(station,referencetimeFrom,referencetimeTo,timeResolution,element){

  tr_file <- switch(timeResolution,
  #"yearly"  = "yly",
  #"monthly" = "mly",
  #"daily"   = "dly",
  "hourly"  = "hourly",
  stop("no data or not taken into account yet"))

  path <- normalizePath(file.path(.libPaths()[1],"data.synthaq.oslo10.seed123","data","aqoslosynth.rda"),mustWork=FALSE)

  # load the timeseries
  ld <- try(load(path),silent=TRUE)
  if (!inherits(ld,"try-error")) {

    tmp <- get("aqoslosynth",envir=environment())

    # build the results
    if (!is.null(element) ) {
      res <- tmp %>% filter(date>=as.POSIXct(referencetimeFrom,tz="UTC"),date<=as.POSIXct(referencetimeTo,tz="UTC"),ID %in% station,CO_NAME %in% element)  %>% select(date,ID,CO_NAME,timeResolution,unit,value)
    } else {
       res <- short_data_init()
    }
    names(res) <- c("date","ID","CO_NAME","timeResolution","unit","value")

    rm(tmp)

  } else {
    res <- short_data_init()
  }

  return(res)
}

short_data_init <- function(){
  df <- data.frame(date  = character(0),
                   ID  = character(0),
                   CO_NAME  = character(0),
                   timeResolution = character(0),
                   unit = character(0),
                   value = numeric(0)
                 )
  return(df)
}