##' Generate and Subset a XenaHub Object from 'XenaData'

##'

##' @author Shixiang Wang <w_shixiang@163.com>

##' @param XenaData a `data.frame`. Default is `data(XenaData)`.

##' The input of this option can only be `data(XenaData)` or its subset.

##' @param subset logical expression indicating elements or rows to keep.

##' @return a [XenaHub] object.

##' @export

##' @examples

##' # 1 get all datasets

##' XenaGenerate()

##' # 2 get TCGA BRCA

##' XenaGenerate(subset = XenaCohorts == "TCGA Breast Cancer (BRCA)")

##' # 3 get all datasets containing BRCA

##' XenaGenerate(subset = grepl("BRCA", XenaCohorts))

XenaGenerate <- function(XenaData = UCSCXenaTools::XenaData,

                         subset = TRUE) {

  enclos <- parent.frame()

  subset <- substitute(subset)

  row_selector <- eval(subset, XenaData, enclos)

  XenaData <- XenaData[row_selector, ]

  .XenaHub(

    hosts = unique(XenaData$XenaHosts),

    cohorts = unique(XenaData$XenaCohorts),

    datasets = XenaData$XenaDatasets

  )

}