#' Create a comparison editor.
#'
#' @param options Global application options
#' @noRd
comparison_editor_ui <- function(id, options) {
  verticalLayout(
    h3("Comparison"),
    selectInput(
      NS(id, "comparison_genes"),
      "Comparison genes",
      choices = c(
        "Your genes",
        "Random genes",
        names(options$comparison_gene_sets)
      )
    ),
    conditionalPanel(
      condition = sprintf(
        "input['%s'] == 'Your genes'",
        NS(id, "comparison_genes")
      ),
      gene_selector_ui(NS(id, "custom_genes"))
    )
  )
}

#' Create a server for the comparison editor.
#'
#' @param id ID for namespacing the inputs and outputs.
#' @param preset A reactive containing the current preset.
#' @param options Global application options
#'
#' @return A reactive containing the comparison gene IDs.
#'
#' @noRd
comparison_editor_server <- function(id, preset, options) {
  moduleServer(id, function(input, output, session) {
    custom_gene_ids <- gene_selector_server("custom_genes")

    reactive({
      if (input$comparison_genes == "Random genes") {
        preset <- preset()
        gene_pool <- preset$gene_ids
        reference_gene_ids <- preset$reference_gene_ids
        gene_pool <- gene_pool[!gene_pool %chin% reference_gene_ids]
        gene_pool[sample(length(gene_pool), length(reference_gene_ids))]
      } else if (input$comparison_genes == "Your genes") {
        custom_gene_ids()
      } else {
        options$comparison_gene_sets[[input$comparison_genes]]
      }
    })
  })
}