prepare_colors <- function(colors = NULL) {
  if (is.null(colors) || length(colors) < 1) return(NULL)

  if (is.null(names(colors))) {
    stop(
      "`colors` must have names corresponding to valid CSS classes",
      call. = FALSE
    )
  }

  if (any(grepl("\\s", names(colors)))) {
    stop(
      "Color names in `colors` must be valid CSS classes",
      " and cannot contain spaces",
      call. = FALSE)
  }

  if (any(grepl("[^[:alpha:]_-]", names(colors)))) {
    stop("Color names in `colors` must be valid CSS classes", call. = FALSE)
  }

  whisker::iteratelist(colors, "color_name")
}

full_length_hex <- function(x) {
  if (!grepl("^#", x)) {
    stop(paste0('"', x, '" is not a hexadecimal color'))
  }
  x <- sub("^#", "", x)
  if (nchar(x) == 3) {
    x <- strsplit(x, character(0))[[1]]
    x <- rep(x, each = 2)
    x <- paste(x, collapse = "")
  } else if (nchar(x) != 6) {
    stop(paste0('"', x, '" is not a hexadecimal color'))
  }
  paste0("#", x)
}