apply_tag <- function(ll, tag, class = NULL, extra_attributes = NULL) {
  lapply(ll, function(x) htmltools::tag(tag, c(x, class = class, extra_attributes)))
}

dots2list <- function(...) {
  # Convert dots to list, but return first element if the first element is a list
  # and the length of ... is 1
  x <- list(...)
  if (length(x) == 1 && is.list(x[[1]])) return(x[[1]])
  x
}

tag_function <- function(.tag = "div") {
  function(...) htmltools::tag(.tag, list(...))
}

validate_value <- function(value = NULL, choices, several.ok = TRUE, value_name = "") {
  if (!is.null(value)) {
    value_name <- if (nchar(value_name) > 0) glue("`{value_name}` - ") else ""
    if (!several.ok && length(value) > 1) {
      msg <- glue("{value_name}Using the first of {length(value)} values: {value[1]}")
      rlang::warn(msg)
      value <- value[1]
    }
    not_in_choices <- setdiff(value, choices)
    if (length(not_in_choices)) {
      msg <- glue("{value_name}Ignoring invalid choices: ",
                  "\"{paste(not_in_choices, collapse = '\", \"')}\"")
      rlang::warn(msg)
      value <- intersect(value, choices)
    }
    if (length(value)) {
      value
    } else {
      rlang::abort(glue("{value_name}Must be one of the following valid choices: ",
                        "\"{paste(choices, collapse = '\", \"')}\""))
    }
  }
}