/**
 * @typedef {import('hast').Nodes} Nodes
 */

// HTML whitespace expression.
// See <https://infra.spec.whatwg.org/#ascii-whitespace>.
const re = /[ \t\n\f\r]/g

/**
 * Check if the given value is *inter-element whitespace*.
 *
 * @param {Nodes | string} thing
 *   Thing to check (`Node` or `string`).
 * @returns {boolean}
 *   Whether the `value` is inter-element whitespace (`boolean`): consisting of
 *   zero or more of space, tab (`\t`), line feed (`\n`), carriage return
 *   (`\r`), or form feed (`\f`); if a node is passed it must be a `Text` node,
 *   whose `value` field is checked.
 */
export function whitespace(thing) {
  return typeof thing === 'object'
    ? thing.type === 'text'
      ? empty(thing.value)
      : false
    : empty(thing)
}

/**
 * @param {string} value
 * @returns {boolean}
 */
function empty(value) {
  return value.replace(re, '') === ''
}