import { JSXPrimitive, JSXElement } from './jsx'

/**
 * A fast duck-type to check whether any value is a JSX Element. A JSX Element
 * must always be an object with *at least* a string `elementName`, so that’s
 * all we check for.
 */
export const isJSXElement = (value: any): value is JSXElement =>
     value != null
  && typeof value === 'object'
  && typeof value.elementName === 'string'

/**
 * Gets whether a value is a `JSXPrimitive`
 */
export const isJSXPrimitive = (value: any): value is JSXPrimitive =>
     value == null
  || typeof value === 'boolean'
  || typeof value === 'number'
  || typeof value === 'string'

/**
 * Transforms a JSX primitive node to a string.
 *
 * If the node is null or undefined, an empty string is returned. If the node
 * is a boolean an empty string is returned (even for `true`!). If the node is
 * a number the node gets cast into a string. If the node is a string, nothing
 * happens.
 *
 * These are fairly intuitive rules, all except for `true` returning an empty
 * string.
 */
export const primitiveToString = (node: JSXPrimitive): string => {
  if (node == null) return ''
  if (typeof node === 'boolean') return ''
  return String(node)
}