import {isFn} from '../util/core'
import {inBrowser} from './env'

const cacheNode = {}

/**
 * Get Node
 * @param  {String|Element} el
 * @param  {Boolean} noCache
 * @return {Element}
 */
export function getNode(el, noCache = false) {
  if (typeof el === 'string') {
    if (typeof window.Vue !== 'undefined') {
      return find(el)
    }
    el = noCache ? find(el) : cacheNode[el] || (cacheNode[el] = find(el))
  }

  return el
}

export const $ = inBrowser && document

export const body = inBrowser && $.body

export const head = inBrowser && $.head

/**
 * Find element
 * @example
 * find('nav') => document.querySelector('nav')
 * find(nav, 'a') => nav.querySelector('a')
 */
export function find(el, node) {
  return node ? el.querySelector(node) : $.querySelector(el)
}

/**
 * Find all elements
 * @example
 * findAll('a') => [].slice.call(document.querySelectorAll('a'))
 * findAll(nav, 'a') => [].slice.call(nav.querySelectorAll('a'))
 */
export function findAll(el, node) {
  return [].slice.call(
    node ? el.querySelectorAll(node) : $.querySelectorAll(el)
  )
}

export function create(node, tpl) {
  node = $.createElement(node)
  if (tpl) {
    node.innerHTML = tpl
  }
  return node
}

export function appendTo(target, el) {
  return target.appendChild(el)
}

export function before(target, el) {
  return target.insertBefore(el, target.children[0])
}

export function on(el, type, handler) {
  isFn(type) ?
    window.addEventListener(el, type) :
    el.addEventListener(type, handler)
}

export function off(el, type, handler) {
  isFn(type) ?
    window.removeEventListener(el, type) :
    el.removeEventListener(type, handler)
}

/**
 * Toggle class
 *
 * @example
 * toggleClass(el, 'active') => el.classList.toggle('active')
 * toggleClass(el, 'add', 'active') => el.classList.add('active')
 */
export function toggleClass(el, type, val) {
  el && el.classList[val ? type : 'toggle'](val || type)
}

export function style(content) {
  appendTo(head, create('style', content))
}