/*global NodeList */
(function(window) {
  'use strict'

  // Get element(s) by CSS selector:
  window.qs = function(selector, scope) {
    return (scope || document).querySelector(selector)
  }
  window.qsa = function(selector, scope) {
    return (scope || document).querySelectorAll(selector)
  }

  // addEventListener wrapper:
  window.$on = function(target, type, callback, useCapture) {
    target.addEventListener(type, callback, !!useCapture)
  }

  // Attach a handler to event for all elements that match the selector,
  // now or in the future, based on a root element
  window.$delegate = function(target, selector, type, handler) {
    function dispatchEvent(event) {
      var targetElement = event.target
      var potentialElements = window.qsa(selector, target)
      var hasMatch = Array.prototype.indexOf.call(potentialElements, targetElement) >= 0

      if (hasMatch) {
        handler.call(targetElement, event)
      }
    }

    // https://developer.mozilla.org/en-US/docs/Web/Events/blur
    var useCapture = type === 'blur' || type === 'focus'

    window.$on(target, type, dispatchEvent, useCapture)
  }

  // Find the element's parent with the given tag name:
  // $parent(qs('a'), 'div');
  window.$parent = function(element, tagName) {
    if (!element.parentNode) {
      return
    }
    if (element.parentNode.tagName.toLowerCase() === tagName.toLowerCase()) {
      return element.parentNode
    }
    return window.$parent(element.parentNode, tagName)
  }

  // Allow for looping on nodes by chaining:
  // qsa('.foo').forEach(function () {})
  NodeList.prototype.forEach = Array.prototype.forEach
})(window)