var on = require("../events/on")
var clone = require("../util/clone")

var attrState = "data-pjax-state"

var linkAction = function(el, event) {
  if (isDefaultPrevented(event)) {
    return
  }

  // Since loadUrl modifies options and we may add our own modifications below,
  // clone it so the changes don't persist
  var options = clone(this.options)

  var attrValue = checkIfShouldAbort(el, event)
  if (attrValue) {
    el.setAttribute(attrState, attrValue)
    return
  }

  event.preventDefault()

  // don’t do "nothing" if user try to reload the page by clicking the same link twice
  if (
    this.options.currentUrlFullReload &&
    el.href === window.location.href.split("#")[0]
  ) {
    el.setAttribute(attrState, "reload")
    this.reload()
    return
  }

  el.setAttribute(attrState, "load")

  options.triggerElement = el
  this.loadUrl(el.href, options)
}

function checkIfShouldAbort(el, event) {
  // Don’t break browser special behavior on links (like page in new window)
  if (event.which > 1 || event.metaKey || event.ctrlKey || event.shiftKey || event.altKey) {
    return "modifier"
  }

  // we do test on href now to prevent unexpected behavior if for some reason
  // user have href that can be dynamically updated

  // Ignore external links.
  if (el.protocol !== window.location.protocol || el.host !== window.location.host) {
    return "external"
  }

  // Ignore anchors on the same page (keep native behavior)
  if (el.hash && el.href.replace(el.hash, "") === window.location.href.replace(location.hash, "")) {
    return "anchor"
  }

  // Ignore empty anchor "foo.html#"
  if (el.href === window.location.href.split("#")[0] + "#") {
    return "anchor-empty"
  }
}

var isDefaultPrevented = function(event) {
  return event.defaultPrevented || event.returnValue === false
}

module.exports = function(el) {
  var that = this

  el.setAttribute(attrState, "")

  on(el, "click", function(event) {
    linkAction.call(that, el, event)
  })

  on(el, "keyup", function(event) {
    if (event.keyCode === 13) {
      linkAction.call(that, el, event)
    }
  }.bind(this))
}