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

var attrState = "data-pjax-state"

var formAction = 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)

  // Initialize requestOptions
  options.requestOptions = {
    requestUrl: el.getAttribute("action") || window.location.href,
    requestMethod: el.getAttribute("method") || "GET"
  }

  // create a testable virtual link of the form action
  var virtLinkElement = document.createElement("a")
  virtLinkElement.setAttribute("href", options.requestOptions.requestUrl)

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

  event.preventDefault()

  if (el.enctype === "multipart/form-data") {
    options.requestOptions.formData = new FormData(el)
  }
  else {
    options.requestOptions.requestParams = parseFormElements(el)
  }

  el.setAttribute(attrState, "submit")

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

function parseFormElements(el) {
  var requestParams = []
  var formElements = el.elements

  for (var i = 0; i < formElements.length; i++) {
    var element = formElements[i]
    var tagName = element.tagName.toLowerCase()
    // jscs:disable disallowImplicitTypeConversion
    if (!!element.name && element.attributes !== undefined && tagName !== "button") {
      // jscs:enable disallowImplicitTypeConversion
      var type = element.attributes.type

      if ((!type || type.value !== "checkbox" && type.value !== "radio") || element.checked) {
        // Build array of values to submit
        var values = []

        if (tagName === "select") {
          var opt

          for (var j = 0; j < element.options.length; j++) {
            opt = element.options[j]
            if (opt.selected && !opt.disabled) {
              values.push(opt.hasAttribute("value") ? opt.value : opt.text)
            }
          }
        }
        else {
          values.push(element.value)
        }

        for (var k = 0; k < values.length; k++) {
          requestParams.push({
            name: encodeURIComponent(element.name),
            value: encodeURIComponent(values[k])
          })
        }
      }
    }
  }

  return requestParams
}

function checkIfShouldAbort(virtLinkElement, options) {
  // Ignore external links.
  if (virtLinkElement.protocol !== window.location.protocol || virtLinkElement.host !== window.location.host) {
    return "external"
  }

  // Ignore click if we are on an anchor on the same page
  if (virtLinkElement.hash && virtLinkElement.href.replace(virtLinkElement.hash, "") === window.location.href.replace(location.hash, "")) {
    return "anchor"
  }

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

  // if declared as a full reload, just normally submit the form
  if (options.currentUrlFullReload && virtLinkElement.href === window.location.href.split("#")[0]) {
    return "reload"
  }
}

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

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

  el.setAttribute(attrState, "")

  on(el, "submit", function(event) {
    formAction.call(that, el, event)
  })
}