pageCache = {} cacheSize = 10 transitionCacheEnabled = false

currentState = null loadedAssets = null

referer = null

createDocument = null xhr = null

fetch = (url) ->

url = new ComponentUrl url

rememberReferer()
cacheCurrentPage()
reflectNewUrl url

if transitionCacheEnabled and cachedPage = transitionCacheFor(url.absolute)
  fetchHistory cachedPage
  fetchReplacement url
else
  fetchReplacement url, resetScrollPosition

transitionCacheFor = (url) ->

cachedPage = pageCache[url]
cachedPage if cachedPage and !cachedPage.transitionCacheDisabled

enableTransitionCache = (enable = true) ->

transitionCacheEnabled = enable

fetchReplacement = (url, onLoadFunction = =>) ->

triggerEvent 'page:fetch', url: url.absolute

xhr?.abort()
xhr = new XMLHttpRequest
xhr.open 'GET', url.withoutHashForIE10compatibility(), true
xhr.setRequestHeader 'Accept', 'text/html, application/xhtml+xml, application/xml'
xhr.setRequestHeader 'X-XHR-Referer', referer

xhr.onload = ->
  triggerEvent 'page:receive'

  if doc = processResponse()
    changePage extractTitleAndBody(doc)...
    reflectRedirectedUrl()
    onLoadFunction()
    triggerEvent 'page:load'
  else
    document.location.href = url.absolute

xhr.onloadend = -> xhr = null
xhr.onerror   = -> document.location.href = url.absolute

xhr.send()

fetchHistory = (cachedPage) ->

xhr?.abort()
changePage cachedPage.title, cachedPage.body
recallScrollPosition cachedPage
triggerEvent 'page:restore'

cacheCurrentPage = ->

currentStateUrl = new ComponentUrl currentState.url

pageCache[currentStateUrl.absolute] =
  url:                      currentStateUrl.relative,
  body:                     document.body,
  title:                    document.title,
  positionY:                window.pageYOffset,
  positionX:                window.pageXOffset,
  cachedAt:                 new Date().getTime(),
  transitionCacheDisabled:  document.querySelector('[data-no-transition-cache]')?

constrainPageCacheTo cacheSize

pagesCached = (size = cacheSize) ->

cacheSize = parseInt(size) if /^[\d]+$/.test size

constrainPageCacheTo = (limit) ->

pageCacheKeys = Object.keys pageCache

cacheTimesRecentFirst = pageCacheKeys.map (url) ->
  pageCache[url].cachedAt
.sort (a, b) -> b - a

for key in pageCacheKeys when pageCache[key].cachedAt <= cacheTimesRecentFirst[limit]
  triggerEvent 'page:expire', pageCache[key]
  delete pageCache[key]

changePage = (title, body, csrfToken, runScripts) ->

document.title = title
document.documentElement.replaceChild body, document.body
CSRFToken.update csrfToken if csrfToken?
executeScriptTags() if runScripts
currentState = window.history.state
triggerEvent 'page:change'
triggerEvent 'page:update'

executeScriptTags = ->

scripts = Array::slice.call document.body.querySelectorAll 'script:not([data-turbolinks-eval="false"])'
for script in scripts when script.type in ['', 'text/javascript']
  copy = document.createElement 'script'
  copy.setAttribute attr.name, attr.value for attr in script.attributes
  copy.appendChild document.createTextNode script.innerHTML
  { parentNode, nextSibling } = script
  parentNode.removeChild script
  parentNode.insertBefore copy, nextSibling
return

removeNoscriptTags = (node) ->

node.innerHTML = node.innerHTML.replace /<noscript[\S\s]*?<\/noscript>/ig, ''
node

reflectNewUrl = (url) ->

if (url = new ComponentUrl url).absolute isnt referer
  window.history.pushState { turbolinks: true, url: url.absolute }, '', url.absolute

reflectRedirectedUrl = ->

if location = xhr.getResponseHeader 'X-XHR-Redirected-To'
  location = new ComponentUrl location
  preservedHash = if location.hasNoHash() then document.location.hash else ''
  window.history.replaceState currentState, '', location.href + preservedHash

rememberReferer = ->

referer = document.location.href

rememberCurrentUrl = ->

window.history.replaceState { turbolinks: true, url: document.location.href }, '', document.location.href

rememberCurrentState = ->

currentState = window.history.state

recallScrollPosition = (page) ->

window.scrollTo page.positionX, page.positionY

resetScrollPosition = ->

if document.location.hash
  document.location.href = document.location.href
else
  window.scrollTo 0, 0

popCookie = (name) ->

value = document.cookie.match(new RegExp(name+"=(\\w+)"))?[1].toUpperCase() or ''
document.cookie = name + '=; expires=Thu, 01-Jan-70 00:00:01 GMT; path=/'
value

triggerEvent = (name, data) ->

event = document.createEvent 'Events'
event.data = data if data
event.initEvent name, true, true
document.dispatchEvent event

pageChangePrevented = ->

!triggerEvent 'page:before-change'

processResponse = ->

clientOrServerError = ->
  400 <= xhr.status < 600

validContent = ->
  xhr.getResponseHeader('Content-Type').match /^(?:text\/html|application\/xhtml\+xml|application\/xml)(?:;|$)/

extractTrackAssets = (doc) ->
  for node in doc.head.childNodes when node.getAttribute?('data-turbolinks-track')?
    node.getAttribute('src') or node.getAttribute('href')

assetsChanged = (doc) ->
  loadedAssets ||= extractTrackAssets document
  fetchedAssets  = extractTrackAssets doc
  fetchedAssets.length isnt loadedAssets.length or intersection(fetchedAssets, loadedAssets).length isnt loadedAssets.length

intersection = (a, b) ->
  [a, b] = [b, a] if a.length > b.length
  value for value in a when value in b

if not clientOrServerError() and validContent()
  doc = createDocument xhr.responseText
  if doc and !assetsChanged doc
    return doc

extractTitleAndBody = (doc) ->

title = doc.querySelector 'title'
[ title?.textContent, removeNoscriptTags(doc.body), CSRFToken.get(doc).token, 'runScripts' ]

CSRFToken =

get: (doc = document) ->
  node:   tag = doc.querySelector 'meta[name="csrf-token"]'
  token:  tag?.getAttribute? 'content'

update: (latest) ->
  current = @get()
  if current.token? and latest? and current.token isnt latest
    current.node.setAttribute 'content', latest

browserCompatibleDocumentParser = ->

createDocumentUsingParser = (html) ->
  (new DOMParser).parseFromString html, 'text/html'

createDocumentUsingDOM = (html) ->
  doc = document.implementation.createHTMLDocument ''
  doc.documentElement.innerHTML = html
  doc

createDocumentUsingWrite = (html) ->
  doc = document.implementation.createHTMLDocument ''
  doc.open 'replace'
  doc.write html
  doc.close()
  doc

# Use createDocumentUsingParser if DOMParser is defined and natively
# supports 'text/html' parsing (Firefox 12+, IE 10)
#
# Use createDocumentUsingDOM if createDocumentUsingParser throws an exception
# due to unsupported type 'text/html' (Firefox < 12, Opera)
#
# Use createDocumentUsingWrite if:
#  - DOMParser isn't defined
#  - createDocumentUsingParser returns null due to unsupported type 'text/html' (Chrome, Safari)
#  - createDocumentUsingDOM doesn't create a valid HTML document (safeguarding against potential edge cases)
try
  if window.DOMParser
    testDoc = createDocumentUsingParser '<html><body><p>test'
    createDocumentUsingParser
catch e
  testDoc = createDocumentUsingDOM '<html><body><p>test'
  createDocumentUsingDOM
finally
  unless testDoc?.body?.childNodes.length is 1
    return createDocumentUsingWrite

# The ComponentUrl class converts a basic URL string into an object # that behaves similarly to document.location.

# # If an instance is created from a relative URL, the current document # is used to fill in the missing attributes (protocol, host, port).

class ComponentUrl

constructor: (@original = document.location.href) ->
  return @original if @original.constructor is ComponentUrl
  @_parse()

withoutHash: -> @href.replace @hash, ''

# Intention revealing function alias
withoutHashForIE10compatibility: -> @withoutHash()

hasNoHash: -> @hash.length is 0

_parse: ->
  (@link ?= document.createElement 'a').href = @original
  { @href, @protocol, @host, @hostname, @port, @pathname, @search, @hash } = @link
  @origin = [@protocol, '//', @hostname].join ''
  @origin += ":#{@port}" unless @port.length is 0
  @relative = [@pathname, @search, @hash].join ''
  @absolute = @href

# The Link class derives from the ComponentUrl class, but is built from an # existing link element. Provides verification functionality for Turbolinks # to use in determining whether it should process the link when clicked. class Link extends ComponentUrl

@HTML_EXTENSIONS: ['html']

@allowExtensions: (extensions...) ->
  Link.HTML_EXTENSIONS.push extension for extension in extensions
  Link.HTML_EXTENSIONS

constructor: (@link) ->
  return @link if @link.constructor is Link
  @original = @link.href
  super

shouldIgnore: ->
  @_crossOrigin() or 
    @_anchored() or 
    @_nonHtml() or 
    @_optOut() or 
    @_target()

_crossOrigin: ->
  @origin isnt (new ComponentUrl).origin

_anchored: ->
  ((@hash and @withoutHash()) is (current = new ComponentUrl).withoutHash()) or 
    (@href is current.href + '#') 

_nonHtml: ->
  @pathname.match(/\.[a-z]+$/g) and not @pathname.match(new RegExp("\\.(?:#{Link.HTML_EXTENSIONS.join('|')})?$", 'g'))

_optOut: ->
  link = @link
  until ignore or link is document
    ignore = link.getAttribute('data-no-turbolink')?
    link = link.parentNode
  ignore

_target: ->
  @link.target.length isnt 0

# The Click class handles clicked links, verifying if Turbolinks should # take control by inspecting both the event and the link. If it should, # the page change process is initiated. If not, control is passed back # to the browser for default functionality. class Click

@installHandlerLast: (event) ->
  unless event.defaultPrevented
    document.removeEventListener 'click', Click.handle, false
    document.addEventListener 'click', Click.handle, false

@handle: (event) ->
  new Click event

constructor: (@event) ->
  return if @event.defaultPrevented
  @_extractLink()
  if @_validForTurbolinks()
    visit @link.href unless pageChangePrevented()
    @event.preventDefault() 

_extractLink: ->
  link = @event.target
  link = link.parentNode until !link.parentNode or link.nodeName is 'A'
  @link = new Link(link) if link.nodeName is 'A' and link.href.length isnt 0

_validForTurbolinks: ->
  @link? and not (@link.shouldIgnore() or @_nonStandardClick())

_nonStandardClick: ->
  @event.which > 1 or 
    @event.metaKey or 
    @event.ctrlKey or 
    @event.shiftKey or 
    @event.altKey

# Delay execution of function long enough to miss the popstate event # some browsers fire on the initial page load. bypassOnLoadPopstate = (fn) ->

setTimeout fn, 500

installDocumentReadyPageEventTriggers = ->

document.addEventListener 'DOMContentLoaded', ( ->
  triggerEvent 'page:change'
  triggerEvent 'page:update'
), true

installJqueryAjaxSuccessPageUpdateTrigger = ->

if typeof jQuery isnt 'undefined'
  jQuery(document).on 'ajaxSuccess', (event, xhr, settings) ->
    return unless jQuery.trim xhr.responseText
    triggerEvent 'page:update'

installHistoryChangeHandler = (event) ->

if event.state?.turbolinks
  if cachedPage = pageCache[(new ComponentUrl(event.state.url)).absolute]
    cacheCurrentPage()
    fetchHistory cachedPage
  else
    visit event.target.location.href

initializeTurbolinks = ->

rememberCurrentUrl()
rememberCurrentState()
createDocument = browserCompatibleDocumentParser()

document.addEventListener 'click', Click.installHandlerLast, true

bypassOnLoadPopstate ->
  window.addEventListener 'popstate', installHistoryChangeHandler, false

# Handle bug in Firefox 26/27 where history.state is initially undefined historyStateIsDefined =

window.history.state != undefined or navigator.userAgent.match /Firefox\/2[6|7]/

browserSupportsPushState =

window.history and window.history.pushState and window.history.replaceState and historyStateIsDefined

browserIsntBuggy =

!navigator.userAgent.match /CriOS\//

requestMethodIsSafe =

popCookie('request_method') in ['GET','']

browserSupportsTurbolinks = browserSupportsPushState and browserIsntBuggy and requestMethodIsSafe

browserSupportsCustomEvents =

document.addEventListener and document.createEvent

if browserSupportsCustomEvents

installDocumentReadyPageEventTriggers()
installJqueryAjaxSuccessPageUpdateTrigger()

if browserSupportsTurbolinks

visit = fetch
initializeTurbolinks()

else

visit = (url) -> document.location.href = url

# Public API # Turbolinks.visit(url) # Turbolinks.pagesCached() # Turbolinks.pagesCached(20) # Turbolinks.enableTransitionCache() # Turbolinks.allowLinkExtensions('md') # Turbolinks.supported @Turbolinks = { visit, pagesCached, enableTransitionCache, allowLinkExtensions: Link.allowExtensions, supported: browserSupportsTurbolinks }