/* ----------------------------------
 * PUSH v1.0.0
 * Licensed under The MIT License
 * inspired by chris's jquery.pjax.js
 * http://opensource.org/licenses/MIT
 * ---------------------------------- */

!function () {

  var noop = function () {};


  // Pushstate cacheing
  // ==================

  var isScrolling;
  var maxCacheLength = 20;
  var cacheMapping   = sessionStorage;
  var domCache       = {};
  var transitionMap  = {
    'slide-in'  : 'slide-out',
    'slide-out' : 'slide-in',
    'fade'      : 'fade'
  };
  
  var bars = {
    bartab             : '.bar-tab',
    bartitle           : '.bar-title',
    barfooter          : '.bar-footer',
    barheadersecondary : '.bar-header-secondary'
  };

  var cacheReplace = function (data, updates) {
    PUSH.id = data.id;
    if (updates) data = getCached(data.id);
    cacheMapping[data.id] = JSON.stringify(data);
    window.history.replaceState(data.id, data.title, data.url);
    domCache[data.id] = document.body.cloneNode(true);
  };

  var cachePush = function () {
    var id = PUSH.id;

    var cacheForwardStack = JSON.parse(cacheMapping.cacheForwardStack || '[]');
    var cacheBackStack    = JSON.parse(cacheMapping.cacheBackStack    || '[]');

    cacheBackStack.push(id);

    while (cacheForwardStack.length)               delete cacheMapping[cacheForwardStack.shift()];
    while (cacheBackStack.length > maxCacheLength) delete cacheMapping[cacheBackStack.shift()];

    window.history.pushState(null, '', cacheMapping[PUSH.id].url);

    cacheMapping.cacheForwardStack = JSON.stringify(cacheForwardStack);
    cacheMapping.cacheBackStack    = JSON.stringify(cacheBackStack);
  };

  var cachePop = function (id, direction) {
    var forward           = direction == 'forward';
    var cacheForwardStack = JSON.parse(cacheMapping.cacheForwardStack || '[]');
    var cacheBackStack    = JSON.parse(cacheMapping.cacheBackStack    || '[]');
    var pushStack         = forward ? cacheBackStack    : cacheForwardStack;
    var popStack          = forward ? cacheForwardStack : cacheBackStack;

    if (PUSH.id) pushStack.push(PUSH.id);
    popStack.pop();

    cacheMapping.cacheForwardStack = JSON.stringify(cacheForwardStack);
    cacheMapping.cacheBackStack    = JSON.stringify(cacheBackStack);
  };

  var getCached = function (id) {
    return JSON.parse(cacheMapping[id] || null) || {};
  };

  var getTarget = function (e) {
    var target = findTarget(e.target);

    if (
      !  target
      || e.which > 1
      || e.metaKey
      || e.ctrlKey
      || isScrolling
      || location.protocol !== target.protocol
      || location.host     !== target.host
      || !target.hash && /#/.test(target.href)
      || target.hash && target.href.replace(target.hash, '') === location.href.replace(location.hash, '')
      || target.getAttribute('data-ignore') == 'push'
    ) return;

    return target;
  };


  // Main event handlers (touchend, popstate)
  // ==========================================

  var touchend = function (e) {
    var target = getTarget(e);

    if (!target) return;

    e.preventDefault();

    PUSH({
      url        : target.href,
      hash       : target.hash,
      timeout    : target.getAttribute('data-timeout'),
      transition : target.getAttribute('data-transition')
    });
  };

  var popstate = function (e) {
    var key;
    var barElement;
    var activeObj;
    var activeDom;
    var direction;
    var transition;
    var transitionFrom;
    var transitionFromObj;
    var id = e.state;

    if (!id || !cacheMapping[id]) return;

    direction = PUSH.id < id ? 'forward' : 'back';

    cachePop(id, direction);

    activeObj = getCached(id);
    activeDom = domCache[id];

    if (activeObj.title) document.title = activeObj.title;

    if (direction == 'back') {
      transitionFrom    = JSON.parse(direction == 'back' ? cacheMapping.cacheForwardStack : cacheMapping.cacheBackStack);
      transitionFromObj = getCached(transitionFrom[transitionFrom.length - 1]);
    } else {
      transitionFromObj = activeObj;
    }

    if (direction == 'back' && !transitionFromObj.id) return PUSH.id = id;

    transition = direction == 'back' ? transitionMap[transitionFromObj.transition] : transitionFromObj.transition;

    if (!activeDom) {
      return PUSH({
        id         : activeObj.id,
        url        : activeObj.url,
        title      : activeObj.title,
        timeout    : activeObj.timeout,
        transition : transition,
        ignorePush : true
      });
    }

    if (transitionFromObj.transition) {
      activeObj = extendWithDom(activeObj, '.content', activeDom.cloneNode(true));
      for (key in bars) {
        barElement = document.querySelector(bars[key])
        if (activeObj[key]) swapContent(activeObj[key], barElement);
        else if (barElement) barElement.parentNode.removeChild(barElement);
      }
    }

    swapContent(
      (activeObj.contents || activeDom).cloneNode(true),
      document.querySelector('.content'),
      transition
    );

    PUSH.id = id;

    document.body.offsetHeight; // force reflow to prevent scroll
  };


  // Core PUSH functionality
  // =======================

  var PUSH = function (options) {
    var key;
    var data = {};
    var xhr  = PUSH.xhr;

    options.container = options.container || options.transition ? document.querySelector('.content') : document.body;

    for (key in bars) {
      options[key] = options[key] || document.querySelector(bars[key]);
    }

    if (xhr && xhr.readyState < 4) {
      xhr.onreadystatechange = noop;
      xhr.abort()
    }

    xhr = new XMLHttpRequest();
    xhr.open('GET', options.url, true);
    xhr.setRequestHeader('X-PUSH', 'true');

    xhr.onreadystatechange = function () {
      if (options._timeout) clearTimeout(options._timeout);
      if (xhr.readyState == 4) xhr.status == 200 ? success(xhr, options) : failure(options.url);
    };

    if (!PUSH.id) {
      cacheReplace({
        id         : +new Date,
        url        : window.location.href,
        title      : document.title,
        timeout    : options.timeout,
        transition : null
      });
    }

    if (options.timeout) {
      options._timeout = setTimeout(function () {  xhr.abort('timeout'); }, options.timeout);
    }

    xhr.send();

    if (xhr.readyState && !options.ignorePush) cachePush();
  };


  // Main XHR handlers
  // =================

  var success = function (xhr, options) {
    var key;
    var barElement;
    var data = parseXHR(xhr, options);

    if (!data.contents) return locationReplace(options.url);

    if (data.title) document.title = data.title;

    if (options.transition) {
      for (key in bars) {
        barElement = document.querySelector(bars[key])
        if (data[key]) swapContent(data[key], barElement);
        else if (barElement) barElement.parentNode.removeChild(barElement);
      }
    }

    swapContent(data.contents, options.container, options.transition, function () {
      cacheReplace({
        id         : options.id || +new Date,
        url        : data.url,
        title      : data.title,
        timeout    : options.timeout,
        transition : options.transition
      }, options.id);
      triggerStateChange();
    });

    if (!options.ignorePush && window._gaq) _gaq.push(['_trackPageview']) // google analytics
    if (!options.hash) return;
  };

  var failure = function (url) {
    throw new Error('Could not get: ' + url)
  };


  // PUSH helpers
  // ============

  var swapContent = function (swap, container, transition, complete) {
    var enter;
    var containerDirection;
    var swapDirection;

    if (!transition) {
      if (container) container.innerHTML = swap.innerHTML;
      else if (swap.classList.contains('content')) document.body.appendChild(swap);
      else document.body.insertBefore(swap, document.querySelector('.content'));
    } else {
      enter  = /in$/.test(transition);

      if (transition == 'fade') {
        container.classList.add('in');
        container.classList.add('fade');
        swap.classList.add('fade');
      }

      if (/slide/.test(transition)) {
        swap.classList.add(enter ? 'right' : 'left');
        swap.classList.add('slide');
        container.classList.add('slide');
      }

      container.parentNode.insertBefore(swap, container);
    }

    if (!transition) complete && complete();

    if (transition == 'fade') {
      container.offsetWidth; // force reflow
      container.classList.remove('in');
      container.addEventListener('webkitTransitionEnd', fadeContainerEnd);

      function fadeContainerEnd() {
        container.removeEventListener('webkitTransitionEnd', fadeContainerEnd);
        swap.classList.add('in');
        swap.addEventListener('webkitTransitionEnd', fadeSwapEnd);
      }
      function fadeSwapEnd () {
        swap.removeEventListener('webkitTransitionEnd', fadeSwapEnd);
        container.parentNode.removeChild(container);
        swap.classList.remove('fade');
        swap.classList.remove('in');
        complete && complete();
      }
    }

    if (/slide/.test(transition)) {
      container.offsetWidth; // force reflow
      swapDirection      = enter ? 'right' : 'left'
      containerDirection = enter ? 'left' : 'right'
      container.classList.add(containerDirection);
      swap.classList.remove(swapDirection);
      swap.addEventListener('webkitTransitionEnd', slideEnd);

      function slideEnd() {
        swap.removeEventListener('webkitTransitionEnd', slideEnd);
        swap.classList.remove('slide');
        swap.classList.remove(swapDirection);
        container.parentNode.removeChild(container);
        complete && complete();
      }
    }
  };

  var triggerStateChange = function () {
    var e = new CustomEvent('push', {
      detail: { state: getCached(PUSH.id) },
      bubbles: true,
      cancelable: true
    });

    window.dispatchEvent(e);
  };

  var findTarget = function (target) {
    var i, toggles = document.querySelectorAll('a');
    for (; target && target !== document; target = target.parentNode) {
      for (i = toggles.length; i--;) { if (toggles[i] === target) return target; }
    }
  };

  var locationReplace = function (url) {
    window.history.replaceState(null, '', '#');
    window.location.replace(url);
  };

  var parseURL = function (url) {
    var a = document.createElement('a'); a.href = url; return a;
  };

  var extendWithDom = function (obj, fragment, dom) {
    var i;
    var result    = {};

    for (i in obj) result[i] = obj[i];

    Object.keys(bars).forEach(function (key) {
      var el = dom.querySelector(bars[key]);
      if (el) el.parentNode.removeChild(el);
      result[key] = el;
    });

    result.contents = dom.querySelector(fragment);

    return result;
  };

  var parseXHR = function (xhr, options) {
    var head;
    var body;
    var data = {};
    var responseText = xhr.responseText;

    data.url = options.url;

    if (!responseText) return data;

    if (/<html/i.test(responseText)) {
      head           = document.createElement('div');
      body           = document.createElement('div');
      head.innerHTML = responseText.match(/<head[^>]*>([\s\S.]*)<\/head>/i)[0]
      body.innerHTML = responseText.match(/<body[^>]*>([\s\S.]*)<\/body>/i)[0]
    } else {
      head           = body = document.createElement('div');
      head.innerHTML = responseText;
    }

    data.title = head.querySelector('title');
    data.title = data.title && data.title.innerText && data.title.innerText.trim();

    if (options.transition) data = extendWithDom(data, '.content', body);
    else data.contents = body;

    return data;
  };


  // Attach PUSH event handlers
  // ==========================

  window.addEventListener('touchstart', function () { isScrolling = false; });
  window.addEventListener('touchmove', function () { isScrolling = true; })
  window.addEventListener('touchend', touchend);
  window.addEventListener('click', function (e) { if (getTarget(e)) e.preventDefault(); });
  window.addEventListener('popstate', popstate);

}();