/* ========================================================================
 * Mui: push.js v1.0.0
 * ======================================================================== */

/* global _gaq: true */

!(function () {
  'use strict';

  var noop = function () {};


  // Pushstate caching
  // ==================

  var isScrolling;
  var maxCacheLength = 20;
  var cacheMapping   = sessionStorage;
  var domCache       = {};
  // Change these to unquoted camelcase in the next major version bump
  var transitionMap  = {
    'slide-in'  : 'slide-out',
    'slide-out' : 'slide-in',
    fade     : 'fade'
  };

  var bars = {
    bartab             : '.bar-tab',
    barnav             : '.bar-nav',
    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) {
        if (bars.hasOwnProperty(key)) {
          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 xhr = PUSH.xhr;

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

    for (key in bars) {
      if (bars.hasOwnProperty(key)) {
        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 : options.transition
      });
    }

    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) {
        if (bars.hasOwnProperty(key)) {
          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('sliding-in', enter ? 'right' : 'left');
        swap.classList.add('sliding');
        container.classList.add('sliding');
      }

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

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

    if (transition === 'fade') {
      container.offsetWidth; // force reflow
      container.classList.remove('in');
      var fadeContainerEnd = function () {
        container.removeEventListener('webkitTransitionEnd', fadeContainerEnd);
        swap.classList.add('in');
        swap.addEventListener('webkitTransitionEnd', fadeSwapEnd);
      };
      var fadeSwapEnd = function () {
        swap.removeEventListener('webkitTransitionEnd', fadeSwapEnd);
        container.parentNode.removeChild(container);
        swap.classList.remove('fade');
        swap.classList.remove('in');
        complete && complete();
      };
      container.addEventListener('webkitTransitionEnd', fadeContainerEnd);

    }

    if (/slide/.test(transition)) {
      var slideEnd = function () {
        swap.removeEventListener('webkitTransitionEnd', slideEnd);
        swap.classList.remove('sliding', 'sliding-in');
        swap.classList.remove(swapDirection);
        container.parentNode.removeChild(container);
        complete && complete();
      };

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

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

    for (i in obj) {
      if (obj.hasOwnProperty(i)) {
        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');
    var text = 'innerText' in data.title ? 'innerText' : 'textContent';
    data.title = data.title && data.title[text].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);
  window.PUSH = PUSH;

}());
