(function() {
  // bail in IE
  var doc = document;
  if (doc.all) { return; }

  var disableBuilds = false; // true; // false; //true;

  var ctr = 0;
  var spaces = /\s+/, a1 = [""];

  var toArray = function(list) {
    return Array.prototype.slice.call(list||[], 0);
  };

  var byId = function(id) {
    if (typeof id == "string") { return doc.getElementById(id); }
    return id;
  };

  var query = function(query, root) {
    if (!query) { return []; }
    if (typeof query != "string") { return toArray(query); }
    if (typeof root == "string"){
      root = byId(root);
      if(!root){ return []; }
    }

    root = root||document;
    var rootIsDoc = (root.nodeType == 9);
    var doc = rootIsDoc ? root : (root.ownerDocument||document);

    // rewrite the query to be ID rooted
    if (!rootIsDoc || (">~+".indexOf(query.charAt(0)) >= 0)) {
      root.id = root.id||("qUnique"+(ctr++));
      query = "#"+root.id+" "+query;
    }
    // don't choke on something like ".yada.yada >"
    if (">~+".indexOf(query.slice(-1)) >= 0) { query += " *"; }

    return toArray(doc.querySelectorAll(query));
  };

  var strToArray = function(s) {
    if (typeof s == "string" || s instanceof String) {
      if (s.indexOf(" ") < 0) {
        a1[0] = s;
        return a1;
      } else {
        return s.split(spaces);
      }
    }
    return s;
  };

  var trim = function(str) {
    return str.replace(/^\s\s*/, '').replace(/\s\s*$/, '');
  };

  var addClass = function(node, classStr) {
    classStr = strToArray(classStr);
    var cls = " " + node.className + " ";
    for (var i = 0, len = classStr.length, c; i < len; ++i) {
      c = classStr[i];
      if (c && cls.indexOf(" " + c + " ") < 0) {
        cls += c + " ";
      }
    }
    node.className = trim(cls);
  };

  var removeClass = function(node, classStr) {
    var cls;
    if (classStr !== undefined) {
      classStr = strToArray(classStr);
      cls = " " + node.className + " ";
      for (var i = 0, len = classStr.length; i < len; ++i) {
        cls = cls.replace(" " + classStr[i] + " ", " ");
      }
      cls = trim(cls);
    } else {
      cls = "";
    }
    if (node.className != cls) {
      node.className = cls;
    }
  };

  var toggleClass = function(node, classStr) {
    var cls = " " + node.className + " ";
    if (cls.indexOf(" " + trim(classStr) + " ") >= 0) {
      removeClass(node, classStr);
    } else {
      addClass(node, classStr);
    }
  };

  var ua = navigator.userAgent;
  var isFF = parseFloat(ua.split("Firefox/")[1]) || undefined;
  var isWK = parseFloat(ua.split("WebKit/")[1]) || undefined;
  var isOpera = parseFloat(ua.split("Opera/")[1]) || undefined;

  var canTransition = (function() {
    var ver = parseFloat(ua.split("Version/")[1]) || undefined;
    // test to determine if this browser can handle CSS transitions.
    var cachedCanTransition = 
      (isWK || (isFF && isFF > 3.6 ) || (isOpera && ver >= 10.5));
    return function() { return cachedCanTransition; }
  })();

  addClass(document.body, (isWK ? "composited" : "generic"));

  //
  // Slide class
  //
  var Slide = function(node, idx, slides) {
    this._node = node;
    if (idx >= 0) {
      this._count = idx+1;
    }
    if (this._node) {
      addClass(this._node, "slide distant-future");
    }
    this._makeCustomType();
    this._makeCounter(slides);
    this._makeBuildList();
  };

  Slide.prototype = {
    _node: null,
    _count: 0,
    _buildList: [],
    _visited: false,
    _currentState: "",
    _states: [ "distant-past", "far-past",
               "past", "current", "future",
               "far-future", "distant-future" ],
    setState: function(state) {
      if (typeof state != "string") {
        state = this._states[state];
      }
      if (state == "current" && !this._visited) {
        this._visited = true;
        this._makeBuildList();
      }
      removeClass(this._node, this._states);
      addClass(this._node, state);
      this._currentState = state;

      // delay first auto run. Really wish this were in CSS.
      /*
      this._runAutos();
      */
      var _t = this;
      setTimeout(function(){ _t._runAutos(); } , 400);
    },

    _makeCustomType: function() {
      var img = this._node.getAttribute("data-image");
      if (img) {
        this._node.style.background = "url(" + img + ") center no-repeat";
      }
    },

    _makeCounter: function(slides) {
      if(!this._count || !this._node) { return; }
      var c = doc.createElement("span");
      c.innerHTML = this._count + " / " + slides.length;
      c.className = "counter";
      this._node.appendChild(c);
    },

    _makeBuildList: function() {
      this._buildList = [];
      if (disableBuilds) { return; }
      if (this._node) {
        this._buildList = query("[data-build] > *", this._node);
      }
      this._buildList.forEach(function(el) {
        addClass(el, "to-build");
      });
    },

    _runAutos: function() {
      if (this._currentState != "current") {
        return;
      }
      // find the next auto, slice it out of the list, and run it
      var idx = -1;

      this._buildList.some(function(n, i) {
        if (n.hasAttribute("data-auto")) {
          idx = i;
          return true;
        }
        return false;
      });

      if (idx >= 0) {
        var elem = this._buildList.splice(idx, 1)[0];
        var transitionEnd = isWK ? "webkitTransitionEnd" : (isFF ? "mozTransitionEnd" : "oTransitionEnd");
        var _t = this;
        if (canTransition()) {
          var l = function(evt) {
            elem.parentNode.removeEventListener(transitionEnd, l, false);
            _t._runAutos();
          };
          elem.parentNode.addEventListener(transitionEnd, l, false);
          removeClass(elem, "to-build");
        } else {
          setTimeout(function() {
            removeClass(elem, "to-build");
            _t._runAutos();
          }, 400);
        }
      }
    },

    buildNext: function() {
      if (!this._buildList.length) {
        return false;
      }
      removeClass(this._buildList.shift(), "to-build");
      return true;
    },

  };

  //
  // SlideShow class
  //
  var SlideShow = function(slides) {
    this._slides = (slides||[]).map(function(el, idx, arr) {
      return new Slide(el, idx, arr);
    });

    var h = window.location.hash;
    try {
      this.current = parseInt(h.split('#slide')[1], 10);
    }catch (e) { /* squelch */ }
    this.current = isNaN(this.current) ? 1 : this.current;
    var _t = this;
    doc.addEventListener('keydown', 
        function(e) { _t.handleKeys(e); }, false);
    doc.addEventListener('mousewheel', 
        function(e) { _t.handleWheel(e); }, false);
    doc.addEventListener('DOMMouseScroll', 
        function(e) { _t.handleWheel(e); }, false);
    doc.addEventListener('touchstart', 
        function(e) { _t.handleTouchStart(e); }, false);
    doc.addEventListener('touchend', 
        function(e) { _t.handleTouchEnd(e); }, false);
    window.addEventListener('popstate', 
        function(e) { if (e.state) { _t.go(e.state); } }, false);
    this._update(); 
  };

  SlideShow.prototype = {
    _slides: [],
    _update: function(dontPush) {
      if (history.pushState) {
        if (!dontPush) {
          history.pushState(this.current, "Slide " + this.current, "#slide" + this.current);
        }
      } else {
        window.location.hash = "slide" + this.current;
      }
      for (var x = this.current-1; x < this.current+7; x++) {
        if (this._slides[x-4]) {
          this._slides[x-4].setState(Math.max(0, x-this.current));
        }
      }
    },

    current: 0,
    next: function() {
      if (!this._slides[this.current-1].buildNext()) {
        this.current = Math.min(this.current+1, this._slides.length);
        this._update();
      }
    },
    prev: function() {
      this.current = Math.max(this.current-1, 1);
      this._update();
    },
    go: function(num) {
      if (history.pushState && this.current != num) {
        history.replaceState(this.current, "Slide " + this.current, "#slide" + this.current);
      }
      this.current = num;
      this._update(true);
    },

    _notesOn: false,
    showNotes: function() {
      var isOn = this._notesOn = !this._notesOn;
      query(".notes").forEach(function(el) {
        el.style.display = (notesOn) ? "block" : "none";
      });
    },
    switch3D: function() {
      toggleClass(document.body, "three-d");
    },
    handleWheel: function(e) {
      var delta = 0;
      if (e.wheelDelta) {
        delta = e.wheelDelta/120;
        if (isOpera) {
          delta = -delta; 
        }
      } else if (e.detail) { 
        delta = -e.detail/3;
      }

      if (delta > 0 ) {
        this.prev();
        return;
      }
      if (delta < 0 ) {
        this.next();
        return;
      }
    },
    handleKeys: function(e) {
      switch (e.keyCode) {
        case 37: // left arrow
          this.prev(); break;
        case 39: // right arrow
        case 32: // space
          this.next(); break;
        case 50: // 2
          this.showNotes(); break;
        case 51: // 3
          this.switch3D(); break;
      }
    },
    _touchStartX: 0,
    handleTouchStart: function(e) {
      this._touchStartX = e.touches[0].pageX;
    },
    handleTouchEnd: function(e) {
      var delta = this._touchStartX - e.changedTouches[0].pageX;
      var SWIPE_SIZE = 150;
      if (delta > SWIPE_SIZE) {
        this.next();
      } else if (delta< -SWIPE_SIZE) {
        this.prev();
      }
    },
  };

  // Initialize
  var slideshow = new SlideShow(query(".slide"));
})();