angular.module('ionic.service.view', ['ui.router'])


.run(     ['$rootScope', '$state', '$location', '$document', 
  function( $rootScope,   $state,   $location,   $document) {

  // init the variables that keep track of the view history
  $rootScope.$viewHistory = {
    histories: { root: { historyId: 'root', parentHistoryId: null, stack: [], cursor: -1 } },
    backView: null,
    forwardView: null,
    currentView: null
  };

  $rootScope.$on('viewState.changeHistory', function(e, data) {
    if(!data) return;

    var hist = (data.historyId ? $rootScope.$viewHistory.histories[ data.historyId ] : null );
    if(hist && hist.cursor > -1 && hist.cursor < hist.stack.length) {
      // the history they're going to already exists
      // go to it's last view in its stack
      var view = hist.stack[ hist.cursor ];
      return view.go(data);
    }

    // this history does not have a URL, but it does have a uiSref
    // figure out its URL from the uiSref
    if(!data.url && data.uiSref) {
      data.url = $state.href(data.uiSref);
    }
    
    if(data.url) {
      // don't let it start with a #, messes with $location.url()
      if(data.url.indexOf('#') === 0) {
        data.url = data.url.replace('#', '');
      }
      if(data.url !== $location.url()) {
        // we've got a good URL, ready GO!
        $location.url(data.url);
      }
    }
  });

  // Set the document title when a new view is shown
  $rootScope.$on('viewState.viewEnter', function(e, data) {
    if(data && data.title) {
      $document[0].title = data.title;
    }
  });

}])

.factory('$ionicViewService', ['$rootScope', '$state', '$location', '$window', '$injector', 
                      function( $rootScope,   $state,   $location,   $window,   $injector) {
  var $animate = $injector.has('$animate') ? $injector.get('$animate') : false;

  var View = function(){};
  View.prototype.initialize = function(data) {
    if(data) {
      for(var name in data) this[name] = data[name];
      return this;
    }
    return null;
  };
  View.prototype.go = function(opts) {

    if(this.stateName) {
      return $state.go(this.stateName, this.stateParams);
    }

    if(this.url && this.url !== $location.url()) {

      if($rootScope.$viewHistory.backView === this) {
        return $window.history.go(-1);
      } else if($rootScope.$viewHistory.forwardView === this) {
        return $window.history.go(1);
      }

      $location.url(this.url);
      return;
    }

    return null;
  };
  View.prototype.destory = function() {
    if(this.scope) {
      this.scope.destory && this.scope.destory();
      this.scope = null;
    }
  };

  function createViewId(stateId) {
    return ('_' + stateId + '_' + Math.round(Math.random() * 99999999)).replace(/\./g, '_');
  }

  return {

    register: function(containerScope) {
      var viewHistory = $rootScope.$viewHistory,
          currentStateId = this.getCurrentStateId(),
          hist = this._getHistory(containerScope),
          currentView = viewHistory.currentView,
          backView = viewHistory.backView,
          forwardView = viewHistory.forwardView,
          rsp = {
            viewId: null,
            navAction: null,
            navDirection: null,
            historyId: hist.historyId
          };

      if(currentView && 
         currentView.stateId === currentStateId &&
         currentView.historyId === hist.historyId) {
        // do nothing if its the same stateId in the same history
        rsp.navAction = 'noChange';
        return rsp;
      }

      if(backView && backView.stateId === currentStateId) {
        // they went back one, set the old current view as a forward view
        rsp.viewId = backView.viewId;
        rsp.navAction = 'moveBack';
        if(backView.historyId === currentView.historyId) {
          // went back in the same history
          rsp.navDirection = 'back';
        }

      } else if(forwardView && forwardView.stateId === currentStateId) {
        // they went to the forward one, set the forward view to no longer a forward view
        rsp.viewId = forwardView.viewId;
        rsp.navAction = 'moveForward';
        if(forwardView.historyId === currentView.historyId) {
          rsp.navDirection = 'forward';
        }

        var parentHistory = this._getParentHistoryObj(containerScope);
        if(forwardView.historyId && parentHistory.scope) {
          // if a history has already been created by the forward view then make sure it stays the same
          parentHistory.scope.$historyId = forwardView.historyId;
          rsp.historyId = forwardView.historyId;
        }

      } else if(currentView && currentView.historyId !== hist.historyId && 
                hist.cursor > -1 && hist.stack.length > 0 && hist.cursor < hist.stack.length &&
                hist.stack[hist.cursor].stateId === currentStateId) {
        // they just changed to a different history and the history already has views in it
        rsp.viewId = hist.stack[hist.cursor].viewId;
        rsp.navAction = 'moveBack';

      } else {

        // set a new unique viewId
        rsp.viewId = createViewId(currentStateId);

        if(currentView) {
          // set the forward view if there is a current view (ie: if its not the first view)
          currentView.forwardViewId = rsp.viewId;

          // its only moving forward if its in the same history
          if(hist.historyId === currentView.historyId) {
            rsp.navDirection = 'forward';
          }
          rsp.navAction = 'newView';

          // check if there is a new forward view
          if(forwardView && currentView.stateId !== forwardView.stateId) {
            // they navigated to a new view but the stack already has a forward view
            // since its a new view remove any forwards that existed
            var forwardsHistory = this._getView(forwardView.historyId);
            if(forwardsHistory) {
              // the forward has a history
              for(var x=forwardsHistory.stack.length - 1; x >= forwardView.index; x--) {
                // starting from the end destory all forwards in this history from this point
                forwardsHistory.stack[x].destory();
                forwardsHistory.stack.splice(x);
              }
            }
          }

        } else {
          // there's no current view, so this must be the initial view
          rsp.navAction = 'initialView';
        }

        // add the new view to the stack
        viewHistory.histories[rsp.viewId] = this.createView({ 
          viewId: rsp.viewId,
          index: hist.stack.length,
          historyId: hist.historyId,
          backViewId: (currentView && currentView.viewId ? currentView.viewId : null),
          forwardViewId: null,
          stateId: currentStateId,
          stateName: this.getCurrentStateName(),
          stateParams: this.getCurrentStateParams(),
          url: $location.url()
        });

        // add the new view to this history's stack
        hist.stack.push(viewHistory.histories[rsp.viewId]);
      }

      this.setNavViews(rsp.viewId);

      hist.cursor = viewHistory.currentView.index;

      return rsp;
    },

    setNavViews: function(viewId) {
      var viewHistory = $rootScope.$viewHistory;

      viewHistory.currentView = this._getView(viewId);
      viewHistory.backView = this._getBackView(viewHistory.currentView);
      viewHistory.forwardView = this._getForwardView(viewHistory.currentView);

      $rootScope.$broadcast('$viewHistory.historyChange', {
        showBack: (viewHistory.backView && viewHistory.backView.historyId === viewHistory.currentView.historyId)
      });
    },

    registerHistory: function(scope) {
      scope.$historyId = 'h' + Math.round(Math.random() * 99999999999);
    },

    createView: function(data) {
      var newView = new View();
      return newView.initialize(data);
    },

    getCurrentView: function() {
      return $rootScope.$viewHistory.currentView;
    },

    getBackView: function() {
      return $rootScope.$viewHistory.backView;
    },

    getForwardView: function() {
      return $rootScope.$viewHistory.forwardView;
    },

    getNavDirection: function() {
      return $rootScope.$viewHistory.navDirection;
    },

    getCurrentStateName: function() {
      return ($state && $state.current ? $state.current.name : null);
    },

    isCurrentStateNavView: function(navView) {
      return ($state && 
              $state.current && 
              $state.current.views && 
              $state.current.views[navView] ? true : false);
    },

    getCurrentStateParams: function() {
      var rtn;
      if ($state && $state.params) {
        for(var key in $state.params) {
          if($state.params.hasOwnProperty(key)) {
            rtn = rtn || {};
            rtn[key] = $state.params[key];
          }
        }
      }
      return rtn;
    },

    getCurrentStateId: function() {
      var id;
      if($state && $state.current && $state.current.name) {
        id = $state.current.name;
        if($state.params) {
          for(var key in $state.params) {
            if($state.params.hasOwnProperty(key) && $state.params[key]) {
              id += "_" + key + "=" + $state.params[key];
            }
          }
        }
        return id;
      }
      // if something goes wrong make sure its got a unique stateId
      return 'r' + Math.round(Math.random() * 9999999);
    },

    _getView: function(viewId) {
      return (viewId ? $rootScope.$viewHistory.histories[ viewId ] : null );
    },

    _getBackView: function(view) {
      return (view ? this._getView(view.backViewId) : null );
    },

    _getForwardView: function(view) {
      return (view ? this._getView(view.forwardViewId) : null );
    },

    _getHistory: function(scope) {
      var histObj = this._getParentHistoryObj(scope);

      if( !$rootScope.$viewHistory.histories[ histObj.historyId ] ) {
        // this history object exists in parent scope, but doesn't
        // exist in the history data yet
        $rootScope.$viewHistory.histories[ histObj.historyId ] = { 
          historyId: histObj.historyId, 
          parentHistoryId: this._getParentHistoryObj(histObj.scope.$parent).historyId,
          stack: [],
          cursor: -1
        };
      }

      return $rootScope.$viewHistory.histories[ histObj.historyId ];
    },

    _getParentHistoryObj: function(scope) {
      var parentScope = scope;
      while(parentScope) {
        if(parentScope.hasOwnProperty('$historyId')) {
          // this parent scope has a historyId
          return { historyId: parentScope.$historyId, scope: parentScope };
        }
        // nothing found keep climbing up
        parentScope = parentScope.$parent;
      }
      // no history for for the parent, use the root
      return { historyId: 'root', scope: $rootScope };
    },

    transition: function(opts) {
      if(!opts || !opts.enteringElement) return;

      if (opts.leavingScope) {
        opts.leavingScope.$destroy();
        opts.leavingScope = null;
      }

      // use the directive's animation attribute first
      // if it doesn't exist, then use the given animation
      var animationClass = opts.animation || getAnimationClass();

      if($animate && animationClass && opts.doAnimation !== false && opts.navDirection) {
        // set the animation we're gonna use
        this.setAnimationClass(opts.parentElement, animationClass, opts.navDirection);
        opts.enteringElement.addClass('ng-enter');

        // disable any pointer-events from being able to fire
        document.body.classList.add('disable-pointer-events');

        // start the animations
        if(opts.leavingElement) {
          $animate.leave(opts.leavingElement, function() {
            // re-enable pointer-events
            document.body.classList.remove('disable-pointer-events');
          });
        }
        $animate.enter(opts.enteringElement, opts.parentElement);

      } else {
        // no animation, just plain ol' add/remove DOM elements
        if(opts.leavingElement) {
          opts.leavingElement.remove();
        }
        opts.parentElement.append(opts.enteringElement);
      }

      function getAnimationClass(){
        // go up the ancestors looking for an animation value
        var climbScope = opts.enteringScope;
        while(climbScope) {
          if(climbScope.animation) {
            return climbScope.animation;
          }
          climbScope = climbScope.$parent;
        }
      }
    },

    setAnimationClass: function(element, animationClass, navDirection) {
      // add the animation we're gonna use
      element[0].classList.add(animationClass);

      if(navDirection === 'back') {
        // animate backward
        element[0].classList.add('reverse');
      } else {
        // defaults to animate forward
        // make sure the reverse class isn't already added
        element[0].classList.remove('reverse');
      }
    },

    clearHistory: function() {
      var historyId, x, view,
      histories = $rootScope.$viewHistory.histories,
      currentView = $rootScope.$viewHistory.currentView;

      for(historyId in histories) {

        if(histories[historyId].stack) {
          histories[historyId].stack = [];
          histories[historyId].cursor = -1;
        }

        if(currentView.historyId === historyId) {
          currentView.backViewId = null;
          currentView.forwardViewId = null;
          histories[historyId].stack.push(currentView);
        } else if(histories[historyId].destroy) {
          histories[historyId].destroy();
        }

      }

      this.setNavViews(currentView.viewId);
    }

  };

}]);