Initial commit

lib/assets/javascripts/builder/components/stack-layout/stack-layout-model.js

@@ -0,0 +1,60 @@
+var Backbone = require('backbone');
+
+/**
+ *  Stack layout model checks and decides if next or previous
+ *  positions are possible.
+ */
+
+module.exports = Backbone.Model.extend({
+
+  defaults: {
+    position: 0
+  },
+
+  initialize: function (attrs, opts) {
+    this.stackLayoutItems = opts.stackLayoutItems;
+  },
+
+  goToStep: function (position) {
+    var stackLayoutItemsSize = this.stackLayoutItems.size();
+
+    if (position >= stackLayoutItemsSize) {
+      throw new Error('There is no ' + position + ' stack view in the collection');
+    } else {
+      this.set({
+        position: position
+      }, {
+        silent: true
+      });
+      this._rememberStep.apply(this, arguments);
+      this._triggerPositionChanged(position, Array.prototype.slice.call(arguments, 1));
+    }
+  },
+
+  nextStep: function () {
+    var currentPos = this.get('position');
+    var nextPosition = ++currentPos;
+    this.goToStep.apply(this, Array.prototype.concat.apply([nextPosition], arguments));
+  },
+
+  prevStep: function () {
+    var currentPos = this.get('position');
+    var prevPosition = --currentPos;
+    this.goToStep.apply(this, Array.prototype.concat.apply([prevPosition], arguments));
+  },
+
+  goBack: function () {
+    if (this._goBackToArguments) {
+      this.goToStep.apply(this, this._goBackToArguments);
+    }
+  },
+
+  _triggerPositionChanged: function (position, args) {
+    this.trigger('positionChanged', position, Array.prototype.slice.call(args));
+  },
+
+  _rememberStep: function () {
+    this._goBackToArguments = this._lastStepArguments || [ 0 ];
+    this._lastStepArguments = arguments;
+  }
+});