add session model

lib/model/index.js

@@ -8,5 +8,6 @@ Model.Notification = require('./notification');
 Model.Preferences = require('./preferences');
 Model.Email = require('./email');
 Model.TxNote = require('./txnote');
+Model.Session = require('./session');
 
 module.exports = Model;

lib/model/session.js

@@ -0,0 +1,52 @@
+var _ = require('lodash');
+var Uuid = require('uuid');
+
+var Defaults = require('../common/defaults');
+
+function Session() {};
+
+Session.create = function(opts) {
+  opts = opts || {};
+
+  var now = Math.floor(Date.now() / 1000);
+
+  var x = new Session();
+
+  x.id = Uuid.v4();
+  x.version = 1;
+  x.createdOn = now;
+  x.updatedOn = now;
+  x.copayerId = opts.copayerId;
+  x.walletId = opts.walletId;
+
+  return x;
+};
+
+Session.fromObj = function(obj) {
+  var x = new Session();
+
+  x.id = obj.id;
+  x.version = obj.version;
+  x.createdOn = obj.createdOn;
+  x.updatedOn = obj.updatedOn;
+  x.copayerId = obj.copayerId;
+  x.walletId = obj.walletId;
+
+  return x;
+};
+
+Session.prototype.toObject = function() {
+  return this;
+};
+
+Session.prototype.isValid = function() {
+  var now = Math.floor(Date.now() / 1000);
+  return (now - this.updatedOn) <= Defaults.SESSION_EXPIRATION;
+};
+
+Session.prototype.touch = function() {
+  var now = Math.floor(Date.now() / 1000);
+  this.updatedOn = now;
+};
+
+module.exports = Session;