add File storage class and tests

js/models/storage/File.js

@@ -0,0 +1,87 @@
+'use strict';
+var imports = require('soop').imports();
+var fs = imports.fs || require('fs');
+
+function Storage(opts) {
+  opts = opts || {};
+
+  this.data = {};
+  this.filename = opts.filename;
+}
+
+Storage.prototype.load = function(callback) {
+  if (!this.filename)
+    throw new Error('No filename');
+
+  fs.readFile(this.filename, function(err, data) {
+    if (err) return callback(err);
+
+    try {
+      this.data = JSON.parse(data);
+    } catch (err) {
+      return callback(err);
+    }
+
+    return callback(null);
+  });
+};
+
+Storage.prototype.save = function(callback) {
+  var data = JSON.stringify(this.data);
+
+  //TODO: update to use a queue to ensure that saves are made sequentially
+  fs.writeFile(this.filename, data, function(err) {
+    return callback(err);
+  });
+};
+
+Storage.prototype._read = function(k) {
+  return this.data[k];
+};
+
+Storage.prototype._write = function(k, v, callback) {
+  this.data[k] = v;
+  this.save(callback);
+};
+
+// get value by key
+Storage.prototype.getGlobal = function(k) {
+  return this.data[k];
+};
+
+// set value for key
+Storage.prototype.setGlobal = function(k, v, callback) {
+  this._write(k, v, callback);
+};
+
+// remove value for key
+Storage.prototype.removeGlobal = function(k, callback) {
+  delete this.data[k];
+  this.save(callback);
+};
+
+Storage.prototype._key = function(walletId, k) {
+  return walletId + '::' + k;
+};
+// get value by key
+Storage.prototype.get = function(walletId, k) {
+  return this.getGlobal(this._key(walletId, k));
+};
+
+// set value for key
+Storage.prototype.set = function(walletId, k, v, callback) {
+  this.setGlobal(this._key(walletId,k), v, callback);
+};
+
+// remove value for key
+Storage.prototype.remove = function(walletId, k, callback) {
+  this.removeGlobal(this._key(walletId, k), callback);
+};
+
+// remove all values
+Storage.prototype.clearAll = function(callback) {
+  this.data = {};
+  this.save(callback);
+};     
+
+module.exports = require('soop')(Storage);