helper: ScenarioHelper to simplify writing basic simulation scenarios

Primary use of the ScenarioHelper will be in the unit tests, but it can
also be used to write real simulation scenarios.

Change-Id: I3b8c6370d4e5e35c8b36d91e19aa11d18ab46fdc
diff --git a/helper/ndn-scenario-helper.hpp b/helper/ndn-scenario-helper.hpp
new file mode 100644
index 0000000..0085f58
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+++ b/helper/ndn-scenario-helper.hpp
@@ -0,0 +1,169 @@
+/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
+/**
+ * Copyright (c) 2011-2015  Regents of the University of California.
+ *
+ * This file is part of ndnSIM. See AUTHORS for complete list of ndnSIM authors and
+ * contributors.
+ *
+ * ndnSIM is free software: you can redistribute it and/or modify it under the terms
+ * of the GNU General Public License as published by the Free Software Foundation,
+ * either version 3 of the License, or (at your option) any later version.
+ *
+ * ndnSIM is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
+ * without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
+ * PURPOSE.  See the GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * ndnSIM, e.g., in COPYING.md file.  If not, see <http://www.gnu.org/licenses/>.
+ **/
+
+#include "ndn-stack-helper.hpp"
+
+#include "ns3/net-device.h"
+#include "ns3/node.h"
+
+#include <ndn-cxx/name.hpp>
+#include <map>
+
+namespace ns3 {
+namespace ndn {
+
+/**
+ * @ingroup ndn-helpers
+ * @brief Helper class to simplify writing basic simulation scenarios
+ *
+ * The following code with scenario helper creates a 3-node topology,
+ * with manual routes between nodes and 2 applications, installed on first and last node
+ * of the topology:
+ *
+ *     ScenarioHelper helper;
+ *     helper.createTopology({
+ *         {"1", "2"},
+ *         {"2", "3"}
+ *       });
+ *
+ *     helper.addRoutes({
+ *         {"1", "2", "/prefix", 1},
+ *         {"2", "3", "/prefix", 1}
+ *       });
+ *
+ *     helper.addApps({
+ *         {"1", "ns3::ndn::ConsumerCbr",
+ *             {{"Prefix", "/prefix"}, {"Frequency", "1"}},
+ *             "0s", "100s"},
+ *         {"3", "ns3::ndn::Producer",
+ *             {{"Prefix", "/prefix"}, {"PayloadSize", "1024"}},
+ *             "0s", "100s"}
+ *       });
+ *
+ */
+class ScenarioHelper
+{
+public:
+  /**
+   * @brief Route information for addRoutes method
+   *
+   * It is preferred to use initializer list to indirectly pass RouteInfo's to addRoutes
+   * method.
+   */
+  struct RouteInfo
+  {
+    std::string node1;
+    std::string node2;
+    Name prefix;
+    int32_t metric;
+  };
+
+  /*
+   * @brief Application information for addApps method
+   *
+   * It is preferred to use initializer list to indirectly pass AppInfo's to addApps
+   * method.
+   */
+  struct AppInfo
+  {
+    std::string node;
+    std::string name;
+    std::initializer_list<std::pair<std::string, std::string>> params;
+    std::string start;
+    std::string end;
+  };
+
+public:
+  ScenarioHelper();
+
+  /**
+   * @brief Create topology
+   * @throw std::logic_error if createTopology is called more than once
+   *
+   * Example:
+   *
+   *     ScenarioHelper helper;
+   *     helper.createTopology({
+   *         {"1", "2"},
+   *         {"2", "3"}
+   *       });
+   */
+  void
+  createTopology(std::initializer_list<std::initializer_list<std::string>/*node clique*/> topology);
+
+  /**
+   * @brief Create routes between topology nodes
+   * @throw std::invalid_argument if the nodes or links between nodes do not exist
+   *
+   * Example:
+   *
+   *     helper.addRoutes({
+   *         {"1", "2", "/prefix", 1},
+   *         {"2", "3", "/prefix", 1}
+   *       });
+   */
+  void
+  addRoutes(std::initializer_list<RouteInfo> routes);
+
+  /**
+   * @brief Create and install application on nodes
+   * @throw std::invalid_argument if the nodes or links between nodes do not exist
+   *
+   * Example:
+   *
+   *     helper.addApps({
+   *         {"1", "ns3::ndn::ConsumerCbr",
+   *             {{"Prefix", "/prefix"}, {"Frequency", "1"}},
+   *             "0s", "100s"},
+   *         {"3", "ns3::ndn::Producer",
+   *             {{"Prefix", "/prefix"}, {"PayloadSize", "1024"}},
+   *             "0s", "100s"}
+   *       });
+   */
+  void
+  addApps(std::initializer_list<AppInfo> apps);
+
+public: // topology accessors
+  /**
+   * @brief Get node
+   * @throw std::invalid_argument if the node does not exist
+   */
+  Ptr<Node>
+  getNode(const std::string& nodeName);
+
+  /**
+   * @brief Get face on the @p node1 pointing towards @p node2
+   * @throw std::invalid_argument if the link does not exist
+   */
+  shared_ptr<Face>
+  getFace(const std::string& node1, const std::string& node2);
+
+private:
+  Ptr<Node>
+  getOrCreateNode(const std::string& nodeName);
+
+private:
+  bool m_isTopologyInitialized;
+  StackHelper ndnHelper;
+  std::map<std::string, std::map<std::string, Ptr<NetDevice>>> links;
+  std::map<std::string, Ptr<Node>> nodes;
+};
+
+} // namespace ndn
+} // namespace ns3