include <RoundRobin.h>
  include <stdexcept>
  include <iostream>
  using namespace std;
  
  //
  // Forward declaration for NetworkRequest
  // Implementation details omitted
  //
  class NetworkRequest {};
  
  //
  // Simple Host class that serves as a proxy for a physical machine.
  // Implementation details omitted.
  //
  class Host
  {
  public:
    //
    // Implementation of processRequest would forward
    // the request to the network host represented by the
    // object. Omitted here.
    //
    void processRequest(NetworkRequest& request) {} 
  };
  
  //
  // Simple load balancer that distributes incoming requests
  // to its hosts using a round-robin scheme.
  //
  class LoadBalancer
  {
  public:
    //
    // Constructor takes a vector of hosts.
    //
    LoadBalancer(const vector<Host>& hosts);
    ~LoadBalancer() {}
  
    //
    // Ship the incoming request to the next host using
    // a round-robin scheduling algorithm
    //
    void distributeRequest(NetworkRequest& request);
  
  protected:
    RoundRobin<Host> rr;
  };
  
  LoadBalancer::LoadBalancer(const vector<Host>& hosts)
  {
    // add the hosts
    for (size_t i = 0; i < hosts.size(); ++i) {
      rr.add(hosts[i]);
    }
  }
  
  void LoadBalancer::distributeRequest(NetworkRequest& request)
  {
    try {
      rr.getNext().processRequest(request);
    } catch (out_of_range& e) {
      cerr << "No more hosts.\n";
    }
  }
  
  int main(int argc, char** argv)
  {
    vector<Host> hosts;
    hosts.push_back(Host());
    hosts.push_back(Host());
    hosts.push_back(Host());
    LoadBalancer lb(hosts);
    NetworkRequest r;
    lb.distributeRequest(r);
    lb.distributeRequest(r);
    lb.distributeRequest(r);
    lb.distributeRequest(r);
    lb.distributeRequest(r);
    lb.distributeRequest(r);
  }