//  Copyright (c) 2005-2009 Hartmut Kaiser
// 
//  Distributed under the Boost Software License, Version 1.0. (See accompanying 
//  file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)

#include <iostream>
#include <cassert>
#include <saga/saga.hpp>
#include <boost/lexical_cast.hpp>

///////////////////////////////////////////////////////////////////////////////
// Start this example by providing an arbitrary number of hosts on the command 
// line. It will re-spawn itself on each of the hosts. Each instance will 
// increment a number stored in a central result store.

///////////////////////////////////////////////////////////////////////////////
#define RESULT_STORE  "/tutorial/depending_jobs/result"   // place in advert to store result to
#define JOB_PATH      "./depending_jobs"                  // put the correct path here

///////////////////////////////////////////////////////////////////////////////
// retrieve the current value from the advert (result store)
bool get_result(int& result)
{
    result = 0;
    try {
        saga::advert::entry e(RESULT_STORE, 
                              saga::advert::CreateParents | saga::advert::Create | saga::advert::Read);
        result = e.retrieve_object <int> ();
    }
    catch (saga::exception const& e) {
        if (e.get_error() != saga::NoSuccess)
            std::cerr << "saga::exception caught: " << e.what () << std::endl;
        return false;
    }
    catch (std::exception const& e) {
        std::cerr << "std::exception caught: " << e.what () << std::endl;
        return false;
    }
    catch (...) {
        std::cerr << "unexpected exception caught" << std::endl;
        return false;
    }
    return true;
}

///////////////////////////////////////////////////////////////////////////////
// store the current value into the advert (result store)
bool set_result(int result)
{
    try {
        saga::advert::entry e(RESULT_STORE, 
            saga::advert::CreateParents | saga::advert::Create | saga::advert::ReadWrite);
        e.store_object (result);
    }
    catch (saga::exception const& e) {
        std::cerr << "saga::exception caught: " << e.what () << std::endl;
        return false;
    }
    catch (std::exception const& e) {
        std::cerr << "std::exception caught: " << e.what () << std::endl;
        return false;
    }
    catch (...) {
        std::cerr << "unexpected exception caught" << std::endl;
        return false;
    }
    return true;
}

///////////////////////////////////////////////////////////////////////////////
// the routine spawning the SAGA jobs and waiting for their results
void respawn(int argc, char *argv[])
{
    assert(argc > 1);     // we shouldn't end up here without any given hosts
    try {
        saga::job::service js (argv[1]);

        // compose the command line, skip first argument
        std::string commandline (JOB_PATH);
        for (int i = 2; i < argc; ++i) {
            commandline += " ";
            commandline += argv[i];
        }

        // run the job on host given by first argument
        saga::job::job j = js.run_job(commandline, argv[1]);

        // wait for the job to start
        saga::job::state s = j.get_state();
        while (s != saga::job::Running && s != saga::job::Failed)
            s = j.get_state();

        // if the job didn't start successfully, print error message
        if (s == saga::job::Failed) {
            std::cerr << "SAGA job: " << j.get_job_id() << " failed (state: " 
                      << saga::job::detail::get_state_name(s) << ")\n";
        }

        // wait for the job to Finish
        s = j.get_state();
        while (s == saga::job::Running)
            s = j.get_state();
    }
    catch (saga::exception const& e) {
        std::cerr << "saga::exception caught: " << e.what () << std::endl;
    }
    catch (std::exception const& e) {
        std::cerr << "std::exception caught: " << e.what () << std::endl;
    }
    catch (...) {
        std::cerr << "unexpected exception caught" << std::endl;
    }
}

///////////////////////////////////////////////////////////////////////////////
int main(int argc, char* argv[])
{
    if (argc == 1) {
    // no more hosts are given, we're done!
        int result = 0;
        if (get_result(result))
            std::cout << "The overall result is: " << result << std::endl;
    }
    else {
    // otherwise get current value, increment it, and store new value
        int result = 0;
        get_result(result);   // ignore errors, will set result to zero

        // re-spawn this job, increment result
        if (set_result(result + 1)) 
            respawn(argc, argv);
    }
    return 0;
}