//  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 URLs on the command 
// line. It will re-spawn itself to each of the URLs. Each instance will 
// increment a number stored in a central counter store, using the advert service.
//
//
// example usage (slightly shortened):
//
//   merzky@boskop:~/saga/core/examples/tutorial$ saga-advert remove_entry /tutorial/depending_jobs/counter
//
//   merzky@boskop:~/saga/core/examples/tutorial$ saga-advert dump_directory /tutorial/depending_jobs/
//     /tutorial/depending_jobs/
//
//   merzky@boskop:~/saga/core/examples/tutorial$ make && ./depending_jobs fork://localhost fork://localhost
//   advert entry does not yet exist - initialize counter to 0
//
//   merzky@boskop:~/saga/core/examples/tutorial$ saga-advert dump_directory /tutorial/depending_jobs/
//     /tutorial/depending_jobs/
//         /tutorial/depending_jobs/counter
//           value     	: 2
//
//   merzky@boskop:~/saga/core/examples/tutorial$ make && ./depending_jobs fork://localhost fork://localhost
//
//   merzky@boskop:~/saga/core/examples/tutorial$ saga-advert dump_directory /tutorial/depending_jobs/
//     /tutorial/depending_jobs/
//         /tutorial/depending_jobs/counter
//           value     	: 4
//
///////////////////////////////////////////////////////////////////////////////
#define RESULT_STORE  "/tutorial/depending_jobs/counter"   // place in advert to store counter to
#define JOB_PATH      "./depending_jobs"                  // put the correct path here

///////////////////////////////////////////////////////////////////////////////
// retrieve the current value from the advert (counter store)
bool get_counter(int& counter)
{
    counter = 0;
    try {
        saga::advert::entry e (RESULT_STORE, saga::advert::Read);
        counter = boost::lexical_cast <int> (e.get_attribute ("value"));
    }
    catch (saga::does_not_exist const& e) {
        std::cout << "advert entry does not yet exist - initialize counter to 0" << std::endl;
        counter = 0;
        return true;
    }
    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 (counter store)
bool set_counter(int counter)
{
    try {
        saga::advert::entry e(RESULT_STORE, 
                              saga::advert::CreateParents | saga::advert::Create | saga::advert::ReadWrite);
        e.set_attribute ("value", boost::lexical_cast <std::string> (counter));
    }
    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 counter
void respawn(int argc, char *argv[])
{
    assert(argc > 1);     // we shouldn't end up here without any given URL
    try 
    {
        // start the johb server on the given URL   
        saga::url url (argv[1]);
        saga::job::service js (url);

        // 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 
        saga::job::job j = js.run_job(commandline);

        // 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 URLs are given, we're done!
        int counter = 0;
        if (get_counter(counter))
            std::cout << "The overall counter is: " << counter << std::endl;
    }
    else {
    // otherwise get current value, increment it, and store new value
        int counter = 0;
        get_counter (counter);   // will set counter to zero initially

        // re-spawn this job, increment counter
        // if set_counter fails, don't bother to respawn
        if (set_counter(counter + 1)) 
            respawn(argc, argv);
    }

    return 0;
}