# include <boost/thread.hpp>
# include <cppad/cppad.hpp>
# include "../team_thread.hpp"
# define MAX_NUMBER_THREADS 48

namespace {
     using CppAD::thread_alloc;

     // number of threads in the team
     size_t num_threads_ = 1;

     // no need to cleanup up thread specific data
     void cleanup(size_t*)
     {     return; }

     // thread specific pointer the thread number (initialize as null)
     boost::thread_specific_ptr<size_t> thread_num_ptr_(cleanup);

     // type of the job currently being done by each thread
     enum thread_job_t { init_enum, work_enum, join_enum } thread_job_;

     // barrier used to wait for other threads to finish work
     boost::barrier* wait_for_work_ = CPPAD_NULL;

     // barrier used to wait for master thread to set next job
     boost::barrier* wait_for_job_ = CPPAD_NULL;

     // Are we in sequential mode; i.e., other threads are waiting for
     // master thread to set up next job ?
     bool sequential_execution_ = true;

     // structure with information for one thread
     typedef struct {
          // The thread
          boost::thread*       bthread;
          // CppAD thread number as global (pointed to by thread_num_ptr_)
          size_t               thread_num;
          // true if no error for this thread, false otherwise.
          bool                 ok;
     } thread_one_t;

     // vector with information for all threads
     thread_one_t thread_all_[MAX_NUMBER_THREADS];

     // pointer to function that does the work for one thread
     void (* worker_)(void) = CPPAD_NULL;

     // ---------------------------------------------------------------------
     // in_parallel()
     bool in_parallel(void)
     {     return ! sequential_execution_; }

     // ---------------------------------------------------------------------
     // thread_number()
     size_t thread_number(void)
     {     // return thread_all_[thread_num].thread_num
          return *thread_num_ptr_.get();
     }
     // --------------------------------------------------------------------
     // function that gets called by boost thread constructor
     void thread_work(size_t thread_num)
     {     bool ok = wait_for_work_ != CPPAD_NULL;
          ok     &= wait_for_job_  != CPPAD_NULL;
          ok     &= thread_num     != 0;

          // thread specific storage of thread number for this thread
          thread_num_ptr_.reset(& thread_all_[thread_num].thread_num );

          while( true )
          {
               // Use wait_for_jog_ to give master time in sequential mode
               // (so it can change global information like thread_job_)
               wait_for_job_->wait();

               // case where we are terminating this thread (no more work)
               if( thread_job_ == join_enum)
                    break;

               // only other case once wait_for_job_ has been completed (so far)
               ok &= thread_job_ == work_enum;
               worker_();

               // Use wait_for_work_ to inform master that our work is done and
               // that this thread will not use global infromation until
               // passing its barrier wait_for_job_ above.
               wait_for_work_->wait();

          }
          thread_all_[thread_num].ok &= ok;
          return;
     }
}

bool team_create(size_t num_threads)
{     bool ok = true;;

     if( num_threads > MAX_NUMBER_THREADS )
     {     std::cerr << "team_create: num_threads greater than ";
          std::cerr << MAX_NUMBER_THREADS << std::endl;
          exit(1);
     }
     // check that we currently do not have multiple threads running
     ok  = num_threads_ == 1;
     ok &= wait_for_work_ == CPPAD_NULL;
     ok &= wait_for_job_  == CPPAD_NULL;
     ok &= sequential_execution_;

     size_t thread_num;
     for(thread_num = 0; thread_num < num_threads; thread_num++)
     {     // Each thread gets a pointer to its version of this thread_num
          // so it knows which section of thread_all it is working with
          thread_all_[thread_num].thread_num = thread_num;

          // initialize
          thread_all_[thread_num].ok = true;
          thread_all_[0].bthread     = CPPAD_NULL;
     }
     // Finish setup of thread_all_ for this thread
     thread_num_ptr_.reset(& thread_all_[0].thread_num);

     // Now that thread_number() has necessary information for the case
     // num_threads_ == 1, and while still in sequential mode,
     // call setup for using CppAD::AD<double> in parallel mode.
     thread_alloc::parallel_setup(num_threads, in_parallel, thread_number);
     thread_alloc::hold_memory(true);
     CppAD::parallel_ad<double>();

     // now change num_threads_ to its final value.
     num_threads_ = num_threads;

     // initialize two barriers, one for work done, one for new job ready
     wait_for_work_ = new boost::barrier( (unsigned int) num_threads );
     wait_for_job_  = new boost::barrier( (unsigned int) num_threads );

     // initial job for the threads
     thread_job_           = init_enum;
     if( num_threads > 1 )
          sequential_execution_ = false;

     // This master thread is already running, we need to create
     // num_threads - 1 more threads
     for(thread_num = 1; thread_num < num_threads; thread_num++)
     {     // Create the thread with thread number equal to thread_num
          thread_all_[thread_num].bthread =
               new boost::thread(thread_work, thread_num);
     }

     // Current state is other threads are at wait_for_job_.
     // This master thread (thread zero) has not completed wait_for_job_
     sequential_execution_ = true;
     return ok;
}

bool team_work(void worker(void))
{
     // Current state is other threads are at wait_for_job_.
     // This master thread (thread zero) has not completed wait_for_job_
     bool ok = sequential_execution_;
     ok     &= thread_number() == 0;
     ok     &= wait_for_work_  != CPPAD_NULL;
     ok     &= wait_for_job_   != CPPAD_NULL;

     // set global version of this work routine
     worker_ = worker;

     // set the new job that other threads are waiting for
     thread_job_ = work_enum;

     // Enter parallel exectuion when master thread calls wait_for_job_
     if( num_threads_ > 1 )
          sequential_execution_ = false;
     wait_for_job_->wait();

     // Now do the work in this thread and then wait
     // until all threads have completed wait_for_work_
     worker();
     wait_for_work_->wait();

     // Current state is other threads are at wait_for_job_.
     // This master thread (thread zero) has not completed wait_for_job_
     sequential_execution_ = true;

     size_t thread_num;
     for(thread_num = 0; thread_num < num_threads_; thread_num++)
          ok &= thread_all_[thread_num].ok;
     return ok;
}

bool team_destroy(void)
{     // Current state is other threads are at wait_for_job_.
     // This master thread (thread zero) has not completed wait_for_job_
     bool ok = sequential_execution_;
     ok     &= thread_number() == 0;
     ok     &= wait_for_work_ != CPPAD_NULL;
     ok     &= wait_for_job_  != CPPAD_NULL;

     // set the new job that other threads are waiting for
     thread_job_ = join_enum;

     // enter parallel exectuion soon as master thread completes wait_for_job_
     if( num_threads_ > 1 )
               sequential_execution_ = false;
     wait_for_job_->wait();

     // now wait for the other threads to be destroyed
     size_t thread_num;
     ok &= thread_all_[0].bthread == CPPAD_NULL;
     for(thread_num = 1; thread_num < num_threads_; thread_num++)
     {     thread_all_[thread_num].bthread->join();
          delete thread_all_[thread_num].bthread;
          thread_all_[thread_num].bthread = CPPAD_NULL;
     }
     // now we are down to just the master thread (thread zero)
     sequential_execution_ = true;

     // destroy wait_for_work_
     delete wait_for_work_;
     wait_for_work_ = CPPAD_NULL;

     // destroy wait_for_job_
     delete wait_for_job_;
     wait_for_job_ = CPPAD_NULL;

     // check ok before changing num_threads_
     for(thread_num = 0; thread_num < num_threads_; thread_num++)
          ok &= thread_all_[thread_num].ok;

     // now inform CppAD that there is only one thread
     num_threads_ = 1;
     thread_alloc::parallel_setup(num_threads_, CPPAD_NULL, CPPAD_NULL);
     thread_alloc::hold_memory(false);
     CppAD::parallel_ad<double>();

     return ok;
}

const char* team_name(void)
{     return "bthread"; }