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#include <cstdlib>
#include <mutex>
#include <random>
#include <thread>
#include <vector>
#include <hpc/aux/slices.hpp>
#include <hpc/matvec/gematrix.hpp>
#include <hpc/matvec/iterators.hpp>
#include <hpc/matvec/print.hpp>
#include <hpc/matvec/views.hpp>

using namespace hpc;
using namespace hpc::aux;
using namespace hpc::matvec;

struct Guard {
   Guard(std::mutex& mutex) : mutex(mutex) {
      mutex.lock();
   }
   ~Guard() {
      mutex.unlock();
   }
   std::mutex& mutex;
};

struct MyRandomGenerator {
      MyRandomGenerator() : mt(std::random_device()()), uniform(-100, 100) {
      }
      double gen() {
	 Guard guard(mutex);
	 return uniform(mt);
      }
   private:
      std::mutex mutex;
      std::mt19937 mt;
      std::uniform_real_distribution<double> uniform;
};

template <
   template<typename> class MatrixA, typename T,
   typename RNG,
   Require< Ge<MatrixA<T>> > = true
>
void randomInit(MatrixA<T>& A, RNG& rng) {
   for (auto [i, j, Aij]: A) {
      Aij = rng.gen();
      (void) i; (void) j; // suppress gcc warning
   }
}

int main() {
   MyRandomGenerator rng;
   GeMatrix<double> A(51, 7);
   std::size_t nof_threads = std::thread::hardware_concurrency();

   std::vector<std::thread> threads(nof_threads);
   UniformSlices<std::size_t> slices(nof_threads, A.numRows());
   for (std::size_t index = 0; index < nof_threads; ++index) {
      auto firstRow = slices.offset(index);
      auto numRows = slices.size(index);
      threads[index] = std::thread([
	       A_ = A.view(firstRow, 0, numRows, A.numCols()),
	       &rng
	    ]() mutable {
	 randomInit(A_, rng);
      });
   }
   for (std::size_t index = 0; index < nof_threads; ++index) {
      threads[index].join();
   }
   print(A, " %7.2f");
}