#include <limits>

#include <cctk.h>
#include <cctk_Arguments.h>
#include <cctk_Parameters.h>

#include <carpet.hh>



namespace Carpet {
  
  using namespace std;
  
  void CarpetRefineTimeStep (CCTK_ARGUMENTS)
  {
    DECLARE_CCTK_ARGUMENTS;
    DECLARE_CCTK_PARAMETERS;
    
    // Find the smallest CFL factor for all refinement levels
    CCTK_REAL min_cfl = numeric_limits<CCTK_REAL>::max();
    for (int rl = 0; rl < reflevels; ++ rl) {
      CCTK_REAL const level_cfl =
        timereffacts.AT(rl) / maxval (spacereffacts.AT(rl));
      min_cfl = min (min_cfl, level_cfl);
    }
    
    // Reduce the time step correspondingly
    cctkGH->cctk_delta_time *= min_cfl;
    CCTK_VInfo (CCTK_THORNSTRING,
                "Timestep reduced by a factor of %g to %g",
                double (1 / min_cfl),
                double (cctkGH->cctk_delta_time/cctkGH->cctk_timefac));
  }
  
} // namespace Carpet