////////////////////////////////////////////////////////////////////////////////
//
// Copyright (c) 2008 The Regents of the University of California
//
// This file is part of Qbox
//
// Qbox is distributed under the terms of the GNU General Public License
// as published by the Free Software Foundation, either version 2 of
// the License, or (at your option) any later version.
// See the file COPYING in the root directory of this distribution
// or <http://www.gnu.org/licenses/>.
//
////////////////////////////////////////////////////////////////////////////////
//
// DistanceCmd.h:
//
////////////////////////////////////////////////////////////////////////////////

#ifndef DISTANCECMD_H
#define DISTANCECMD_H

#include <iostream>
#include "UserInterface.h"
#include "Sample.h"
#include <cstdlib>

class DistanceCmd : public Cmd
{
  public:

  Sample *s;

  DistanceCmd(Sample *sample) : s(sample) {};

  const char *name(void) const { return "distance"; }
  const char *help_msg(void) const
  {
    return
    "\n distance\n\n"
    " syntax: distance [-pbc] name1 name2\n\n"
    "   The distance command prints the distance between two atoms.\n"
    "   If the -pbc option is used, the smallest distance is\n"
    "   computed taking into account periodic boundary conditions.\n\n";
  }

  int action(int argc, char **argv)
  {
    if ( ! ( argc == 3 || argc == 4 ) )
    {
      if ( ui->onpe0() )
      {
        cout << " use: distance [-pbc] name1 name2" << endl;
      }
      return 1;
    }

    string name1, name2;
    bool use_pbc = false;

    if ( argc == 3 )
    {
      name1 = argv[1];
      name2 = argv[2];
    }
    if ( argc == 4 )
    {
      if ( strcmp(argv[1],"-pbc") )
      {
        if ( ui->onpe0() )
        {
          cout << " use: distance [-pbc] name1 name2" << endl;
        }
        return 1;
      }
      use_pbc = true;
      name1 = argv[2];
      name2 = argv[3];
    }

    Atom* a1 = s->atoms.findAtom(name1);
    Atom* a2 = s->atoms.findAtom(name2);
    if ( a1 == 0 || a2 == 0 )
    {
      // either a1 or a2 was not found
      if ( ui->onpe0() )
      {
        if ( a1 == 0 )
          cout << " DistanceCmd: atom " << name1 << " not defined"
               << endl;
        if ( a2 == 0 )
          cout << " DistanceCmd: atom " << name2 << " not defined"
               << endl;
      }
      return 1;
    }

    if ( ui->onpe0() )
    {
      D3vector r12 = a1->position()-a2->position();
      if ( use_pbc )
      {
        const UnitCell& cell = s->wf.cell();
        cell.fold_in_ws(r12);
      }
      const double d = length(r12);
      cout.setf(ios::fixed,ios::floatfield);
      cout << " distance " << name1 << "-" << name2 << ": "
           << setprecision(3)
           << d << " (a.u.) / " << 0.529177*d << " (Ang)" << endl;
    }
    return 0;
  }
};
#endif