/* ----------------------------------------------------------------------
   LAMMPS - Large-scale Atomic/Molecular Massively Parallel Simulator
   https://www.lammps.org/, Sandia National Laboratories
   Steve Plimpton, sjplimp@sandia.gov

   Copyright (2003) Sandia Corporation.  Under the terms of Contract
   DE-AC04-94AL85000 with Sandia Corporation, the U.S. Government retains
   certain rights in this software.  This software is distributed under
   the GNU General Public License.

   See the README file in the top-level LAMMPS directory.
------------------------------------------------------------------------- */

/* Single-processor "stub" versions of MPI routines */

#include "mpi.h"

#include "../version.h"

#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#if defined(_WIN32)
#define WIN32_LEAN_AND_MEAN
#include <windows.h>
#else
#include <sys/time.h>
#endif

/* data structure for double/int */

struct _mpi_double_int {
  double value;
  int proc;
};
typedef struct _mpi_double_int double_int;

/* extra MPI_Datatypes registered by MPI_Type_contiguous */

#define MAXEXTRA_DATATYPE 16

int nextra_datatype;
MPI_Datatype *ptr_datatype[MAXEXTRA_DATATYPE];
int index_datatype[MAXEXTRA_DATATYPE];
int size_datatype[MAXEXTRA_DATATYPE];

static int _mpi_is_initialized = 0;

/* ---------------------------------------------------------------------- */
/* MPI Functions */
/* ---------------------------------------------------------------------- */

int MPI_Init(int *argc, char ***argv)
{
  if (_mpi_is_initialized > 0) {
    printf("MPI Stub WARNING: MPI already initialized\n");
    return 1;
  }
  if (_mpi_is_initialized < 0) {
    printf("MPI Stub WARNING: MPI already finalized\n");
    return 1;
  }
  _mpi_is_initialized = 1;
  return 0;
}

/* ---------------------------------------------------------------------- */

int MPI_Initialized(int *flag)
{
  *flag = (_mpi_is_initialized > 0) ? 1 : 0;
  return 0;
}

/* ---------------------------------------------------------------------- */

int MPI_Finalized(int *flag)
{
  *flag = (_mpi_is_initialized < 0) ? 1 : 0;
  return 0;
}

/* ---------------------------------------------------------------------- */

/* return "LAMMPS MPI STUBS" as name of the library */

int MPI_Get_library_version(char *version, int *resultlen)
{
  const char string[] = "LAMMPS MPI STUBS for LAMMPS version " LAMMPS_VERSION;
  int len;

  if (!version || !resultlen) return MPI_ERR_ARG;

  len = strlen(string);
  memcpy(version, string, len + 1);
  *resultlen = len;
  return MPI_SUCCESS;
}

/* ---------------------------------------------------------------------- */

/* return "localhost" as name of the processor */

int MPI_Get_processor_name(char *name, int *resultlen)
{
  const char host[] = "localhost";
  int len;

  if (!name || !resultlen) return MPI_ERR_ARG;

  len = strlen(host);
  memcpy(name, host, len + 1);
  *resultlen = len;
  return MPI_SUCCESS;
}

/* ---------------------------------------------------------------------- */

/* return MPI version level. v1.2 is not 100% correct, but close enough */

int MPI_Get_version(int *major, int *minor)
{
  if (!major || !minor) return MPI_ERR_ARG;

  *major = 1;
  *minor = 2;
  return MPI_SUCCESS;
}

/* ---------------------------------------------------------------------- */

int MPI_Comm_rank(MPI_Comm comm, int *me)
{
  *me = 0;
  return 0;
}

/* ---------------------------------------------------------------------- */

int MPI_Comm_size(MPI_Comm comm, int *nprocs)
{
  *nprocs = 1;
  return 0;
}

/* ---------------------------------------------------------------------- */

int MPI_Abort(MPI_Comm comm, int errorcode)
{
  exit(1);
  return 0;
}

/* ---------------------------------------------------------------------- */

int MPI_Finalize()
{
  if (_mpi_is_initialized == 0) {
    printf("MPI Stub WARNING: MPI not yet initialized\n");
    return 1;
  }
  if (_mpi_is_initialized < 0) {
    printf("MPI Stub WARNING: MPI already finalized\n");
    return 1;
  }
  _mpi_is_initialized = -1;
  return 0;
}

/* ---------------------------------------------------------------------- */

double MPI_Wtime()
{
#if defined(_MSC_VER)
  double t;

  t = GetTickCount();
  t /= 1000.0;
  return t;
#else
  double time;
  struct timeval tv;

  gettimeofday(&tv, NULL);
  time = 1.0 * tv.tv_sec + 1.0e-6 * tv.tv_usec;
  return time;
#endif
}

/* ---------------------------------------------------------------------- */

/* include sizes of user defined datatypes, stored in extra lists */

static int stubtypesize(MPI_Datatype datatype)
{
  if (datatype == MPI_INT)
    return sizeof(int);
  else if (datatype == MPI_FLOAT)
    return sizeof(float);
  else if (datatype == MPI_DOUBLE)
    return sizeof(double);
  else if (datatype == MPI_CHAR)
    return sizeof(char);
  else if (datatype == MPI_BYTE)
    return sizeof(char);
  else if (datatype == MPI_LONG)
    return sizeof(long);
  else if (datatype == MPI_LONG_LONG)
    return sizeof(uint64_t);
  else if (datatype == MPI_DOUBLE_INT)
    return sizeof(double_int);
  else {
    int i;
    for (i = 0; i < nextra_datatype; i++)
      if (datatype == index_datatype[i]) return size_datatype[i];
  }
  return 0;
}

/* ---------------------------------------------------------------------- */

int MPI_Type_size(MPI_Datatype datatype, int *size)
{
  if (size == NULL) return MPI_ERR_ARG;

  *size = stubtypesize(datatype);
  return 0;
}

/* ---------------------------------------------------------------------- */

int MPI_Request_free(MPI_Request *request)
{
  return 0;
}

/* ---------------------------------------------------------------------- */

int MPI_Send(const void *buf, int count, MPI_Datatype datatype, int dest, int tag, MPI_Comm comm)
{
  static int callcount = 0;
  if (callcount == 0) {
    printf("MPI Stub WARNING: Should not send message to self\n");
    ++callcount;
  }
  return 0;
}

/* ---------------------------------------------------------------------- */

int MPI_Isend(const void *buf, int count, MPI_Datatype datatype, int source, int tag, MPI_Comm comm,
              MPI_Request *request)
{
  static int callcount = 0;
  if (callcount == 0) {
    printf("MPI Stub WARNING: Should not send message to self\n");
    ++callcount;
  }
  return 0;
}

/* ---------------------------------------------------------------------- */

int MPI_Rsend(const void *buf, int count, MPI_Datatype datatype, int dest, int tag, MPI_Comm comm)
{
  static int callcount = 0;
  if (callcount == 0) {
    printf("MPI Stub WARNING: Should not rsend message to self\n");
    ++callcount;
  }
  return 0;
}

/* ---------------------------------------------------------------------- */

int MPI_Recv(void *buf, int count, MPI_Datatype datatype, int source, int tag, MPI_Comm comm,
             MPI_Status *status)
{
  static int callcount = 0;
  if (callcount == 0) {
    printf("MPI Stub WARNING: Should not recv message from self\n");
    ++callcount;
  }
  return 0;
}

/* ---------------------------------------------------------------------- */

int MPI_Irecv(void *buf, int count, MPI_Datatype datatype, int source, int tag, MPI_Comm comm,
              MPI_Request *request)
{
  static int callcount = 0;
  if (callcount == 0) {
    printf("MPI Stub WARNING: Should not recv message from self\n");
    ++callcount;
  }
  return 0;
}

/* ---------------------------------------------------------------------- */

int MPI_Wait(MPI_Request *request, MPI_Status *status)
{
  static int callcount = 0;
  if (callcount == 0) {
    printf("MPI Stub WARNING: Should not wait on message from self\n");
    ++callcount;
  }
  return 0;
}

/* ---------------------------------------------------------------------- */

int MPI_Waitall(int n, MPI_Request *request, MPI_Status *status)
{
  static int callcount = 0;
  if (callcount == 0) {
    printf("MPI Stub WARNING: Should not wait on message from self\n");
    ++callcount;
  }
  return 0;
}

/* ---------------------------------------------------------------------- */

int MPI_Waitany(int count, MPI_Request *request, int *index, MPI_Status *status)
{
  static int callcount = 0;
  if (callcount == 0) {
    printf("MPI Stub WARNING: Should not wait on message from self\n");
    ++callcount;
  }
  return 0;
}

/* ---------------------------------------------------------------------- */

int MPI_Sendrecv(const void *sbuf, int scount, MPI_Datatype sdatatype, int dest, int stag,
                 void *rbuf, int rcount, MPI_Datatype rdatatype, int source, int rtag,
                 MPI_Comm comm, MPI_Status *status)
{
  static int callcount = 0;
  if (callcount == 0) {
    printf("MPI Stub WARNING: Should not send message to self\n");
    ++callcount;
  }
  return 0;
}

/* ---------------------------------------------------------------------- */

int MPI_Get_count(MPI_Status *status, MPI_Datatype datatype, int *count)
{
  static int callcount = 0;
  if (callcount == 0) {
    printf("MPI Stub WARNING: Should not get count of message to self\n");
    ++callcount;
  }
  return 0;
}

/* ---------------------------------------------------------------------- */

int MPI_Comm_split(MPI_Comm comm, int color, int key, MPI_Comm *comm_out)
{
  *comm_out = comm + 1;
  return 0;
}

/* ---------------------------------------------------------------------- */

int MPI_Comm_dup(MPI_Comm comm, MPI_Comm *comm_out)
{
  *comm_out = comm + 1;
  return 0;
}

/* ---------------------------------------------------------------------- */

int MPI_Comm_free(MPI_Comm *comm)
{
  return 0;
}

/* ---------------------------------------------------------------------- */

MPI_Fint MPI_Comm_c2f(MPI_Comm comm)
{
  return comm;
};

/* ---------------------------------------------------------------------- */

MPI_Comm MPI_Comm_f2c(MPI_Fint comm)
{
  return comm;
};

/* ---------------------------------------------------------------------- */

int MPI_Comm_group(MPI_Comm comm, MPI_Group *group)
{
  *group = comm;
  return 0;
}

/* ---------------------------------------------------------------------- */

int MPI_Comm_create(MPI_Comm comm, MPI_Group group, MPI_Comm *newcomm)
{
  *newcomm = group;
  return 0;
}

/* ---------------------------------------------------------------------- */

int MPI_Group_incl(MPI_Group group, int n, int *ranks, MPI_Group *newgroup)
{
  if (n > 0)
    *newgroup = MPI_COMM_WORLD;
  else
    *newgroup = group;
  return 0;
}
/* ---------------------------------------------------------------------- */

int MPI_Cart_create(MPI_Comm comm_old, int ndims, int *dims, int *periods, int reorder,
                    MPI_Comm *comm_cart)
{
  *comm_cart = comm_old;
  return 0;
}

/* ---------------------------------------------------------------------- */

int MPI_Cart_get(MPI_Comm comm, int maxdims, int *dims, int *periods, int *coords)
{
  dims[0] = dims[1] = dims[2] = 1;
  periods[0] = periods[1] = periods[2] = 1;
  coords[0] = coords[1] = coords[2] = 0;
  return 0;
}

/* ---------------------------------------------------------------------- */

int MPI_Cart_shift(MPI_Comm comm, int direction, int displ, int *source, int *dest)
{
  *source = *dest = 0;
  return 0;
}

/* ---------------------------------------------------------------------- */

int MPI_Cart_rank(MPI_Comm comm, int *coords, int *rank)
{
  *rank = 0;
  return 0;
}

/* ---------------------------------------------------------------------- */

/* store size of user datatype in extra lists */

int MPI_Type_contiguous(int count, MPI_Datatype oldtype, MPI_Datatype *newtype)
{
  if (nextra_datatype == MAXEXTRA_DATATYPE) return -1;
  ptr_datatype[nextra_datatype] = newtype;
  index_datatype[nextra_datatype] = -(nextra_datatype + 1);
  size_datatype[nextra_datatype] = count * stubtypesize(oldtype);
  nextra_datatype++;
  return 0;
}

/* ---------------------------------------------------------------------- */

/* set value of user datatype to internal negative index,
   based on match of ptr */

int MPI_Type_commit(MPI_Datatype *datatype)
{
  int i;
  for (i = 0; i < nextra_datatype; i++)
    if (datatype == ptr_datatype[i]) *datatype = index_datatype[i];
  return 0;
}

/* ---------------------------------------------------------------------- */

/* remove user datatype from extra lists */

int MPI_Type_free(MPI_Datatype *datatype)
{
  int i;
  for (i = 0; i < nextra_datatype; i++)
    if (datatype == ptr_datatype[i]) {
      ptr_datatype[i] = ptr_datatype[nextra_datatype - 1];
      index_datatype[i] = index_datatype[nextra_datatype - 1];
      size_datatype[i] = size_datatype[nextra_datatype - 1];
      nextra_datatype--;
      break;
    }
  return 0;
}

/* ---------------------------------------------------------------------- */

int MPI_Op_create(MPI_User_function *function, int commute, MPI_Op *op)
{
  return 0;
}

/* ---------------------------------------------------------------------- */

int MPI_Op_free(MPI_Op *op)
{
  return 0;
}

/* ---------------------------------------------------------------------- */

int MPI_Barrier(MPI_Comm comm)
{
  return 0;
}

/* ---------------------------------------------------------------------- */

int MPI_Bcast(void *buf, int count, MPI_Datatype datatype, int root, MPI_Comm comm)
{
  return 0;
}

/* ---------------------------------------------------------------------- */

/* copy values from data1 to data2 */

int MPI_Allreduce(void *sendbuf, void *recvbuf, int count, MPI_Datatype datatype, MPI_Op op,
                  MPI_Comm comm)
{
  int n = count * stubtypesize(datatype);

  if (sendbuf == MPI_IN_PLACE || recvbuf == MPI_IN_PLACE) return 0;
  memcpy(recvbuf, sendbuf, n);
  return 0;
}

/* ---------------------------------------------------------------------- */

/* copy values from data1 to data2 */

int MPI_Reduce(void *sendbuf, void *recvbuf, int count, MPI_Datatype datatype, MPI_Op op, int root,
               MPI_Comm comm)
{
  int n = count * stubtypesize(datatype);

  if (sendbuf == MPI_IN_PLACE || recvbuf == MPI_IN_PLACE) return 0;
  memcpy(recvbuf, sendbuf, n);
  return 0;
}

/* ---------------------------------------------------------------------- */

int MPI_Scan(void *sendbuf, void *recvbuf, int count, MPI_Datatype datatype, MPI_Op op,
             MPI_Comm comm)
{
  int n = count * stubtypesize(datatype);

  if (sendbuf == MPI_IN_PLACE || recvbuf == MPI_IN_PLACE) return 0;
  memcpy(recvbuf, sendbuf, n);
  return 0;
}

/* ---------------------------------------------------------------------- */

/* copy values from data1 to data2 */

int MPI_Allgather(void *sendbuf, int sendcount, MPI_Datatype sendtype, void *recvbuf, int recvcount,
                  MPI_Datatype recvtype, MPI_Comm comm)
{
  int n = sendcount * stubtypesize(sendtype);

  if (sendbuf == MPI_IN_PLACE || recvbuf == MPI_IN_PLACE) return 0;
  memcpy(recvbuf, sendbuf, n);
  return 0;
}

/* ---------------------------------------------------------------------- */

/* copy values from data1 to data2 */

int MPI_Allgatherv(void *sendbuf, int sendcount, MPI_Datatype sendtype, void *recvbuf,
                   int *recvcounts, int *displs, MPI_Datatype recvtype, MPI_Comm comm)
{
  int n = sendcount * stubtypesize(sendtype);

  if (sendbuf == MPI_IN_PLACE || recvbuf == MPI_IN_PLACE) return 0;
  memcpy(recvbuf, sendbuf, n);
  return 0;
}

/* ---------------------------------------------------------------------- */

/* copy values from data1 to data2 */

int MPI_Reduce_scatter(void *sendbuf, void *recvbuf, int *recvcounts, MPI_Datatype datatype,
                       MPI_Op op, MPI_Comm comm)
{
  int n = *recvcounts * stubtypesize(datatype);

  if (sendbuf == MPI_IN_PLACE || recvbuf == MPI_IN_PLACE) return 0;
  memcpy(recvbuf, sendbuf, n);
  return 0;
}

/* ---------------------------------------------------------------------- */

/* copy values from data1 to data2 */

int MPI_Gather(void *sendbuf, int sendcount, MPI_Datatype sendtype, void *recvbuf, int recvcount,
               MPI_Datatype recvtype, int root, MPI_Comm comm)
{
  int n = sendcount * stubtypesize(sendtype);

  if (sendbuf == MPI_IN_PLACE || recvbuf == MPI_IN_PLACE) return 0;
  memcpy(recvbuf, sendbuf, n);
  return 0;
}

/* ---------------------------------------------------------------------- */

/* copy values from data1 to data2 */

int MPI_Gatherv(void *sendbuf, int sendcount, MPI_Datatype sendtype, void *recvbuf, int *recvcounts,
                int *displs, MPI_Datatype recvtype, int root, MPI_Comm comm)
{
  int n = sendcount * stubtypesize(sendtype);

  if (sendbuf == MPI_IN_PLACE || recvbuf == MPI_IN_PLACE) return 0;
  memcpy(recvbuf, sendbuf, n);
  return 0;
}

/* ---------------------------------------------------------------------- */

/* copy values from data1 to data2 */

int MPI_Scatter(void *sendbuf, int sendcount, MPI_Datatype sendtype, void *recvbuf, int recvcount,
                MPI_Datatype recvtype, int root, MPI_Comm comm)
{
  int n = recvcount * stubtypesize(recvtype);

  if (sendbuf == MPI_IN_PLACE || recvbuf == MPI_IN_PLACE) return 0;
  memcpy(recvbuf, sendbuf, n);
  return 0;
}

/* ---------------------------------------------------------------------- */

/* copy values from data1 to data2 */

int MPI_Scatterv(void *sendbuf, int *sendcounts, int *displs, MPI_Datatype sendtype, void *recvbuf,
                 int recvcount, MPI_Datatype recvtype, int root, MPI_Comm comm)
{
  int n = recvcount * stubtypesize(recvtype);

  if (sendbuf == MPI_IN_PLACE || recvbuf == MPI_IN_PLACE) return 0;
  memcpy(recvbuf, sendbuf, n);
  return 0;
}

/* ---------------------------------------------------------------------- */

/* copy values from data1 to data2 */

int MPI_Alltoall(void *sendbuf, int sendcount, MPI_Datatype sendtype, void *recvbuf, int recvcount,
                 MPI_Datatype recvtype, MPI_Comm comm)
{
  int n = sendcount * stubtypesize(sendtype);

  if (sendbuf == MPI_IN_PLACE || recvbuf == MPI_IN_PLACE) return 0;
  memcpy(recvbuf, sendbuf, n);
  return 0;
}

/* ---------------------------------------------------------------------- */

/* copy values from data1 to data2 */

int MPI_Alltoallv(void *sendbuf, int *sendcounts, int *sdispls, MPI_Datatype sendtype,
                  void *recvbuf, int *recvcounts, int *rdispls, MPI_Datatype recvtype,
                  MPI_Comm comm)
{
  int n = *sendcounts * stubtypesize(sendtype);

  if (sendbuf == MPI_IN_PLACE || recvbuf == MPI_IN_PLACE) return 0;
  memcpy(recvbuf, sendbuf, n);
  return 0;
}

/* ---------------------------------------------------------------------- */