#include "nbc.h"

#ifdef NBC_CACHE_SCHEDULE
/* tree comparison function for schedule cache */
int NBC_Scan_args_compare(NBC_Scan_args *a, NBC_Scan_args *b, void *param) {

	if( (a->sendbuf == b->sendbuf) && 
      (a->recvbuf == b->recvbuf) &&
      (a->count == b->count) && 
      (a->datatype == b->datatype) &&
      (a->op == b->op) ) {
    return  0;
  }
	if( a->sendbuf < b->sendbuf ) {	
    return -1;
	}
	return +1;
}
#endif

/* linear iscan
 * working principle:
 * 1. each node (but node 0) receives from left neigbor
 * 2. performs op
 * 3. all but rank p-1 do sends to it's right neigbor and exits
 *
 */
int NBC_Iscan(void* sendbuf, void* recvbuf, int count, MPI_Datatype datatype, MPI_Op op, MPI_Comm comm, NBC_Handle* handle) {
  int rank, p, res;
  MPI_Aint ext;
  NBC_Schedule *schedule;
#ifdef NBC_CACHE_SCHEDULE
  NBC_Scan_args *args, *found, search;
#endif
  char inplace;
  
  NBC_IN_PLACE(sendbuf, recvbuf, inplace);
  
  res = NBC_Init_handle(handle, comm);
  if(res != NBC_OK) { printf("Error in NBC_Init_handle(%i)\n", res); return res; }
  res = MPI_Comm_rank(comm, &rank);
  if (MPI_SUCCESS != res) { printf("MPI Error in MPI_Comm_rank() (%i)\n", res); return res; }
  res = MPI_Comm_size(comm, &p);
  if (MPI_SUCCESS != res) { printf("MPI Error in MPI_Comm_size() (%i)\n", res); return res; }
  res = MPI_Type_extent(datatype, &ext);
  if (MPI_SUCCESS != res) { printf("MPI Error in MPI_Type_extent() (%i)\n", res); return res; }
  
  handle->tmpbuf = malloc(ext*count);
  if(handle->tmpbuf == NULL) { printf("Error in malloc()\n"); return NBC_OOR; }

  if((rank == 0) && !inplace) {
    /* copy data to receivebuf */
    res = NBC_Copy(sendbuf, count, datatype, recvbuf, count, datatype, comm);
    if (NBC_OK != res) { printf("Error in NBC_Copy() (%i)\n", res); return res; }
  }

#ifdef NBC_CACHE_SCHEDULE
  /* search schedule in communicator specific tree */
  search.sendbuf=sendbuf;
  search.recvbuf=recvbuf;
  search.count=count;
  search.datatype=datatype;
  search.op=op;
  found = hb_tree_search(handle->comminfo->NBC_Dict[NBC_SCAN], &search);
  if(found == NULL) {
#endif
    schedule = malloc(sizeof(NBC_Schedule));
    if (NULL == schedule) { printf("Error in malloc()\n"); return res; }

    res = NBC_Sched_create(schedule);
    if(res != NBC_OK) { printf("Error in NBC_Sched_create (%i)\n", res); return res; }

    if(rank != 0) {
      res = NBC_Sched_recv(0, true, count, datatype, rank-1, schedule);
      if (NBC_OK != res) { free(handle->tmpbuf); printf("Error in NBC_Sched_recv() (%i)\n", res); return res; }
      /* we have to wait until we have the data */
      res = NBC_Sched_barrier(schedule);
      if (NBC_OK != res) { free(handle->tmpbuf); printf("Error in NBC_Sched_barrier() (%i)\n", res); return res; }
      /* perform the reduce in my local buffer */
      res = NBC_Sched_op(recvbuf, false, sendbuf, false, 0, true, count, datatype, op, schedule);
      if (NBC_OK != res) { free(handle->tmpbuf); printf("Error in NBC_Sched_op() (%i)\n", res); return res; }
      /* this cannot be done until handle->tmpbuf is unused :-( */
      res = NBC_Sched_barrier(schedule);
      if (NBC_OK != res) { free(handle->tmpbuf); printf("Error in NBC_Sched_barrier() (%i)\n", res); return res; }
    }
    if(rank != p-1) {
      res = NBC_Sched_send(recvbuf, false, count, datatype, rank+1, schedule);
      if (NBC_OK != res) { free(handle->tmpbuf); printf("Error in NBC_Sched_send() (%i)\n", res); return res; }
    }

    res = NBC_Sched_commit(schedule);
    if (NBC_OK != res) { free(handle->tmpbuf); printf("Error in NBC_Sched_commit() (%i)\n", res); return res; }

#ifdef NBC_CACHE_SCHEDULE
    /* save schedule to tree */
    args = malloc(sizeof(NBC_Alltoall_args));
    args->sendbuf=sendbuf;
    args->recvbuf=recvbuf;
    args->count=count;
    args->datatype=datatype;
    args->op=op;
    args->schedule=schedule;
	  res = hb_tree_insert (handle->comminfo->NBC_Dict[NBC_SCAN], args, args, 0);
    if(res != 0) printf("error in dict_insert() (%i)\n", res);
    /* increase number of elements for A2A */
    if(++handle->comminfo->NBC_Dict_size[NBC_SCAN] > SCHED_DICT_UPPER) {
      NBC_SchedCache_dictwipe(handle->comminfo->NBC_Dict[NBC_SCAN], &handle->comminfo->NBC_Dict_size[NBC_SCAN]);
    }
  } else {
    /* found schedule */
    schedule=found->schedule;
  }
#endif
  
  res = NBC_Start(handle, schedule);
  if (NBC_OK != res) { free(handle->tmpbuf); printf("Error in NBC_Start() (%i)\n", res); return res; }
  
  /* tmpbuf is freed with the handle */
  return NBC_OK;
}