/*
 * Copyright(C) 1999-2021, 2023 National Technology & Engineering Solutions
 * of Sandia, LLC (NTESS).  Under the terms of Contract DE-NA0003525 with
 * NTESS, the U.S. Government retains certain rights in this software.
 *
 * See packages/seacas/LICENSE for details
 */

#include <exodusII.h>
#include <limits.h>
#include <math.h>
#include <pthread.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

/*
 * Create an exodus file with NUM_NODES nodes and 0 elements.
 * Initial mesh is created on main thread.
 * Nodal var data and names is written on multiple threads
 * -- Each thread handles a single nodal variable
 * -- Coordinate data is written by first 3 threads
 */

#define NUM_THREADS 8
#define NUM_NODES   64

static int ulpsDistance(float a, float b)
{
  int ia, ib;
  if (a == b)
    return 0;
  memcpy(&ia, &a, sizeof(a));
  memcpy(&ib, &b, sizeof(b));

  if ((ia < 0) != (ib < 0))
    return INT_MAX;
  int distance = ia - ib;
  if (distance < 0)
    distance = -distance;
  return distance;
}
static int approx_equal(float f1, float f2)
{
  if (f1 == f2)
    return 1;

  return ulpsDistance(f1, f2) <= 2;
}

typedef struct
{
  long threadid;
  int  exoid;
  int  timestep;
} param;

void *input_nodal_var(void *varg)
{
  char   db_name[33];
  char   ex_name[33];
  param *arg      = (param *)varg;
  int    num_node = ex_inquire_int(arg->exoid, EX_INQ_NODES);
  float *data     = malloc(num_node * sizeof(float));
  int    i;

  if (arg->timestep == 1) {
    switch (arg->threadid) {
    case 0:
      ex_get_coord(arg->exoid, data, NULL, NULL);
      for (i = 0; i < num_node; i++) {
        if (!approx_equal(data[i], arg->threadid + 1 + (float)i / 100.0)) {
          fprintf(stderr,
                  "ERROR: Thread %ld: X Coordinate mismatch at node %d: Got: %f, expected %f\n",
                  arg->threadid, i + 1, data[i], arg->threadid + 1 + (float)i / 100.0);
        }
      }
      break;
    case 1:
      ex_get_coord(arg->exoid, NULL, data, NULL);
      for (i = 0; i < num_node; i++) {
        if (!approx_equal(data[i], arg->threadid + 1 + (float)i / 100.0)) {
          fprintf(stderr,
                  "ERROR: Thread %ld: Y Coordinate mismatch at node %d: Got: %f, expected %f\n",
                  arg->threadid, i + 1, data[i], arg->threadid + 1 + (float)i / 100.0);
        }
      }
      break;
    case 2:
      ex_get_coord(arg->exoid, NULL, NULL, data);
      for (i = 0; i < num_node; i++) {
        if (!approx_equal(data[i], arg->threadid + 1 + (float)i / 100.0)) {
          fprintf(stderr,
                  "ERROR: Thread %ld: Z Coordinate mismatch at node %d: Got: %f, expected %f\n",
                  arg->threadid, i + 1, data[i], arg->threadid + 1 + (float)i / 100.0);
        }
      }
      break;
    default: break;
    }
  }

  snprintf(ex_name, 33, "NodalVar%ld", arg->threadid + 1);
  ex_get_variable_name(arg->exoid, EX_NODAL, arg->threadid + 1, db_name);
  if (strcmp(db_name, ex_name) != 0) {
    fprintf(stderr,
            "ERROR: Thread %ld: Incorrect variable name for variable %d: Got: %s, expected %s\n",
            arg->threadid, (int)arg->threadid + 1, db_name, ex_name);
  }

  ex_get_var(arg->exoid, arg->timestep, EX_NODAL, arg->threadid + 1, 1, num_node, data);
  for (i = 0; i < num_node; i++) {
    if (!approx_equal(data[i], (arg->timestep - 1) * 10 + arg->threadid + 1 + (float)i / 100.0)) {
      fprintf(stderr,
              "ERROR: Thread %ld: Nodal variable %d mismatch at node %d: Got: %f, expected %f\n",
              arg->threadid, (int)arg->threadid + 1, i + 1, data[i],
              (arg->timestep - 1) * 10 + arg->threadid + 1 + (float)i / 100.0);
    }
  }
  free(data);
  return NULL;
}

int init_file(int num_nodal_vars)
{
  int   exoid;
  float version;
  int   CPU_word_size = 0; /* sizeof(float) */
  int   IO_word_size  = 0; /* use what is stored in file */

  ex_opts(EX_VERBOSE | EX_ABORT);

  /* open EXODUS II files */
  exoid = ex_open("test.exo",     /* filename path */
                  EX_READ,        /* access mode = READ */
                  &CPU_word_size, /* CPU word size */
                  &IO_word_size,  /* IO word size */
                  &version);      /* ExodusII library version */

  if (exoid < 0)
    exit(1);

  if (!ex_inquire_int(exoid, EX_INQ_THREADSAFE)) {
    fprintf(stderr,
            "ERROR: This exodus library is not compiled to allow thread-safe operations.\n");
    exit(1);
  }

  return exoid;
}

int main(int argc, char *argv[])
{
  int exoid = init_file(NUM_THREADS);

  param arg[NUM_THREADS];

  pthread_t threads[NUM_THREADS];
  printf("Running on %d threads\n", NUM_THREADS);
  for (long t = 0; t < NUM_THREADS; t++) {
    arg[t].exoid    = exoid;
    arg[t].threadid = t;
    arg[t].timestep = 1;

    int rc = pthread_create(&threads[t], NULL, input_nodal_var, (void *)(arg + t));
    if (rc) {
      printf("ERROR; return code from pthread_create() is %d\n", rc);
      exit(-1);
    }
  }

  for (long t = 0; t < NUM_THREADS; t++) {
    pthread_join(threads[t], NULL);
  }

  ex_close(exoid);
}