//----------------------------------------------------------------------------

#ifndef EXTENSION_H
#define EXTENSION_H

void
concatArray(double **inout_left,
            int *inout_leftCount,
            const double *right,
            int rightCount);

void
twiceArray(double **inout_values,
           int *inout_valueCount);

void
extendArray(double **inout_values,
            int *inout_valueCount,
            int extension);

#endif // EXTENSION_H

//----------------------------------------------------------------------------

//----------------------------------------------------------------------------

#include "extension.h"

#include <stdlib.h>

void
concatArray(double **inout_left,
            int *inout_leftCount,
            const double *right,
            int rightCount)
{
  //-- load inout-parameters --
  double *left=*inout_left; 
  int leftCount=*inout_leftCount;
  //-- perform work --
  const int offset=leftCount;
  leftCount+=rightCount;
  left=(double *)realloc(left, leftCount*sizeof(*left));
  if(left==NULL)
  {
    abort();
  }
  for(int i=0; i<rightCount; ++i)
  {
    left[offset+i]=right[i];
  }
  //-- store out-parameters --
  *inout_left=left;
  *inout_leftCount=leftCount;
}

void
twiceArray(double **inout_values,
           int *inout_valueCount)
{
  //-- load inout-parameters --
  double *values=*inout_values; 
  int valueCount=*inout_valueCount;
  //-- perform work --
  const int offset=valueCount;
  valueCount*=2;
  values=(double *)realloc(values, valueCount*sizeof(*values));
  if(values==NULL)
  {
    abort();
  }
  for(int i=0; i<offset; ++i)
  {
    values[offset+i]=values[i];
  }
  //-- store out-parameters --
  *inout_values=values;
  *inout_valueCount=valueCount;
}

void
extendArray(double **inout_values,
            int *inout_valueCount,
            int extension)
{
  //-- load inout-parameters --
  double *values=*inout_values; 
  int valueCount=*inout_valueCount;
  //-- perform work --
  const int offset=valueCount;
  valueCount+=extension;
  values=(double *)realloc(values, valueCount*sizeof(*values));
  if(values==NULL)
  {
    abort();
  }
  const double lastValue=values[offset-1];
  for(int i=0; i<extension; ++i)
  {
    values[offset+i]=lastValue;
  }
  //-- store out-parameters --
  *inout_values=values;
  *inout_valueCount=valueCount;
}

//----------------------------------------------------------------------------

//----------------------------------------------------------------------------

#include "extension.h"

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

void
displayArray(const char *title,
             const double *elements,
             int count)
{
  printf("%s:", title);
  for(int i=0; i<count; ++i)
  {
    printf(" %g", elements[i]);
  }
  printf("\n");
}

void
test_concatArray(void)
{
  printf("\n~~~~ %s() ~~~~\n", __func__);
  int aCount=10;
  double *a=(double *)malloc(aCount*sizeof(double));
  if(a==NULL)
  {
    abort();
  }
  for(int i=0; i<aCount; ++i)
  {
    a[i]=1.1*i;
  }
  const double b[]={100.0, 102.2, 104.4, 106.6, 108.8};
  const int bCount=(int)(sizeof(b)/sizeof(b[0]));
  displayArray("a before", a, aCount);
  displayArray("b before", b, bCount);
  concatArray(&a, &aCount, b, bCount);
  displayArray("a after", a, aCount);
  displayArray("b after", b, bCount);
  free(a);
}

void
test_twiceArray(void)
{
  printf("\n~~~~ %s() ~~~~\n", __func__);
  int valueCount=5;
  double *values=(double *)malloc(valueCount*sizeof(double));
  if(values==NULL)
  {
    abort();
  }
  for(int i=0; i<valueCount; ++i)
  {
    values[i]=1.1*(i+1);
  }
  displayArray("before", values, valueCount);
  twiceArray(&values, &valueCount);
  displayArray("after", values, valueCount);
  free(values);
}

void
test_extendArray(void)
{
  printf("\n~~~~ %s() ~~~~\n", __func__);
  int valueCount=5;
  double *values=(double *)malloc(valueCount*sizeof(double));
  if(values==NULL)
  {
    abort();
  }
  for(int i=0; i<valueCount; ++i)
  {
    values[i]=1.1*(i+1);
  }
  displayArray("before", values, valueCount);
  extendArray(&values, &valueCount, 10);
  displayArray("after", values, valueCount);
  free(values);
}

int
main(void)
{
  test_concatArray();
  test_twiceArray();
  test_extendArray();
  return 0;
}

//----------------------------------------------------------------------------