/**
 * new type to define an enum view
 */
pcilib_value_enum_s {
  const char *name; /**<corresponding string to value*/
  pcilib_register_value_t value, min, max; 
};


/**
 * new type to define a formula view
 */
pcilib_view_formula_s {
  const char *name; /**<name of the view*/
  const char *read_formula; /**< formula to parse to read from a register*/
  const char *write_formula; /**<formula to parse to write to a register*/
	// **see it later**        const char *unit; (?)
}


/**
 *
 * replace a substring within a string by another
 * @param[in] txt - the string to be modified
 *@param[in] before - the substring in the string that will be replaced
 *@param[in] after - the new value of before substring
 *@return the modified txt string
 */
char *formula_replace (const char *txt, const char *before, const char *after)
{
	const char *pos; 
	char *return_txt; 
	size_t pos_return_txt; 
	size_t len; 
	size_t allocated_size; 
	
	/*get the first occurence of before. then we need one time to be out of the loop to correctly set the diverses varaibles (malloc instead of realloc notably)*/
	pos = strstr (txt, before);
	 
	if (pos == NULL)
	{
		pcilib_warning("problem with a formula");
	}
 
	/* get the position of this occurence*/
	len = (size_t)pos - (size_t)txt;
	allocated_size = len + strlen (after) + 1;
	return_txt = malloc (allocated_size);
	pos_return_txt = 0;
	
	/* we copy there the in a newly allocated string the start of txt before the "before" occurence, and then we copy after instead*/
	strncpy (return_txt + pos_return_txt, txt, len);
	pos_return_txt += len;
	txt = pos + strlen (before);
	 
	len = strlen (after);
	strncpy (return_txt + pos_return_txt, after, len);
	pos_return_txt += len;
	
	/* we then iterate with the same principle to all occurences of before*/
	pos = strstr (txt, before);
	while (pos != NULL)
	{
		len = (size_t)pos - (size_t)txt;
		allocated_size += len + strlen (after);
		return_txt = (char *)realloc (return_txt, allocated_size);
		 
		strncpy (return_txt + pos_return_txt, txt, len);
		pos_return_txt += len;
		 
		txt = pos + strlen (before);
		 
		len = strlen (after);
		strncpy (return_txt + pos_return_txt, after, len);
		pos_return_txt += len;
		pos = strstr (txt, before);
	}
	/* put the rest of txt string at the end*/
	len = strlen (txt) + 1;
	allocated_size += len;
	return_txt = realloc (return_txt, allocated_size);
	strncpy (return_txt + pos_return_txt, txt, len);
	
	return return_txt;
}

/*
 * function used to get the substring of a string s, from the starting and ending indexes
  * @param[in] s string containing the substring we want to extract.
 * @param[in] start the start index of the substring.
 * @param[in] end the ending index of the substring.
 * @return the extracted substring.
 */
char *str_sub (const char *s, unsigned int start, unsigned int end)
{
   char *new_s = NULL;

   if (s != NULL && start < end)
   {
      new_s = malloc (sizeof (*new_s) * (end - start + 2));
      if (new_s != NULL)
      {
         int i;

         for (i = start; i <= end; i++)
         {
            new_s[i-start] = s[i];
         }
         new_s[i-start] = '\0';
      }
      else
      {
         pcilib_error("insufficient memory for string manipulation\n");
         return NULL;
      }
   }
   return new_s;
}

static int
pcilib_view_compute_plain_registers{
  /* hsould i used regexp.h??? or compile everythin myself? */
}





/*
 * this function calls the python script and the function "evaluate" in it to evaluate the given formula
 *@param[in] the formula to be evaluated
 *@return the integer value of the evaluated formula (maybe go to float instead)
 */
static int
pcilib_view_eval_formula(char* formula){
/* !!!! cf !!!!*/
  // setenv("PYTHONPATH",".",1);
   PyObject *pName, *pModule, *pDict, *pFunc, *pValue, *presult=NULL;
   char* pythonfile;

   /* path to the python file, we may need a way to set it, maybe with a variable like PCILIB_PYTHON_PATH*/
   pythonfile="pythonscripts.py";
   
   /* initialization of python interpreter*/
   Py_Initialize();

   pName = PyUnicode_FromString(pythonfile);
   pModule = PyImport_Import(pName); /* get the python file*/
	if(!pModule) {
		pcilib_error("no python file found for python evaluation of formulas\n");
		PyErr_Print();
		return -1;
	}
   pDict = PyModule_GetDict(pModule); /*useless but needed*/

   pFunc = PyDict_GetItemString(pDict, (char*)"evaluate"); /*getting of the function "evaluate" in the script*/
   /* if the function is ok, then call it*/
   if (PyCallable_Check(pFunc))
   {
        /* execution of the function*/
       pValue=Py_BuildValue("(z)",formula);
       PyErr_Print();
       presult=PyObject_CallObject(pFunc,pValue);
       PyErr_Print();
   } else 
   {
       PyErr_Print();
   }
   /* remove memory*/
   Py_DECREF(pModule);
   Py_DECREF(pName);
   
   /* close interpreter*/
   Py_Finalize();
   
   return PyLong_AsLong(presult); /*this function is due to python 3.3, as PyLong_AsInt was there in python 2.7 and is no more there, resulting in using cast futhermore*/
}


static int
pcilib_view_apply_read_formula(pcilib_t* ctx, char* formula, pcilib_register_value_t reg_value, pcilib_register_value_t* out_value)
{
  /* when applying a formula, we need to:
     1) compute the values of all registers present in plain name in the formulas and replace their name with their value : for example, if we have the formula" ((1./4)*(@reg - 1200)) if @freq==0 else ((3./10)*(@reg - 1000)) " we need to get the value of the register "freq"
     2) compute the "@reg" component, corresponding to the raw value of the register
     3) pass the formula to python interpreter for evaluation
     4) return the final evaluation
     
     remark: it might be worth to use python regular expression interpreter (the following return all words following @ in formula : 
         >>> import re
	 >>> m = re.search('(?<=@)\w+', formula)
	 >>> m.group(0)
  */
  
  char reg_value_string[66]; /* to register reg_value as a string, need to check the length*/
  sprintf(reg_value_string,"%lu",reg_value);
  
  /*computation of plain registers in the formula*/
  formula=pcilib_view_formula_compute_plain_registers(formula);
  /* computation of @reg with register value*/
  formula=pcilib_view_formula_replace(formula,"@reg",reg_value_string);
  
  /* evaluation of the formula*/
  *out_value=(pcilib_register_value_t) pcilib_view_eval_formula(formula);

}

static int
pcilib_view_apply_write_formula()
{
}

int pcilib_read_view(pcilib_t *ctx, const char *bank, const char *regname, const char *view/*, const char *unit*/, size_t value_size, void *value)
{
  int i,j,err;
  pcilib_register_value_t temp_value;
  
  /* we get the index of the register to find the corresponding register context*/
  if((i=pcilib_find_register(ctx,bank,regname))==PCILIB_REGISTER_INVALID){
    pcilib_error("can't get the index of the register %s", regname);
    return PCILIB_ERROR_INVALID_REQUEST;
  }
  
  /* we get the value of the register, as we will apply the view on it*/
  if((err==pcilib_read_register_by_id(ctx,i,&temp_value))>0){
    pcilib_error("can't read the register %s value before applying views",regname);
  }
    /*in the case we don't ask for a view's name, we know it will be for views of type enum. Especially, it's faster to search directly on the values of those views instead of a given name.
      we iterate so through the views of type enum to verify if the value we have corresponds to an enum command*/
  if(!(view)){
    for(j=0; ctx->register_ctx[i].enums[j].value;j++){
      if((temp_value >= ctx->register_ctx[i].enums[j].min) && (temp_value <= ctx->register_ctx[i].enums[j].max)){
	value_size=strlen(ctx->register_ctx[i].enums[j].name)*sizeof(char);
	value=malloc(sizeof(value_size));
	if(!(value)){
	  pcilib_error("can't allocate memory for the returning value of the view %s",view);
	  return PCILIB_ERROR_MEMORY;
	}
	/* in the case the value of register is between min and max, then we return the correponding enum command*/
	value=*(char*)ctx->register_ctx[i].enums[j].name;
	return 0;
      }
    }
    pcilib_warning("the value of the register asked do not correspond to any enum views");
    return PCILIB_ERROR_NOTAVAILABLE;
  }
  
  /** in the other case we ask for a view of type formula. Indeed, wa can't directly ask for a formula, so we have to provide a name for those views*/
  j=0;
  while((ctx->register_ctx[i].formulas[j].name)){
    if(!(strcasecmp(ctx->register_ctx[i].formulas[j].name))){
      /* when we have found the correct view of type formula, we apply the formula, that get the good value for return*/
      pcilib_view_apply_read_formula(ctx->register_ctx[i].formulas[j].read_formula,temp_value, value,....);
      return 0;
    }
    j++;
   }

  pcilib_warning("the view asked and the register do not correspond");
  return PCILIB_ERROR_NOTAVAILABLE;
}