/*
Copyright 2015-2022 Ian Jauslin

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

#include "meantools_deriv.h"

#include <stdio.h>
#include <stdlib.h>
#include "parse_file.h"
#include "cli_parser.h"
#include "istring.h"
#include "definitions.cpp"
#include "array.h"
#include "grouped_polynomial.h"


#define CP_FLAG_DERIVS 1
#define CP_FLAG_VARS 2
// read command line arguments
int tool_deriv_read_args(int argc, const char* argv[], Str_Array* str_args, Meantools_Options* opts){
  // file to read the polynomial from in flow mode
  const char* file="";
  // whether a file was specified on the command-line
  int exists_file=0;
  // flag
  int flag=0;
  // buffer in which to read the variables
  Char_Array buffer;
  int i;
  char* ptr;

  // defaults
  // differentiate once
  (*opts).deriv_derivs=1;
  // differentiate with respect to all variables
  (*opts).deriv_vars.length=-1;
  // do not chain
  (*opts).chain=0;


  // loop over arguments
  for(i=2;i<argc;i++){
    // flag
    if(argv[i][0]=='-'){
      for(ptr=((char*)argv[i])+1;*ptr!='\0';ptr++){
	switch(*ptr){
	// number of derivatives
	case 'd':
	  flag=CP_FLAG_DERIVS;
	  break;
	case 'V':
	  flag=CP_FLAG_VARS;
	  break;
	// chain
	case 'C':
	  (*opts).chain=1;
	  break;
	}
      }
    }
    // number of derivatives
    else if(flag==CP_FLAG_DERIVS){
      sscanf(argv[i],"%d",&((*opts).deriv_derivs));
      flag=0;
    }
    // variables
    else if(flag==CP_FLAG_VARS){
      // if the argument is "all" then differentiate wrt all variables
      if(str_cmp((char*)argv[i],"all")){
	(*opts).deriv_vars.length=-2;
      }
      else{
	str_to_char_array((char*)argv[i], &buffer);
	int_array_read(buffer,&((*opts).deriv_vars));
	free_Char_Array(buffer);
      }
      flag=0;
    }
    // read file name from command-line
    else{
      file=argv[i];
      exists_file=1;
    }
  }

  read_config_file(str_args, file, 1-exists_file);

  return(0);
}


// differentiate a flow equation
int tool_deriv(Str_Array str_args, Meantools_Options opts){
  // index of the entry in the input file
  int arg_index;
  // flow equation
  Grouped_Polynomial flow_equation;
  // flow equation for the derivatives
  Grouped_Polynomial flow_equation_deriv;
  int i;
  // header of the entry
  Char_Array arg_header;


  // parse flow equation
  // if there is a unique argument, assume it is the flow equation
  if(str_args.length==1){
    char_array_to_Grouped_Polynomial(str_args.strs[0], &flow_equation);
  }
  else{
    arg_index=find_str_arg("flow_equation", str_args);
    if(arg_index<0){
      fprintf(stderr,"error: no flow equation entry in the configuration file\n");
      exit(-1);
    }
    else{
      char_array_to_Grouped_Polynomial(str_args.strs[arg_index], &flow_equation);
    }

    // variables
    // check they were not specified on the command line
    if(opts.deriv_vars.length==-1){
      arg_index=find_str_arg("variables", str_args);
      if(arg_index>=0){
	int_array_read(str_args.strs[arg_index],&(opts.deriv_vars));
      }
    }
  }

  // if variables length is negative then set the variables to all of the available ones
  if(opts.deriv_vars.length<0){
    init_Int_Array(&(opts.deriv_vars), flow_equation.length);
    for(i=0;i<flow_equation.length;i++){
      int_array_append(flow_equation.indices[i], &(opts.deriv_vars));
    }
  }

  // compute derivatives
  flow_equation_derivative(opts.deriv_derivs, opts.deriv_vars, flow_equation, &flow_equation_deriv);

  // print
  // if chain then print config file
  if(opts.chain==1){
    for(i=0;i<str_args.length;i++){
      // check whether to print the str_arg
      get_str_arg_title(str_args.strs[i], &arg_header);
      if (\
	str_cmp(arg_header.str, "flow_equation")==0 &&\
	str_cmp(arg_header.str, "virtual_fields")==0 &&\
	str_cmp(arg_header.str, "groups")==0 &&\
	str_cmp(arg_header.str, "fields")==0 &&\
	str_cmp(arg_header.str, "identities")==0 &&\
	str_cmp(arg_header.str, "propagator")==0 &&\
	str_cmp(arg_header.str, "input_polynomial")==0 &&\
	str_cmp(arg_header.str, "id_table")==0 ){

	  printf("%s\n&\n",str_args.strs[i].str);
      }
      free_Char_Array(arg_header);
    }
    // print flow equation
    printf("#!flow_equation\n");
  }
  grouped_polynomial_print(flow_equation_deriv,'%','%');

  // free memory
  free_Grouped_Polynomial(flow_equation);
  free_Grouped_Polynomial(flow_equation_deriv);
  free_Int_Array(opts.deriv_vars);
  return(0);
}


// n first derivatives of a flow equation wrt to variables
int flow_equation_derivative(int n, Int_Array variables, Grouped_Polynomial flow_equation, Grouped_Polynomial* flow_equation_derivs){
  Grouped_Polynomial dflow;
  Grouped_Polynomial tmpflow;
  Int_Array indices;
  int i,j;

  int_array_cpy(variables, &indices);

  // output polynomial
  grouped_polynomial_cpy(flow_equation, flow_equation_derivs);

  // init dflow to flow_equation
  grouped_polynomial_cpy(flow_equation, &dflow);

  for(j=0;j<n;j++){
    // tmp flow contains the result of the previous derivative
    grouped_polynomial_cpy(dflow, &tmpflow);
    // free dflow
    free_Grouped_Polynomial(dflow);
    // next derivative
    flow_equation_derivx(tmpflow, indices, &dflow);
    // free tmpflow
    free_Grouped_Polynomial(tmpflow);

    // add the differentiated indices as variables for the next derivative
    for(i=0;i<variables.length;i++){
      if(variables.values[i]>=0){
	int_array_append((j+1)*DOFFSET+variables.values[i], &indices);
      }
      // constants have a negative index
      else{
	int_array_append(-(j+1)*DOFFSET+variables.values[i], &indices);
      }
    }

    // add to flow equation
    grouped_polynomial_concat(dflow, flow_equation_derivs);
  }

  if(n>0){
    free_Grouped_Polynomial(dflow);
  }
  free_Int_Array(indices);
  return(0);
}