#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>
#include "struct_TAC_in.h"
#include "struct_ROI.h"

/* C source code name: fit_sv_akc.c */
/* edit, e.g., with emacs. compile with Makefile  */

/* By: Alexander K. Converse, University of Wisconsin-Madison */
/* Created: 22 Nov 2012 */
/* Modified: 26 March 2014 */

/* Purpose: fit sv to ROI data using brute force minimization  */
/* usage: fit_sv_akc(index, ROI struct, TAC struct, int MAT) */

void fit_sv_akc(int index, struct ROI *iROI, struct TAC_t *q, int MAT)
{

  double difference;
  double smallestDifference;
  int found;
  int lastIndex;
  int i;
  double sv_start;
  double bestSV;
  double sv;
  double E;

  found = 0;

  // Define some epsilon the (observed - bound) calculation must be within
  E = .00005;
  // Set the starting, current, and prior sv to 0
  sv_start = 0;
  sv = 0;
  //oldSV = 0;
  // Set the prior difference to arbitrarily large number
  smallestDifference = 1000;
  // Determine index of the last value in the array
  lastIndex = q->nFrames - 1;

  for (i = 0; i < 100; i++) {
    find_MAT_akc(index, 1, iROI, q, sv, MAT);

    difference = iROI->observed[lastIndex] - iROI->bound[lastIndex];
    if (difference < 0) {
      difference = difference * -1;
    }

    //printf("Difference: %f SV: %f\n", difference, sv);
    if (difference < smallestDifference) {
      smallestDifference = difference;
      bestSV = sv;
    }

    sv = sv + 0.00001;
  } 

  iROI->sv = bestSV;
  printf("Best sv: %f\n", iROI->sv);

/*
  do {

    // Run model calculations for initial sv value. This gives starting observed and bound values
    // Goal is to minimize difference between observed and bound values at tfinal
    find_MAT_akc(index, 1, iROI, q, sv, MAT);

    // Calculate difference
    difference = iROI->observed[lastIndex] - iROI->bound[lastIndex];
    
    // Make difference positive
    if (difference < 0) {
      difference = difference * -1;
    }

    // If difference is less than specified epsilon, store that value and exit by setting found = 1
    if (difference < E) {
      iROI->sv = sv;
      found = 1;
      printf("Difference less than E\n");
    } 

    // If difference is greater than the previous difference, epsilon value was not reached
    // Store the previous difference as the smallest achievable difference and exit
    else if (difference >= oldDifference) {
      iROI->sv = oldSV;
      found = 1;
      printf("Difference > oldDifference, difference not < %f\n", E);
    } 

    // If neither condition met, increase sv
    else {
      oldSV = sv;
      sv = sv + .00001;
      oldDifference = difference;
      found = 0;
    }

    } while (found == 0);
*/
}