/********************************************************
  BCL Example Problems
  ====================

  file xbexpl3.c
  ``````````````
  User error handling.

  (c) 2008-2024 Fair Isaac Corporation
      author: S.Heipcke, Jan. 2000, rev. Mar. 2011
********************************************************/

#include <stdio.h>
#include <setjmp.h>
#include <string.h>
#include "xprb.h"

/* This small, infeasible example shows how the error handling and all
   printed messages can be intercepted by the user's program. This is done
   by defining the corresponding BCL callback functions and changing
   the error handling flag. */

/***********************************************************************/

jmp_buf model_failed;

void modexpl3(XPRBprob prob)
{
 XPRBvar x[3];
 XPRBctr ctr[2], cobj;
 int i;

 for(i=0;i<2;i++) x[i]=XPRBnewvar(prob,XPRB_UI,XPRBnewname("x_%d",i),0,100);

                /* Create the constraints:
                   C1: 2x0 + 3x1 >= 41
                   C2:  x0 + 2x1  = 13 */
 ctr[0]=XPRBnewctr(prob,"C1",XPRB_G);
 XPRBaddterm(ctr[0],x[0],2);
 XPRBaddterm(ctr[0],x[1],3);
 XPRBaddterm(ctr[0],NULL,41);

 ctr[1]=XPRBnewctr(prob,"C2",XPRB_E);
 XPRBaddterm(ctr[1],x[0],1);
 XPRBaddterm(ctr[1],x[1],2);
 XPRBaddterm(ctr[1],NULL,13);

/* Uncomment the following line to cause an error in the model that
   triggers the user error handling: */

/* x[2]=XPRBnewvar(prob,XPRB_UI,"x_2",10,1); */

                /* Objective: minimize x0+x1 */
 cobj = XPRBnewctr(prob,"OBJ",XPRB_N);
 for(i=0;i<2;i++) XPRBaddterm(cobj,x[i],1);
 XPRBsetobj(prob,cobj);          /* Select objective function */
 XPRBsetsense(prob,XPRB_MINIM);  /* Set objective sense to minimization */

 XPRBprintprob(prob);            /* Print current problem definition */

 XPRBlpoptimize(prob,"");        /* Solve the LP */
 XPRBprintf(prob,"problem status: %d  LP status: %d  MIP status: %d\n",
    XPRBgetprobstat(prob),XPRBgetlpstat(prob),XPRBgetmipstat(prob));

/* This problem is infeasible, that means the following command will fail.
   It prints a warning if the message level is at least 2 */

 XPRBprintf(prob,"Objective: %g\n",XPRBgetobjval(prob));

 for(i=0;i<2;i++)                /* Print solution values */
  XPRBprintf(prob,"%s:%g, ", XPRBgetvarname(x[i]), XPRBgetsol(x[i]));
 XPRBprintf(prob,"\n");
}

/***********************************************************************/

/**** User error handling function ****/
void XPRB_CC usererror(XPRBprob prob, void *vp, int num, int type,
                       const char *t)
{
 printf("BCL error %d: %s\n", num, t);
 if(type==XPRB_ERR) longjmp(model_failed,1);
}

/**** User printing function ****/
void XPRB_CC userprint(XPRBprob prob, void *vp, const char *msg)
{
 static int rtsbefore=1;

    /* Print 'BCL output' whenever a new output line starts,
       otherwise continue to print the current line. */
 if(rtsbefore)
  printf("BCL output: %s", msg);
 else
  printf("%s",msg);
 rtsbefore=(msg[strlen(msg)-1]=='\n');
}

/***********************************************************************/

int main(int argc, char **argv)
{
 XPRBprob prob;

 XPRBseterrctrl(0);         /* Switch to error handling by the user's program */

 XPRBsetmsglevel(NULL,2);   /* Set the printing flag. Try other values:
                                0 - no printed output, 1 - only errors,
                                2 - errors and warnings, 3 - all messages */
 XPRBdefcbmsg(NULL,userprint, NULL);
                            /* Define the printing callback function */

 if((prob=XPRBnewprob("Expl3"))==NULL)
 {                          /* Initialize a new problem in BCL */
  fprintf(stderr,"I cannot create the problem\n");
  return 1;
 }
 else
  if(setjmp(model_failed))
  {
   fprintf(stderr,"I cannot build the problem\n");
   XPRBdelprob(prob);
   XPRBdefcberr(prob,NULL, NULL);
   return 1;
  }
  else
  {
   XPRBdefcberr(prob,usererror, NULL);
   modexpl3(prob);          /* Formulate and solve the problem */
   XPRBdefcberr(prob,NULL, NULL);
   return 0;
  }
}