//   I'm sorry, it is one of my first programs in C++.              //
//   So it looks a little erratic.                                  //
//                                                                  //
//   You've been warned ;)                                          //
//                                                                  //
//   Newly updated, code ported to Linux and updated for CGI        //

#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <string.h>
#include <ctype.h>

// set up the filename for the file with unit descriptions
#define INIFILENAME "/usr/share/ucalc.ini"

//If this is defined, generate code for a CGI script: take input from querystring, output as HTML.

//#define IS_CGI

#ifdef IS_CGI
#define LOGFILENAME "ucalc.log"
#include "cgi.h"
#include "log.c"
#endif

typedef struct
{ char utype[10]; // unit type (length, volume...)
  char uname[20]; // unit name
  char ushrt[10]; // unit shortcut
  double conv;    // multiply with...
  double convadd; // ...and add...
  double rangel;  // do not show if result lower than this
  double rangeh;  // do not show if result higher than this
  int metric;     // is metric?
  int invert;     // invert - for freq/vawelength etc.
  int allowpref[16]; // flags of metric prefixes
} METRICUNIT;

typedef struct
{ char   prefchar; // prefix character
  double order;    // exponent
  double orders;   // size of subrange
} METRICPREFIX;


const METRICPREFIX prefix[14]=
{{'a',1e-18,1e3},
 {'f',1e-15,1e3},
 {'p',1e-12,1e3},
 {'n',1e-9 ,1e3},
 {'u',1e-6 ,1e3},
 {'m',1e-3 ,1e3},
 {'c',1e-2 ,1e2},
 {'d',1e-1 ,1e1},
 {' ',1    ,1e3},
 {'h',1e2  ,1e2},
 {'k',1e3  ,1e3},
 {'M',1e6  ,1e3},
 {'G',1e9  ,1e3},
 {'T',1e12 ,1e3}};



char*strupr(char*s)
{ char*sp;sp=s;
  while(s[0]){s[0]=toupper(s[0]);s++;}
  return s;}
  
char*strlwr(char*s)
{ char*sp;sp=s;
  while(s[0]){s[0]=tolower(s[0]);s++;}
  return s;}



/* HELP OUTPUT BEGINS HERE */

void printhelpunits(char*paramstr1,char*paramstr2)
{ char s[250];
  char unittype[10];
  FILE *f;
  METRICUNIT m;
  int n,t;
#ifdef IS_CGI
      dedicate();
      printf("</CENTER><P>\n<PRE>\n");
#endif
//      f=fopen(inifile,"r");
      f=fopen(INIFILENAME,"r");
      if (!f) {printf("\nINIfile open error on \"%s\"!\n",INIFILENAME);return;}
      if (strcasecmp(paramstr2,"?")==0) printf("\nAvailable typedefs:\n");
#ifdef IS_CGI
                                  else printf("\n<PRE>  <B>Available units:</B>\n");
#else
                                  else printf("\n  Available units:\n");
#endif
      strcpy(unittype,"");
      seeksection(f,"[unitdef]");
      while (!feof(f))
       {fgets(s,250,f);
        if (readinirow(&m,s))
         if ((strcmp(paramstr2,"")==0)||(strcasecmp(paramstr2,m.utype)==0)||(strcasecmp(paramstr2,"?")==0))
         { if (strcasecmp(unittype,m.utype)!=0)
            {if (strcmp(paramstr2,"?")==0) printf("  %s\n",m.utype);
#ifdef IS_CGI
                                        else printf("\n  <B>%s:</B>\n",m.utype);
#else
                                        else printf("\n  %s:\n",m.utype);
#endif
             strcpy(unittype,m.utype);
             }
           if (strcmp(paramstr2,"?")!=0)
           {
           printf("    %-20s ",m.uname);
           for (t=0,n=0;t<14;t++)
             if (m.allowpref[t])
             {if(n) printf(", ");
              //if (prefix[t].prefchar=='u') printf("&micro;"); else
              if (prefix[t].prefchar!=' ') printf("%c",prefix[t].prefchar);
              printf("%s",m.ushrt);n=1;}
           printf("\n");}
         }}
#ifdef IS_CGI
      printf("\n</PRE>\n");
#endif
      fclose(f);return;
}

void printhelp(char*runname)
{
#ifdef IS_CGI
    dedicate();
    printf("</CENTER><P>\n<PRE>\n");
#endif
    printf("Usage: %s <value> <unit>    for conversion\n",runname);
    printf("    or %s /units [typedef]  for list of unit identificators\n",runname);
    printf("    or %s /units ?          for list of unit typedefs\n\n",runname);
#ifdef IS_CGI
    printf("</PRE>");
#endif
    exit(0);
}

/* HELP OUTPUT ENDS HERE */



int readinirow(METRICUNIT *met,char *s)
{ char sn[64];
  int st=0,n=0,n1=0,sl=0;
  int t=0,t1=0;
//  int st,n,n1,sl;
//  int t,t1;

//  st=0;sl=0;n=0;
  strcat(s," ");
  memset(met,0,sizeof(METRICUNIT));
  if ((s[0]==0) || (s[0]==';')) return(0);
  while(s[st]==' ') st++;

  for(t=st;t<strlen(s);t++)
   {switch(s[st])
     {case ' ':
      case 0:   st++;sn[sl]=0;sl=0;
                switch(n)
                 {case 0: strncpy((*met).utype,sn,sizeof((*met).utype));break;
                  case 1: strncpy((*met).uname,sn,sizeof((*met).uname));break;
                  case 2: strncpy((*met).ushrt,sn,sizeof((*met).ushrt));break;
                  case 3: n1=0;if(!strncmp(sn,"INV:",4)){n1=4;(*met).invert=1;}
		          (*met).conv=atof(sn+n1);break;
                  case 4: (*met).convadd=atof(sn);break;
                  case 5: (*met).rangel=atof(sn);break;
                  case 6: (*met).rangeh=atof(sn);break;
                  case 7: (*met).metric=atoi(sn);break;
                  case 8: for (t1=0;t1<14;t1++)
                          {(*met).allowpref[t1]=((sn[t1]=='+')||(sn[t1]=='1'));}
                  case 9: break;
                 }
                n++;
                while (s[st]==' ') st++;
                break;
      default:  sn[sl]=s[st];if (sn[sl]=='_') sn[sl]=' ';sl++;st++;break;
     }
   }

  return((*met).conv!=0);
}

int seeksection(FILE *f,char *name)
{ char s[250];
  int t;
  strcpy(s,"");t=0;
  while ((strncasecmp(s+t,name,strlen(name))!=0) && !feof(f))
   {fgets(s,250,f);
    t=0;while(s[t]==' ')t++;}
  return 0;
}

int isunit(METRICUNIT *m,char *s,double *res)
{ int t,n;
//printf("%s %s\n",m->uname,s);
  for (t=0;t<14;t++)
   if ((*m).allowpref[t])
    {if ((prefix[t].prefchar==' ')&&(strcmp(s,(*m).ushrt)==0)) return(1);else
     if ((prefix[t].prefchar==s[0])&&(strcmp(s+1,(*m).ushrt)==0))
           {*res*=prefix[t].order;n=strlen(s);
            if (s[n-1]=='2') *res*=prefix[t].order;
            if (s[n-1]=='3') {*res*=prefix[t].order;*res*=prefix[t].order;}
            return(1);}}
  return(0);
}

double correctprefix(double prfx,int order)
{ switch (order)
   {case 2: return(prfx*prfx);
    case 3: return(prfx*prfx*prfx);
    default:return(prfx);}
}

void convertunit(METRICUNIT *m,double *res,char *s)
{ int t;
  double r,r1;
  char str[20];
  int used;
  int volmod;

  volmod=1;if (s[strlen(s)-1]=='2') volmod=2;else if (s[strlen(s)-1]=='3') volmod=3;
  r=0;r1=0;strcpy(str," ");
  for (t=0;t<14;t++)
   if ((*m).allowpref[t])
    {r1=r;
     if((prefix[t].orders>=1000)||(volmod>1))
     if ((r1==0)||(r1>=prefix[t].orders))
       {r=(*res) / correctprefix(prefix[t].order,volmod);
        str[0]=prefix[t].prefchar;used=t;}
    }
  if (str[0]!=' ') {strcat(str,s);strcpy(s,str);*res/=correctprefix(prefix[used].order,volmod);}
}

void printunit_name(char*s)
{ char*sp,c=0;
  sp=strchr(s,'2');if(!sp)sp=strchr(s,'3');
  if(sp){c=sp[0];sp[0]=0;}
  printf("%s",s);
#ifdef IS_CGI
  if(c)printf("<SUP>%c</SUP>",c);
#else
  if(c)printf("^%c",c);
#endif
}

void printunit_unit(char*s)
{
#ifdef IS_CGI
  if(s[0]==0x10){printf("&micro");s[0]=';';}else 
  if(s[0]==0x60){printf("&deg");s[0]=';';}
#else
  if(s[0]==0x10){s[0]='u';}else 
  if(s[0]==0x60){s[0]='\'';}
#endif
  printunit_name(s);
}


char*getfracstr(double r,int ismetric)
{
  static char s[32]="";
  double fr,in;
  int t,t1;
  int steps2=256;
  int steps3=3^5;
  int steps5=5^4;
  int steps7=7^4;
  int steps;

  int minstep=-1;
  int minsteps=-1;
  double mindiff=2,diff;
  int primes[]={2,3,5,7,11,13,17,19,23,29,31,37};
  int primesteps[]={256,243,625,343,11^3,13^2};
  fr=modf(r,&in);

  if(in>=1000)return NULL;
  if(fr==0.0)return NULL;

//  for(t=0;t<steps2;t++){
//    diff=fabs(fr-((double)t/(double)steps2));
//    if(diff<mindiff){mindiff=diff;minstep=t;minsteps=steps2;}
//  }
//for(t1=0;t1<4;t1++)printf("  %i",primesteps[t1]);printf("\n");

  for(t1=0;t1<2;t1++){
    for(t=0;t<primesteps[t1];t++){
      diff=fabs(fr-((double)t/(double)primesteps[t1]));
      if(diff<mindiff){mindiff=diff;minstep=t;minsteps=primesteps[t1];}
    }
  }

//  printf("                                        %12g     %4g + %8g    %i/%i (%g)\n",r,in,fr,minstep,minsteps,mindiff);
  // find least common denominator
  for(t1=0;t1<4;t1++){
    for(t=0;t<8;t++){
      if(minstep%primes[t1]!=0)break;
      if(minsteps%primes[t1]!=0)break;
      minstep/=primes[t1];
      minsteps/=primes[t1];
    }
  }

//  for(t=0;t<8;t++){
//    if(minstep%2!=0)break;
//    minstep>>=1;
//    minsteps>>=1;
//  }
//  printf("                                        %12g     %4g + %8g    %i/%i (%g)\n",r,in,fr,minstep,minsteps,mindiff);

  if(minstep==0)return NULL;
  if(mindiff>0.00001)return NULL;
  if(mindiff>0.000001)if(ismetric)return NULL;
  if(minsteps==10)return NULL;
  if(minsteps==100)return NULL;
  //if(steps>64)return NULL;

  //printf("                                        %12g     %4g + %8g    %i/%i (%g)\n",r,in,fr,minstep,steps,mindiff);
  if(in>0)
    snprintf(s,31,"%g %i/%i",in,minstep,minsteps);
  else
    snprintf(s,31,"%i/%i",minstep,minsteps);
  return s;
}


void printunit(METRICUNIT *m,double r,char *s)
{ double r1;
  char sht[20];
  char*sfrac;
  if(!(*m).invert)r1=(r/(*m).conv)+(*m).convadd;
             else r1=((*m).conv/r)+(*m).convadd;
  if ((((*m).rangel==0)||((*m).rangel<r1))&&(((*m).rangeh==0)||((*m).rangeh>r1)))
   {strcpy(s,(*m).ushrt);
    convertunit(m,&r1,s);
#ifdef IS_CGI
    printf("<TR><TD></TD><TD align=left valign=bottom>");
    printunit_name((*m).uname);
    printf("</TD><TD align=right valign=bottom>&nbsp; &nbsp; %12g</TD><TD valign=bottom>&nbsp;",r1);
    printunit_unit(s);
    printf("</TD></TR>\n");
#else
    sfrac=getfracstr(r1,(*m).metric);
    if(sfrac==NULL){
      printf("  %-20s %12g %s\n",(*m).uname,r1,s);
    } else {
      printf("  %-20s %12g %-8s %8s  %s\n",(*m).uname,r1,s,sfrac,s);
    }
//    printf("  %-20s %12s %s\n",(*m).uname,sfrac,s);
#endif
   }
}


void dedicate()
{
#ifdef IS_CGI
  printf("<small>Dedicated to Tiya</small>\n");
#else
  printf("Dedicated to Tiya\n");
#endif
}


void standardizequery(char*s)
{ if(s[0]=='/')return;
  for(;;){if(!s[0])return;if(s[0]==' ')return;
          if(s[0]==',')s[0]='.';else
          if(s[0]=='"')break;
          if(s[0]==0x27)break;
          if(s[0]>='A')break;s++;}
  memmove(s+1,s,strlen(s)+1);
  s[0]=' ';
}

int xstrcompare(char*s,char*s1,char mode,int l)
{ if(mode=='+')
   {if(l)return strncasecmp(s,s1,l);
         return strcasecmp(s,s1);}
  else
   {if(l)return strncmp(s,s1,l);
         return strcmp(s,s1);}
}

void convertvalue(FILE*f,char*s1)
{ char s[256],*sp,*sp1;
  seeksection(f,"[unitmap]");
  while(!feof(f)){s[0]=0;fgets(s,256,f);if(s[0]=='[')return;
    sp=strchr(s,'\n');if(sp)sp[0]=0;
    if(!s[0])continue;if(s[0]==';')continue;
    sp=strchr(s,' ');if(!sp)continue;
    sp[0]=0;sp++;while(sp[0]==' ')sp++;
    sp1=strchr(s,'*');if(sp1)sp1[0]=0;
    if(sp1){if(!xstrcompare(s1,s+1,s[0],strlen(s+1))){strcpy(s1,sp);return;}}
       else{if(!xstrcompare(s1,s+1,s[0],0))          {strcpy(s1,sp);return;}}
  }
}



int main(int argc,char*argv[])
{ char s[250];
  FILE *f;
  METRICUNIT m;
  int n,n1,t;
  double r1,r2;
  double src,src1;
  double srcmet;
  char unit[10];
  char unittype[10];
  
  char*paramstr[3];
  char params[256];
  int paramcnt=3;
//  char *buffer=NULL;
  //
  char rundir[128];
  char rundrive[5];
  char runname[32];
  char runext[16];
//  char inifile[200];
  
#ifdef IS_CGI
  printf("Content-Type: text/html\r\n\r\n");
  logrequest();
#endif
//  strcpy(params,"1 km");
#ifdef IS_CGI
  getvarn("QUERY",params,250);
#else
  params[0]=0;
  if(argc>1)strcat(params,argv[1]);
  strcat(params," ");
  if(argc>2)strcat(params,argv[2]);
#endif
  
  standardizequery(params);
  
  paramstr[0]=params;paramstr[1]=params;
  paramstr[2]=strchr(params,' ');if(!paramstr[2])paramcnt=1;
                       else {paramstr[2][0]=0;paramstr[2]++;}

  strcpy(runname,"ucalc");
#ifdef IS_CGI
  printf("<BODY BGCOLOR=#FFFFCC TEXT=#000000>\n");
  printf("<CENTER><B>Unit Calculator v0.99<BR><SMALL><SMALL>(C)1997 New Wave Microtechnology</SMALL></SMALL></B><BR>");
  if (paramcnt!=3){printhelp(runname);return;}
#else
  if (argc<3){printhelp(runname);return;}
#endif
  if (strcasecmp(paramstr[1],"/UNITS")==0){printhelpunits(paramstr[1],paramstr[2]);return;}
  //fractional inch
  char*sp;
  sp=strchr(paramstr[1],'/');
  if(sp){
    sp[0]=0;sp++;
    src=atof(paramstr[1])/atof(sp);
  }
  else src=atof(paramstr[1]);
  // fractional inch 2
  sp=strchr(paramstr[2],'/');if(sp){
    int v1,v2;
    sp++;
    v1=atoi(paramstr[2]);
    v2=atoi(sp);
    if(v2!=0){
      src=src+((float)v1/(float)v2);
      strncpy(paramstr[2],argv[3],20); // POTENTIAL BUG HERE!
    }
  }
  //
  src1=src;
  f=fopen(INIFILENAME,"r");
  if (!f) {printf("INIfile open error on \"%s\"!\n",INIFILENAME);return;}
  strcpy(unittype,"");
  //
  convertvalue(f,paramstr[2]);
  strncpy(unit,paramstr[2],10);
  seeksection(f,"[unitdef]");
  while (!feof(f))
   {s[0]=0;
    fgets(s,250,f);
    if (readinirow(&m,s))
     if (isunit(&m,unit,&src))
      {strcpy(unittype,m.utype);
       if(!m.invert)srcmet=(src-m.convadd)*m.conv;
               else srcmet=m.conv/(src-m.convadd);
//       srcmet=(src-m.convadd)*m.conv;
       strcpy(rundir,m.utype);strcat(rundir,":");strcat(rundir,m.uname);      
#ifdef IS_CGI
       printf("<P><CENTER><TABLE>\n<TR><TD COLSPAN=4><B>Input:</B></TD></TR>\n");
       printf("<TR><TD>&nbsp;&nbsp;&nbsp;&nbsp;</TD><TD align=left valign=bottom>");
       printunit_name(rundir);
       printf("</TD><TD align=right valign=bottom>%12g</TD><TD valign=bottom>&nbsp;",src1);
       printunit_unit(paramstr[2]);
       printf("</TD></TR>\n");
#else
       printf("Input:\n");
       printf("  %-20s %12g %s\n\n",rundir,src1,paramstr[2]);
#endif
//       printf("  %-20s %12g %s\n\n",rundir,src1,paramstr[2]);
       break;}
   }
  //
  if (unittype[0]!=0)
  {
#ifdef IS_CGI
  printf("<TR><TD COLSPAN=4><B>Results:</B></TD></TR>\n");
#else
  printf("Results:\n");
#endif
  fseek(f,0,SEEK_SET);
  seeksection(f,"[unitdef]");
  while (!feof(f))
   {s[0]=0;
    fgets(s,250,f);
    if (readinirow(&m,s))
     if (strcasecmp(m.utype,unittype)==0)
      printunit(&m,srcmet,unit);
   }
#ifdef IS_CGI
   printf("</TABLE>\n");
#endif
  }
  else
#ifdef IS_CGI
   printf("<CENTER><P>Unit <B>\"%s\"</B> cannot be recognized<P>OR<P>'Improper use of prefix'.</CENTER>\n",unit);
#else
  printf("Unit \"%s\" cannot be recognized  OR  'Improper use of prefix'.\n",unit);
#endif
  fclose(f);
  printf("\n");
#ifdef IS_CGI
  printf("</BODY></HTML>\n");
#endif
  return 0;
}