/*
  LibRCD

  Copyright (C) 2005-2018 Suren A. Chilingaryan <csa@suren.me>

  This library is free software; you can redistribute it and/or modify it
  under the terms of the GNU Lesser General Public License version 2.1 or later
  as published by the Free Software Foundation.

  This library is distributed in the hope that it will be useful, but WITHOUT
  ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public License 
  for more details.

  You should have received a copy of the GNU Lesser General Public License 
  along with this program; if not, write to the Free Software Foundation, Inc.,
  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/

#include <stdio.h>
#include <string.h>

#include "../config.h"

#define _LIBRCD_C
#include "librcd.h"

#define NF_VALUE -2
#define max(a,b) ((a>b)?a:b)
#define min(a,b) ((a<b)?a:b)
#define bit(i) (1<<i)

typedef struct lng_stat2 {
  unsigned char a;
  unsigned char b;
  double rate;
  double srate;
  double erate;
} lng_stat2;

#include "russian_table.h"


static int end_symbol(char ch) {
    if (ch=='\r'||ch=='\n'||ch==0||ch==' '||ch=='\t'||ch==','||ch=='.'||ch=='!'||ch=='?'||ch==';'||ch=='-'||ch==':'||ch=='"'||ch=='\''||ch==')') return 1;
    return 0;
}

static int start_symbol(char ch) {
    if ((ch=='\t')||ch=='\r'||ch=='\n'||(ch==' ')||(ch=='(')||(ch=='"')||(ch=='\'')) return 1;
    return 0;
}    

typedef const struct lng_stat2 *lng_stat2_ptr;

static void bfind(const unsigned char *a, lng_stat2_ptr *w, lng_stat2_ptr *k, lng_stat2_ptr *al) {
  const struct lng_stat2 *winptr, *koiptr,*altptr;
  int ki,wi,ai,d,ws=0,ks=0,as=0;
    d=npow2>>1;
    wi=d;
    ki=d;
    ai=d;
    winptr=0;
    koiptr=0;
    altptr=0;
    do{
      d>>=1;
    
      if(!ws){
       if (wi>indexes2) wi-=d;
       else {
        winptr=enc_win+wi-1;
        if(a[0]==winptr->a){
          if(a[1]==winptr->b){
        	ws=1;
          }else if(a[1]<winptr->b){
            wi-=d;
          }else{ //b>win[wi].b
            wi+=d;
          }
        }else if(a[0]<winptr->a){
          wi-=d;
        }else{ //a>win[wi].a
          wi+=d;
        }
       }
      }
      if(!ks){
       if (ki>indexes2) ki-=d;
       else {
        koiptr=enc_koi+ki-1;
        if(a[0]==koiptr->a){
          if(a[1]==koiptr->b){
        	ks=1;
          }else if(a[1]<koiptr->b){
            ki-=d;
          }else{ //b>win[wi].b
            ki+=d;
          }
        }else if(a[0]<koiptr->a){
          ki-=d;
        }else{ //a>win[wi].a
          ki+=d;
        }
       }
      }
      if(!as){
       if (ai>indexes2) ai-=d;
       else {
        altptr=enc_alt+ai-1;
        if(a[0]==altptr->a){
          if(a[1]==altptr->b){
        	as=1;
          }else if(a[1]<altptr->b){
            ai-=d;
          }else{ //b>win[wi].b
            ai+=d;
          }
        }else if(a[0]<altptr->a){
          ai-=d;
        }else{ //a>win[wi].a
          ai+=d;
        }
       }
      }
    }while(d);
    if (ws) *w=winptr;
    else *w=NULL;
    if (ks) *k=koiptr;
    else *k=NULL;
    if (as) *al=altptr;
    else *al=NULL;
}

static double calculate(double s, double m, double e) {
    return s+m+e;
}

static int is_win_charset2(const unsigned char *txt, int len){
  const struct lng_stat2 *winptr, *koiptr,*altptr;
  double winstep,koistep,altstep,winestep,koiestep,altestep,winsstep,koisstep,altsstep;
  double winstat=0,koistat=0,altstat=0,winestat=0,koiestat=0,altestat=0,winsstat=0,koisstat=0,altsstat=0;
  long j;
  
#ifdef _AUTO_DEBUG
  fprintf(stderr,"Word: %s\n",txt);
#endif
  for(j=0;j<len-1;j++){
    //skip bottom half of table
    if(txt[j]<128 || txt[j+1]<128) continue;
#ifdef _AUTO_DEBUG
    fprintf(stderr,"Pair: %c%c",txt[j],txt[j+1]);
#endif
    bfind(txt+j,&winptr,&koiptr,&altptr);

    if ((j==0)||(start_symbol(txt[j-1]))) {
	if (winptr) winsstep=winptr->srate;
	else winsstep=NF_VALUE;
	if (koiptr) koisstep=koiptr->srate;
	else koisstep=NF_VALUE;
	if (altptr) altsstep=altptr->srate;
	else altsstep=NF_VALUE;
	winestep=0;
	koiestep=0;
	altestep=0;
	winstep=0;
	koistep=0;
	altstep=0;
#ifdef _AUTO_DEBUG
	fprintf(stderr,", Win %lf, Koi %lf, Alt: %lf\n",winsstep,koisstep,altsstep);
#endif
    } else if ((j==len-2)||(end_symbol(txt[j+2]))) {
	if (winptr) winestep=winptr->erate;
	else winestep=NF_VALUE;
	if (koiptr) koiestep=koiptr->erate;
	else koiestep=NF_VALUE;
	if (altptr) altestep=altptr->erate;
	else altestep=NF_VALUE;
	winsstep=0;
	koisstep=0;
	altsstep=0;
	winstep=0;
	koistep=0;
	altstep=0;
#ifdef _AUTO_DEBUG
	fprintf(stderr,", Win %lf, Koi %lf, Alt %lf\n",winestep,koiestep,altestep);
#endif
    } else {
	if (winptr) winstep=winptr->rate;
	else winstep=NF_VALUE;
	if (koiptr) koistep=koiptr->rate;
	else koistep=NF_VALUE;
	if (altptr) altstep=altptr->rate;
	else altstep=NF_VALUE;
	winsstep=0;
	winestep=0;
	koisstep=0;
	koiestep=0;
	altsstep=0;
	altestep=0;
#ifdef _AUTO_DEBUG
	fprintf(stderr,", Win %lf, Koi %lf, Alt %lf\n",winstep,koistep,altstep);
#endif
    }
    
    winstat+=winstep;
    koistat+=koistep;
    altstat+=altstep;
    winsstat+=winsstep;
    koisstat+=koisstep;
    altsstat+=altsstep;
    winestat+=winestep;
    koiestat+=koiestep;
    altestat+=altestep;
  }
  
#ifdef _AUTO_DEBUG
  fprintf(stderr,"Start.  Win: %lf, Koi: %lf, Alt: %lf\n",winsstat,koisstat,altsstat);
  fprintf(stderr,"Middle. Win: %lf, Koi: %lf, Alt: %lf\n",winstat,koistat,altstat);
  fprintf(stderr,"End.    Win: %lf, Koi: %lf, Alt: %lf\n",winestat,koiestat,altestat);
  fprintf(stderr,"Final.  Win: %lf, Koi: %lf, Alt: %lf\n",calculate(winsstat,winstat,winestat),calculate(koisstat,koistat,koiestat),calculate(altsstat,altstat,altestat));
#endif
  if ((calculate(altsstat,altstat,altestat)>calculate(koisstat,koistat,koiestat))&&(calculate(altsstat,altstat,altestat)>calculate(winsstat,winstat,winestat))) return 3;
  if (calculate(koisstat,koistat,koiestat)>calculate(winsstat,winstat,winestat)) return 1;
  return 0;
}


static int check_utf8(const unsigned char *buf, int len) {
    long i,j;
    int bytes=0,rflag=0;
    unsigned char tmp;
    int res=0;

    for (i=0;i<len;i++) {
	if (buf[i]<128) continue;
	
	if (bytes>0) {
	    if ((buf[i]&0xC0)==0x80) {
		if (rflag) {
		    tmp=buf[i]&0x3F;
		    // Russian is 0x410-0x44F
		    if ((rflag==1)&&(tmp>=0x10)) res++;
		    else if ((rflag==2)&&(tmp<=0x0F)) res++;
		}
		bytes--;
	    } else {
		res--;
		bytes=1-bytes;
		rflag=0;
	    }
	} else {
	    for (j=6;j>=0;j--)
		if ((buf[i]&bit(j))==0) break;
	    
	    if ((j==0)||(j==6)) {
		if ((j==6)&&(bytes<0)) bytes++;
		else res--;
		continue;
	    }
	    bytes=6-j;
	    if (bytes==1) {
		// Cyrrilic D0-D3, Russian - D0-D1
		if (buf[i]==0xD0) rflag=1;
		else if (buf[i]==0xD1) rflag=2;
	    }
	}
	    
	if ((buf[i]==0xD0)||(buf[i]==0xD1)) {
	    if (i+1==len) break;
	    	    
	}
    }
    return res;
}

/* In russian language we will have whole word consisting of >127 characters,
with latin languages there is in every word besides umlauts should exist at
least one standard latin character with code < 127. */
static int check_latin(const unsigned char *buf, int len) {
    long i;
    int cyr = 0;
    int latin = 0;
    
    for (i=0;i<len;i++) {
	if (buf[i]<128) {
	    if (((buf[i]>='a')&&(buf[i]<='z'))||((buf[i]>='A')&&(buf[i]<='Z'))) {
		    // Latin character inside a word, so it probably isn't cyrillic word
		latin++;
	    } else {
		    // Treating as a word separator.
		if (cyr > 0) {
		    if (!latin) return 0;
		    if (cyr>latin) return 0;
		}

		cyr = 0;
		latin = 0;
	    }
	} else {
		// Could be cyrillic word
	    cyr++;
	}
    }
    
    if (cyr > 0) {
	if (!latin) return 0;
	if (cyr>latin) return 0;
    }
//    printf("C%u:L%u\n",cyr,latin);

    return 1;
}


rcd_russian_charset rcdGetRussianCharset(const char *buf,int len) {
    long l;

    l = len?len:strlen(buf);
    if (check_utf8(buf,l)>1) return RUSSIAN_CHARSET_UTF8;
#ifdef DETECT_LATIN
    if (check_latin(buf,l)) return RUSSIAN_CHARSET_LATIN;
#endif /* DETECT_LATIN */
    return is_win_charset2(buf,l);
}

/*
rcd_russian_charset rcdGetRussianCharset(const char *buf,int len) {
    int res;
    res = rcdGetRussianCharset1(buf, len);
    printf("%u: %s\n", res, (buf&&!len)?buf:"null");
    return res;
}
*/

/* Compatibility */
rcd_russian_charset get_russian_charset(const char *buf,int len) {
    return rcdGetRussianCharset(buf, len);
}