// xcode.C (formerly auto2unix.cc)
// This program tries to determine input document encoding
// and to convert it to koi8, CP-1251 or cp866.

// Written  by Andrey V. Lukyanov on May 14, 1997
// Last modified on May 18, 1997

// Updated to convert to /don't kill me/ cp1251 (oh, god! I hate it!) // instead of KOI-8(original)
// by Cyril Rotmistrovsky
// Updated to make conversions to cp1251, cp866 and koi8-r (default) // depending on flags
// by Cyril Rotmistrovsky
// Modified on Oct 19, 1997
// Modified by Cyril Rotmistrovsky to be compiled by Watcom C++
// 10.0 // (Oh, God! what a non-standard compiler!)
// Last modified on Jun 18 1998

// Modified by Igor V. Krassikov (KIV without Co)
// for quoted-printable decodeing

// Name changed to xcode 


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

#ifndef KOI8_WIN
#define KOI8_WIN \
"\x94\x83\xaa\x8f\x90\xa9\x93\x84\x92\x91\x95\xaf\xac\xab\xad\xae" \
"\x80\x81\x82\xb4\xbe\xb9\xbb\xb7\xb3\xb2\xbf\xb5\xb8\xbd\xba\xb6" \
"\x9d\x8a\xa5\xb1\xa6\x99\x88\x87\x8b\xa4\xa3\x98\x8e\x8d\x8c\x96" \
"\x97\x9c\x85\xb0\x86\x89\xa1\xa2\x9b\x9f\xa0\x9a\xa8\xa7\x9e\xbc" \
"\xfe\xe0\xe1\xf6\xe4\xe5\xf4\xe3\xf5\xe8\xe9\xea\xeb\xec\xed\xee" \
"\xef\xff\xf0\xf1\xf2\xf3\xe6\xe2\xfc\xfb\xe7\xf8\xfd\xf9\xf7\xfa" \
"\xde\xc0\xc1\xd6\xc4\xc5\xd4\xc3\xd5\xc8\xc9\xca\xcb\xcc\xcd\xce" \
"\xcf\xdf\xd0\xd1\xd2\xd3\xc6\xc2\xdc\xdb\xc7\xd8\xdd\xd9\xd7\xda"
#endif
#ifndef KOI8_ALT
#define KOI8_ALT \
                  "\xc4\xb3\xda\xbf\xc0\xd9\xc3\xb4" \
                  "\xc2\xc1\xc5\xdf\xdc\xdb\xdd\xde" \
                  "\xb0\xb1\xb2\xf4\xfe\xf9\xfb\xf7" \
                  "\xf3\xf2\xff\xf5\xf8\xfd\xfa\xf6" \
                  "\xcd\xba\xd5\xf1\xd6\xc9\xb8\xb7" \
                  "\xbb\xd4\xd3\xc8\xbe\xbd\xbc\xc6" \
                  "\xc7\xcc\xb5\xf0\xb6\xb9\xd1\xd2" \
                  "\xcb\xcf\xd0\xca\xd8\xd7\xce\xfc" \
                  "\xee\xa0\xa1\xe6\xa4\xa5\xe4\xa3" \
                  "\xe5\xa8\xa9\xaa\xab\xac\xad\xae" \
                  "\xaf\xef\xe0\xe1\xe2\xe3\xa6\xa2" \
                  "\xec\xeb\xa7\xe8\xed\xe9\xe7\xea" \
                  "\x9e\x80\x81\x96\x84\x85\x94\x83" \
                  "\x95\x88\x89\x8a\x8b\x8c\x48\x8e" \
                  "\x8f\x9f\x90\x91\x92\x93\x86\x82" \
                  "\x9c\x9b\x87\x98\x9d\x99\x97\x9a"

#endif

#define NUMCOD 5

unsigned char* destTab[]={
	(unsigned char *)KOI8_ALT,
	(unsigned char *)KOI8_WIN
};

char * help[]={
	"This program tries to determine input document encoding\n", "and to convert it to desired one\n",
	"\n",
	"Written by Andrey V. Lukyanov on May 14, 1997  "
	"Last modified on May 18, 1997\n",
	"Updated by Cyril Rotmistrovsky                "
	"Last modified on Oct 19, 1997\n",
	"Updated by Igor V. Krassikov                  "
	"Last modified on Oct 29, 1998\n",
	"\n",
	"Usage: %s [-h|-H|-?] [-w|-k|-a] [+w|+k|+a|+i|+m] [-q] " "[input [output]]\n",
	"-q to disable quoted-pritable decoding\n",
	"-k to set  koi8      output\n",
	"-w to set  cp1251    output\n",
	"-a to set  cp866    output(default)\n",
	"+k to force koi8      input\n",
	"+w to force cp1251    input\n",
	"+a to force cp866    input\n",
	"+i to force iso8859-5 input\n",
	"+m to force mac      input\n",
	0
};

char * encName[]={"koi8","cp866","cp1251","iso8859-5","mac"}; 

unsigned char recode_table[NUMCOD][128]={
	{  //koi8
		128,129,130,131,132,133,134,135,136,137,138,139,140,141,142,143,
		144,145,146,147,148,149,150,151,152,153,154,155,156,157,158,159,
		160,161,162,163,164,165,166,167,168,169,170,171,172,'-',174,175,
		176,177,178,179,180,181,182,183,184,185,186,187,188,189,190,191,
		192,193,194,195,196,197,198,199,200,201,202,203,204,205,206,207,
		208,209,210,211,212,213,214,215,216,217,218,219,220,221,222,223,
		224,225,226,227,228,229,230,231,232,233,234,235,236,237,238,239,
		240,241,242,243,244,245,246,247,248,249,250,251,252,253,254,255 },
	{ //dos
		225,226,247,231,228,229,246,250,233,234,235,236,237,238,239,240,
		242,243,244,245,230,232,227,254,251,253,255,249,248,252,224,241,
		193,194,215,199,196,197,214,218,201,202,203,204,205,206,207,208,
		128,129,130,131,132,133,134,135,136,137,186,139,140,141,142,143,
		144,145,146,147,148,149,150,151,152,153,154,191,156,157,158,159,
		160,161,162,176,164,165,166,167,168,169,170,171,172,173,174,175,
		210,211,212,213,198,200,195,222,219,221,223,217,216,220,192,209,
		179,163,'+','+','+','+','+','+',184,'+','+','+','+','+',190,' ' },
	{ //win
		'+','+', 39,'+', 34,'+','+','+','+','+','+', 39,'+','+','+','+', '+', 39, 39, 34,
		34,'+','+','-','-','*','+', 39,'+','+','+','+', ' ','+','I','+','+','+','+','+',179,188,'E',
		34,'+','+','*','I', 184,'+','i',199,'*','*','*','*',163,'N','e', 34,'j','S','s','i',
		225,226,247,231,228,229,246,250,233,234,235,236,237,238,239,240,
		242,243,244,245,230,232,227,254,251,253,255,249,248,252,224,241,
		193,194,215,199,196,197,214,218,201,202,203,204,205,206,207,208,
		210,211,212,213,198,200,195,222,219,221,223,217,216,220,192,209 },
	{ //iso
		'+','+','+','+','+','+','+','+','+','+','+','+','+','+','+','+',
		'+','+','+','+','+','+','+','+','+','+','+','+','+','+','+','+',
		'*',179,'*','*','*','*','*','*','*','*','*','*','*','*','*','*',
		225,226,247,231,228,229,246,250,233,234,235,236,237,238,239,240,
		242,243,244,245,230,232,227,254,251,253,255,249,248,252,224,241,
		193,194,215,199,196,197,214,218,201,202,203,204,205,206,207,208,
		210,211,212,213,198,200,195,222,219,221,223,217,216,220,192,209,
		'*',163,'*','*','*','*','*','*','*','*','*','*','*','*','*','*' },
	{ //mac
		225,226,247,231,228,229,246,250,233,234,235,236,237,238,239,240,
		242,243,244,245,230,232,227,254,251,253,255,249,248,252,224,241,
		'*',184,'*','*','*','*','*','I','*','*','*','*','*','*','*','*',
		'*',179,177,178,'i','*',199,'J','E','e','I','i','*','*','*','*',
		'j','S','*','*','f','*','*','*','*','*','*','*','*','*','*','s', '-','-', 34, 34, 39, 39,'*',
		39,'*','*','*','*','N',163,179,209,
		193,194,215,199,196,197,214,218,201,202,203,204,205,206,207,208,
		210,211,212,213,198,200,195,222,219,221,223,217,216,220,192,'*' }
};
int letter_frequency[32]=
{
	125,1606,331,65,598,1714,22,356,168,1312,206,636,1050,658,1295,2259,
	544,447,887,1049,1217,572,200,823,398,400,355,168,67,78,285,4
};

// Added by KIV
// Yes, we have Quoted-Printable...
int hasQP = 0;
int chkQP = 1;
inline int getQP(int first, int second)
{
	if (first  > '9') first  = toupper(first)  - 'A' + 1 +'9';
	if (second > '9') second = toupper(second) - 'A' + 1 +'9';
	return (first-'0')*16 + (second-'0');
};

int main(int argc,char ** argv)
{
	int c=0, a=0, c_old, i, j, force=-1;
	int    decide[NUMCOD];
	double  rating[NUMCOD];
	FILE *f,*out=stdout,*in=stdin;
	int enc=0;
	int I=0;
	
	for(I=1;argc>I&&(*argv[I]=='+'||*argv[I]=='-'||*argv[I]=='/');I++) {   switch(argv[I][1]) {
	default: HELP:
	case 'h': case 'H': case '?':
		do {
			char * c = argv[0] + strlen(argv[0]);
			while( (c != argv[0]) && (*c != '\\') && 
				   (*c != '/')) c--;
			if (c != argv[0]) c++;
			for(j=0;help[j];j++) printf(help[j],c);
			return 1;
		} while(0);
		//#ifndef __WATCOMC__
	case 'k': case 'K': (*argv[I]=='+'?force:enc)=0; break;
	case 'a': case 'A': (*argv[I]=='+'?force:enc)=1; break;
	case 'w': case 'W': (*argv[I]=='+'?force:enc)=2; break;
	case 'q': case 'Q': chkQP = 0; break;
		//#else
		// I hate Watcom for it's stupidity!
		// ?: - operator CAN be lvalue
		// by both K&R and ANSI standard.
		// Why Watcom does not support it?
		//            case 'k': case 'K': if(*argv[I]=='+')force=0;
		//            else enc=0; break;
        //            case 'a': case 'A': if(*argv[I]=='+')force=1;
		//            else enc=1; break;
		//            case 'w': case 'W': if(*argv[I]=='+')force=2;
		//            else enc=2; break;
		//#endif
	case 'i': case 'I': force=3; if(*argv[I]!='+') goto HELP; 
		break;
	case 'm': case 'M': force=4; if(*argv[I]!='+') goto HELP; 
		break;
	}
	}
	
	if(I<argc) {
		in=fopen(argv[I++],"rt");
		assert(in!=0);
	}
	
	for(i=0; i<NUMCOD; i++){ decide[i]=1; rating[i]=0;}
	
	f=tmpfile();
	if(f==NULL){ perror("\"tmpfile\""); exit(1);} 
	
	while(1) {
		c_old=c;
		c=getc(in);
		if(c=='\r') continue;
		if(c_old=='\r' && c!='\n') fputc('\n',f);
		if(c==EOF) break;
		
		// Added by KIV
		if (chkQP && (c == '=')) {
			//Maybe, QP?
			int q1 = getc(in);
			if (!isxdigit(q1)) {
				if (hasQP && ((q1 == '\r')||(q1 == '\n'))) {
					q1 = getc(in);
					if ((q1 == '\r')||(q1 == '\n')) 
                        continue;
				};
				ungetc(q1,in);
			} else {
				int q2 = getc(in);
				if (!isxdigit(q2)) {
					ungetc(q2,in);
					ungetc(q1,in);
				} else {
					c = getQP(q1,q2);
					hasQP = 1;
				};
			}
		};
		
		if(c>=128)
			for(i=0; i<NUMCOD; i++)
				if(recode_table[i][c-128]>=192)
					rating[i]+=letter_frequency
                        [((int)recode_table[i][c-128]-
                          192)%32];
		fputc(c,f);
	}
	
	for(i=0; i<NUMCOD; i++)
		for(j=0; j<NUMCOD; j++)
			if(i!=j && rating[i]<rating[j]) decide[i]=0;
	
	for(i=NUMCOD-1; i>=0; i--) if(decide[i]) a=i;
	
	fprintf(stderr,"Guessed input encoding: %s\n",encName[a]); if(force>=0)
		fprintf(stderr,"Forced input encoding: %s\n",encName[a=force]); 
	
	fprintf(stderr,"Output encoding: %s\n",encName[enc]); 
	
	rewind(f);
	
	if(I<argc) {
		out=fopen(argv[I++],"wt");
		assert(out!=0);
	}
	
	while(1) {
		c=fgetc(f);
		if(c==EOF) break;
		if(c>=128) c=recode_table[a][c-128];
		if(enc&&c>=128) c=destTab[enc-1][c-128];
		fputc(c,out);
	}
	//for(i=0; i<NUMCOD; i++) printf("\n%d\n", rating[i]); return(0);
}