/*
 * International Chemical Identifier (InChI)
 * Version 1
 * Software version 1.04
 * September 9, 2011
 *
 * The InChI library and programs are free software developed under the
 * auspices of the International Union of Pure and Applied Chemistry (IUPAC).
 * Originally developed at NIST. Modifications and additions by IUPAC 
 * and the InChI Trust.
 *
 * IUPAC/InChI-Trust Licence No.1.0 for the 
 * International Chemical Identifier (InChI) Software version 1.04
 * Copyright (C) IUPAC and InChI Trust Limited
 * 
 * This library is free software; you can redistribute it and/or modify it 
 * under the terms of the IUPAC/InChI Trust InChI Licence No.1.0, 
 * or any later version.
 * 
 * Please note that this library is distributed WITHOUT ANY WARRANTIES 
 * whatsoever, whether expressed or implied.  See the IUPAC/InChI Trust 
 * Licence for the International Chemical Identifier (InChI) Software 
 * version 1.04, October 2011 ("IUPAC/InChI-Trust InChI Licence No.1.0") 
 * for more details.
 * 
 * You should have received a copy of the IUPAC/InChI Trust InChI 
 * Licence No. 1.0 with this library; if not, please write to:
 * 
 * The InChI Trust
 * c/o FIZ CHEMIE Berlin
 *
 * Franklinstrasse 11
 * 10587 Berlin
 * GERMANY
 *
 * or email to: ulrich@inchi-trust.org.
 * 
 */
 
 
/*^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

    InChIKey: calculation of hash for InChI string

    Uses truncated SHA-256 function.
    SHA-256 implementation: Copyright (C) Brainspark B.V., 
                            see files sha2.c, sha2.h.

^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^*/

#ifdef _MSC_VER
#if _MSC_VER > 1000
#pragma warning( disable : 4996 )
#endif
#endif

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

#include "sha2.h"
#include "ikey_base26.h"

#include "ichisize.h"
#include "mode.h"
#include "inchi_api.h"

#include "util.h"




/*^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Local options 
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^*/

#define INCHIKEY_DEBUG 0 /* 2 */

#define INCHIKEY_FLAG_OK 0
#define INCHIKEY_NOT_VALID_FLAG 1

enum { MINOUTLENGTH=256 };  



/*^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
                            Local functions
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^*/

void fprint_digest(FILE* fw, const char *header, unsigned char *a);


/*^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
                            EXPORTED FUNCTIONS
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^*/

EXPIMP_TEMPLATE INCHI_API int INCHI_DECL GetStdINCHIKeyFromStdINCHI(const char* szINCHISource, 
                                                                 char* szINCHIKey)
{
    if ( strlen(szINCHISource) < LEN_INCHI_STRING_PREFIX+3 )                         
        return INCHIKEY_INVALID_STD_INCHI;    
    if (szINCHISource[LEN_INCHI_STRING_PREFIX+1]!='S')            
            return INCHIKEY_INVALID_STD_INCHI;
    return GetINCHIKeyFromINCHI(szINCHISource, 0, 0, szINCHIKey, (char *) NULL, (char *) NULL);
}

EXPIMP_TEMPLATE INCHI_API int INCHI_DECL GetINCHIKeyFromINCHI(const char* szINCHISource, 
                                                              const int xtra1,
                                                              const int xtra2,
                                                              char* szINCHIKey,
                                                              char* szXtra1,
                                                              char* szXtra2)
{
int ret = INCHIKEY_OK;
int ret1 = INCHIKEY_OK;
int cn;
size_t slen, i, j, jproto=0, ncp, pos_slash1=0;
char *str = NULL, *smajor = NULL, *sminor = NULL, 
     *sproto=NULL,
     *stmp = NULL, tmp[MINOUTLENGTH]; 
unsigned char 
    digest_major[32], digest_minor[32];     

char flagstd = 'S', /* standard key */
     flagnonstd = 'N', /* non-standard key */
     flagver = 'A', /* InChI v. 1 */
     flagproto = 'N'; /* no [de]protonization , by default */
int  nprotons;
/*
Protonization encoding:
N 0
O +1 P +2 Q +3 R +4 S +5 T +6 U +7 V +8 W +9 X +10 Y +11 Z +12
M -1 L-2 K -3 J -4 I -5 H -6 G -7 F -8 E -9 D -10 C -11 B -12 
A < -12 or > +12
*/
static const char *pplus = "OPQRSTUVWXYZ";
static const char *pminus = "MLKJIHGFEDCB";

int bStdFormat = 0;
size_t bytelen = 32;


    /* Check if input is a valid InChI string */

    /* .. non-empty */
    if (szINCHISource==NULL)
        return INCHIKEY_EMPTY_INPUT;
    
    slen = strlen(szINCHISource);
    
    /* .. has valid prefix */
    if (slen<LEN_INCHI_STRING_PREFIX+3)                         
        return INCHIKEY_INVALID_INCHI_PREFIX;    
    if (memcmp(szINCHISource,INCHI_STRING_PREFIX,LEN_INCHI_STRING_PREFIX))    
        return INCHIKEY_INVALID_INCHI_PREFIX;

    /* .. has InChI version 1 */
    /* if (!isdigit(szINCHISource[LEN_INCHI_STRING_PREFIX]) )  */
    if ( szINCHISource[LEN_INCHI_STRING_PREFIX] != '1' )  
        return INCHIKEY_INVALID_INCHI_PREFIX;

    /* .. optionally has a 'standard' flag character */
    pos_slash1 = LEN_INCHI_STRING_PREFIX+1;
    if (szINCHISource[pos_slash1]=='S')            
    {
        /* Standard InChI ==> standard InChIKey */
        bStdFormat = 1;
        pos_slash1++;
    }

    /* .. has trailing slash in the right place */
    if (szINCHISource[pos_slash1]!='/')            
        return INCHIKEY_INVALID_INCHI_PREFIX;

    /* .. the rest of source string contains at least one a..Z0.9 or slash */
    /* TODO: improve/add full string check */
    if (!isalnum(szINCHISource[pos_slash1+1] ) &&
       ( szINCHISource[pos_slash1+1]!='/' )     ) 
        return INCHIKEY_INVALID_INCHI;    


    /*^^^ Ok. Will use a local copy of the source. */
    
    extract_inchi_substring(&str, szINCHISource, slen);
    if (NULL==str)
    { 
        ret = INCHIKEY_NOT_ENOUGH_MEMORY; 
        goto fin; 
    }
    slen = strlen(str);


    /*^^^ Make buffers. */
    smajor = (char*) inchi_calloc( slen+1, sizeof(char)); 
    if (NULL==smajor)
        { ret = INCHIKEY_NOT_ENOUGH_MEMORY; goto fin; }
    sminor = (char*) inchi_calloc( 2*slen + 2, sizeof(char)); /* we may double the length ... */ 
    if (NULL==sminor)
        { ret = INCHIKEY_NOT_ENOUGH_MEMORY; goto fin; }
    stmp = (char*) inchi_calloc( slen+1, sizeof(char)); 
    if (NULL==stmp)
        { ret = INCHIKEY_NOT_ENOUGH_MEMORY; goto fin; }
    sproto = (char*) inchi_calloc( slen+1, sizeof(char)); 
    if (NULL==sproto)
        { ret = INCHIKEY_NOT_ENOUGH_MEMORY; goto fin; }


    szINCHIKey[0] = '\0';

    
    
    /*^^^ Extract the major block. */
    
    smajor[0]  = '\0';
    for (j = pos_slash1 + 1; j < slen-1; j++)
    {
        if (str[j]=='/')    
        {
            cn = str[j+1];
            switch (cn) 
            { 
                /* anything allowed from a major part */
                case 'c': case 'h': case 'q':   continue; 
                
                /* "/p"; protons now go to to special string, not to minor hash */
                case 'p':						jproto = j;
                                                continue;
                
                /* "/f",  "/r" : may not occur in stdInChI */
                case 'f': case 'r':		        if ( bStdFormat )
                                                {
                                                    ret = INCHIKEY_INVALID_STD_INCHI; 
                                                    goto fin;
                                                }
                                                break;
                
                /* anything allowed from a minor part */
                default:                        break; 
            }
            break;
        }
    }       
    j++;
    if (j==slen) 
        j++;
    else 
        j--;

    if (jproto)
        ncp = jproto - pos_slash1 - 1; 
    else
        ncp = j - pos_slash1 - 1; 
    

    /*^^^ Trim 'InChI=1[S]/' */
    memcpy(smajor,str+pos_slash1+1, ncp*sizeof(str[0]));
    smajor[ncp]='\0';


    /* Treat protonization */
    if (jproto)
    {
        /* 2009-01-07 fix bug/typo: assigned incorrect length to the protonation segment of 
        /* source string ( was sproto[ncp]='\0'; should be sproto[lenproto]='\0'; )  */
        int lenproto = j - (int) jproto;
        if (lenproto<3)
        {	
            /* empty "/p", should not occur */
            ret = INCHIKEY_INVALID_INCHI; 
            goto fin;
        }
        
        memcpy(sproto,str+pos_slash1+ncp+1, lenproto*sizeof(str[0]));
        sproto[lenproto]='\0';
       
        nprotons = strtol( sproto+2, NULL, 10 );        
        
        if (nprotons > 0)
        {
            if (nprotons > 12) flagproto = 'A';
            else			   flagproto = pplus[nprotons-1];
        }
        else if (nprotons < 0)
        {
            if (nprotons < -12) flagproto = 'A';
            else				flagproto = pminus[-nprotons-1];
        }
        else
        {
            /* should never occur */
            ret = INCHIKEY_INVALID_STD_INCHI; 
            goto fin;
        }
    }



    /*^^^ Extract the minor block. */

    if (j != slen+1)    /*^^^ check that something exists at right.*/
    {
        ncp = slen-j; 
        memcpy(sminor,str+j, (ncp)*sizeof(str[0]));
        sminor[ncp]='\0';
    }
    else 
        sminor[0]='\0'; 
        

#if INCHIKEY_DEBUG 
    fprintf(stdout,"Source:  {%-s}\n",str);
    fprintf(stdout,"SMajor:  {%-s}\n",smajor);
    fprintf(stdout,"SMinor:  {%-s}\n",sminor);
    fprintf(stdout,"SProto:  {%-s}\n",sproto);
#endif      



    /*^^^ Compute and compose the InChIKey string. */


    /*^^^ Major hash sub-string. */    
    for( i = 0; i < 32; i++ ) 
        digest_major[i] = 0;            
    sha2_csum( (unsigned char *) smajor, (int) strlen(smajor), digest_major );    

    sprintf(tmp,"%-.3s%-.3s%-.3s%-.3s%-.2s", 
                base26_triplet_1(digest_major), base26_triplet_2(digest_major),
                base26_triplet_3(digest_major), base26_triplet_4(digest_major),
                base26_dublet_for_bits_56_to_64(digest_major));
    strcat(szINCHIKey, tmp);    
#if (INCHIKEY_DEBUG>1)
        fprint_digest(stderr, "Major hash, full SHA-256",digest_major);         
#endif  



    /*^^^ Minor hash sub-string. */
    for( i = 0; i < 32; i++ ) 
        digest_minor[i] = 0; 
    slen = strlen(sminor); 
    if ((slen>0)&&(slen<255)) 
    { 
        strcpy(stmp, sminor); 
        strcpy(sminor+slen,stmp); 
    }
    sha2_csum( (unsigned char *) sminor, (int) strlen(sminor), digest_minor );
#if (INCHIKEY_DEBUG>1)  
        fprint_digest(stderr, "Minor hash, full SHA-256",digest_minor);
#endif

    strcat(szINCHIKey, "-");
    sprintf(tmp,"%-.3s%-.3s%-.2s", 
        base26_triplet_1(digest_minor), 
        base26_triplet_2(digest_minor), 
        base26_dublet_for_bits_28_to_36(digest_minor));  
    strcat(szINCHIKey, tmp); 


    /* Append a standard/non-standard flag */
    slen = strlen(szINCHIKey);
    if ( bStdFormat )
        szINCHIKey[slen] = flagstd; 
    else
        szINCHIKey[slen] = flagnonstd; 

    /*^^^ Append InChI v.1 flag */
    szINCHIKey[slen+1] = flagver; 
    
    /*^^^ Append dash  */
    szINCHIKey[slen+2] = '-'; 
    
    /*^^^ Append protonization flag */
    szINCHIKey[slen+3] = flagproto; 
    szINCHIKey[slen+4] = '\0';


#if INCHIKEY_DEBUG 
    fprintf(stdout,"szINCHIKey:  {%-s}\n",szINCHIKey);
#endif

    /* Hash extensions */
    if ( xtra1 && szXtra1 )
    {
        get_xtra_hash_major_hex(digest_major, szXtra1);
#if INCHIKEY_DEBUG 
        fprintf(stderr,"XHash1=%-s\n",szXtra1);
        fprintf(stderr,"j=%-d\n",j);
#endif
    }
    if ( xtra2 && szXtra2 )
    {
        get_xtra_hash_minor_hex(digest_minor, szXtra2);
#if INCHIKEY_DEBUG 
        fprintf(stderr,"XHash2=%-s\n",szXtra2);
        fprintf(stderr,"j=%-d\n",j);
#endif
    }
        

fin:if (NULL!=str)      inchi_free(str);
    if (NULL!=smajor)   inchi_free(smajor);
    if (NULL!=sminor)   inchi_free(sminor);
    if (NULL!=stmp)     inchi_free(stmp);
    if (NULL!=sproto)   inchi_free(sproto);

    if ( (ret==INCHIKEY_OK) && (ret1!=INCHIKEY_OK) )
        ret = ret1;
    return ret;

}




/*^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Check if the string represents valid InChIKey.          
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^*/
EXPIMP_TEMPLATE INCHI_API int INCHI_DECL CheckINCHIKey(const char *szINCHIKey)
{
size_t slen, j;


    slen = strlen(szINCHIKey);

    
    /*^^^ Proper length is 27  */
    if (slen != 27) 
        return INCHIKEY_INVALID_LENGTH;

    /*^^^ Should have dash in 14-th position */   
    if (szINCHIKey[14] !='-')   
        return INCHIKEY_INVALID_LAYOUT;
    /*^^^ Should have dash in 25-th position */   
    if (szINCHIKey[25] !='-')   
        return INCHIKEY_INVALID_LAYOUT;
    
    /*^^^ All other should be uppercase */  
    for (j = 0;  j < 14; j++)   
        if ( !isbase26(szINCHIKey[j]) ) 
            return INCHIKEY_INVALID_LAYOUT; /* first block */
    for (j = 15; j < 25; j++)   
        if ( !isbase26(szINCHIKey[j]) ) 
            return INCHIKEY_INVALID_LAYOUT; /* second block */
    if ( !isbase26(szINCHIKey[26]) ) 
        return INCHIKEY_INVALID_LAYOUT; /* (de)protonation flag */
    
    
    /*^^^ No 'E' may appear in 0,3,6,and 9 positions of the 1st block ... */ 
    for (j=0; j <10; j+=3)  
        if (szINCHIKey[j]=='E')        
            return INCHIKEY_INVALID_LAYOUT;
    /*^^^ ... and 0 and 3 pos. of the second block. */
    for (j=15; j <19; j+=3) 
        if (szINCHIKey[j]=='E')        
            return INCHIKEY_INVALID_LAYOUT;
    
    /*^^^ Check for version (only 1 allowed) */
    if (szINCHIKey[24] !='A')   
        return INCHIKEY_INVALID_VERSION;

    /*^^^ Check for standard-ness */
    if (szINCHIKey[23] == 'S')   
        return INCHIKEY_VALID_STANDARD;
    else if (szINCHIKey[23] == 'N')
        return INCHIKEY_VALID_NON_STANDARD;
    else
        return INCHIKEY_INVALID_LAYOUT;
}







/*^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^*/
void fprint_digest(FILE* fw, const char *header, unsigned char *a)
{
size_t i, bytelen = 32;
    fprintf(fw,"%s\n", header);
    for( i = 0; i < bytelen; i++ )
        fprintf(fw,"%02x ", a[i]);
    fprintf(fw,"\n" );
}



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

#if ( defined( _WIN32 ) && defined( _MSC_VER ) && _MSC_VER >= 800 && defined(_USRDLL) && defined(BUILD_LINK_AS_DLL) )
    /* Win32 & MS VC ++, compile and link as a DLL */
/*********************************************************/
/*   C calling conventions export from Win32 dll         */
/*********************************************************/
/* prototypes */
#ifndef COMPILE_ALL_CPP
#ifdef __cplusplus
extern "C" {
#endif
#endif

int cdecl_CheckINCHIKey(const char *szINCHIKey,const int strict);
int cdecl_GetINCHIKeyFromINCHI(const char* szINCHISource, 
                               const int xtra1,const int xtra2,
                               char* szINCHIKey, char* szXtra1, char* szXtra2); 
int cdecl_GetStdINCHIKeyFromStdINCHI(const char* szINCHISource, char* szINCHIKey); 

#ifndef COMPILE_ALL_CPP
#ifdef __cplusplus
}
#endif
#endif

/* implementation */
/* libinchi.def provides export without cdecl_ prefixes */

/********************************************************/
int cdecl_GetStdINCHIKeyFromStdINCHI(const char* szINCHISource, char* szINCHIKey)
{
    return GetStdINCHIKeyFromStdINCHI(szINCHISource, szINCHIKey);
}
/********************************************************/
int cdecl_CheckINCHIKey(const char *szINCHIKey,const int strict)
{
    return CheckINCHIKey(szINCHIKey);
}
/********************************************************/
int cdecl_GetINCHIKeyFromINCHI(const char* szINCHISource, 
                               const int xtra1,const int xtra2,
                               char* szINCHIKey, char* szXtra1, char* szXtra2)
{
    return GetINCHIKeyFromINCHI(szINCHISource, xtra1, xtra2, szINCHIKey, szXtra1, szXtra2);
}
#endif



#if ( defined(__GNUC__) && __GNUC__ >= 3 && defined(__MINGW32__) && defined(_WIN32) )
#include <windows.h>
/*********************************************************/
/*   Pacal calling conventions export from Win32 dll     */
/*********************************************************/
#ifndef COMPILE_ALL_CPP
#ifdef __cplusplus
extern "C" {
#endif
#endif
/* prototypes */
int PASCAL pasc_CheckINCHIKey(const char *szINCHIKey);
#ifndef COMPILE_ALL_CPP
#ifdef __cplusplus
}
#endif
#endif

/* implementation */
/* libinchi.def provides export without PASCAL pasc_ prefixes */
/********************************************************/
int PASCAL pasc_CheckINCHIKey(const char *szINCHIKey)
{
    return CheckINCHIKey(szINCHIKey);
}
#endif