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/*              Parse HyperText Document Address                HTParse.c
**              ================================
*/


#include "HTUtils.h"
#include "HTParse.h"
#include "tcp.h"

#define HEX_ESCAPE '%'

struct struct_parts {
        char * access;
        char * host;
        char * absolute;
        char * relative;
/*      char * search;          no - treated as part of path */
        char * anchor;
};


/*      Strip white space off a string
**      ------------------------------
**
** On exit,
**      Return value points to first non-white character, or to 0 if none.
**      All trailing white space is OVERWRITTEN with zero.
*/


#ifdef __STDC__
char * HTStrip(char * s)
#else
char * HTStrip(s)
        char *s;
#endif
{
#define SPACE(c) ((c==' ')||(c=='\t')||(c=='\n'))
    char * p=s;
    for(p=s;*p;p++);                    /* Find end of string */
    for(p--;p>=s;p--) {
        if(SPACE(*p)) *p=0;     /* Zap trailing blanks */
        else break;
    }
    while(SPACE(*s))s++;        /* Strip leading blanks */
    return s;
}


/*      Scan a filename for its consituents
**      -----------------------------------
**
** On entry,
**      name    points to a document name which may be incomplete.
** On exit,
**      absolute or relative may be nonzero (but not both).
**      host, anchor and access may be nonzero if they were specified.
**      Any which are nonzero point to zero terminated strings.
*/

#ifdef __STDC__
PRIVATE void scan(char * name, struct struct_parts *parts)
#else
PRIVATE void scan(name, parts)
    char * name;
    struct struct_parts *parts;
#endif
{
    char * after_access;
    char * p;
    int length = strlen(name);
   
    parts->access = 0;
    parts->host = 0;
    parts->absolute = 0;
    parts->relative = 0;
    parts->anchor = 0;
   
    after_access = name;
    for(p=name; *p; p++) {
        if (*p==':') {
                *p = 0;
                parts->access = name;   /* Access name has been specified */
                after_access = p+1;
        }
        if (*p=='/') break;
        if (*p=='#') break;
    }
   
    for(p=name+length-1; p>=name; p--) {
        if (*p =='#') {
            parts->anchor=p+1;
            *p=0;                               /* terminate the rest */
        }
/*      else if (*p =='?') {
            parts->search=p+1;
            *p=0;
        }
*/

    }
    p = after_access;
    if (*p=='/'){
        if (p[1]=='/') {
            parts->host = p+2;          /* host has been specified      */
            *p=0;                       /* Terminate access             */
            p=strchr(parts->host,'/');  /* look for end of host name if any */
            if(p) {
                *p=0;                   /* Terminate host */
                parts->absolute = p+1;          /* Root has been found */
            }
        } else {
            parts->absolute = p+1;              /* Root found but no host */
        }          
    } else {
        parts->relative = (*after_access) ? after_access : 0;   /* zero for "" */
    }

    /* Access specified but no host: the anchor was not really one
       e.g. news:j462#36487@foo.bar -- JFG 10/7/92, from bug report */

    if (parts->access && ! parts->host && parts->anchor) {
      *(parts->anchor - 1) = '#';  /* Restore the '#' in the address */
      parts->anchor = 0;
    }

#ifdef NOT_DEFINED      /* search is just treated as part of path */
    {
        char *p = parts->relative ? parts->relative : parts->absolute;
        if (p) {
            char * q = strchr(p, '?');  /* Any search string? */
            if (q) {
                *q = 0;                 /* If so, chop that off. */
                parts->search = q+1;
            }
        }
    }
#endif
} /*scan */    


/*      Parse a Name relative to another name
**      -------------------------------------
**
**      This returns those parts of a name which are given (and requested)
**      substituting bits from the related name where necessary.
**
** On entry,
**      aName           A filename given
**      relatedName     A name relative to which aName is to be parsed
**      wanted          A mask for the bits which are wanted.
**
** On exit,
**      returns         A pointer to a malloc'd string which MUST BE FREED
*/

#ifdef __STDC__
char * HTParse(const char * aName, const char * relatedName, int wanted)
#else
char * HTParse(aName, relatedName, wanted)
    char * aName;
    char * relatedName;
    int wanted;
#endif

{
    char * result = 0;
    char * return_value = 0;
    int len;
    char * name = 0;
    char * rel = 0;
    char * p;
    char * access;
    struct struct_parts given, related;
   
    /* Make working copies of input strings to cut up:
    */

    len = strlen(aName)+strlen(relatedName)+10;
    result=(char *)malloc(len);         /* Lots of space: more than enough */
    if (result == NULL) outofmem(__FILE__, "HTParse");
   
    StrAllocCopy(name, aName);
    StrAllocCopy(rel, relatedName);
   
    scan(name, &given);
    scan(rel,  &related);
    result[0]=0;                /* Clear string  */
    access = given.access ? given.access : related.access;
    if (wanted & PARSE_ACCESS)
        if (access) {
            strcat(result, access);
            if(wanted & PARSE_PUNCTUATION) strcat(result, ":");
        }
       
    if (given.access && related.access) /* If different, inherit nothing. */
        if (strcmp(given.access, related.access)!=0) {
            related.host=0;
            related.absolute=0;
            related.relative=0;
            related.anchor=0;
        }
       
    if (wanted & PARSE_HOST)
        if(given.host || related.host) {
            char * tail = result + strlen(result);
            if(wanted & PARSE_PUNCTUATION) strcat(result, "//");
            strcat(result, given.host ? given.host : related.host);
#define CLEAN_URLS
#ifdef CLEAN_URLS
            /* Ignore default port numbers, and trailing dots on FQDNs
               which will only cause identical adreesses to look different */

            {
                char * p;
                p = strchr(tail, ':');
                if (p && access) {              /* Port specified */
                    if (  (   strcmp(access, "http") == 0
                           && strcmp(p, ":80") == 0 )
                        ||
                          (   strcmp(access, "gopher") == 0
                           && strcmp(p, ":70") == 0 )
                        )
                    *p = (char)0;       /* It is the default: ignore it */
                }
                if (!p) p = tail + strlen(tail); /* After hostname */
                p--;                            /* End of hostname */
                if (*p == '.') *p = (char)0; /* chop final . */
            }
#endif
        }
       
    if (given.host && related.host)  /* If different hosts, inherit no path. */
        if (strcmp(given.host, related.host)!=0) {
            related.absolute=0;
            related.relative=0;
            related.anchor=0;
        }
       
    if (wanted & PARSE_PATH) {
        if(given.absolute) {                            /* All is given */
            if(wanted & PARSE_PUNCTUATION) strcat(result, "/");
            strcat(result, given.absolute);
        } else if(related.absolute) {   /* Adopt path not name */
            strcat(result, "/");
            strcat(result, related.absolute);
            if (given.relative) {
                p = strchr(result, '?');        /* Search part? */
                if (!p) p=result+strlen(result)-1;
                for (; *p!='/'; p--);   /* last / */
                p[1]=0;                                 /* Remove filename */
                strcat(result, given.relative);         /* Add given one */
                HTSimplify (result);
            }
        } else if(given.relative) {
            strcat(result, given.relative);             /* what we've got */
        } else if(related.relative) {
            strcat(result, related.relative);
        } else {  /* No inheritance */
            strcat(result, "/");
        }
    }
               
    if (wanted & PARSE_ANCHOR)
        if(given.anchor || related.anchor) {
            if(wanted & PARSE_PUNCTUATION) strcat(result, "#");
            strcat(result, given.anchor ? given.anchor : related.anchor);
        }
    free(rel);
    free(name);
   
    StrAllocCopy(return_value, result);
    free(result);
    return return_value;                /* exactly the right length */
}


/*              Simplify a filename
//              -------------------
//
// A unix-style file is allowed to contain the seqeunce xxx/../ which may be
// replaced by "" , and the seqeunce "/./" which may be replaced by "/".
// Simplification helps us recognize duplicate filenames.
//
//      Thus,   /etc/junk/../fred       becomes /etc/fred
//              /etc/junk/./fred        becomes /etc/junk/fred
//
//      but we should NOT change
//              http://fred.xxx.edu/../..
//
//      or      ../../albert.html
*/

#ifdef __STDC__
void HTSimplify(char * filename)
#else
void HTSimplify(filename)
    char * filename;
#endif

{
    char * p;
    char * q;
    if (filename[0] && filename[1])     /* Bug fix 12 Mar 93 TBL */
     for(p=filename+2; *p; p++) {
        if (*p=='/') {
            if ((p[1]=='.') && (p[2]=='.') && (p[3]=='/' || !p[3] )) {
                for (q=p-1; (q>=filename) && (*q!='/'); q--); /* prev slash */
                if (q[0]=='/' && 0!=strncmp(q, "/../", 4)
                        &&!(q-1>filename && q[-1]=='/')) {
                    strcpy(q, p+3);     /* Remove  /xxx/..      */
                    if (!*filename) strcpy(filename, "/");
                    p = q-1;            /* Start again with prev slash  */
                } else {                        /*   xxx/.. leave it!   */
#ifdef BUG_CODE
                    strcpy(filename, p[3] ? p+4 : p+3); /* rm  xxx/../  */
                    p = filename;               /* Start again */
#endif
                }
            } else if ((p[1]=='.') && (p[2]=='/' || !p[2])) {
                strcpy(p, p+2);                 /* Remove a slash and a dot */
            }
        }
    }
}


/*              Make Relative Name
**              ------------------
**
** This function creates and returns a string which gives an expression of
** one address as related to another. Where there is no relation, an absolute
** address is retured.
**
**  On entry,
**      Both names must be absolute, fully qualified names of nodes
**      (no anchor bits)
**
**  On exit,
**      The return result points to a newly allocated name which, if
**      parsed by HTParse relative to relatedName, will yield aName.
**      The caller is responsible for freeing the resulting name later.
**
*/

#ifdef __STDC__
char * HTRelative(const char * aName, const char *relatedName)
#else
char * HTRelative(aName, relatedName)
   char * aName;
   char * relatedName;
#endif
{
    char * result = 0;
    CONST char *p = aName;
    CONST char *q = relatedName;
    CONST char * after_access = 0;
    CONST char * path = 0;
    CONST char * last_slash = 0;
    int slashes = 0;
   
    for(;*p; p++, q++) {        /* Find extent of match */
        if (*p!=*q) break;
        if (*p==':') after_access = p+1;
        if (*p=='/') {
            last_slash = p;
            slashes++;
            if (slashes==3) path=p;
        }
    }
   
    /* q, p point to the first non-matching character or zero */
   
    if (!after_access) {                        /* Different access */
        StrAllocCopy(result, aName);
    } else if (slashes<3){                      /* Different nodes */
        StrAllocCopy(result, after_access);
    } else if (slashes==3){                     /* Same node, different path */
        StrAllocCopy(result, path);
    } else {                                    /* Some path in common */
        int levels= 0;
        for(; *q && (*q!='#'); q++)  if (*q=='/') levels++;
        result = (char *)malloc(3*levels + strlen(last_slash) + 1);
      if (result == NULL) outofmem(__FILE__, "HTRelative");
        result[0]=0;
        for(;levels; levels--)strcat(result, "../");
        strcat(result, last_slash+1);
    }
    if (TRACE) fprintf(stderr, "HT: `%s' expressed relative to\n    `%s' is\n   `%s'.",
                aName, relatedName, result);
    return result;
}


/*              Escape undesirable characters using %           HTEscape()
**              -------------------------------------
**
**      This function takes a pointer to a string in which
**      some characters may be unacceptable unescaped.
**      It returns a string which has these characters
**      represented by a '%' character followed by two hex digits.
**
**      Unlike HTUnEscape(), this routine returns a malloced string.
*/


PRIVATE CONST unsigned char isAcceptable[96] =

/*      Bit 0           xalpha          -- see HTFile.h
**      Bit 1           xpalpha         -- as xalpha but with plus.
**      Bit 3 ...       path            -- as xpalphas but with /
*/

    /*   0 1 2 3 4 5 6 7 8 9 A B C D E F */
    {    0,0,0,0,0,0,0,0,0,0,7,6,0,7,7,4,       /* 2x   !"#$%&'()*+,-./  */
         7,7,7,7,7,7,7,7,7,7,0,0,0,0,0,0,       /* 3x  0123456789:;<=>?  */
         7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,       /* 4x  @ABCDEFGHIJKLMNO  */
         7,7,7,7,7,7,7,7,7,7,7,0,0,0,0,7,       /* 5X  PQRSTUVWXYZ[\]^_  */
         0,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,       /* 6x  `abcdefghijklmno  */
         7,7,7,7,7,7,7,7,7,7,7,0,0,0,0,0 };     /* 7X  pqrstuvwxyz{\}~  DEL */

PRIVATE char *hex = "0123456789ABCDEF";

PUBLIC char * HTEscape ARGS2 (CONST char *, str,
        unsigned char, mask)
{
#define ACCEPTABLE(a)   ( a>=32 && a<128 && ((isAcceptable[a-32]) & mask))
    CONST char * p;
    char * q;
    char * result;
    int unacceptable = 0;
    for(p=str; *p; p++)
        if (!ACCEPTABLE((unsigned char)TOASCII(*p)))
                unacceptable++;
    result = (char *) malloc(p-str + unacceptable+ unacceptable + 1);
    if (result == NULL) outofmem(__FILE__, "HTEscape");
    for(q=result, p=str; *p; p++) {
        unsigned char a = TOASCII(*p);
        if (!ACCEPTABLE(a)) {
            *q++ = HEX_ESCAPE;  /* Means hex commming */
            *q++ = hex[a >> 4];
            *q++ = hex[a & 15];
        }
        else *q++ = *p;
    }
    *q++ = 0;                   /* Terminate */
    return result;
}


/*              Decode %xx escaped characters                   HTUnEscape()
**              -----------------------------
**
**      This function takes a pointer to a string in which some
**      characters may have been encoded in %xy form, where xy is
**      the acsii hex code for character 16x+y.
**      The string is converted in place, as it will never grow.
*/


PRIVATE char from_hex ARGS1(char, c)
{
    return  c >= '0' && c <= '9' ?  c - '0'
            : c >= 'A' && c <= 'F'? c - 'A' + 10
            : c - 'a' + 10;     /* accept small letters just in case */
}

PUBLIC char * HTUnEscape ARGS1( char *, str)
{
    char * p = str;
    char * q = str;
    while(*p) {
        if (*p == HEX_ESCAPE) {
            p++;
            if (*p) *q = from_hex(*p++) * 16;
            if (*p) *q = FROMASCII(*q + from_hex(*p++));
            q++;
        } else {
            *q++ = *p++;
        }
    }
   
    *q++ = 0;
    return str;
   
} /* HTUnEscape */