/*
 * LEVEE, or Captain Video;  A vi clone
 *
 * Copyright (c) 1982-1997 David L Parsons
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms are permitted
 * provided that the above copyright notice and this paragraph are
 * duplicated in all such forms and that any documentation,
 * advertising materials, and other materials related to such
 * distribution and use acknowledge that the software was developed
 * by David L Parsons (orc@pell.chi.il.us).  My name may not be used
 * to endorse or promote products derived from this software without
 * specific prior written permission.  THIS SOFTWARE IS PROVIDED
 * AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING,
 * WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF MERCHANTIBILITY AND
 * FITNESS FOR A PARTICULAR PURPOSE.
 */
#include "levee.h"
#include "extern.h"
#include "grep.h"
#include <ctype.h>
#include <string.h>

static int arg;		/* arguments inside of a RE */

int PROC
REmatch(char *pattern, int start, int end)
{
    register char *endp = &core[end];

    if (!*pattern)
	return -1;
    arg = 0;
    while (start <= end && !amatch(pattern, &core[start], endp))
	start++;
    return start;
}

int PROC
omatch(char *pattern, char **cp, char *endp)
{
    register int flag;
    extern int ignorecase;

    switch (*pattern) {
      case LEND:
	  return (**cp == EOL);
      case LSTART:
	  return (*cp == core) || (*(*cp-1) == EOL);
      case TOKENB:
	  return (*cp == core) || !isalnum(*(*cp-1));
      case TOKENE:
	  return !isalnum(**cp);
      case LITCHAR:
#ifdef TOUPPER_FTN
#undef toupper
#endif
	  if (ignorecase)
	      flag = (toupper(**cp) == toupper(*(pattern+1)));
	  else
	      flag = (**cp == *(pattern+1));
	  break;
      case ANY:
	  flag = (**cp != EOL);
	  break;
      case CCL:
	  flag = locate(pattern,*cp);
	  break;
      case NCCL:
	  flag = !locate(pattern,*cp);
	  break;
      case ARGSTART:
	  RE_start[arg] = (*cp)-core;
	  return TRUE;
      case ARGEND:
	  RE_size[arg] = ((*cp)-core) - RE_start[arg];
	  ++arg;
	  return TRUE;
      default:
	  return TRUE;
    }

    if (*cp <= endp && flag) {
	(*cp)++;
	return TRUE;
    }
    return FALSE;
}

int PROC
amatch(char *pattern, char *start, char *endp)
{
    register int sarg = arg;	/* save old arg match count for errors */

    while (*pattern) {
	if (*pattern == CLOSURE) {
	/*	Find the longest closure possible and work backwards trying
	 *	to match the rest of the pattern.
	 */
	    char *oldstart = start;

	    ++pattern;	/* skip over the closure token */
	    while (start <= endp && omatch(pattern,&start,endp))
		 ;
	/*	start points at the character that failed the search.
	 *	Try to match the rest of the pattern against it, working
	 *	back down the line if failure
	 */
	    patsize(&pattern);
	    while (start >= oldstart)
		if (amatch(pattern,start--,endp))
		    return TRUE;
	    arg = sarg;
	    return FALSE;
	}
	else {
	    if (!omatch(pattern,&start,endp)) {
		arg = sarg;
		return FALSE;
	    }
	    patsize(&pattern);
	}
    }
    lastp = start-core;
    return TRUE;
}

/*  increment pattern by the size of the token being scanned
 */
PROC
patsize(char **pattern)
{
    register int count;

    switch (**pattern) {
      case LITCHAR:
	*pattern += 2;
	break;
      case CCL:
      case NCCL:
	count = *(++*pattern) & 0xff;
	*pattern += 1+count;
	break;
      default:
	(*pattern)++;
	break;
    }
}

PROC
locate(char *pattern, char *linep)
/* locate: find a character in a closure */
{
    register char *p = 1+pattern;
    register int count;

    if ((count = (*p++)&0xff) == 0)
	return FALSE;
    while (count--)
	if (*p++ == *linep)
	    return TRUE;
    return FALSE;
}
char *p;

PROC
concatch(char c)
{
    if (p < &pattern[MAXPAT-1])
	*p++ = c;
}

char PROC
esc(s)
  register char **s;
{
    if (**s != ESCAPE || *(1+*s) == 0)
	return **s;
    ++(*s);
    switch (**s) {
      case 't': return TAB;
      case 'n': return EOL;
    }
    return **s;
}

char * PROC
dodash(char *src)

/* parse the innards of a [] */
{
    register int k;
    char *start = src;
    char cs[128];

    fillchar(cs,sizeof(cs),FALSE);
    while (*src && *src != CCLEND) {
	if (*src == DASH && src>start && src[1] != CCLEND && src[-1]<src[1]) {
	    for ( k = src[-1]; k <= src[1]; k++)
		cs[k] = TRUE;
	    src++;
	}
	else
	    cs[esc(&src)] = TRUE;
	src++;
    }
    for (k=0; k < sizeof(cs); k++)
	if (cs[k])
	    concatch((char)k);
    return src;
}

char * PROC badccl(char *src)
/* a [] was encountered. is it a CCL (match one of the included
 *  characters); or is it a NCCL (match all but the included characters)?
 */
{
    register char *jstart;

    if (*src == NEGATE) {
	concatch(NCCL);
	++src;
    }
    else
	concatch(CCL);
    jstart = p;
    concatch(0);		/* this will be the length of the pattern */
    src = dodash(src);
    *jstart = (p-jstart)-1;
    return src;
}

	/* patterns that cannot be closed */
char badclose[] = { LSTART, LEND, CLOSURE, 0 };

char * PROC makepat(char *string, char delim)
/* make up the pattern string for find	-- ripped from 'Software Tools' */
{
    register char *cp;
    register char *oldcp;
    char *start = string;
    int inarg = FALSE;

    for(arg=0;arg<9;++arg)
	RE_start[arg] = RE_size[arg] = (-1);
    arg = 0;
    p = pattern;

    while ((*string != delim) && (*string != 0)) {
	oldcp = cp;
	cp = p;

	if (!magic)		/* kludge for nonmagical patterns */
	    goto normal;
	if (*string == ANY)
	    concatch(ANY);
	else if ((*string == LSTART) && (string == start))
	    concatch(LSTART);
	else if ((*string == LEND) && (string[1] == delim || string[1] == 0))
	    concatch(LEND);
	else if (*string == CCL)
	    string = badccl(1+string);
	else if ((*string == CLOSURE) && (p > pattern)) {
	    cp = oldcp;
	    if (strchr(badclose, *cp) || p >= &pattern[MAXPAT-1])
		return NULL;
	    moveright(cp,1+cp,(int)(p-cp));
	    *cp = CLOSURE;
	    p++;
	}
	else if (*string == ESCAPE) {
	    if (string[1] == ARGSTART || string[1] == ARGEND) {
		if (string[1] == ARGEND)
		    if (!inarg)
			goto normal;
		if (string[1] == ARGSTART) {
		    if (inarg)
			goto normal;
		    if (++arg > 9)
			return NULL;
		}
		inarg = !inarg;
	    }
	    else if (string[1] != TOKENB && string[1] != TOKENE)
		goto normal;
	    ++string;
	    concatch(*string);
	}
	else {
     normal:concatch(LITCHAR);
	    concatch(esc(&string));
	}
	if (*string)
	    string++;
    }
    if (inarg)
	concatch(ARGEND);
    if (p > pattern) {		/* new pattern was created */
	strncpy(lastpatt,start,(int)(string-start));
	lastpatt[string-start] = 0;
	concatch(0);
	if (p-pattern >= MAXPAT)
	    return NULL;
    }
    return (*string == delim)?(string+1):(string);
}

PROC
findfwd(char *pattern, int start, int endp)
/* look for a regular expression forward */
{
    register int ep;

     while (start < endp) {
	 ep = fseekeol(start);
	 if ((start = REmatch(pattern, start, ep)) <= ep)
	     return start;
     }
     return ERR;
 }

PROC
findback(char *pattern, int start, int endp)
/* look for a regular expression backwards */
{
    register int i;
    int ep,j;

     while (start > endp) {
	 ep = bseekeol(start);
	 if ((j = REmatch(pattern, ep, start)) <= start)
             {
             i = j;
             while((j=REmatch(pattern, i+1, start)) <= start)
                 {
                 i = j;
                 }
	     return i;
             }
	 start = ep-1;
     }
     return ERR;
 }

bool s_wrapped = 0;

char * PROC
search(char *pat, int *start)
/* get a token for find & find it in the buffer
 */
{
    bool forwd;
    register int  pos;
    char *p;

    forwd = ((nlsearch = *pat) == '/');
    if ((p=makepat(pat+1,*pat)) == NULL) {
	*start = ERR;
	return pat;
    }
    do {
	if (forwd) {
	    pos = findfwd(pattern, (*start)+1, bufmax-1);
	    if ((pos == ERR) && wrapscan) {
		s_wrapped = 1;
		pos = findfwd(pattern, 0, (*start)-1);
	    }
	}
	else {
	    pos = findback(pattern, (*start)-1, 0);
	    if ((pos == ERR) && wrapscan) {
		s_wrapped = 1;
		pos = findback(pattern, bufmax-1, (*start)+1);
	    }
	}
	*start = pos;
    } while (--count > 0 && *start != ERR);
    return p;
}

char * PROC
findparse(char *src, int *idx, int start) /* driver for ?, /, && : lineranges */
{
    int addr = start;
    register char c;

    s_wrapped = 0;

    switch (*src) {
	case '/':
	case '?':
	    /* get a token for find & find it in the buffer */
	    src = search(src,&addr);
	break;
	case '0': case '1': case '2': case '3': case '4':
	case '5': case '6': case '7': case '8': case '9':
	    /* fabricate a count */
	    count = 0;
	    while (*src >= '0' && *src <= '9')
		count = (count*10) + *(src++) - '0';

	    addr = to_index(count);
	break;
	case '$':
	    addr = bufmax-1;
	    src++;
	break;
	case '.' :
	    src++;
	break;
	case '`':
	case '\'':
	    addr = lvgetcontext(*(src+1), (*src == '\''));
	    src += 2;
	break;
    }

    while (addr>=0 && (*src =='+' || *src == '-')) {
	c = *(src++);
	/* skip delimiter */
	if (*src == '/' || *src == '?') {
	    count = 1;
	    if ((src = search(src,&addr)) == NULL)
		break;
	}
	else {
	    if (*src >= '0' && *src <= '9') {
		/* fabricate a count */
		count = 0;
		while (*src >= '0' && *src <= '9')
		    count = (count*10) + *(src++) - '0';
	    }
	    else
		count = -1;		/* for naked + & - */
	    if (count == 0)		/* +0 goes to beginning of line */
		addr = bseekeol(addr);
	    else {
		addr = nextline((c=='+'), addr, count);
		if (c=='-' && addr > 0)
		    addr = bseekeol(addr);
	    }
	    if (addr >= bufmax)
		addr = -1;
	}
    }
    *idx = addr;
    return(src);
}

int PROC
nextline(advance, dest, count)
  bool advance;
  register int dest;
  int count;
{
    if (advance)
	do {
	    dest = fseekeol(dest) + 1;
	    count--;
	} while (count>0 && dest<bufmax);
    else
	do {
	    dest = bseekeol(dest) - 1;
	    count--;
	} while (count>0 && dest>=0);
    return(dest);
}

int PROC
fseekeol(origin)
  register int origin;
{
    return(origin + lvscan(bufmax-origin-1,'=',EOL,&core[origin]));
}

int PROC
bseekeol(origin)
  register int origin;
{
    return(origin + lvscan(-origin,'=',EOL,&core[origin-1]));
}

/* get something from the context table */

int PROC
lvgetcontext(char c, bool begline)
{
    register int i;

    if (c == '\'')
	c = '`';
    if (c >= '`' && c <= 'z')
	i = contexts[c-'`'];
    else
	i = -1;
    if (begline && i>=0)
	return(bseekeol(i));
    return(i);
}
