/*	Copyright (c) 1984, 1986, 1987, 1988, 1989 AT&T	*/
/*	  All Rights Reserved  	*/

/*	THIS IS UNPUBLISHED PROPRIETARY SOURCE CODE OF AT&T	*/
/*	The copyright notice above does not evidence any   	*/
/*	actual or intended publication of such source code.	*/

#ident	"@(#)diffh.c	1.10	95/03/22 SMI"	/* SVr4.0 1.3	*/

#include <stdio.h>
#include <ctype.h>
#include <locale.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <limits.h>

#define	C		3
#define	RANGE		30
#define	LEN		255
#define	INF		16384

char *text[2][RANGE];
long lineno[2] = {1, 1};	/* no. of 1st stored line in each file */
int ntext[2];		/* number of stored lines in each */
long n0, n1;		/* scan pointer in each */
int bflag;
int debug = 0;
FILE *file[2];

	/* return pointer to line n of file f */
char *
getl(f, n)
long n;
{
	register char *t;
	register delta, nt;

again:
	delta = n - lineno[f];
	nt = ntext[f];
	if (delta < 0)
		progerr("1");
	if (delta < nt)
		return (text[f][delta]);
	if (delta > nt)
		progerr("2");
	if (nt >= RANGE)
		progerr("3");
	if (feof(file[f]))
		return (NULL);
	t = text[f][nt];
	if (t == 0) {
		t = text[f][nt] = (char *)malloc(LEN+1);
		if (t == NULL)
			if (hardsynch())
				goto again;
			else
				progerr("5");
	}
	t = fgets(t, LEN, file[f]);
	if (t != NULL)
		ntext[f]++;
	return (t);
}

	/* remove thru line n of file f from storage */
clrl(f, n)
long n;
{
	register i, j;

	j = n-lineno[f]+1;
	for (i = 0; i+j < ntext[f]; i++)
		movstr(text[f][i+j], text[f][i]);
	lineno[f] = n+1;
	ntext[f] -= j;
}

movstr(s, t)
register char *s, *t;
{
	while (*t++ = *s++)
		continue;
}

main(argc, argv)
char **argv;
{
	char *s0, *s1;

	FILE *dopen();
	if (*argv[1] == '-') {
		argc--;
		argv++;
		while (*++argv[0])
			if (*argv[0] == 'b')
				bflag++;
	}

	(void) setlocale(LC_ALL, "");
#if !defined(TEXT_DOMAIN)		/* Should be defined by cc -D */
#define	TEXT_DOMAIN	"SYS_TEST"	/* Use this only if it weren't */
#endif
	(void) textdomain(TEXT_DOMAIN);

	if (argc != 3)
		error("must have 2 file arguments", "");
	file[0] = dopen(argv[1], argv[2]);
	file[1] = dopen(argv[2], argv[1]);
	for (;;) {
		s0 = getl(0, ++n0);
		s1 = getl(1, ++n1);
		if (s0 == NULL || s1 == NULL)
			break;
		if (cmp(s0, s1) != 0) {
			if (!easysynch() && !hardsynch())
				progerr("5");
		} else {
			clrl(0, n0);
			clrl(1, n1);
		}
	}
	if (s0 == NULL && s1 == NULL)
		return;
	if (s0 == NULL)
		output(-1, INF);
	if (s1 == NULL)
		output(INF, -1);
}

	/* synch on C successive matches */
easysynch()
{
	int i, j;
	register k, m;
	char *s0, *s1;

	for (i = j = 1; i < RANGE && j < RANGE; i++, j++) {
		s0 = getl(0, n0+i);
		if (s0 == NULL)
			return (output(INF, INF));
		for (k = C-1; k < j; k++) {
			for (m = 0; m < C; m++)
				if (cmp(getl(0, n0+i-m),
					getl(1, n1+k-m)) != 0)
					goto cont1;
			return (output(i-C, k-C));
cont1:
			;
		}
		s1 = getl(1, n1+j);
		if (s1 == NULL)
			return (output(INF, INF));
		for (k = C-1; k <= i; k++) {
			for (m = 0; m < C; m++)
				if (cmp(getl(0, n0+k-m),
					getl(1, n1+j-m)) != 0)
					goto cont2;
			return (output(k-C, j-C));
cont2:
			;
		}
	}
	return (0);
}

output(a, b)
{
	register i;
	char *s;

	if (a < 0)
		change(n0-1, 0, n1, b, "a");
	else if (b < 0)
		change(n0, a, n1-1, 0, "d");
	else
		change(n0, a, n1, b, "c");
	for (i = 0; i <= a; i++) {
		s = getl(0, n0+i);
		if (s == NULL)
			break;
		printf("< %s", s);
		clrl(0, n0+i);
	}
	n0 += i-1;
	if (a >= 0 && b >= 0)
		printf("---\n");
	for (i = 0; i <= b; i++) {
		s = getl(1, n1+i);
		if (s == NULL)
			break;
		printf("> %s", s);
		clrl(1, n1+i);
	}
	n1 += i-1;
	return (1);
}

change(a, b, c, d, s)
long a, c;
char *s;
{
	range(a, b);
	printf("%s", s);
	range(c, d);
	printf("\n");
}

range(a, b)
long a;
{
	if (b == INF)
		printf("%ld,$", a);
	else if (b == 0)
		printf("%ld", a);
	else
		printf("%ld,%ld", a, a+b);
}

cmp(s, t)
char *s, *t;
{
	if (debug)
		printf("%s:%s\n", s, t);
	for (;;) {
		if (bflag && isspace(*s) && isspace(*t)) {
			while (isspace(*++s))
				;
			while (isspace(*++t))
				;
		}
		if (*s != *t || *s == 0)
			break;
		s++;
		t++;
	}
	return (*s-*t);
}

FILE *
dopen(f1, f2)
char *f1, *f2;
{
	FILE *f;
	char b[PATH_MAX], *bptr, *eptr;
	struct stat statbuf;
	if (cmp(f1, "-") == 0)
		if (cmp(f2, "-") == 0)
			error("can't do - -", "");
		else
			return (stdin);
	if (stat(f1, &statbuf) == -1)
		error("can't access ", f1);
	if ((statbuf.st_mode & S_IFMT) == S_IFDIR) {
		for (bptr = b; *bptr = *f1++; bptr++)
			;
		*bptr++ = '/';
		for (eptr = f2; *eptr; eptr++)
			if (*eptr == '/' && eptr[1] != 0 && eptr[1] != '/')
				f2 = eptr+1;
		while (*bptr++ = *f2++)
			;
		f1 = b;
	}
	f = fopen(f1, "r");
	if (f == NULL)
		error("can't open", f1);
	return (f);
}


progerr(s)
char *s;
{
	error("program error ", s);
}

error(s, t)
char *s, *t;
{
	fprintf(stderr, "diffh: %s%s\n", gettext(s), t);
	exit(1);
}

	/* stub for resychronization beyond limits of text buf */
hardsynch()
{
	change(n0, INF, n1, INF, "c");
	printf(gettext("---change record omitted\n"));
	error("can't resynchronize", "");
	return (0);
}